nathand

I bought my son a used Scott Scale RC24. It has a 1x11 SRAM drivetrain. Everything spins smoothly individually - hub, freewheel, bottom bracket and cranks - and the chain is properly lubed, but at the extreme ends of the cassette, the entire drivetrain feels stiff, as though there's extra friction somewhere when I turn the pedals.

I'm wondering if the problem is the steep angle of the chain due to the short chainstays (24" wheel frame), combined with the width of the 1x11, especially because it feels smoother with the chain in the middle of the cassette. Is this an issue with 1x systems generally? Any other ideas on what might cause this feeling? Anything I can do to improve it?

Iride01 

The links have to bend more to get around that small 11 tooth cog. So if you have a new and stiff chain then that might be what you are feeling when turning the pedals by hand. The lateral bend in the chain might also be more with the 1x and perhaps that can be felt too. But likely isn't any issue for actual riding.

Or do you feel this when on the biggest rear cog also?

Andrew R Stewart 

Sure sounds like you're experiencing chain friction due to the extreme angles it runs at when in the small/big cogs.

What to do? Live with it as a cost of buying into the "better" system that looses gear range and increases chain angles. Keep the system as clean and neatly lubed as you can to reduce the noise and increase the short life span these very narrow spacings/chains tend to have. There likely will be some noise change after the cassette and/or chain are replaced and their new surfaces will interact with less friction, until they too become worn and gritty.

A cool thing to do to see how much friction the chain has in general is to shift into a fairly central cog and ring combo. With the bike stationary and upright back spin the cranks and remove your hand from the cranks watching how many more revolutions the cranks spin for before they stop. Do this a few times to get a feel for how much force you are applying (how fast are the cranks spinning as you take your hand off them). Now with your free hand place a little bit of pressure on the rear der cage at its lower pulley (the tension one, well named). The chain should have a slight droop as it is under now nearly zero tension. Release that hand and the chain should tension up as usual. Go back to the crank and place that free hand back on the rear der cage but don't yet push it forward. Spin the crank and watch it come to a stop. Spin it again but this time slight push on the rear cage so the chain looses tension and now watch how many extra rotations the crank goes through. That difference of the crank's spin down amount is chain friction (and in an ideal condition, no cross chaining and we hope with a clean and lubed chain).

A chain drive system can approach upper 90s of % efficiency in ideal conditions. But real der system riding life the efficiency will drop a lot. Andy

70sSanO

I don’t know the Scott Scale models, but your 24RC chainstay is a very respectable 415mm considering the 24” wheels; especially when comparing this to 29er models the 925 (425mm) and 965 (440mm). I would also expect the chainstays on gravel to be in the same neighborhood.

That said the 1x11 does have more severe chain angles, especially at the extremes, and shortening the chainstay 1/2” to 1” just exacerbates the issue.

My advice is to keep the chain clean and lubed and don’t force a shift into the lower gears; actually any gear.

John

nathand

I notice it most in the biggest rear cog, because I expect it to be really easy to spin the wheel in that gear, and that's not what I'm feeling (turning the cranks by hand). In the smallest cog it's harder to distinguish between the effect of the gear and any other source of friction.
The rear derailleur also feels much firmer on this bike than on my other bikes, but I have trouble believing that the spring could be pulling hard enough to add substantial friction, and if it did I would expect it to be more consistent across the whole cassette.

FBinNY 

Feels stiffer how? Specifically< I asking whether you're talking about turning cranks by hand on a stand vs. actually feeling unexplained drag when riding.

I suspect the former, and my best advise it to tune it out. Chain friction does vary with alignment, but even in the worst possible case the chain would simply fall off the chainring long before the added friction is meaningful in the scheme of things. Consider he difference in chain drag vs the kind of forces you apply when riding.

Unfortunately, now that you've observed the difference it'll be hard to forget about it when riding. It's why I stay out of the kitchen when someone else is cooking.

scottfsmith

Yes. Friction is much worse cross-chaining with a dirty or poorly lubed chain. If the chain was not cleaned recently give it a thorough clean and re-lube. This is in fact the major sign for me that I need to lube my chain, cross-chaining gets annoying.

BTinNYC 

If you tried an 11sp chain with a few thousand miles, I wonder if it would be as stiff.