[Closed] Do chains stretch quicker single speed?

Doesn't torque come from length of crank and power applied?

My single speed chains last around 2,000 miles and currently on a KMC EPT 3/32 fitted in March and will be replacing in a months time as replace it annually and it will have done over 2,000 miles.

Yes and yes.
You can use the chain for ages SS by adjusting the tension.

Technically it doesn't stretch, it lengthens due to the rollers wearing down

For the price of a new chain and sprocket, maybe even a new basic chairing, (although steel ones last ages) there's even less point in doing routine chain replacement on a singlespeed than a geared bike.

Also, did you check the chain when it was new? How much "stretch" did it have when you put it on? I'd hazard that singlespeed chains are made to far less tolerance than multispeed ones.

Doesn’t torque come from length of crank and power applied?

Technically, a chain isn't transferring torque, it's in tension, not twisting.

The maximum tension on the chain will be proportional to the ratio of the crank length divided by the chainring diameter. If the chainring is 170mm in diameter and you have 170mm (radius) cranks, the chain tension will be 2 x the rider's weight. A rider who is twice the weight will put twice the tension on the chain.

If you have a double or triple on the front, the chain tension will be much higher in the small ring than in the middle or large ring.

However, on a geared bike, you are not putting maximum tension through the chain most of the time because you are sitting and spinning. On a singlespeed, you will be standing up a lot more to get up hills.

It really doesn't matter whether it does or not, just run everything until the rear sprocket is knackered then swap it and the chain out and reverse the chainring. I've never once measured  the stretch on my Rohloff drivetrain, I just run it till the rear sprocket is worn out and an oil change is due. Chain and sprocket have typically lasted for 3 years each time.

Once again thols2 beat me to it 🙂 as you have the ability to apply higher chain loads with a granny ring rather than regular 32t ss setup.

I think you maybe notice chain "stretch" a bit more ss. When you heave on the cranks, the top run goes tight and all the slack concentrates on the lower run of the chain. When this gets too baggy, bumps make it unship the flappy chain where it meets the underside of the lower sprocket. On my commuter (E-stay frame so also slightly flexy "compressible" chainstays) I get to the point where tensioning the worn chain isn't enough - it still develops too much flap in the slack side and a new chain is the only solution.

SS with the right components can be very economical on other drivetrain parts (4 bolt equi-spaced cranks arms) as it lets you rotate chainrings by a quadrant and also flip over to wear the reverse side of the teeth. In theory you can also do this with a NW derailleur setup, but I've always found it gets a bit chain-sucky.

I think you maybe notice chain “stretch” a bit more ss

Definitely. To notice it on a geared bike it would have to be very worn and causing issues whereas to notice it on SS the chain is visibly slacker way before it would cause any issues (plus it can be adjusted out anyway)

I change mine every Spring just so I have a nice new chain in the better weather and have an old chain by the time winter comes and then remove it after winter.

"stretch" or a change in the pitch from the STD 1/2" is down to wear on the pins and inner plates where they they mate (inner plate holes elongate and pins wear) the slack this results in and the under tension makes the pitch grow. Rollers wearing is a secondary issue.

And yep as about SS is far more tolerant of wear before it becomes an issue.

I've had plenty of cheap singlespeed specific chains need adjusting after just one ride. Doesn't happen on my geared bikes. I tend to not buy the cheapest ones anymore, I splash the cash on the ones around £15.

If you have a SS specific chainring and sprocket then (as written above) will be more tolerant of chain stretch. It's due to their longer teeth compared to geared types.

I splash the cash on the ones around £15

Which would you recommend didnthurt?

Although technically you can technically generate more torque on the geared bike, using the granny ring is offset against the large rear sprockets on modern bikes. You'd have to be using the harder gears on your cassette whilst riding up hills to make the overall torque harder than a singlespeed.

You may visually notice chain stretch on a singlespeed, however its rare for it to actually cause a problem. The chain is not liable to skip unless you have a tensioner, even then it would have to be very worn to jump over full height teeth.

I ran one of my chains on an Alfine hub with tensioner until it got so noisy I couldn't put up with it, when I took it apart the pins had crescents worn into them and the outer plates had the inside chamfer worn away. Despite the tensioner it never skipped, the rollers just got so slack they could hula around the rivets which was noisy. The chain checker was sat on top of the wrong roller, it couldn't even reach the gap it was meant to drop into.

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Which would you recommend didnthurt?

I used Wipperman 808 for around 15 years which were very good but have recently started using KMC Z1 EPT narrow which faired very well over last 12 months. The coating stops any rust so handles winter/rain putting bike away wet very well. Just bought another one for this year.

Wippermann, agree the do seem to make a very durable chain.

@spooky_b329
blimey that is getting your money's worth! and great pic to show the wear on the pins and inner plates