2021 Brompton C-Line Explore

[wafter]

A bit of a musing on chain wear having idly wondered through the updates in this thread on the subject..

Granted the data is all a bit sketchy due to my patchy records and the range of questionable methods I've employed to try and gauge chain wear (comparison to a new item over entire length, measuring with a tape over entire length, measuring with a vernier caliper), however there does seem to be a trend unfolding across both chains.

At around 900 miles wear present suggested a total service life to 0.5% wear of around 5500 miles. At 1100 miles service life was calculated at around 4500 miles. Most recently at around 2100 miles the service life works out to around 3000 miles.

Given this apparant decay in total service life as the chains wear it seems reasonable to assume a life to 0.5% wear of maybe 2500-3000 miles.

Peering down this rabbithole makes me want to stick my head in further and check wear more regularly / accurately to get a better understanding of how chains behave; however this is easier said than done thanks to the inherent shortcomings of accessible methods.

I think on the Brompton at least measuring the same set of rollers internally and externally then taking the mean to get the pin pitch is probably the most accurate (especially if repeated at a number of different sites on the chain) however this is a bit of a faff and doesn't work so well on other bikes as the narrower chain pitch makes getting the vernier in difficult and the derailleaurs tend to get in the way..

I did quite fancy a KMC digital chain checker; however was put off by its relative shortness (and associated increase in potential measurement error), potential that it measures "incorrectly" so also includes roller wear (and will overstate chain elongation) plus the fact that it's over a hundred quid for something that otherwise looks like a pretty cheap vernier variant..

Anyway the sun's out and I could do with some fresh air so I'm off to the farm shop to grind another infintesimal amount of material off the little b*stard's drivetrain

 

[wafter]

More excitement and intrigue...

Checked the currently-fitted, original SRAM chain with the vernier - which seemed all good and suggested moon-miles. Then tried it with the Shimano chain checker which begrudgingly suggested "OK" but popped into the "shafted" position with little encouragement; so I suspect that at around 2200 miles the original SRAM chain is not long for this world.

I'll check it again before it comes off for the next wax - obviously if it fails it'll be junked; if it passes I'll give it a wax but I suspect that'll be the last time.

Conversely I've just checked the KMC E8 EPT that's on similar miles (IIRC about 2160) and the checker is resolute in its approval; so it seems that the KMC is more resistant to wear than the SRAM.

Of course if we're looking at value the SRAM could still come out on top depending on price; OEM Brompton chains (which are presumably this, unless they've changed in the interim) are £16, I suspect if this apparently modest-spec chain was purchased without the B-tax it'd be less.

The KMC chain cost £23 (so almost 50% more, although irritatingly now £21 from the same supplier) however the corrosion-resistant EPT coating adds cost and I'm not really sure brought any tangible value as it corroded once worn, to a similar extent as the SRAM. The X8 is £16, however I think the E8s are made to a better standard than these on account of their target e-bike application.

This raises the question of where to go when the SRAM's dead - I do have a c. 50% worn X9 that came off the Fuji I could use as a testbed for moving up a speed on the chain spec; although this came off the bike because it squeaked (I suspect because I'd not cleaned out all the cack accumulated when it was previously running oiled) and I'm a bit reluctant to chuck it in the wax pan for fear of contamination. It would be good to get some use out of it though, and sticking it on the Brompton seems like as good-a-way-as-any to give it a swift coup-de-grace..

There's also the issue of how best to integrate new chains... it seems that rotation works best when all chains are worn to a similar extent; and currently struggling with a way of accurately quantifying elongation leaves me a bit in the dark on that one.

 

[wafter]

Waxed a couple of chains last night, including the seemingly victorious KMC E8.

Before going in the pan this chain was measured along its entire length with a steel tape (which I think is the least-worst way I have of quanfitying wear currently) - suggesting around 0.23% wear at 2160 miles for a service life of approximately 4800 miles; give or take.

This in inkeeping with measurements I've taken for this chain in the past - I think much of the stuff in post #541 about chain wear is b*llocks - due to erroneous conflation of similar wear between two chains that were actually wearing at very different rates, as well as significant measurement error due to flawed methods (namely attempting to use the vernier).

If correct this suggests a service life for the KMC E8 EPT in the region of twice as long as the original SRAM item, yet (at realistic discounted prices rather than quoted retail) it only costs in the region of 20-50% more - as such offering better value.

Once the chain checker finally confirms the death of the SRAM chain it'll be interesting to check this against measured elongation with the tape to see how badly they don't correlate

 

[wafter]

Before departing work on monday night I mentioned to a colleage how the bike hadn't shat the bed for a while.

Around an hour later the bike shat the bed.

A mile or two from the car the chain had started skipping conistantly on the 13T sprocket, then only moments later the front hub began to emit unspeakable noises..

I got back to the car alright then spent a good chunk of the remaining evening buggering about trying to reduce the extent to which the bike was shafted.

The front wheel came off, hub stripped, guts chucked into a jar of paraffin and everything reassembled with lashings of moly. The DS bearing on the hub looks good, the NDS not as it's evidently got water in it and corroded. the Ball bearings are dull and brown-tinted, the cone pretty heavily / inconsistantly damaged (unsure if it's wear, corrosion, plastic deformation or a combination) while the cup in the hub has a pretty good bearing surface but this is bounded by pitting.

Back together and gingerly nipped up it's a bit rough but useable. Of course Brompton offer no spares for these, however SJS do a complete JTEK axle assy. I only really want the cones but I suspect they'll fit the original axle (the JTEK one's a bit longer than std). Typically I'd put an order in with SJS literally the day before... I'll sit on this for a while incase I can find some decent loose cones - no luck so far as they're the apparently slighlty esoteric 5/16" x 26tpi..


The skipping chain was the nearly-dead original SRAM item. I chucked on the half-worn KMC chain I've been using on rotation with the SRAM, which on a quick test ride still skipped..

I was however pleasantly surprised on Tuesday morning to find that the drivetrain was once again behaving itself; presumably once the waxed chain had freed up with a bit of use.

The sprocket no doubt remains on borrowed time but it's got me to work and back this week, and serves to illustrate the difference chain elongation can make when running on a worn sprocket.

Still to get my head around what to in terms of chain / sprocket fitment from this point... for now I'll just keep running the KMC exclusively on the current sprockets since the SRAM is essentially dead; being non viable on these sprockets, while it would no doubt accelerate wear of a new set of sprockets..

 

[wafter]

This week's seen the bike reach around 4550 miles; trumping the Genesis to make it the highest-mileage ride in the stable. I've likely still covered more on my old deceased Giant but that did take 16yrs..

It remains covered in filth thanks to the ravages of the winter weather and the usual minimal provision to guard against this found on the bike..

Once again the little bleeder's had it's hand in my pocket (spoiler, all these bits remain resolutely not attached to it):

I'm well aware that fitting the seatpost insert without the necessary reaming will probably only end in disaster, however I have nothing to lose and would welcome an alternative to paying someone to bodge a new one in on my behalf. I suspect this will remain in its bag at least until the current Red Bull-sponsored shim has become unserviceable; forcing me to confirm my inevitable folly..

Likewise the sprockets remain unfitted as the less-worn KMC chain continues to play nicely with the originals, unlike the original SRAM chain now retired with just under 0.5% wear around 2200 miles covered.


The single remaining KMC chain has had a hammering thanks to the consistantly wet weather and was waxed for the third time in as many weeks today; along with its new counterpart after it had been trimmed to length and degreased in a jar of paraffin.

I took the liberty of hanging the two side by side (pre-trim & wax) since the earlier chain's really had a hard week so should give a good indication of elongation without remaining wax skewing the outcome..

The wear was more than I'd expected; measuring (from the photo) at anything between 0.38 and 0.40% depending on whether I compared the two at the rollers or plate ends.

I also measured it against a tape which suggested in the region of 0.27% wear - vindicating all those who've told me this is a crap method due to the chain not being tensioned. Unfortunately it seems that measuring the hanging chain with the tape is next to impossible..

Old and new side by side; the fomer probably looking a bit grottier than it is thanks to the residual wax..

Post-wax, showing the very obvious difference in colour:

The pin on one of the earlier chain's quick links (pre-wax) showing wear and corrosion on the faces that contact the inner plates:

So... on paper it looks like I'll get maybe 400 miles more out of the earlier KMC chain until it reaches 0.5% wear; although since the SRAM didn't quite reach this point before it started skipping on the 13T sprocket I presume this will also be the factor that determines the life of the KMC.

At least when the KMC starts skipping this will give a definitive point to compare its lifespan to that of the SRAM. Contrary to previous expectations I suspect that the KMC will end up representing worse value than the cheaper OEM-fitment SRAM item, which is irritating considering I've just bought another

The greater-than-expected wear of the earlier KMC is especially annoying as I'd planned to run the new one until a similar mileage on its own then start rotating them; however given how worn the earlier one is I suspect it might just have been better to have run this in isolation until death then started with a fresh pair of chains - perhaps taking the opportunity to re-space the sprockets and try 11sp items instead..

Alternatively I might have tried a vanilla KMC X8 - according to the manufacturer these aren't as wear-resistant as the E8, however they can be picked up for about half the price of the E8s and I suspect would last more than half as long.

Anyway, on to some more crushingly boring observations...

I noticed that the E8 doesn't come with a "reusable" quick link; which is irritating - although neither did the old one and that's been on and off many, many times without any obvious issues.

I do have some reuseable links bought as spares however, so figured it was sensible to swap them so that the reuseable item was in constant use and the single-use job in the bag for for emergencies. I've never really known what the difference is between these two types of links, so took a few comparisons shots..

The CL573 on the left is the "single use" item, the CL573R on the right billed as reuseable.

The big difference appears to be the hole shape and the little punched tab inboard of it on the non-R version.. from a geometry perpective I see no reason why one of these should be more difficult / expensive to make than the other - although perhaps it goes deeper than that with differing materials, heat treatment etc..

Meh.

 

[Fastpedaller]

The subject of chains and waxing leads me to ask........ Has anyone here used an ultrasonic cleaner to clean a chain, and was it a success?

 

[wafter]

The subject of chains and waxing leads me to ask........ Has anyone here used an ultrasonic cleaner to clean a chain, and was it a success?

Nup - bit of a niche question that you'd probably have more chance of getting answered in a new post in a more general forum


This week's shot of raw adrenaline comes courtesy of the fact that the earlier KMC chain has now covered around 180 miles / 8% more distance than the bit-over-2200 miles the SRAM item had covered at the time it was retired due to wear.

Looking at value the original SRAM chains retail at £16 while the last two KMC E8s I've bought have cost around £23 and £20 respectively... although RRP is a fair bit more. So, under the most charitable conditions the cheaper E8 would have to cover around 25% or 550 miles more than the SRAM item to reach comparable value on a cost-per-mileage basis; the actual E8 fitted would need to do ballpark 45% or around 1000 miles more... which seems highly unlikely since it's already about 80% towards its wear limit.

I think it makes more sense to run this near-dead chain exclusively on the original sprockets and - as tight as I am - replace the whole lot en-bloc the next time a component fails since both the chain and 13T sprocket appear close to the end of their working lives.

It seems that running mis-matched components (be that an old chain on a new sprocket or vice-versa) will potentially accelerate wear in both parts, so when this chain dies I'll try to resist the urge to squeeze a bit more life out of the existing sprockets by just banging on the new chain...

 

[EckyH]

The subject of chains and waxing leads me to ask........ Has anyone here used an ultrasonic cleaner to clean a chain, and was it a success?

Not me but one of my acquaintances does so - with new chains. He uses water with one single drop of kitchen cleaner to reduce the water surface tension as fluid. He is satisfied with the outcome.
Our common opinion is that the (initial) effort to degrease a chain is worthwile basically only for new chains.

E.

 

[wafter]

I threw some lacquer on a few areas of the bike earlier to address some spots of cable rub.

Most irritatingly were a couple of bits on the frame's hinge - known problem areas but difficult to protect as thier size / shape doesn't well accommodate protection tape.

The silver lining upon this particular turd came in the form of the satisfaction of seeing the white, abraded patches of lacquer disappear as the new finish was applied; confirming that thankfully the wear hadn't made it all the way through to bare metal

I also put some messy dabs on the protection tape on the side of the frame, as the cables are rapidly wearing through this in one spot; so a bit of lacquer should help abate the degradation and lessen the potential for the tape to wear through without my noticing.


In other news I idly chucked the chain checker into the last-man-standing KMC E8 chain; now 70-odd miles post-wax to be greeted by this:

I checked in multiple places and it fell straight in maybe 80% of the time.. Looks like that's dead too, then.

The one thing I don't understand is how the now-written-off, seemingly-less-elongated SRAM chain could skip so badly on the 13T sprocket yet this KMC item remains working perfectly..?

I recall conditions were very wet when the SRAM chain started skipping so perhaps this played a part - maybe contamination in the links was making them reluctant to articulate under load? Perhaps it's actually worn past 0.5% but the contamination accumulated by the time I got back made it appear less-so?

For some unknown reason I did re-wax the SRAM chain when it came off (I had to do another anyway); Im quite tempted to chuck it back on the bike for few laps round the block to see how it behaves now..

 

[wafter]

Right, back from a quick shakedown with the SRAM chain. Before leaving it was unsurprisingly all good on the checker since all the links were full of fresh wax; after five miles that may have passed the Chinese the checker suggests "shafted" on 50% of tests.

So in summary both chains are at the end of their lives; based on this test the SRAM perhaps marginally less-so than the KMC. Mileages are close enough (the KMC has done about 8.5% more) and measurement sufficiently fuzzy to suggest that realistically this is a draw; the winner being the original SRAM item since this costs considerably less than the KMC.

Of course this is a great time to find this out, having just put my hand in my pocket for another KMC E8

Since there were evidently extenuating circumstances surrounding the skipping, plus the fact that the sprocket in question doesn't look catastrophically worn I think I'll chance the new chain on the original sprockets.

While I don't necessary envisage covering enough mileage to wear out the new chain any time soon there's merit to having a couple to allow rotation (it's handly if one gets soaked, for example); so I might supplement it with another.

I'm tempted to go the other way and try a boggo KMC X8 as Hopkinson cycles have them in for less than £12 posted and it would be interesting to compare its wear characteristics to those of the new E8..

 

[wafter]

Last night I'd decided that my curiousity about the state of the sprockets was out-weighed by my lack of desire to pull the bike to bits to get a closer look.

This morning fate intervened with a slow flat on the rear meaning the wheel had to come off anyway; so of course it would have been rude not to have had a poke about..

After the usual trip through the kitchen sink parts wash the tyre and tube were removed and inspected. Unfortuately the tyre is fairly convincingly shafted due to delamination / apparent failing ply resulting from yet another historic cut; possibly complicated by the presence of dried sealant inside the tyre carcass.

I'd been getting a rythmic thumping from the back end for a while that gradually seemed to get worse; suggesting something's degrading. The last time I had symptoms like this the sidewall was failing and the tyre died fairly rapidly, allowing the tube to herneate through the hole and puncture.

Since the bike gives me enough grief already I've written the tyre off and fitted the spare Continental, moving the one already on the front to the rear. The tube from the rear has been moved to the front as I couldn't locate the puncture (it held air fine when removed altough I did patch an area of abrasion to be on the safe side) and the front end is easier to work on.

Irritatingly this is the third tyre I've written off; all have been due to damage rather than wear (and probably to an extent my own dicking about with ill-fated stabs at tubeless). I think each has probably averaged about 2.5k miles before going in the bin; and from the remaining tread would probably have lasted significantly longer were it not for the glass and flint apparently littering my commute



On to somewhat less depressing things and the sprockets look remarkably good; more worn than when previously photographed around 2k miles ago but (to my untrained eye) not excessively so..

The undercutting on the 13T sprocket is more pronounced; I can't help but think continuing to use (at least one of) the existing elongated chains might erode this little bump.. I've read that teeth wear in this way when the chain elongates at a comparatively slower rate than the tooth, so the contact patch between the two migrates slowly and allows wear to accumulate over a smaller area rather than being distributed more evenly along the whole tooth. This would figure as I'm running two chains so the effective wear rate is effectively half what it would be with only one..

Compared to the last photos of the same area the edges of the angled transitions on the sides of the teeth have been softened while the small, rough, untouched patches at the tips of the teeth have further shrunk.

Harder to gauge wear on the 16T sprocket but again it doesn't look terrible. I was surprised to see burrs / apparent plastic deformation at the edges of the teeth, however the wear face (which in this case extends all the way to the end of the cropped tooth) apparently remains pretty perpendicular to the direction of travel (if not as rear-sloping as previously) so presumably should still transmit drive with no issues. I've certainly had no problems with this sprocket skipping so far.

I wonder if the teeth are cut short to prevent the sort of undercutting seen on the full size teeth of the 13T and make the sprocket more tolerant of differing chain wear characteristics.


The final job before refitting the wheels was to clear out the unfeasible amount of mud that had accumulated inside the guards - to the extent that at one point it was evidently rubbing the front tyre..

I plan on running the two near / already dead chains while their current wax treatment remains effective, then I'm not sure where to go:

- Keep running the worn chains until they start to skip (potentially to the detriment of the chainring)
- Fit a new chain / chains but retain the existing sprockets until they give problems
- Replace both sprockets and chain(s) with new items

Thoughts welcome as always - if anyone's still reading

 

[Gunk]

As Brompton chains are only moving across two cogs, you can run a much more worn chain than you would on a conventional bike with front and rear mechs.

 

[Rocky]

I'd keep running the worn chains and monitor the front chainring. I bet you get a few more months commuting out of them - then change the chainring, chain and back cogs all together. I suspect you'll have to change the chainring at some stage any how - so I'd just let it wear out.

(I think that's what @Gunk is suggesting - apologies if I'm wrong)

 

[wafter]

As Brompton chains are only moving across two cogs, you can run a much more worn chain than you would on a conventional bike with front and rear mechs.

Thanks - I'd not considered the chainline angle!

Since the chains are officially toast I'd be happy to run it all until it ceases to function; although not if this acts to the detriment of the chainring..

I'd keep running the worn chains and monitor the front chainring. I bet you get a few more months commuting out of them - then change the chainring, chain and back cogs all together. I suspect you'll have to change the chainring at some stage any how - so I'd just let it wear out.

(I think that's what @Gunk is suggesting - apologies if I'm wrong)

Cheers - that sounds like a reasonable plan although really I have no accurate way of assessing the chainring. Currently it appears to have very little wear but it's hard to get a good idea due to the limited access and my minimal knowledge..

I'm not really sure how long the chainrings are "supposed" to last on a Brompton but I'd guess they shouldn't be any worse than anything else if chain elongation's kept on top of. I'd not want to cause disproportionate wear to the chainring for the sake of getting a few more miles out of the chains.

Have you had cause to replace one before? I'm trying to resist the urge to buy a chainring checking tool

I keep trying to quantify costs etc in my head but there are too many unknowns!