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I've recently had an issue with my gearing, struggling to shift down onto the last few cogs on the cassette.

I've got a Shimano Ultegra 6800 groupset, but when I shift whilst riding, I get a "tick-tick-tick" then it shifts.

This isn't the issue though. I understand that a tweak of the barrel adjuster should sort it.

My issue is that when I put my bike in the bike stand, it doesn't happen.

I have thoroughly cleaned the bike and groupset, and re-lubed it. When shifting up and down to test, everything flies smoothly!

I then took it out on a test spin to make sure everything was hunky-dory, and my shifting issue was back!

Does anyone know of a way that I can replicate the riding conditions/forces on my bike whilst on the stand?

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    Yeah I've had this problem... the chain and everything is not under the same tension when the bike's up in a stand, so you're not replicating the riding environment in some crucial way. If you have a roller or wind trainer or something, get someone to ride it while you watch. (do mind the fingers though or you'll only be counting up to nine) I've had the same happen on a climb where the extra pressure causes a jump over the top, but the limit screw is right for flat-rides. – Criggie Nov 10 '15 at 11:30
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    Just thinking about the stresses that are put onto the frame while you're riding, I doubt you can replicate it on a stand. However, if you have a turbo trainer (where you're not moving so its safe to stare down at your pedals for long periods), you can readily see how the force of your spinning makes the frame flex. If it is any consolation I have the same issue - (with my carbon bike) I can get my adjustments 90% there on the stand, but that last 10% has to happen on the road. – PeteH Nov 10 '15 at 14:43
  • Check the torque on the cassette. – paparazzo Nov 11 '15 at 13:58
  • "Fettling"…? Doesn't that mean laying railway tracks? – stib Nov 12 '15 at 11:22
  • @stib I know of fettling in a UK engineering context as meaning making fine adjustments. But slightly differently to the OP the first thing it means to me is something like making fine adjustments to a part using a file so that it mates properly. – Chris H Dec 25 '15 at 19:48
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You need a local test route for this and other things. For some things just up and down your street will do, but for this issue you might need to put the bike through its paces properly.

Ride your test route, paying particular attention to the feel of the problem. Stop the bike, tweak something relevant (your best guess) and ride it again. Better or worse? If better but not perfect - adjust some more the same way, if worse go the other way.

You may be able to use your commute in the same way if commuting on this bike is an option.

In your case I'd get it perfect on the stand, then tighten the rear derailleur cable a little. Test ride and see.

Actually of course this is a tedious version of normal adjustment procedure. The nice thing about a rear derailleur adjustment issue is you don't need the bike on the stand for minor tweaks.

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