I'm pretty new to MTB and as you may expect know nothing about the maintanence of the bike.
I recently got a second hand cannondale (no idea which frame) and sent it to a local MTB service shop to have a new casette and chain. When it came back I notice that when the chain was on both the smallest cogs the rear deraileur was completly doubled back so the bottom wheel was almost touching the deraileur body.
Now, I am pretty sure that this should'nt be the case as my last chain did not do this. Is it just a case of too long a chain or somthing else?
The shop has aked to see the bike again but I would like to know a little of what they are talking about so they dont try to pull the wool over my eyes.
Thanks Martin
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It depends, cross shift your chain to the opposite case (largest cog and ring) and see how extended the derailleur is. If there is plenty of room for more extension you can probably have one more link taken out of the chain. If not, which is often the case these days with "mega" gearing ranges, then just enough tension to hold the chain from slack is correct. It's a technique for blockheads like myself who sometimes cross-shift to the extreme and if the safety margin wasn't there, adios derailleur.