2021 Brompton C-Line Explore

[Kell]

Just consider the number of times it's got you to work and back reliably compared to the number of times it didn't. I suspect that the balance is heavily in favour of reliability. Even when punctured, you made it to work and back somehow.

Spare tubes, spare patches and a fresh unopened tube of rubber solvent. If you haven't had a puncture for a while it's more than inconvenient to find that a previously opened one contains only air as it has an amazing ability to evaporate despite a tightly screwed on cap. You can get packs of small ones on ebay quite cheaply.

One positive aspect of all this is that once you've had the wheel off a few times it gets less daunting to fix a rear wheel puncture.

This ^^^

Which is why last time I bought some patches, I bought the ones that don't require glue.

 

[wafter]

Its your call, but I would add a couple of points

• there is a big difference between marathons and marathon plus for rideability / rolling resistance. I doubt they (marathons) would feel much different to your Racers to ride.
• because of the small wheels, to avoid rim damage etc you need to run bromptons at quite high pressures, I doubt you would get away with much under 80psi. Tubeless setups really need to be run under 50-60spi to be reliable. At 80psi you'd get sealant pissing out without sealing.
• There are no official tubeless rims and valves for Bromptons AFAIK.

Thanks for your thoughts

While I fully appreciate that Marathons will doubtless ride better than M+ and will offer more puncture protection than the Racers, the question still remains as to how that improved puncture resistance would translate into number of punctures reduced.

If recent experiences are anything to go by, by far the biggest danger on my route is piercings from long, thin, pointy things (predominently thorns) and I'm not sure that the thicker but softer protection layer in either of the higher-end Marathon variants would have prevented air loss in these circumstances.


I hear you on the tyre pressure - I'm currently running about 85-90 rear and 65-70 front. Before this however I was running probably 40 rear and 20 front as I didn't have a decent pump and didn't know any better as there were no obvious issues. Clearly this wasn't ideal (and over time would have ruined the tyres) however I think there's some reasonable waggle room between the two extremes.

While undoubtedly faster the higher pressure in the back end does make it feel pretty skittish on uneven / wet surfaces so could probably do with knocking back a bit anyway. I appreciate that tubeless potentially works better at lower pressures, however (not that I see the appeal) but road tubeless is obviously a thing and they must be running some fairly high pressures.

Granted lower pressures will doubtless seal easier; however as above I only expect very small actual punctures from pointy things (rather than gashes from jagged rocks etc) which should be easier to seal.


Pretty sure you're right about the parts situation; however I've heard it's been done already by others and obviously many people have ghetto-tubelessed other types of bike with non-tubeless-specific components..

Of course I can't claim that it will definitely work, however the outlay to try is relatively small and I've been meaning to do a tubeless setup for the Genesis for ages so potentially bits bought wouldn't be wasted if it didn't work. I find the idea extremely attractive if it significantly reduces the chances of me having to dick about for 30 mins plus in the pouring rain / freezing cold / pitch black of winter whilst attempting to sort a puncture (which, let's face it I've not actually achieved yet in the field on this bike!).

This ^^^

Which is why last time I bought some patches, I bought the ones that don't require glue.

Cheers - have plenty of solution however and have never found it to be a problem if the lid's kept firmly tightened



So.. today has been pretty interesting.

The rattle of the letterbox earlier this morning signalled the arrival of a few repair patches and a bit more solvent; bit concerned I might not have bought enough however...

The plan for today was to patch the battered rear tube removed during all the "fun" earlier in the week, swap it back onto the bike in place of the currently minty Schwalbe replacement and take some dims of the rim while I was at it.

In a now-depressingly-familiar scenario despite a fourth patch being added to the tube it refused to hold air - the leak(s) being traced to a dense row of tiny piercings / near piercings running around the outer circumference of the tube away from the patch - evidently the result of the tyre slowly precessing on the rim as I walked the bike to work, causing the point of the drawing pin to work its way along the tube - comprehensively knackering it

At this point I gave up; resigned to leaving the current tube fitted and buying another replacement.


I still wanted to look at the rim geometry however, so removed and stripped the front wheel.

The first obvious thing was a lot of burrs present on the edges of the spoke nipple holes in this double-walled rim. Unfortunately I couldn't really get the rotary tool in there, so cleaned them up by hand with a jeweller's file.


The rim has a fairly pronounced central channel:

A few of the more pertinent dims:

Rim width, external = 23.2mm
Rim width, interal across hooks = 17.4mm
Rim width, internal across bead seats = c. 20.4mm
Rim width, internal across channel = c. 10.5mm


The existing tape is 18mm wide:

As I worked with the rim my mind wandered to thoughts of the roll of PVC / electrical tape say in the tool chest and the now-dead tub lying upstairs, and soon a super-council-ghetto-lashup was in progress

I ran a single thickness of the 19mm PVC tape around the rim, keeping it stretched and leaving an overlap at the valve. I cut the valve out of the old tube and pushed this through a small "X" cut into the tape at the valve hole. The tyre was refitted with a sparing smear of synthetic grease around its bead; as I've come to appreciate as it makes getting them on and seated properly much easier.


Hooked up to the floor pump and it actually sealed first time

Of course it couldn't be all roses. While it had sealed convincingly to around 60psi, pushing it higher elicited an increasingly loud hiss from around the valve area; air escaping at a rate that meant I couldn't get more than about 100psi in the tyre. I'm pretty certain because one of the slits I'd made in the tape had run to the outside of the valve hole causing it to fail to seal in this area.

I pulled it apart a few more times, re-shaped and greased the valve in the hope of getting it to seal but struggled. It was all good though as this is proof enough to me that the idea is worth pursuing with some proper bits... it remains to be seen how well the bead seals over time or how permeable the tyre walls are, however there were no big, obvious leaks other than the valve so hopefully the sealant will take care of any little problems.


Budget tubeless valve - note the amount of moisture present, which evidently came from pumping the tyre up just once..

While the PVC tape evidently proved workable it was thinner than ideal and unsurprisingly the single layer deformed a lot over the spoke holes - tbh I was expecting it to fail completely in these areas as the pressure rose. It probably would have had the holes not been deburred as some were fairly savage.

In the area where it was doubled up it fared a lot better and I think a triple layer would be fine in the short term at least.. however I suspect it might also creep over time so could potentially still give problems. On top of that it left a bit of residue behind which was a pain to get off..


Anyway, considering the abject bodgery involved I think we can call that test a success. I'm going to look at bits for a tubeless conversion so have a few decisions to make. Given the 20.5mm-ish width across the bead seat channels as well as the fairly steep walls inboard of them I think I might go for something around 24-25mm no idea about brand as they all seem to get a slagging for something.

People seem to prefer Presta valves for tubeless, however the rims are drilled for Schrader valves, so either tubeless schrader valves or some bodgery will be required. I have no idea what sealant to use, and don't have an inflation tank (as I've been planning to make for ages) but this example seated well without one - probably due to the grease, fact the tyre's been fitted / used for quite a while and its relatively low volume.

 

[Tenkaykev]

Thanks for your thoughts

While I fully appreciate that Marathons will doubtless ride better than M+ and will offer more puncture protection than the Racers, the question still remains as to how that improved puncture resistance would translate into number of punctures reduced.

If recent experiences are anything to go by, by far the biggest danger on my route is piercings from long, thin, pointy things (predominently thorns) and I'm not sure that the thicker but softer protection layer in either of the higher-end Marathon variants would have prevented air loss in these circumstances.


I hear you on the tyre pressure - I'm currently running about 85-90 rear and 65-70 front. Before this however I was running probably 40 rear and 20 front as I didn't have a decent pump and didn't know any better as there were no obvious issues. Clearly this wasn't ideal (and over time would have ruined the tyres) however I think there's some reasonable waggle room between the two extremes.

While undoubtedly faster the higher pressure in the back end does make it feel pretty skittish on uneven / wet surfaces so could probably do with knocking back a bit anyway. I appreciate that tubeless potentially works better at lower pressures, however (not that I see the appeal) but road tubeless is obviously a thing and they must be running some fairly high pressures.

Granted lower pressures will doubtless seal easier; however as above I only expect very small actual punctures from pointy things (rather than gashes from jagged rocks etc) which should be easier to seal.


Pretty sure you're right about the parts situation; however I've heard it's been done already by others and obviously many people have ghetto-tubelessed other types of bike with non-tubeless-specific components..

Of course I can't claim that it will definitely work, however the outlay to try is relatively small and I've been meaning to do a tubeless setup for the Genesis for ages so potentially bits bought wouldn't be wasted if it didn't work. I find the idea extremely attractive if it significantly reduces the chances of me having to dick about for 30 mins plus in the pouring rain / freezing cold / pitch black of winter whilst attempting to sort a puncture (which, let's face it I've not actually achieved yet in the field on this bike!).




Cheers - have plenty of solution however and have never found it to be a problem if the lid's kept firmly tightened



So.. today has been pretty interesting.

The rattle of the letterbox earlier this morning signalled the arrival of a few repair patches and a bit more solvent; bit concerned I might not have bought enough however...

View attachment 706595


The plan for today was to patch the battered rear tube removed during all the "fun" earlier in the week, swap it back onto the bike in place of the currently minty Schwalbe replacement and take some dims of the rim while I was at it.

In a now-depressingly-familiar scenario despite a fourth patch being added to the tube it refused to hold air - the leak(s) being traced to a dense row of tiny piercings / near piercings running around the outer circumference of the tube away from the patched - evidently the result of the tyre slowly precessing on the rim as I walked the bike to work, causing the point of the drawing pin to work its way along the tube - comprehensively knackering it

At this point I gave up; resigned to leaving the current tube fitted and buying another replacement.


I still wanted to look at the rim geometry however, so removed and stripped the front wheel.

View attachment 706596

The first obvious thing was a lot of burrs present on the edges of the spoke nipple holes in the double-walled rim. Unfortunately I couldn't really get the rotary tool in there, so cleaned them up by hand with a jeweller's file.


The rim has a fairly pronounced central channel:
View attachment 706600


A few of the more pertinent dims:

Rim width, external = 23.2mm
Rim width, interal across hooks = 17.4mm
Rim width, internal across bead seats = c. 20.4mm
Rim width, internal across channel = c. 10.5mm


The existing tape is 18mm wide:

View attachment 706608

View attachment 706609


As I worked with the rim my mind wondered to the roll of PVC / electrical tape say in the tool chest and the now-dead tub lying upstairs, and soon a super-council-ghetto-lashup was in progress

I ran a single thickness of the 19mm PVC tape around the rim, keeping it stretched and leaving an overlap at the valve. I cut the valve out of the old tube and pushed this through a small "X" cut into the tape at the valve hole. The tyre was refitted with a sparing smear of synthetic grease around its bead; as I've come to appreciate as it makes getting them on and seated properly much easier.


Hooked up to the floor pump and it actually sealed first time

Of course it couldn't be all roses. While it had sealed convincingly to around 60psi, pushing it higher elicited an increasingly loud hiss from around the valve area; air escaping at a rate that meant I couldn't get more than about 100psi in the tyre. I'm pretty certain because one of the slits I'd made in the tape had run to the outside of the valve hole causing it to fail to seal in this area.

I pulled it apart a few more times, re-shaped and greased the valve in the hope of getting it to seal but struggled. It was all good though as this is proof enough to me that the idea is worth pursuing with some proper bits... it remains to be seen how well the bead seals over time or how permeable the tyre walls are, however there were no big, obvious leaks other than the valve so hopefully the sealant will take care of any little problems.


Budget tubeless valve - note the amount of moisture present, which evidently came from pumping the tyre up just once..

View attachment 706612


While the PVC tape evidently proved workable it was thinner than ideal and unsurprisingly the single layer deformed a lot over the spoke holes - tbh I was expecting it to fail completely in these areas as the pressure rose. It probably would have had the holes not been deburred as some were fairly savage.

View attachment 706618

In the area where it was doubled up it fared a lot better and I think a triple layer would be fine in the short term at least.. however I suspect it might also creep over time so could potentially still give problems. On top of that it left a bit of residue behind which was a pain to get off..


Anyway, considering the abject bodgery involved I think we can call that test a success. I'm going to look at bits for a tubeless conversion so have a few decisions to make. Given the 20.5mm-ish width across the bead seat channels as well as the fairly steep walls inboard of them I think I might go for something around 24-25mm no idea about brand as they all seem to get a slagging for something.

People seem to prefer Presta valves for tubeless, however the rims are drilled for Schrader valves, so either tubeless schrader valves or some bodgery will be required. I have no idea what sealant to use, and don't have an inflation tank (as I've been planning to make for ages) but this example seated well without one - probably due to the grease, fact the tyre's been fitted / used for quite a while and its relatively low volume.

That's a great read. Interesting idea about the ghetto tubeless, when I was working we used a lot of electrical tape, there was an extra thick version available. Having just re siliconed around the bath tub perhaps silicone sealant in the spoke wells might work?

 

[tinywheels]

I just put a new tube on.
the faff of patches etc ain't worth it.

 

[wafter]

That's a great read. Interesting idea about the ghetto tubeless, when I was working we used a lot of electrical tape, there was an extra thick version available. Having just re siliconed around the bath tub perhaps silicone sealant in the spoke wells might work?

Thanks for the encouragement and I'm glad you found it of interest

I remain slightly tempted by the electrical tape - for one because the adhesive is fairly compliant and the tape stretchy; meaning it can easily be drawn down into the deep centre-channel of the Brompton rim. That said the residue it leaves puts me off, so I think I'll go in a different direction. Not sure about the silicone sealant - how would you get the nipples out!?


After an uncharacteristically (apparently) productive evening of research I think I've settled on the key bits I need to give this a proper go - valves, tape and sealant. I'll get these ordered later if I can muster one final stab of decisiveness, hopefully for arrival in time to have a go at setting it up later next week.

I've not sorted out a tank yet but hope after yesterday's experiences this won't be necessary for this particular escapade, while getting one sorted is likely going to be a bit of a slow burn given the number of factors at play.

The necessaries should be both universally-applicable and plentiful, so worst case if this is a total disaster I can use the bits to do my Genesis and the only things wasted will have been a bit of tape, sealant and time.

While this still absolutely has the potential to die on its arse, currently I'm really appreciating a seemingly achievable, manageable, rewarding and potentially very worthwhile little project

 

[Tenkaykev]

Thanks for the encouragement and I'm glad you found it of interest

I remain slightly tempted by the electrical tape - for one because the adhesive is fairly compliant and the tape stretchy; meaning it can easily be drawn down into the deep centre-channel of the Brompton rim. That said the residue it leaves puts me off, so I think I'll go in a different direction. Not sure about the silicone sealant - how would you get the nipples out!?


After an uncharacteristically (apparently) productive evening of research I think I've settled on the key bits I need to give this a proper go - valves, tape and sealant. I'll get these ordered later if I can muster one final stab of decisiveness, hopefully for arrival in time to have a go at setting it up later next week.

I've not sorted out a tank yet but hope after yesterday's experiences this won't be necessary for this particular escapade, while getting one sorted is likely going to be a bit of a slow burn given the number of factors at play.

The necessaries should be both universally-applicable and plentiful, so worst case if this is a total disaster I can use the bits to do my Genesis and the only things wasted will have been a bit of tape, sealant and time.

While this still absolutely has the potential to die on its arse, currently I'm really appreciating a seemingly achievable, manageable, rewarding and potentially very worthwhile little project

A bit of isopropyl alcohol or methylated spirits on a rag will clean off any residue. I used silicone sealant a lot when I was working, just the small screw tap tubes from RS Components. We'd dab it in over the top of recessed fasteners, if we needed access later then it could be hooked out with a fine screwdriver.

 

[brommieinkorea]

Thanks for your thoughts

While I fully appreciate that Marathons will doubtless ride better than M+ and will offer more puncture protection than the Racers, the question still remains as to how that improved puncture resistance would translate into number of punctures reduced.

If recent experiences are anything to go by, by far the biggest danger on my route is piercings from long, thin, pointy things (predominently thorns) and I'm not sure that the thicker but softer protection layer in either of the higher-end Marathon variants would have prevented air loss in these circumstances.


I hear you on the tyre pressure - I'm currently running about 85-90 rear and 65-70 front. Before this however I was running probably 40 rear and 20 front as I didn't have a decent pump and didn't know any better as there were no obvious issues. Clearly this wasn't ideal (and over time would have ruined the tyres) however I think there's some reasonable waggle room between the two extremes.

While undoubtedly faster the higher pressure in the back end does make it feel pretty skittish on uneven / wet surfaces so could probably do with knocking back a bit anyway. I appreciate that tubeless potentially works better at lower pressures, however (not that I see the appeal) but road tubeless is obviously a thing and they must be running some fairly high pressures.

Granted lower pressures will doubtless seal easier; however as above I only expect very small actual punctures from pointy things (rather than gashes from jagged rocks etc) which should be easier to seal.


Pretty sure you're right about the parts situation; however I've heard it's been done already by others and obviously many people have ghetto-tubelessed other types of bike with non-tubeless-specific components..

Of course I can't claim that it will definitely work, however the outlay to try is relatively small and I've been meaning to do a tubeless setup for the Genesis for ages so potentially bits bought wouldn't be wasted if it didn't work. I find the idea extremely attractive if it significantly reduces the chances of me having to dick about for 30 mins plus in the pouring rain / freezing cold / pitch black of winter whilst attempting to sort a puncture (which, let's face it I've not actually achieved yet in the field on this bike!).




Cheers - have plenty of solution however and have never found it to be a problem if the lid's kept firmly tightened



So.. today has been pretty interesting.

The rattle of the letterbox earlier this morning signalled the arrival of a few repair patches and a bit more solvent; bit concerned I might not have bought enough however...

View attachment 706595


The plan for today was to patch the battered rear tube removed during all the "fun" earlier in the week, swap it back onto the bike in place of the currently minty Schwalbe replacement and take some dims of the rim while I was at it.

In a now-depressingly-familiar scenario despite a fourth patch being added to the tube it refused to hold air - the leak(s) being traced to a dense row of tiny piercings / near piercings running around the outer circumference of the tube away from the patch - evidently the result of the tyre slowly precessing on the rim as I walked the bike to work, causing the point of the drawing pin to work its way along the tube - comprehensively knackering it

At this point I gave up; resigned to leaving the current tube fitted and buying another replacement.


I still wanted to look at the rim geometry however, so removed and stripped the front wheel.

View attachment 706596

The first obvious thing was a lot of burrs present on the edges of the spoke nipple holes in this double-walled rim. Unfortunately I couldn't really get the rotary tool in there, so cleaned them up by hand with a jeweller's file.


The rim has a fairly pronounced central channel:
View attachment 706600


A few of the more pertinent dims:

Rim width, external = 23.2mm
Rim width, interal across hooks = 17.4mm
Rim width, internal across bead seats = c. 20.4mm
Rim width, internal across channel = c. 10.5mm


The existing tape is 18mm wide:

View attachment 706608

View attachment 706609


As I worked with the rim my mind wandered to thoughts of the roll of PVC / electrical tape say in the tool chest and the now-dead tub lying upstairs, and soon a super-council-ghetto-lashup was in progress

I ran a single thickness of the 19mm PVC tape around the rim, keeping it stretched and leaving an overlap at the valve. I cut the valve out of the old tube and pushed this through a small "X" cut into the tape at the valve hole. The tyre was refitted with a sparing smear of synthetic grease around its bead; as I've come to appreciate as it makes getting them on and seated properly much easier.


Hooked up to the floor pump and it actually sealed first time

Of course it couldn't be all roses. While it had sealed convincingly to around 60psi, pushing it higher elicited an increasingly loud hiss from around the valve area; air escaping at a rate that meant I couldn't get more than about 100psi in the tyre. I'm pretty certain because one of the slits I'd made in the tape had run to the outside of the valve hole causing it to fail to seal in this area.

I pulled it apart a few more times, re-shaped and greased the valve in the hope of getting it to seal but struggled. It was all good though as this is proof enough to me that the idea is worth pursuing with some proper bits... it remains to be seen how well the bead seals over time or how permeable the tyre walls are, however there were no big, obvious leaks other than the valve so hopefully the sealant will take care of any little problems.


Budget tubeless valve - note the amount of moisture present, which evidently came from pumping the tyre up just once..

View attachment 706612


While the PVC tape evidently proved workable it was thinner than ideal and unsurprisingly the single layer deformed a lot over the spoke holes - tbh I was expecting it to fail completely in these areas as the pressure rose. It probably would have had the holes not been deburred as some were fairly savage.

View attachment 706618

In the area where it was doubled up it fared a lot better and I think a triple layer would be fine in the short term at least.. however I suspect it might also creep over time so could potentially still give problems. On top of that it left a bit of residue behind which was a pain to get off..


Anyway, considering the abject bodgery involved I think we can call that test a success. I'm going to look at bits for a tubeless conversion so have a few decisions to make. Given the 20.5mm-ish width across the bead seat channels as well as the fairly steep walls inboard of them I think I might go for something around 24-25mm no idea about brand as they all seem to get a slagging for something.

People seem to prefer Presta valves for tubeless, however the rims are drilled for Schrader valves, so either tubeless schrader valves or some bodgery will be required. I have no idea what sealant to use, and don't have an inflation tank (as I've been planning to make for ages) but this example seated well without one - probably due to the grease, fact the tyre's been fitted / used for quite a while and its relatively low volume.

22 mm Velox rim tape works great on Brompton rims, it sounds too wide, but it's pretty much perfect. After you cover up the valve hole use a pointy Xacto knife to cut the hole in the rim tape for the valve.

 

[wafter]

A bit of isopropyl alcohol or methylated spirits on a rag will clean off any residue. I used silicone sealant a lot when I was working, just the small screw tap tubes from RS Components. We'd dab it in over the top of recessed fasteners, if we needed access later then it could be hooked out with a fine screwdriver.

Thanks - I usually use isopropanol but it didn't seem to work well with the residue from the PVC tape.. paraffin did a reasonable job in the end however as I'm sure you're aware unlike IPA it doesn't flash off when left so had to be removed with a little alcohol..

I still have my doubts about silicone - for one the holes in both skins of the rim aren't closed at their circumference - i.e. if you were to fill one hole with something it's going to spread out and ultimately occupy the entire space between the inner and outer walls..

22 mm Velox rim tape works great on Brompton rims, it sounds too wide, but it's pretty much perfect. After you cover up the valve hole use a pointy Xacto knife to cut the hole in the rim tape for the valve.

Thanks - is that the fabric stuff? If so I guess it only seals fully once sealant has been introduced? I'll keep that in mind as my biggest issue currently seems to be with tape; as detailed below...


Spoiler: IT HASN'T WORKED (yet?).

Now we've got that out of the way, the sordid details of today's failings for anyone interested in my perpetual follies..

Over the course of the week various things have presented themselves at my door, culminating in this situation:

Each was carefully chosen based on much research (for what that's worth).

The Tesa tape is apparently comparably to / "the same as" Stan's rim tape, and appears to be what some in the trade use. It cost less for 66m than the Stan's cost for 9m

The Lifeline valves ticked many boxes (cost, length, removable core, stepped retaining ring that's compatable with Schrader rims, colour..).

The Peaty's sealant has excellent reviews and is lauded both for its performance and environtal creds so it was an easy sale. In addition I'd like to extend a special mention to Tweeks, whose packaging appeared to be 100% recyclable / biodegradable (paper tape and packing inside the box) - which was very much appreciated in a world where everyone else seems hell-bent on irresponsibly consuming ourselves and everyone else into oblivion..

Anyway, on to today's folly. The bike was flipped over and its front wheel removed since this is the most accessible so the obvious place to start. Tyre, tube and rim tape removed, rim bed cleaned again with isopropanol.

I'd already had a bit of a go at the valve hole, but gave it a bit more of a tidy with a jeweller's file and some wet and dry paper in an effort to give it the best chance of sealing..

Next it was on to applying the rim tape. I'd read that this stuff's pretty stiff / hard and not the easiest to work with. Stuff I'd watched on the net made me doubt its compatability with the steep-walled, deep rim channel on the Brompton rims, but I thought it worth a go..

Having bolted the bare rim back into the bike's forks to aid the process, unfortunately my fears proved justified. The short of it being that the tape was insufficiently complaint to allow itself to be stretched down into the rim bed; the occasions where I approached enough tensile loading on the tape to deform it into the bed, the adhesive proved insufficient to hold it in place.

In addition, due to the tape's lack of conformity it's difficult to get decent adherance at both ends of the tape run on the rim; making areas of overlap (as shown in the pic below) especially shonky..

This was the worst bit of my first go; and while somewhat improved my subsequent efforts weren't a whole lot better

Lashed back together with the tyre and any attempts to stuff some air up it were greeted by a comphensive p*ssing of gas from around the valve. As I continued to waste my time and resources it became increasingly apparant that the valve was fine and the leak was past the ill-fitting tape and into the void between the two walls of the rim - the easiest escape to atmosphere being past the valve.

Following this abject, if unsurprising disappointment I tried many other things - using the now-defunct tape to try and improve my technique and understanding without ruining and more fresh tape - with little success.

I also took some time to dress down the slightly odd circumferential rib on the rim near the valve to ensure this wasn't providing the air an escape path..

Finally once I'd satisfied myself that the problem was with the tape all around the rim rather than the valve / valve area specifically, I tried a double-wrap of PVC tape. Expectedly after last time this conformed to the rim infinitely better than the Tesa tape; and I made an effort to execute the valve hole to a better standard by using a 6mm punch heated with a propane torch to poke a fairly tidy hole through it..

The good news is that it sealed very well and held pressure up to maybe 70psi; at which point there was a pop and rapid loss of air at the valve as the tape blew out at one of the spoke holes:

Up until this point the assembly had sealed fairly convicingly; maybe suffering a slow leak from somewhere indeterminate; which would probably have been resolved by the sealant had I got that far.

While I'm aware that some moulding flashings around the tyre bead might also cause some small leaks, the tyres have so far been the least-worst factor in this debacle - having a steel bead and spending a couple of years / 700 miles forced into contact with the rim with the standard innertube.. so they hold their shape very well off-rim and quickly confirm once refitted and pressurised..

So, not sure where to go from here. I think I'm going to really struggle with the Tesa tape; it seems that many use it with success but I've really not so far - perhaps due to the Brompton's much smaller wheels and deep rim bed, perhaps due to my own inexperience.

While the Tesa tape is evidently too stiff for this application, the PVC tape is too far the other way; very easy to lay down well on the rim but the counter to its easy-going, pliable nature is that it struggles to withstand the upper end of the tyre's working pressure. I intend to run these quite low, but initially want to leave them for a period at the tyre's max rated pressure to promote seating and give myself the most peace of mind that they're not going to blow off the rim during use.

I've considered a few possible routes - the Tesa tape would probably be more pliable if warm, however with only two hands achieving this might be easier said than done - especially getting an even heat so that its behaviour is consistant throughout application. I briefly tried heating the rim; which might have some merit but probably raises similar concerns - especially when it comes to the area of overlap where the first application of tape will greatly inhibit heat transfer from the rim to the second layer.

I also considered refitting the original rim tape and going over the top of this with the Tesa tape, although this would greatly reduce sealing area while also reducing internal air volume; which I'd like to maximise if possible.

Conceivably this problem can be overcome with another tape with properties somewhere between those tested so far, however the net is hardly awash with factual information as to the exact physical properties of all tapes on the market..

 

[a.twiddler]

I have no experience of tubeless tyres on bicycles but I just wonder if something with the properties of Duct Tape can be got in narrow enough widths. It's fabric reinforced, tough, waterproof and extremely self adhesive. Gorilla tape is probably the same stuff. As long as it's thin enough to allow the bead to seat. It's cheap enough to give it a try. Just a random thought.

 

[wafter]

I have no experience of tubeless tyres on bicycles but I just wonder if something with the properties of Duct Tape can be got in narrow enough widths. It's fabric reinforced, tough, waterproof and extremely self adhesive. Gorilla tape is probably the same stuff. As long as it's thin enough to allow the bead to seat. It's cheap enough to give it a try. Just a random thought.

Thanks - on the one hand I agree its properties might be suitable; on the other I'm not sure you can get it in appropriate widths. I do have some but it's obviously far too wide and I'd like to avoid the ballache of trying to cut it down if possible as this is just another area for cock-ups to creep in.. on top of that you don't want it to be too sticky or stiff as these will resist conformity to the rim bed too..

I'll maybe take a look for some narrow duct tape but tbh I want to avoid ending up with loads of different tapes that don't work!



So, a bit more hopeless tinkering. Having removed the bit of poorly-adhered Tesa tape from the rim, I attempted to re-apply it after having heated the rim up while a hair dryer whilst rotating it, until it was almost too hot to touch. I also gave it a bit more of heat afterwards while working it down onto the rim. The tape certainly went on a lot easier / conformed better; although I still had problems at the start and end.

I did manage to get a tyre inflated to a point; again defeated by a leak at the valve. This time it was pretty obviously starting there as the tape had split across the valve hole; no doubt as a result of my lazily forcing through the heated punch I was trying to use to make a hole.. this tape evidently being a lot more heat resistant than the previous PVC.

On this occasion the wheel was holding air much more convincingly, which allowed me to detect a small leak at the bead as well - I suspect because of the presence of moulding flashes on the tyre's mating face; which presumably aren't there on proper tubeless tyres so probably want removing if that's viable...

This is the single-layered tape after seeing maybe 100psi for a short period of time:

Irritatingly flappy bit at the end of the run:

Split at valve hole:

Tbh I think if I could only get the application of the tape correct at its beginning and end the system would probably be viable.. I've considered applying an excess and cutting off the flappy bits, however this requires the tape lifting away from the rim so always leaves an amount incorrectly stuck.

I've also tried heating and pulling out the extraneous ends, but the tension required to get it to lay in the bed is difficult when gripping just the end, and is potentially enough to overcome the adhesive so just causes it to come unstuck again.

I'll also need to find a better way of cutting the valve hole to avoid splits.. I have a leather punch somewhere if that will fit, but it might be pushing it.

 

[wafter]

This morning saw this particular dead horse get one final kicking before defeat was finally admitted..

I tried various approaches with varying, if all ultimately insufficient, degrees of success. Fresh tape was added to a hot rim, which worked OK but still failed to get the tape right down in the rim bed. Perhaps somewhat oddly repeating this process once the tape had been applied (by removing and re-fitting onto a re-heated rim) gave better adhesion but still no cigar.

I tried double-wrapping it (biasing it to one side then crossing to the other) but this was utterly useless. I did have some luck cutting the valve holes in the tape using a trapizoidal-ish burr in the rotary tool which left a nice hole but presented too much risk to the rim if I slipped (which I did, once) to be a long-term viable solution.

The best I managed was to get the assembly to retain its air for maybe a minute or two from 110bar; the good news being that at least the tyre (veiled under a couple of heavy protective towels) showed no desire to part company with the rim at this pressure.

For now I've chucked the original tube back in and admitted defeat, but have at least learned something and will probably re-visit the idea at some point (probably when I've had a particularly horrible puncture in the depths of winter).


Takeaways from this escapade are:

Tape
The main sealing issue is due to the tape. It's too narrow at 19mm - partially my fault as I'd hoped this might help it seat better in the bed, and if this didn't work I planned to double it up - which also didn't work. In addition it really doesn't conform at all well to the rim; due probably to its small diameter and deep bed.

Really I think I'm going to need an alternative and have seen some non-tape-based solutions which essentially look like a filleted / open innertube, complete with valve. I'm reluctant to butcher a new one, but if anyone has a dead 16" / 300mm tube going begging (which would stretch around the 349mm rim) I'd be happy to pay postage to take it off your hands

There also seem to have been some other solutions that are basically an undersize, continuous circular rubber non-adhesive "tape" with a valve hole - like normal tubed tape but rubber and a tighter fit. Maybe I'm missing something here, but surely this seems like a nicer, more sustainable, potentially easier solution than buggering about with adhesive tape..?


Valves
Generally I can't blame the valves for owt. The threads are a little sloppy but the spec is correct, they've sealed fine (when not blighted by tertiary problems), are a decent format and have generally done what's been asked of them.

I was initially concerned that the tapered rubber plugs that seat against the valve hole are only around 1.2mm larger than the hole itself on their OD (c. 9.7mm v. an 8.5mm hole) however my concerns were unfounded as the valves stayed put and nobody lost an eye.

I did do a quick calculation in the shower and at 110psi there should only be around 45N (equivalent to around 4.5kg force) acting on them, which is very little and likely less than I was applying when pushing them into the rim to do the nut up.


Sealant
I've not cracked open the bottle yet as ideally I wanted to get the system working without (or close to with known leak paths) and didn't want to waste any; so the jury's still out.


Tyres
On the last run I did briefly get the assembly under the tap to check for leaks; revealing a few around the bead and maybe some through the sidewalls themselves (in addition to the main leak from the inadiquate tape exiting through the valve hole). Of course it would be unfair to expect a non-tubeless tyre to be 100% airtight without a tube, but I suspect once the other issues are ironed out the sealant would take care of these small leaks.


So, it's back to stock for now while I consider my next move; predominently with the tape situation as this seems to be the most critical issue.


I have played about a bit with tyre pressures and am currently running 70psi front / 75 rear - the back feels a shade softer than the front (with no front luggage to speak of) and a lot more compliant / potentially planted than it did at the 85-90bar I was previously running; so we'll see how that pans out.

It certainly seemed tangibly better earlier on the egg run, although sadly not enough for yet another box of eggs to up-end themselves in the bag and make a mess.. although thankfully not as catastrophically so as last week's debacle with the Fuji and this time the evidence has already been disposed of in the form of a fat bacon and brie omlette


I think that's all; still plenty of things to do but as usual the lack of absolute, dire urgency means they keep getting pushed back. Since last week wrote off a tube I need to order another spare. I'm tempted to stock up, but am on the fence about sticking with Schrader as I don't much like the need to hold the valve adaptor on under pressure while operating the lever lock - which is surprisingly stiff on my pump.

I also still need to source a decent replacement chain; mainly for its corrosion-resistant properties but also because at 700 miles mine looks maybe 40% through its life; which is pretty shocking.. That said I can appreciate why Bromptons might eat chains faster than other bikes while I've also been told that the Sram items fitted as standard are a bit cack; so it'll be interesting to run this one until it dies and see how that compares to its replacement.

Finally there remains the need for frame protection tape, although the assorted bits of random PVC / gaffer tape are doing fine at the moment so my concience is clear that my tardiness isn't inviting more damage.


To end, a shot of the obstinate little bstard today - alive and well on the parcel / egg run in case anyone was concerned / considering contacting the authorities...

 

[berlinonaut]

Thanks for the interesting and funny report! In terms of rim tape I'd probably go for "real" rim tape or even for dedicated tubeles tape - i.e. Schwalbe has both kinds (scroll down a little): https://www.schwalbe.com/en/zubehoer

An attractive alternative could be veloplugs: https://veloplug.com/en/11-veloplugs

 

[brommieinkorea]

If you start with Velox it will make a nice bed that won't poke through. You could seal it with liquid (brush on) electrical tape before installing the tyre. Damn fascinating read no matter how you're going about it though.

 

[brommieinkorea]

Eggs, wow had never occurred to haul eggs with the Brompton. Oh yeah, no refrigerator or stove so no eggs. As to the tyre pressures, are you fairly light to be running what seems to me like low pressure ?

 

[wafter]

Thanks for the interesting and funny report! In terms of rim tape I'd probably go for "real" rim tape or even for dedicated tubeles tape - i.e. Schwalbe has both kinds (scroll down a little): https://www.schwalbe.com/en/zubehoer

An attractive alternative could be veloplugs: https://veloplug.com/en/11-veloplugs

Cheers

I'd certainly prefer a reusable tape / strip, but finding anything suitable seems difficult. I guess the pressures involved might make this approach difficult / non-viable compared to the alternatives I've seen that were presumably intended for MTB use; I can appreciate how a thin strip of rubber could just blow through the spoke holes in the outer rim, or slowly fail at the edges of these holes as they tend to be not very well finished.

I did find mention that rubber rim strip is only suitable for single-walled rims (where it sits directly on top of the spokes) and stiffer, stronger, essentially plastic tape / strip is used on double-walled rims to span the large spoke holes.

Thanks for the link to the veloplugs - they certainly look intresting and I had considered plugging each hole individually as this could potentially give the most reliable sealing, however wasn't aware of anything on the market to achieve this. That said they only appear to be intended for use instead of conventional rim tape and I suspect would give sealing problems given the rib that runs around the bed of the Brompton rim..

If you start with Velox it will make a nice bed that won't poke through. You could seal it with liquid (brush on) electrical tape before installing the tyre. Damn fascinating read no matter how you're going about it though.

Thanks - that's an interesting thought about the fabric tape; although I'm not hugely keen on the idea of treating it in-situ with something. Will give it some thought though as the idea certainly has some advantages!

Eggs, wow had never occurred to haul eggs with the Brompton. Oh yeah, no refrigerator or stove so no eggs. As to the tyre pressures, are you fairly light to be running what seems to me like low pressure ?

Well, I needed eggs and the Brompton sometimes gets used for this trip if it happens to be the most accessible bike. Please be reminded that putting eggs in the fridge is simply wrong; however I can appreciate that you might like to cook them before eating!

In addition on this occasion I had a parcel to carry, that was only possible thanks to the Bagsket that came with the bike (parcel was too big for any other bike luggage I have). Looks like that won't be getting sold now, then...

I'm not particularly light (around 80kg give or take, last time I had the resolve to check) and am still experimenting with tyre pressures / getting my head around all of the necessary parameters. I was running 85-90psi on the back which felt too hard - occasionally sliding if hitting the edges of damp paving slabs or similar at a sharp angle; which was un-nerving to say the least. At 75psi the bike feels more planted and conspicuously more comfortable with far less vibration and harshness over rough surfaces..