Chain Stretch

d.mart

I've had a real problem with this lately. I ride a Langster with 48x16 gearing and got the new chain from Cycle Surgery at Spitalfields. It was probably my fault for not checking exactly what chain they were putting on but it said Shimano on the box so figured it would be ok.

A month later I had to have links taken out (not fettling minded here) as it had stretched to a point that if I was out of the saddle pushing hard and hit a bump in the road the chain just jumped off the sprocket. Now about another month down the line and it happened again this morning. Out of the saddle going north onto London Bridge trying to stay safely close behind a dump truck and the f***ing thing jumps off again.

I know that grinding uphill will stretch the chain and I only have one hill to get up between here and Charlton (either Vanbrugh Hill (steepest), Greenwich Park, Westcombe Hill or Victoria Way (least steep)) so I'm going Victoria Way until I'm strong enough to get up any of them at a reasonable cadence.

My question really boils down to finding the best chain to avoid so much stretch. Was advised by an Evans bod that Brompton chains were good in that respect, is that reasonable or worthy of a flaming (for him or me)?

prj45

change your sprocket at the same time? If you left old sprocket on that will wreck the new chain,

rjsterry

Are you sure it's not the rear axle slipping forward in the dropouts? I can't see a chain wearing that much in a month unless you do a silly number of miles or ride through a lot of sand.

lost_in_thought

Yeah, echo what RJS says there. Also, a loose chain (although it won't help) shouldn't mean you lose it every time you hit a bump. As a lazy fixie rider of yore, I often had a loose chain before I installed chain tugs (which you should look at).

The chain jumping off can also be caused by a slightly incorrect chainline - if the axle isn't perfectly aligned when you put the wheel on. Equally, if there's been a slight error in the manufacture of your bike meaning the chainring and sprocket are marginally misaligned. The former is also easily fixable with chain tugs.

I have had problems with this in the past and been fobbed off with chain stretch by bike shops as it's the easiest option - not ofc saying that that's what yours are doing - it could be that but it seems unlikely. RJS is right - that much wear in a month is crazy.

For stretch-proof chains, try half-link ones. They stretch a little initially but are then pretty damn bulletproof, and likely a good deal cheaper than Brompton ones! Also, a £3 chain tool will allow you to take out your own links

phy2sll2

d.mart wrote:

only have one hill to get up between here and Charlton (either Vanbrugh Hill (steepest), Greenwich Park, Westcombe Hill or Victoria Way (least steep))

Wow, Vanbrugh Hill in 48x16. That's praiseworthy.

Blue Meanie

Langsters come with 3/32 sprocket and chainring (sugino messenger 42t) as standard, if you've replaced the chainring is it 1/8? If you're running 1/8 chain on 3/32 sprocket and chainring you can get a bit of chatter. If you're running a 3/32 chain on an 1/8 cog or chainring you'll knacker the chain quickly.
Try to keep the drivetrain all the same spec (3/32 or 1/8). Even though it doesn't change gear you still have to clean it and lube it.
Initial chain 'stretch' is annoying, but should settle down after a few hundred miles. I normally buy cheap chains (PC1 or there about) and replace before they're knackered (2-3 times per year, appx 3k miles each)

meanredspider

Chain stretch is such a misnomer as it's wear rather than stretch

TuckerUK

meanredspider wrote:

Chain stretch is such a misnomer as it's wear rather than stretch

Not according to my dictionary.

We generally use the word 'stretch' to denote something that has increased in length. There are many forms of chain wear (roller wear being the most measured yet least important), but it's only really 'stretch' that we are concerned with. I don't think anyone actually thinks the steel links all stretch a little!

d.mart

Thanks for the replies, I hadn't thought about the rear axle slipping and tbh it makes more sense than me having fusion powered thighs (damnit ).

I'll check the dropouts to see if there is any sign of slippage.

Also that's a good point re the chainring size...can't remember if it was 1/8 or 3/32 so will check that also.

Surely the construction of 2010 Spesh Langster wouldn't be so pony that the chainset would out of alignment? Would hope not anyway. Will check though I guess possible if rear axle slipping.

Lastly I wasn't going all the way up Vanbrugh Hill as I had to turn off on Humber Rd just before the third increase in gradient, some of the noises coming from the crank/headset were a bit unnerving mind. Will go all the way up when this issue sorted though...maybe :shock:

fatherted

Buy a Wippermann White Star 108 from CRC for 8.99 , come back in month and tell us how you are getting on.

wgwarburton

d.mart wrote:

...I'll check the dropouts to see if there is any sign of slippage....

It's not obvious- doesn't take much movement to give you noticeable play in the chain.

...Surely the construction of 2010 Spesh Langster wouldn't be so pony that the chainset would out of alignment? ...

I think you may be misunderstanding: "Chainline" is the correct lateral positioning of the front chainring and rear sprocket on their axles, relative to each other. If they are not correctly lined-up then the chain will be permanently accommodating this by flexing laterally, which increases wear, noise and the risk of the chain "derailing" or "unshipping" from the sprockets.
They can both be perfectly aligned to their own axles, frame, wheels etc but if they are offset from each other the chain is forced out of line.

This is most likely to arise as a result of the rear sprocket not being correctly positioned. It can happen on production bikes, especially if they are sold as Single-Speed and subsequently flipped to fixed. The assembly for Fixed running may not have been specced or adapted correctly.

Hope this helps.

Cheers,
W.

itboffin

rjsterry wrote:

Are you sure it's not the rear axle slipping forward in the dropouts?

+1

Almost certainly this ^

d.mart

hmmm, yes indeed it was the rear axle slipping forward :oops:

rear wheel trued and all's right with the world. atrocious headwind all the way home but flew up the Avenue in Greenwich Pk last night in the brilliant sunshine, perfect end to the day.

lost_in_thought

Glad to hear it's sorted

Chain tugs can be bought for very little money at charliethebikemonger (google it)