# Making a fairly old (c15 years) 6-speed Brompton easier on hills



## Mr_T_Wales (28 Apr 2021)

Hi all - I'm looking for some advice. I have a nice 6 speed Brompton and where I now live has a fair few hills, so it's a struggle sometimes. I've literally never used the higher gears so I'm thinking of changing the chain ring to something smaller as I don't care about riding fast.

After looking into this, my my bike has the older crankset and bottom bracket so I'd need to do some replacing. 

Right now, I'm thinking of this (plus a new bottom bracket, plus some tools as I only have a crank remover) https://brilliantbikes.co.uk/brompt...pton-crankset-with-44t-spider-chainwheel.html

My chain is fairly new, as are the rear sprocket things, so I'm hoping I could remove some chain links and get away with not changing the sprockets. Not sure if this is sensible?

My real question is whether I can go lower than 44T. This is the lowest that I can see for specific Brompton kits, but I wonder how much difference it will make. Something like 38T or 40T would be better if it would work and not mess up the folding etc. 

Any advice would be great!


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## berlinonaut (28 Apr 2021)

Sure you can, just that Brompton themselves don't sell these parts. With the older crankset you may be able to simply mount an additional chainwheel directly onto the existing one. Has for a while been relatively common years ago and is the cheapest solution (greasy finger shifting applied). Anyways you can safely contiue to use your existing chain and sprockets if they are in good shape, even if you choose to seitch to the new crankset completely.

Regarding the effects of a smaller chainring: have a look at http://ritzelrechner.de


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## Fab Foodie (28 Apr 2021)

I use a 50/34 Stronglight Chainset on my 6 speed and gets me up most things with a heavy load.
I tend to replace chain and sprockets regularly (they're not expensive) and I certainly would if fitting a new chainset to an old bike.


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## oldwheels (28 Apr 2021)

I have a 40T chainring on my 6 speed which limits my top speed to under 20mph. Suits me fine as I have a lot of shortish but steep hills to climb and not bothered about much above 12mph anyway.
Cannot remember where I got it but not a Brompton part.


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## Mr_T_Wales (28 Apr 2021)

berlinonaut said:


> Sure you can, just that Brompton themselves don't sell these parts. With the older crankset you may be able to simply mount an additional chainwheel directly onto the existing one. Has for a while been relatively common years ago and is the cheapest solution (greasy finger shifting applied). Anyways you can safely contiue to use your existing chain and sprockets if they are in good shape, even if you choose to seitch to the new crankset completely.
> 
> Regarding the effects of a smaller chainring: have a look at http://ritzelrechner.de


 
Thanks. I need to look at that website when I have a clear head! My understanding is limited to: easy hills means small front cog and large back cog. 

I did notice from a Google that some people have the two chainwheels but it may be beyond me, plus to be honest I only use the lower gears anyway.


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## Mr_T_Wales (28 Apr 2021)

Fab Foodie said:


> I use a 50/34 Stronglight Chainset on my 6 speed and gets me up most things with a heavy load.
> I tend to replace chain and sprockets regularly (they're not expensive) and I certainly would if fitting a new chainset to an old bike.



Thanks. The bike is old but I did change the chain, chainring and sprockets a while back (actually I guess it was 6 years or so but I've hardly used the bike since then as I stopped commuting to work, but want to cycle more going forward). 

I did just order this cheap chain set: pliers, breaker and weird measuring thing. The latter is supposed to let you know if the chain has stretched but I have my doubts to be honest. I just can't face changing the rear ones if I can help it.


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## Mr_T_Wales (28 Apr 2021)

oldwheels said:


> I have a 40T chainring on my 6 speed which limits my top speed to under 20mph. Suits me fine as I have a lot of shortish but steep hills to climb and not bothered about much above 12mph anyway.
> Cannot remember where I got it but not a Brompton part.



This is what I want really.

I'm getting confused though. Eg this on eBay seems suspiciously cheap but I think it would work if I had the correct bottom bracket thing? I don't mind paying a bit more for better quality though.

https://www.ebay.co.uk/itm/352870424372?hash=item5228b75f34:g:wwAAAOSwcbpd1Qnm


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## berlinonaut (28 Apr 2021)

Mr_T_Wales said:


> I'm getting confused though. Eg this on eBay seems suspiciously cheap but I think it would work if I had the correct bottom bracket thing? I don't mind paying a bit more for better quality though.
> 
> https://www.ebay.co.uk/itm/352870424372?hash=item5228b75f34:g:wwAAAOSwcbpd1Qnm


In principle it should work. In today's world you often only have the choice between very cheap stuff and very expensive stuff - which does not necessarily mean that the cheap stuff would be of bad quality or endurance. In many cases it is just heavier. In your example it does have a steel chain wheel and seems generically to be made on the cheap side. So the price should be about right and the weight probably relatively high.

You should be aware that todays cranks are in 99% of the cases designed for JIS bottom brackets while you do have an ISO bottom bracket. You can use the newer cranks on the old bottom bracket, however pesonally I would exchange it for a JIS one (not expensive).
Furthermore, in most cases the left crank does need a bit of treatment with an angle grinder to make the folding pedal fold it not using Brompton cranks.


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## oldwheels (28 Apr 2021)

I got the kit from tillercycles.co.uk. Their address is in Stockton but no idea if they are still in business as it was some time ago. It was a ring which fits on to the existing cranks. Easy job to fit.


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## Mr_T_Wales (28 Apr 2021)

berlinonaut said:


> In principle it should work. In today's world you often only have the choice between very cheap stuff and very expensive stuff - which does not necessarily mean that the cheap stuff would be of bad quality or endurance. In many cases it is just heavier. In your example it does have a steel chain wheel and seems generically to be made on the cheap side. So the price should be about right and the weight probably relatively high.
> 
> You should be aware that todays cranks are in 99% of the cases designed for JIS bottom brackets while you do have an ISO bottom bracket. You can use the newer cranks on the old bottom bracket, however pesonally I would exchange it for a JIS one (not expensive).
> Furthermore, in most cases the left crank does need a bit of treatment with an angle grinder to make the folding pedal fold it not using Brompton cranks.



Thanks, I never even thought about the folding pedal being restricted.

Just looking around, the problem I have is that most options don't seem to have a chain guard and I want one for sure.

Just been looking at this, and it comes with the bottom bracket. It looks like it may be better quality, or at least lighter.

https://www.bike-discount.de/en/buy/shimano-alfine-fc-s501-crank-with-single-chainguard-1080150


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## Fab Foodie (29 Apr 2021)

Mr_T_Wales said:


> Thanks. The bike is old but I did change the chain, chainring and sprockets a while back (actually I guess it was 6 years or so but I've hardly used the bike since then as I stopped commuting to work, but want to cycle more going forward).
> 
> I did just order this cheap chain set: pliers, breaker and weird measuring thing. The latter is supposed to let you know if the chain has stretched but I have my doubts to be honest. I just can't face changing the rear ones if I can help it.


Changing the rear cogs is simple, easier than any regular bicycle.


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## T4tomo (29 Apr 2021)

if you wnat a chainguard and dont want to have to mess around with an angle grinder or file to get the pedal to fold, then you want the brompton spinder crankset you linked. If 44T still isn't low enough (is your current one 50T?) then you can either change to a small chainring (such a spa cycles will do you a standard chainring, but no chainguard)

or some places have thought of them problem you face,,,, (tad pricy though)

or you can up the size of the two rear sprockets and keep the standard 44T brommie chainring. Not sure what you have on your rear sprockets but up 1 or 2 teeth is similar or even lower than going from 44 to 40T on front. so can change 13/15 to 15/17 for example


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## Mr_T_Wales (29 Apr 2021)

T4tomo said:


> if you wnat a chainguard and dont want to have to mess around with an angle grinder or file to get the pedal to fold, then you want the brompton spinder crankset you linked. If 44T still isn't low enough (is your current one 50T?) then you can either change to a small chainring (such a spa cycles will do you a standard chainring, but no chainguard)
> 
> or some places have thought of them problem you face,,,, (tad pricy though)
> 
> or you can up the size of the two rear sprockets and keep the standard 44T brommie chainring. Not sure what you have on your rear sprockets but up 1 or 2 teeth is similar or even lower than going from 44 to 44T on front. so can change 13/15 to 15/17 for example



Damn, that's great advice. I didn't consider the rear sprockets, mainly as I'm never sure about having to re-tune the gears etc if all that gets removed and I've found the tension arm thing a bit fiddly (hence getting a solid rear tyre last time I changed a tyre, which I have to say I 100% love). It sounds like you guys manage to change in about 5 mins though so I must be making a meal of it somehow!

Just looking at my email history, I have "Brompton sprocket / disc set 13 / 15 tooth for SRAM rear wheel Item Number 414" as my sprocket set. Not sure if it's the relevant calculation, but 44/17 is lower than 40/15 (even 39/15) so I guess it must be an option.

Right now I'm thinking about either:

(1) Get the Brompton 44T spider set and bottom bracket, and 15/17 sprockets (if I can work out which ones to get). My chain is fairly new but I'm thinking that if I get a new chain, to save hassle, then it may not be a standard size though so I'd have to remove links anyway?

(2) Get something like this https://www.bike-discount.de/en/buy/shimano-alfine-fc-s501-crank-with-single-chainguard-1080150
I think this looks great, and I guess I'd have the option of bigger sprockets if I wanted to go even lower at some point. I have an angle grinder, and file sander for that matter, so provided it doesn't remove the colour and look silly I don't mind fiddling around a bit.


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## byegad (29 Apr 2021)

Not solely Brompton related, but, in the days I rode uprights I often found a new bike was seriously over-geared for a fat, only reasonably fit, older guy in County Durham where we have some 'decent hills'. 

On recumbent trikes, on the other hand, the top gear is often too low and the bottom gear too high. However re-gearing a trike is easy enough as not only are you not limited from using all the available options regarding crossover but I've also discovered that the recommended capacity of mech's, both front and rear, are very conservative. My old QNT ran 55-40-24 to 11-34 and I could and did use all 27 possible combinations when need be to no ill effect in well over 20000 miles of riding.


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## berlinonaut (29 Apr 2021)

Btw: The sprocket-set for the SRAM is no longer avail. from Brompton for some time already. No issues to get a single 13t as this is used on the 3-speed as well. Getting a 15t can become a bit of a task and you won't get it from Brompton apart from maybe a longterm Brompton shop that has old stock. As it is an ordinary 3-spline sprocket there are other sources, namely Sturmey Archer but you should check thickness and form of the sprocket if it fits what is needed. If you lack an oldschool Brompton dealership SJS can be a source as can - as others mentioned - SPA be for chainrings and chainsets. Tillercycles has been out of business already for a while but Graham handed over at least the chainring side of his business to another small shop and I remember the webpage used to be forwarded to this shop. This is no longer the case but this is the shop in question: https://www.brommiemods.co.uk/


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## Tenkaykev (29 Apr 2021)

berlinonaut said:


> Btw: The sprocket-set for the SRAM is no longer avail. from Brompton for some time already. No issues to get a single 13t as this is used on the 3-speed as well. Getting a 15t can become a bit of a task and you won't get it from Brompton apart from maybe a longterm Brompton shop that has old stock. As it is an ordinary 3-spline sprocket there are other sources, namely Sturmey Archer but you should check thickness and form of the sprocket if it fits what is needed. If you lack an oldschool Brompton dealership SJS can be a source as can - as others mentioned - SPA be for chainrings and chainsets. Tillercycles has been out of business already for a while but Graham handed over at least the chainring side of his business to another small shop and I remember the webpage used to be forwarded to this shop. This is no longer the case but this is the shop in question: https://www.brommiemods.co.uk/


Brommiemods we’re outstandingly good when I modded Mrs Tenkaykev’s and my own Brommies. Highly recommended 👍


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## Mr_T_Wales (29 Apr 2021)

berlinonaut said:


> Btw: The sprocket-set for the SRAM is no longer avail. from Brompton for some time already. No issues to get a single 13t as this is used on the 3-speed as well. Getting a 15t can become a bit of a task and you won't get it from Brompton apart from maybe a longterm Brompton shop that has old stock. As it is an ordinary 3-spline sprocket there are other sources, namely Sturmey Archer but you should check thickness and form of the sprocket if it fits what is needed. If you lack an oldschool Brompton dealership SJS can be a source as can - as others mentioned - SPA be for chainrings and chainsets. Tillercycles has been out of business already for a while but Graham handed over at least the chainring side of his business to another small shop and I remember the webpage used to be forwarded to this shop. This is no longer the case but this is the shop in question: https://www.brommiemods.co.uk/



Thanks, I did notice than when I searched for the sprocket set I had on the Brilliant Bikes site it didn't come up with anything. Honestly, I didn't expect it to be simple (or cheap) but it's more complicated than I thought!

Ebay does seem to have 3-spline options - eg 

https://www.ebay.co.uk/itm/261101251168?hash=item3ccad8ea60:g:qoIAAMXQn11RbN1o

but some of them seem to have a ridge and I think the Brompton ones are flat.

If I'm not sure that 44T is enough of a change (from 50T) then I'm starting to think that this is the best option as I could leave the sprocket alone, as I think they are in good shape. I guess I'd need to change at some point if things start slipping and at that point I could consider slightly bigger ones perhaps.

https://www.bike-discount.de/en/buy/shimano-alfine-fc-s501-crank-with-single-chainguard-1080150


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## T4tomo (29 Apr 2021)

Mr_T_Wales said:


> If I'm not sure that 44T is enough of a change (from 50T) then I'm starting to think that this is the best option as I could leave the sprocket alone, as I think they are in good shape. I guess I'd need to change at some point if things start slipping and at that point I could consider slightly bigger ones perhaps.


that's step1 anyway, and then see how you get on. if its still a tad high, then you are only really looking for either say a 16T to replace the 15T, running 13/16 or maybe a 17T and run with 15/17 at the back, utilising your existing 15 in the outward position.
the SRAM compatible sprockets are 3mm 3 spline I think (but check your existing ones)

I also don't think that little ridge on the ebay ones bothers you in the slightest, its just decorative.


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## Mr_T_Wales (29 Apr 2021)

Thanks, the ridge thing just made me think that it's not flat so it may impact how it sits. I've have to get the bike out and snoop around.

The main thing for me is whether the set below should work (possible with some grinding if I want a 100% folding pedal). There is a 39T option and then I can go lower eventually potentially next time I need to replace the back sprockets. 

https://www.bike-discount.de/en/buy/shimano-alfine-fc-s501-crank-with-single-chainguard-1080150


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## TheDoctor (30 Apr 2021)

Surely the easiest option is just to get a Stronglight ST55 chainset? Fit the crank with chain wheel, leave the existing left hand crank alone, and all is good.


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## Kendide (30 Apr 2021)

berlinonaut said:


> Btw: The sprocket-set for the SRAM is no longer avail. from Brompton for some time already. No issues to get a single 13t as this is used on the 3-speed as well. Getting a 15t can become a bit of a task and you won't get it from Brompton apart from maybe a longterm Brompton shop that has old stock. As it is an ordinary 3-spline sprocket there are other sources, namely Sturmey Archer but you should check thickness and form of the sprocket if it fits what is needed. If you lack an oldschool Brompton dealership SJS can be a source as can - as others mentioned - SPA be for chainrings and chainsets. Tillercycles has been out of business already for a while but Graham handed over at least the chainring side of his business to another small shop and I remember the webpage used to be forwarded to this shop. This is no longer the case but this is the shop in question: https://www.brommiemods.co.uk/


Would it be possible to grind off 6 of the splines on the current 6 gear SA sprockets to fit the SRAM hub?
I recall doing something similar to sprockets from Shimano freewheels to fit SA 3 speeds on vintage Moultons with success. I used the spacers off the freewheel as well. I think they had to be reduced in thickness by rubbing on sandpaper.


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## Mr_T_Wales (30 Apr 2021)

TheDoctor said:


> Surely the easiest option is just to get a Stronglight ST55 chainset? Fit the crank with chain wheel, leave the existing left hand crank alone, and all is good.



I did see that but I think I'd need to change the bottom bracket thing, and if so then could I keep the left crank? I could be way off there though.

Another thing is that there is no chainguard and I'd like a fixed strong one. The plastic one I have now is always a bit flakey.


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## T4tomo (30 Apr 2021)

Mr_T_Wales said:


> Thanks, the ridge thing just made me think that it's not flat so it may impact how it sits. I've have to get the bike out and snoop around.
> 
> The main thing for me is whether the set below should work (possible with some grinding if I want a 100% folding pedal). There is a 39T option and then I can go lower eventually potentially next time I need to replace the back sprockets.
> 
> https://www.bike-discount.de/en/buy/shimano-alfine-fc-s501-crank-with-single-chainguard-1080150



someone which more knowledge that me i.e one of the brompton modders, needs to answer this:
will a hollowtech II BB with external cups work fine on a brommie?​​It may throw the chainline out of wonk or interfere with the fold​​


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## berlinonaut (30 Apr 2021)

T4tomo said:


> will a hollowtech II BB with external cups work fine on a brommie?


Yes it will. Obviously you'll need the right kind - it must be BSA threaded 68mm. And depending from the chainset you may need to fiddle with spacers or not. Just converted a Brommi to Hollowtech recently and much to my surprise everything worked flawlessy out of the box w/o need for spacers or anything - but your mileage may vary massively and in many cases it will.


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## berlinonaut (1 May 2021)

Kendide said:


> Would it be possible to grind off 6 of the splines on the current 6 gear SA sprockets to fit the SRAM hub?
> I recall doing something similar to sprockets from Shimano freewheels to fit SA 3 speeds on vintage Moultons with success. I used the spacers off the freewheel as well. I think they had to be reduced in thickness by rubbing on sandpaper.


I've heard of things like that have been done but don't have any own experience. As far as I know the drivers of S/A 3, S/A Sprinter and SRAM 3 are identical in terms of what sprocket fits the driver, so if it worked there it will probably work anywhere, to quote Frank Sinatra (which I never expected to do in a folding bike forum ).


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## Mr_T_Wales (3 May 2021)

Right, I've ordered a 39T crankarm/chainring set that comes with a JIS bottom bracket. I need to get a tool or two I think, and reduce the chain size (by 4 links I think as I'm going from 50T to 39T).

I'll report back with how it goes. I'm guessing not too well but I'm crossing everything!


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## u_i (3 May 2021)

Mr_T_Wales said:


> Right, I've ordered a 39T crankarm/chainring set that comes with a JIS bottom bracket. I need to get a tool or two I think, and reduce the chain size (by 4 links I think as I'm going from 50T to 39T).
> 
> I'll report back with how it goes. I'm guessing not too well but I'm crossing everything!



I do not think that you actually need to shorten the chain. The Brompton tensioner has an astounding capacity. Obviously, you may want to shorten just because you can.


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## Mr_T_Wales (3 May 2021)

u_i said:


> I do not think that you actually need to shorten the chain. The Brompton tensioner has an astounding capacity. Obviously, you may want to shorten just because you can.



It seems like going from 50T to 39T is a lot though? I did Google this and people have gone from 44T to 39T, or something like this, and left the chain alone and it seemed OK. One guy did this but when the bike was serviced they recommended shortening the chain.

I did order a very cheap chain tool for this and if it seems like it will work I will shorten, but maybe in stages just to be sure.

I'll just be happy if I can get the damn thing to work so I don't need to take a bike in pieces to a bike shop.

I'll add that I've had issues with the tensioner before. I can't recall what as it was a while ago but I think it was getting the right tightening or something so anything that helps me not having to worry about that is a good thing for me


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## u_i (3 May 2021)

I have a front derailleur on Brompton and go from 50 to 20T and the Brompton's tensioner swallows it. Is it ideal? No, actually the chain is a bit loose when I fold with the chain on 20T. However, you do not even want to go half of this way. I normally try to make minimal changes and see where things are going and leave myself as much retreat route as possible. After I settle in a new place and feel that it is good, I progress with the further refurnishing.


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## Mr_T_Wales (4 May 2021)

u_i said:


> I have a front derailleur on Brompton and go from 50 to 20T and the Brompton's tensioner swallows it. Is it ideal? No, actually the chain is a bit loose when I fold with the chain on 20T. However, you do not even want to go half of this way. I normally try to make minimal changes and see where things are going and leave myself as much retreat route as possible. After I settle in a new place and feel that it is good, I progress with the further refurnishing.



You have a 20T cog on the front? That must be amazing for going up hills. I've not heard of anything as small as that before.


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## u_i (4 May 2021)

Mr_T_Wales said:


> You have a 20T cog on the front? That must be amazing for going up hills. I've not heard of anything as small as that before.



I got it for some mountainous areas that the Brompton accompanies me to. However, recently I also started using the Brompton mid-winter and the 20T turned out to be great for getting out of snow ditches. For that, I put the studded tires as well. The lowest and next to the lowest gears I have are actually not that useful for riding uphill at a steady pace, as you begin to run out of inertia to get you over the portions of the pedal turn where the applied torque is low. However, those gears are good where a momentary application of the low gear is sufficient, in a turn when you are zigzagging uphill or to get out of the mentioned ditch.


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## Kell (4 May 2021)

I know you said that going from a 50T to a 44T didn't seem like much of a difference, but I tried it a while back and found it made too much of a difference (for me). I have one steep hill on my commute and the change meant I could do it in either first of second (rather than just first), but it compromised the rest of the ride too much for me and I went back to a 50T. 

I tend to change my chain and sprockets every six months and figure it's only an extra £25 to change the chainring so do that too. 

When I was commuting on a full-sized bike I changed the chain and cassette every 6 months, but rarely changed the chainrings and everything worked well. It seemed to me that you could get away with a bit of chain 'stretch' on the chainrings, but almost never on the cassette.

All that said, one year I tried to make my chain last for a lot longer and had one snap on me. I landed on the crossbar and broke my Coccyx and learned a very, very painful lesson about maintenance. So now, even though most people say it's overkill, I swap my whole drivetrain out every six months - normally around the same times as I switch to winter tyres on the cars.


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## Mr_T_Wales (4 May 2021)

I think if my chain ever starts slipping at all I'd change it and the sprockets. I dithered a bit last time as this was the first time it had happened since I got the bike and it quickly got to the stage where if I pulled out at the lights the chain slipped off every time. Since then I've not done many miles so it should be OK. Not sure if it means much but the sprockets do look in good shape. 

I'm really curious to see what 39T feels like. Once I change the bottom bracket and add this crank it doesn't look too bad to chain chainring, but I'm hoping 39T is ideal as most trips are with the kids and involve fairly steep inclines. I've literally never used the top two gears and hardly ever even use the middle two so the gearing is all wrong to me. I'd just accepted it before but not I look at the front chainset it looks huge.


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## berlinonaut (4 May 2021)

Kell said:


> I know you said that going from a 50T to a 44T didn't seem like much of a difference, but I tried it a while back and found it made too much of a difference (for me). I have one steep hill on my commute and the change meant I could do it in either first of second (rather than just first), but it compromised the rest of the ride too much for me and I went back to a 50T.


That's one of the benefits of my conversion of the BWR to 9 gears with 44-12/14/16: You gain the lower end of the 44 and don't loose as much as with 44t on a standard BWR.


Kell said:


> I tend to change my chain and sprockets every six months and figure it's only an extra £25 to change the chainring so do that too.


 About what mileage do you achieve over this period? This seems really often to me.



Kell said:


> learned a very, very painful lesson about maintenance. So now, even though most people say it's overkill, I swap my whole drivetrain out every six months - normally around the same times as I switch to winter tyres on the cars.


I barely ever need to change my chainrings, many of them are 10 to 20 years on the bike. Even with chain and sprockets I seem to be on the longterm side of life - i.e. on the two-speed Brommi I typically achieve between 3000 and 5000 km with one set of sprockets and one to two chains. This is more than most people seem to achieve, still six months for everything including the chainwheel seems way over the top to me apart from if you ride thousands of miles during that period. I am btw. not maintaining the drivetrain too much in terms of lubrication. My impression is that many people that have to change frequently at the same time clean and lubricate their chains very frequently as well and possibly overdo it with both to an amount that is counterproductive in the end.


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## Kell (4 May 2021)

As I said - it's overkill. I know it's overkill, but I don't want to go through the painful period of being off the bike with injuries. I broke my Coccyx over 8-9 years ago and still can't sit in a car for more than 2-hours without having to stop to stand up.

I know you've commented in past about the state of my drivetrain - saying it couldn't possibly get that dirty - but ... my old commute was around Hyde Park and the bike lane is right next to the horse track - which is sand. A lot of that sand got thrown out on to the bike lane and made its way onto my chain. This ended up turning into a grinding paste that was pretty destructive. I'd clean it all out about once a month.

Video of me getting out the crud out of the chain tensioner jockey wheels: Brompton chain pusher clean out - YouTube

It probably doesn't warrant a full change, there are things I could do - especially with the chainring - like just rotate it a couple of of spokes. But I'd rather spend £50 every 6 months, than spend 3-4 months off the bike which is what happened last time. Especially when you consider that just a week off the bike costs me an additional £98 in car parking and tube fares. Three months off the bike would have paid for another bike.

I actually forgot that I did also snap a chain on the Brompton. As there's no high crossbar, I didn't smack my Coccyx, but did sprain my wrist trying to hang on. Another lesson learned.

Add in to the mix that I don't pootle along at 12mph with no pressure on the pedals. I'm very often out the saddle and putting a full 100kg through the pedals. It all adds up to a fairly tough life for my chain.

As for mileage, I was doing upwards of 2,500 miles a year on the Brompton - so changing at about 1,250.


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## berlinonaut (4 May 2021)

Kell said:


> As for mileage, I was doing upwards of 2,500 miles a year on the Brompton - so changing at about 1,250.


I'd say regarding sprockets and chain that's within range where a lot of people with derailleur Bromptons change if at the lower end of the spectrum. For you your "better safe than sorry" strategy regarding the chainwheel makes sense, maybe more for the mind than for the drivetrain or plain necessity but that's fair.


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## u_i (4 May 2021)

I put the 'chain check' into a calendar. The time of 9 months after I put on a new chain is reasonable for me. If the chain is still OK, I move the 'check' by 2 months and so on. Various chain checkers are ubiquitous, but there are also checkers for sprockets, starting with the original Rohloff Cog Wear Indicator. However, the rule for Brompton, of replacing the sprockets together with the chain is good enough, particularly that it can be challenging to arrive at consistent results with the checkers for sprockets.


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## mitchibob (8 May 2021)

6,000ish km seems to be about average for me on chains/sprockets on my Brommie, and I clean/lube pretty regularly. Chainrings go about double time or more, at least for me.


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## Mr_T_Wales (8 May 2021)

Can you tell if sprockets need replacing just by looking at them?


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## berlinonaut (8 May 2021)

Mr_T_Wales said:


> Can you tell if sprockets need replacing just by looking at them?


I can tell you: Normally you will not be able to destroy sprockets by looking at them so that they would need to be replaced. 

But yes, you can visually see if a sprocket needs to be replaced (or rather if they don't).


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## Kell (12 May 2021)

Mr_T_Wales said:


> Can you tell if sprockets need replacing just by looking at them?



TBH - it's £25 to replace a chain and sprockets. There shouldn't be any labour cost on top as it's an easy job for a home mechanic. For that price, and for me, it's almost not worth the bother of trying to get away with it.

That said, it's one of those things where you could be OK if you just change the chain. In fact if you change your chain before it's truly worn out, then it won't have introduced wear to the sprockets. Therefore a new chain will sit nicely on it. If you leave your chain for a long time so it's 'stretched' then it's more likely that you'll need to replace other parts as they'll have worn too. If you don't, your chain will get a bit jumpy.

It's not an exact science, but it's one of the parts of Bromptons that actually cheap to replace so I just do it anyway.


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## mitchibob (12 May 2021)

Mr_T_Wales said:


> Can you tell if sprockets need replacing just by looking at them?



Well, you can tell when you change the chain, then when you put any power through the pedals, the chain skips over the sprockets. 

As they're pretty cheap, I just get sprockets at same time as replacing chain.


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## Mr_T_Wales (13 May 2021)

Thanks. It wasn't really the cost I was worried about, just the hassle of doing so much in one go - plus I think the sprockets I have are older types or something so I'd have to think about what to do about that and there is only so much bike stuff I can handle at once as I'm not great at the mechanical stuff.

I did buy a 39T chainset/crankset and it came with a hollowtec bottom bracket. This is all installed but I can't test yet as I don't have the tools to get the folding pedal off the old crank arm (it needs a 24mm socket, which I got hold of, but the other side is 1/2 inch and I only have 3/8 inch adaptors).

One annoying thing is that when parked I can't turn the pedal at all as the chain presses a tiny bit against a bit of metal. As far as I can see the front chain ring is lined up perfectly to one of the rear cogs, when I guess it should be in the middle, but it looks so close I don't think it's going to be a problem with riding - but I can't test until I have both pedals on and can try to ride up a hill. All I can do I think is undo it all and try to find some kind of 3mm washer to make the chainring slightly more outside or just be careful to note where the pedals are when folding.

Update - I asked in Halfords about this and the guy there really knows his Bromptons. He said that I need spacers so he gave me a couple for free (Halfords don't sell them but he uses them for repairs etc). It looks like they are 3mm and he said that if it's a road bike hollow bracket the drive side thread is the same as the other and you can really only put one spacer in there. What a guy!

So I have to undo everything. Blah.


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## Kell (14 May 2021)

I describe myself as mechanically retarded.

Although my bike is newer than yours, it's a fairly easy job even for me.

So I always figure if I can do it, anyone can.


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## Mr_T_Wales (14 May 2021)

So here is the result, showing all the Shimano goodness. The crankset and chainring really do feel top quality, and it's kind of cute that they load them with green grease as it comes. I tried on the steepest hills near me (some are very steep in parts) and it was way way easier than before.

I'd say that the biggest hassle is knowing what parts and tools are needed, and how much to adjust the chain or what length to get if getting a new one, and then it's mainly just having patience. Oh, and not trying to take a crank arm off before removing the bolt (seriously...).

Adding a 3mm spacer wasn't too bad but I couldn't put 3mm on the other side as the thread for the crank would look a little short (so it's offset from the centre by a tiny amount). Also, even that 3mm adjustment meant that the plastic screwcap thing that helps to keep the crank tight was much harder to get in and find the thread. 

All works now and it rides superbly. The pedals fold properly and the bike can be parked as before with the wheels not jammed (it was probably only 1mm off working before really).


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## 12boy (14 May 2021)

If those are Tannus tires you may find going up hills much easier with lighter pneumatic tires such as Schwalbe Marathons, or the new Contis. I find that heavy tires are a lot more noticeably draggy when climbing hills.


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## Mr_T_Wales (14 May 2021)

12boy said:


> If those are Tannus tires you may find going up hills much easier with lighter pneumatic tires such as Schwalbe Marathons, or the new Contis. I find that heavy tires are a lot more noticeably draggy when climbing hills.



Honestly, getting that tyre was the best thing I've ever done with the Brompton. Repairing rear punctures and topping up air so often got a bit tiring, but no more. With the kind of cycling I do I don't really notice the difference to be honest. Of course I wouldn't win a race with them but I'd need magic tyres for that! Mine is medium. But for worries about getting the damn thing on I may try the harder option next time though, just out of interest.

The hills that I struggled with were short steep inclines (I'm guessing 20% at least), rather than prolonged lesser slopes. It's just the way the land lies on the family trips we do.


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