Transmission Slip

[raleighnut]

I'd never manage to keep track of all the chains on my bikes but 8 of them run on 6/7/8 speed chains and I've got 5 part worn ones in old food tubs, the 'posh' bike has got a 10 speed hollowpin chain on it which is about ready for a new one but it is easy to tell that one apart. The trike has been the only bike I've ridden for the last 16 months but I'm just about healed enough to be back on 2 wheels soon although I doubt I'll be clipping in for a bit so it'll just be the ones with classic racing (bearcage) pedals for a bit.

 

[Tom B]

I am still suprised you have chewed through the chain rings... Our work bikes usually chomp through cha 4-5 cassettes and chains before we need rings.

Our maintenance consists of a squirt of cheapo oil before using and washing with a bucket of water and a jet wash of the non oily bits!

 

[Yellow Saddle]

[QUOTE 3627974, member: 9609"]I regularly measured my last chain during its life, as I knew I was changing the cassette anyway I kept it going until it failed.
here's a little chart showing wear against distance (mm/12 links/miles)
Wear seems to be quite exponential, not much change in the first 2000 miles, but it was never going to make it to 6000 miles
0.5% wear would be 306mm
@Dogtrousers Interestingly your chain started to slip at 310mm a little before mine did but same ball park.

some pictures of the cassette and chain ring in this thread

[/QUOTE]

I can't tell you how much I like this graph. It tells the whole story of chain life mathematically. Like you say, chain wear is not linear. The inflexion point is at 307.8, which represents 0.5% elongation. Chains and sprockets are engineered to not damage each other up to this point. Thereafter, wear of both components is accelerated. This is the point where the incoming tooth on the chainring starts to hit the incoming roller on the chain and forces its way past it. At the rear, the chain now starts to engage only one roller in the job of tensioning the sprocket and thus concentrates wear on only one tooth.

Your start point is interesting too. The immediate elongation a ride or two after fitting the new chain shows how the chain quickly elongates during the first ride. This is not because of wear but because of link correcting. Imagine a wooden latter made with morticed and tennoned rungs but no glue. t's rungs aren't perfectly perpendicular just after manufacture but as soon as its has seen a bit of use, the rungs settle perfectly in the mortices and the ladder straightens out. The same happens with a chain.

I suspect there is a bit of measuring error in the first five measurments. I would have expected the length to suddenly increase (a bit) and then settle. In other words, the 3rd, 4th and 5th data points are too small. I just can't explain them.

PM me your postal address. I have a little gift for you in this line.

 

[velovoice]

Any suggestions on a pair of 110mm bcd 34/50 compact chainrings?

@Dogtrousers Do you still need suggestions on this? How about the Stronglight Impact double crankset from Spa - comes in 50/34, 110 BCD as you say. I'm very happy with it on my re-built Puch.

 

[Dogtrousers]

I am still suprised you have chewed through the chain rings... Our work bikes usually chomp through cha 4-5 cassettes and chains before we need rings.

Our maintenance consists of a squirt of cheapo oil before using and washing with a bucket of water and a jet wash of the non oily bits!

Surprised me too. @Yellow Saddle surmised that it was due to lack of cleaning, and in a way I wish that were true because it would at least give me a clear lesson to learn. The need for chain monitoring and replacement I've learned, but the underlying cause for the disproportionate wear on the chain rings relative to the sprockets still puzzles me.

My guess is that I've hit some kind of sweet spot - or sour spot actually - with a specific combination of:
* Weight - I'm relatively heavy at 92kg and I probably carry more gear than average in the way of extra tools, coffee etc.
* Hills - I do relatively hilly riding, due to living by the North Downs. A typical ride is 100k / 1300-1500m climb.
* Choice of kit - maybe a rather racy double chainset like Apex is just not the tool for the job.

 

[Dogtrousers]

@Dogtrousers Do you still need suggestions on this? How about the Stronglight Impact double crankset from Spa - comes in 50/34, 110 BCD as you say. I'm very happy with it on my re-built Puch.

I'm sorted now having talked to my LBS.

Thanks anyway- my Dawes (which I think you've met) is equipped with a 50/34 Stronglight double from Spa. And twas a bargain.

 

[Yellow Saddle]

Surprised me too. @Yellow Saddle surmised that it was due to lack of cleaning, and in a way I wish that were true because it would at least give me a clear lesson to learn. The need for chain monitoring and replacement I've learned, but the underlying cause for the disproportionate wear on the chain rings relative to the sprockets still puzzles me.
.

I've taken the liberty of cutting a full-size portion of the pictures of the cassette and chain you posted elsewhere.

A chain in that condition will destroy everything in its path within 500km. It is so gritty and so poorly lubricated that it doesn't stand a chance of lasting longer. There is no other cause for the wear. All sprockets are made from the same material (apart from the Titanium ones on Dura Ace and XTR which won't last half as long as steel) and all chains are also of the same material. As for chainrings, the type of aluminium with the best durability is cheap and readily available at more or less the same price as any other type of aluminium. Manufacturers have no secrets on that front and no reason to make them from commercially pure aluminium, the cheapest and weakest type. These things are all 6000 or 7000 series alloys that for all intends and purposes have the same durability. The only reason a manufacturer will chose one or the other, is for manufacturing reasons. Some weld better than others, others machine better etc.

There really is no mystery here. It is all due to a dirty drivetrain.

 

[Yellow Saddle]

I just did an on-screen measurement of that chain and it is worn to beyond 0.5%, the point at which it should be replaced. If you have used it beyond this, wear would accelerate as per the graph you see above.

 

[Dogtrousers]

I won't labour this but that pic was taken directly on return from 100k in drizzly conditions round the back lanes of Kent, prior to doing anything to the bike. The frame was caked in mud, the wheels were filthy, the gear mechanisms were filthy, mud was packed up inside the mudguards. my boots were filthy and, unsurprisingly, the transmission was filthy. Prior to going out the chain had been cleaned and lube applied as per the instructions on the bottle. To avoid the chain getting into this state the only things I could do are stay at home, get a bike with a full oil-bath chaincase, or take up track riding.

 

[theclaud]

I get through chains at a fair old rate. It's the sand, salt, wind and rain combo. It puzzles me that people know how many miles they've done on every component - HTF do you keep track of this stuff? Anyway I err on the side of caution and change chains whenever the little Park Tool thingy tells me mine is farked. Since I've been doing that, the other drivetrain parts seem to last a lot longer. I once had an off due to slippage from a worn chainring that could have been very nasty - if your riding habits involve dashing for small spaces in heavy traffic then it's a particularly inadvisable problem to court.

 

[Dogtrousers]

I get through chains at a fair old rate. It's the sand, salt, wind and rain combo. It puzzles me that people know how many miles they've done on every component - HTF do you keep track of this stuff? Anyway I err on the side of caution and change chains whenever the little Park Tool thingy tells me mine is farked. Since I've been doing that, the other drivetrain parts seem to last a lot longer. I once had an off due to slippage from a worn chainring that could have been very nasty - if your riding habits involve dashing for small spaces in heavy traffic then it's a particularly inadvisable problem to court.

Ridewithgps has a mainainance log feature, but that's only for paid subscriptions.
I record all my rides, and I sometimes note "first ride with new X tyres" or stuff like that - but I'm just a weekend hobby cyclist. If I was a commuter I doubt that I could be arsed keeping records.
When I came off there was a car behind me but it was some way away, so more embarrassing than anything. However it curtailed my period spent lying on the floor counting my limbs as I had to get up and get the bike out of the road. It made me nervous as hell accelerating onto roundabouts later on.