I recently had my Giant Propel SLR serviced (including new chain, Cassette and a new Hub) as gears were beginning to slip. However after the service when I climb into top / hardest gear and put the power down to sprint the slippage continues. Any idea what's causing this or what needs to be done next? Thanks...

  • 3
    Try twiddling the indexing - a quarter turn on the barrel adjuster might make all the difference. That presumes your service person didn't do anything boneheadded, like using the wrong chain width etc.
    – Criggie
    Jul 2, 2021 at 11:09
  • 1
    So this occurs only with the smallest rear sprocket? Are you sure the chain is actually slipping? It’s more likely this is a shifting issue. Does shifting work crisp and smoothly? Is the rear derailleur properly in line with the sprocket? Does it occur regardless of which chainring you are in?
    – Michael
    Jul 2, 2021 at 11:21
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    What do you mean by "slipping"? Jul 2, 2021 at 12:12
  • Yes this crunching / slipping only occurs when putting the power down while on the smallest rear sprocket and front big ring. The Ultegra gears are correctly indexed, shifting smoothly etc. A mate suggested it could be wear on the Chainring (They're not sharp to me)...will take it back and see what the mechanic says. Will also ask about the chain width...thanks! Jul 3, 2021 at 19:33
  • Could it be that the cassette is not tightened properly, or the cassette is not mounted correctly, so that the smallest cog does not engage the (part the cassette is stuck upon, whatever it's called) ?
    – Burki
    Jun 13, 2022 at 8:34


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