What actually happens if I put a new chain on a worn cassette/chainring?

I know you’re not meant to, but why not – what actually happens? Will the chain not run or shift, or does it simply make a nasty noise?

Depends how worn

I tend to get through 3 chains to 1 cassette

If your cassette is very worn, the chain will just slip constantly.

In theory they wear to the shape of the cassette (worn) and therefore wear out quicker, however as uplink says 3 chains to 1 cassette is about right.

The skies will darken and you will be beset by a plague of locusts……

In reality it will either be fine, but possibly a bit noisy, if the teeth aren’t too worn or the chain will jump under power if they are.
If the teeth aren’t noticeably hooked over the only way to find out is to try.

http://pardo.net/bike/pic/fail-004/000.html

depends, i’ve put a new chain on mine recently, had one chain previously, it’ll skip slighty on one gear, which is a pain, but mind you this winter has destroyed my drivetrain, i’ll replace both in march or april, i’ll live with it till then incase we get any further bouts of dodgy weather.

That’s interesting

Just done exactly the same – new rear mech, chainring and chain, old cassette. As I ride my bike like a singlespeed (well dinglespeed really 😆 ) cogs 5 and 6 get the most use and although didn’t appear worn they were noticeably thinner than the others. First ride out and although the gears were set up to shift spot-on, any climbing when using those two cogs resulted in slipping gears and the chain jumping all over the place 😳 . Being a cheapskate and as I’d much rather spend my cash on shiny stuff in pretty colours, I had a quick fettle last night and adjusted my mech to bring the jockey wheel much closer to the cassette (something I’d overlooked when I fitted the mech) and today’s commute was skip free 😀

On the basis of that chart it looks like this is the answer: a Wippermann Connex 10 chain for £27 lasts twice as long as some of the competition.

http://www.amazon.co.uk/Wippermann-Wippermann-chain-Connex-10S8/dp/B00115YLH6/ref=sr_1_3?ie=UTF8&s=sports&qid=1295366157&sr=8-3

What about KMC chains. Better than shimano and sram ime

There is an assumption, promoted and supported by the purveyors of ‘chain wear measuring devices’ that once a chain is worn to a certain degree it must be changed. It’s poo.

Chains and cassettes can be ridden for ages and ages and ages, wearing together, and then replaced together, instead of changing the chain because a tool says so. The deciding factor should be the performance of the whole system, not an arbitrary measurement.

I’ve used a road bike chain and cassette combo that then lasted for 5 years, even though it was taken off my race bike. The chain and cassette on my mountain bike is 3 years old…. It’s visually completely knackered, but rides and shifts perfectly.

Don’t believe the hype…

IMO I reckon KMC chains are better than most.

> There is an assumption, promoted and supported by the purveyors of ‘chain
> wear measuring devices’ that once a chain is worn to a certain degree it
> must be changed. It’s poo.

That’s just BS. It’s not a question of chain wearing off, but stretching; the teeth on the cogs (which cannot stretch to match) will deform to match the chain stretch. At some point the hook-like deformation on the chainrings starts making it impossible for the chain to slide smoothly off, and you get the dreaded chain suck.

At the point you get a chain suck, you have to replace everything (chainrings, chain, cassette) because all the components are too damaged to work with anything new. The chain stretch tool makes it possible to avoid the tooth deformation (which is different from simple wear) by swapping chain early enough, and so maximise the time you get out of the chain rings and cassette.

So, the question is what the cost of swapping your chain early is relative to riding the drive train to chain suck … in my experience swapping the chain early works out better.

This is all interesting (for me). Thanks.

So it sounds like the main concern/impact is chain suck/slip.

A query: can another consequence be the chain snapping outright, with no warning? This happened to me once (on a very worn chain) years ago, when I wasn’t pedalling particularly hard. I suppose this is a silly question, i.e., “does a worn chain snap” – of course it does!

ime, chains just snap every now and then, mind you i’m a heavier rider weighing in somewhere between 16-17st, soo maybe that makes a difference to mine…lesson here is though, never leave home without a chain too.

also generally if a chain snaps easily like you mention, i reckon it’s been burst at one side and you’ve just not noticed it for the last 30 odd miles, your chain will slip if it’s like that too, obvious tell tale.

… a fairy dies 😥

Last time I tried it, recently in fact. Couldn’t get one turn of the pedals, the slightest pressure and it slipped.
KMC9SL on XT.

There’s a risk of sair spuds but could be OK.

Is there any evidence out there to back rotating chains? ie: Having 2-3 or even 4 chains and say use one for a month, swap for another and so on, once they’ve all been used start on the first one again, rinse and repeat…

and you get the dreaded chain suck.

I did say… The deciding factor should be the performance of the whole system, not an arbitrary measurement.

The problem with using a chain wear thingy is that you use new chains on progressively more and more worn cassette and chainrings…. and one of the proposed mechanisms by which chainsuck occurs is the way a new chain rides on worn rings.

http://www.fagan.co.za/Bikes/Csuck/

My way gets the maximum life out of the system, all components wearing away together, then replaced with a new set, rather than a mix of worn and new stuff.

It’s only my opinion, but it works in my experience.

I tried it a few years ago for a couple of years. – Three chains to a cassette. I would get about 400-450 miles with the first chain according to the chain measure I started measuring a bit more often and found the second and third chain would stretch to the almost same as the previous within about 100 miles and then stretch more slowly. I imagine to fit the worn cogs.

Now I just run them until failure.

My reading of the article is that with a new chain, the links are exactly 2″ and engage in valley bottoms of half the teeth on the ring.

As the chain bushings wear, the link lengths increase and they engage on the valley slopes; the chain rides higher on the ring. A worn chain erodes the valley slopes, making the teeth thinner over time.

My guess is that a new chain, with exactly 2″ links, wont engage multiple teeth at once. The tendency is for it to ride up the worn slope of the most loaded tooth, and under excessive pressure, slip off.

What do you think?

I think its marginally cheaper to go for the throw the chain away as it starts to wear so as to save the cassette. Not a huge amount in it compared to running a drivetrain into the ground but I get 3 chains to a cassette and hardly ever need to change chainrings. I do have to use an expensive cassette the as I run pro 11s. With a cheap casette it might be no odds at all.

You do spend more time with a crisp shifting drivetrain tho .

So maybe with cheapy cassette and rings, it’s best to just wear the system out completely. But with expensive cassette and rings, regularly change the chain.

OK I get that!

I just replace stuff when it breaks or stops working. Usually a new granny ring stops any chain suck and I don’t bother changing the chain or anything else at the same time.

I reckon the idea of changing your drive train as a whole is a load of cobblers.

Joolsburger – re your point on the granny ring – do you mean that you only get chain suck when you’re in your granny ring, well in advance of when chain suck happens on the other rings? i.e. the granny ring is the first to go. I ask because I’ve had the exact same thing and it’s motivating me to buy a whole new drivetrain, but hey if there’s life in the rest of the system it would be much easier just to whack on a new granny ring. I wonder why granny rings are the first to go – is it because there’s more torque when you’re using it?

99.99% of the time.

There’s all sorts of ideas about chainsuck but bottom line is it’s usually the granny ring that’s worn or burred, they wear out quicker as they are smaller and usually used under duress all the time. Once worn or damaged they tend to hang onto the chain and you get chainsuck that’s why lube and stuff won’t fix it.

Change the grannny ring and I’ll bet your chainsuck goes – Be sure to put it on the right way round, that would be an easy and annoying mistake and would make things much worse.

I’ve found chains and casstttes last ages, grannys not so much…