Reasonable Chain Wear?

[Jamze]

Just to clarify, my issue with the shop is simply that I bought the bike just a couple of months ago (admittedly I've ridden 900+km in that time) and now the chainring is gone. If you saw the video of how lose the chainring got - which I am sure is not "normal" under any circumstances, I am wondering if I'm in any sort of position to ask the shop to replace parts effectively under warranty because the wear may have been caused by the dodgy chainring.

My take...

If it happened in the first few miles after riding the bike out the shop, or on your first ride, yes take it back, get the lockring tightened. But after 500 miles of hard riding offroad, it's down to you to check for anything coming loose.

That doesn't mean the shop won't help you out a bit to keep you as a happy customer - although them sending you the quote suggests they might not here.

After 400 miles on my new eMTB, I generally agree with the views above. Keep the transmission tough, cheap and no need really for 12 speeds.

So I'm in the same situation with my 12sp GX/NX, but I'll wait until the cassette has worn out before switching to something else. 12sp GX chains are £20, sometimes cheaper, chainring I expect to last as long as the cassette if not longer.

 

[TheBikePilot]

Sounds like the nuts on the Chainring have come a bit loose. Sadly, some shops don't do a full bolt check before a bike goes out of the door.

If you are riding mainly fire roads etc I would say you're going to wear those lower cogs more as you state.

I'd chalk this one to experience. I've had two motor bolts work loose and fall out, the Stilus had real issues with the crank bolt not being tightened out of the factory and the crank coming off.

They should have no problem getting a compatible chainring for you.

 

[Wiltshire Warrior]

As our bikes generate 3-4 Times more power than human power then our chains wear out 3-4 more times quicker(faster if neglected).

So I keep key a spare chain on the garage wall, and check the chain after every ride, as soon as it starts to move off .50 it goes in the bin, and the new one goes one.

The shortest time I have had from one was 250miles and the longest was 550 miles, also when swapping I use the old one for a link count and its amazing how much longer it gets for the same link count as a new one!

It would be nice to be able lease a bike, like we do for cars, with all the servicing included!!!

Also 1000KM - brace yourself for a major motor breakdown!!!

 

[Gary]

Just to clarify, my issue with the shop is simply that I bought the bike just a couple of months ago (admittedly I've ridden 900+km in that time) and now the chainring is gone. If you saw the video of how lose the chainring got - which I am sure is not "normal" under any circumstances, I am wondering if I'm in any sort of position to ask the shop to replace parts effectively under warranty because the wear may have been caused by the dodgy chainring.

could you also clarify how long you actually rode with a loose chainring?
Being just a few months old, If you contacted the bike shop about the issue as soon as you noticed it I'm fairly sure most decent bike shops would have takien the bike in and sorted the issue for you threre and then free of charge. If however you'd been riding with the loose chainring for a couple of months before contacting the shop resulting in premature wear/damaged parts do you really think it's anyone's fault other than your own?

 

[Blakey]

I rode it home (about 5 miles) from when I noticed the wobbly chain ring; which I noted because the chain fell off. And it was fine the day before as I gave the bike a general look over. So it went from firm and working fine to wobbling hugely (see the video) in one ride of about 10 miles. To me it's like something broke, but I don't know enough about the mechanics to comment.

I took it straight into the LBS (Rutland are a long way away) and they sorted it, and to give Rutland their due they paid for that fix. However as soon as I rode it after the chainring was tightened, within 100 meters I noted the chain just fell off in top gear. That's when I went back to Rutland to see what they would do.

 

[Gary]

As our bikes generate 3-4 Times more power than human power then our chains wear out 3-4 more times quicker(faster if neglected).

Oh do Behave.
human effort plus a nominal 250w is not 4 times the power a human can output and even at peak power assistance the motor is only adding 750w. plenty actual fit riders can output way more than 750w more than your average weekend warrior can.
Chain/cassette/chainrings are undder no more strain than they're designed to.
My chains do not wear out any faster than they do on my normal bikes

 

[Gary]

I rode it home (about 5 miles) from when I noticed the wobbly chain ring; which I noted because the chain fell off. And it was fine the day before as I gave the bike a general look over. So it went from firm and working fine to wobbling hugely (see the video) in one ride of about 10 miles. To me it's like something broke, but I don't know enough about the mechanics to comment.

I took it straight into the LBS (Rutland are a long way away) and they sorted it, and to give Rutland their due they paid for that fix.

All sounds absolutely fair enough.

However as soon as I rode it after the chainring was tightened, within 100 meters I noted the chain just fell off in top gear. That's when I went back to Rutland to see what they would do.

sounds like either an unlucky coincidence and your drivetrain is worn to the point of replacement.

or

The shop adjusted your gears. particularly your B-tension. winding it out to the recommended position. this is not WRONG of the shop. But it actually does offer less chainwrap than the minimum jockey wheeel to sprocket position you can manually set it to. less chainwrap = sooner chain slip.
a little hack to eek more mileage from a worn drivetrain is to set the gap as close as possible.

If you are genuinely only using the smallest 3 sprockets I'd suggest you replace your cassette with a 10 speed close ratio road cassette (tiagra will do) , a short cage mech like Zee (with suitable 10 speed shifter) and increase your chainring size by 2 or 4 teeth. hopefully my reasons for suggesting this are obvious.

 

[Another rider]

Oh dear. My bike has now done about 3000 miles on the original chain, chainring and cassette and still works fine. I was thinking of changing the chain but reading this I think I'll just leave well alone for a while longer then just replace the lot in one go.

 

[jimbob]

I'm getting about 650miles from my shimano 10sp chain for comparison. That's to 0.5%wear. So far, after 3 chains the cassette still looks good.

Not sure if that means I'm changing too early or not, but with a £10-15 chain vs £50 cassette I'd prefer to change it early. It also gives me a bit more confidence that it won't snap on me, but I'm not sure if that's well founded or not.

 

[thewrx]

Not sure why your chain ring went out so quickly, unless it was some super fancy lightweight aluminum or carbon/composite chain ring.
ex
on the chain here in the states i get about 500 miles give or take on a chain, and just replace it with a quality chain every 3-6 mos, so i don't have to buy a new cassette/chain ring as frequently. If i do buy a chain ring they are not very $$ but you should probably go +2 if you do. Also, if you have to get a cassette ive been getting the sunrace 11 speed ones and they aren't that pricey and look good too.

 

[Gary]

I'm getting about 650miles from my shimano 10sp chain for comparison. That's to 0.5%wear. So far, after 3 chains the cassette still looks good.

Not sure if that means I'm changing too early or not, but with a £10-15 chain vs £50 cassette I'd prefer to change it early. It also gives me a bit more confidence that it won't snap on me, but I'm not sure if that's well founded or not.

If you're going down the chain swapping route you probably should er on the side of caution.
You can't see cassette sprocket wear until its ridiculously worn.
And even then you'd need to compare the worn sprockets directly with new ones.
Chains generally snap from damage caused either y poor shifting under load or damage caused in a jam/twist rather than simply from high mileage alone.
But yeah. Either way you should have a more reliable chain by swapping it frequently.
Now here's the interesting part.
So far you've done HALF the mileage afforded by my "Run til done" (but always look after it) drivetrain philosophy. And you've spent £30-£45 on chains. (So far) whereas my ONE chain, chairing and cassette is currently at somewhere around 4000 miles and 1.0 wear on a park guage and not yet slipping in any gear. It will of course need replacing soon. And when it begins to slip I'll be replacing the chain, cassette and chain ring together. At the total cost of £38.

 

[7869hodgy]

1600km/5 months in and I checked the cassette and chain today. I bought spares when I bought the bike as had read they wear out quickly.

I have Praxis Wave front ring and shimano SLX cassette and kmc chain.

They are not really showing much wear at all which surprises me. I am not a hard rider or particularity heavy on the drive train but change gear under load etc.

I’ve been out in all weather too and have got through a set of pads front and rear....worn pretty much to the metal.

I guess I’ve been lucky with the rest.

I am now surprised that people are changing after a few 100 miles.