barry beswick

I have a problem with the gears on my Super six. I have just fitted a new 105 cassette (10 speed) & a new Sram chain because every time I stand on the pedals the chain jumps down a gear, is this now purely down to rear derailleur adjustment. thank you Barrybes.:

pdlamb

It's likely either derailer adjustment, or derailer hanger alignment.

RidingMatthew

my Jamis 650b1 is doing the same thing. it keeps jumping out gears when pedaling real hard only in the middle two on the sprocket. the chain does not seem to be stretched. what do i need to do!?

caloso

Sorry if this sounds like a dumb question but I've done this before: is there is a spacer that goes behind the cassette, and if so, did you replace it when you changed cassettes?

desertdork

I've had to tweak my RD adjustments a tad after changing to a different cassette. If your replacement cassette is different than the previous cassette (e.g., SRAM -> 105), then I'd expect a slight adjustment may be necessary. In your case, I'd check the high/low limits first, then add a little tension to the cable. Also be sure the bottom bracket cable guide is clean and the RD cable housing loop is in good condition.

Aceldama

I'll be keeping an eye on this thread because I'm experiencing the same problem with my fairly new Jamis Aurora running Tiagra shifters with a Deore RD (stock).

I've done a RD adjustment a few times already and everything seems fine until I'm really hamming on it out of the saddle.

Perhaps it needs a good chain and cable cleaning.

mcgyver74

I vote for a bent Deraiuller hanger

barry beswick

Yes I did.

Slodad

My bike with a 6 speed Shimano 600 freewheel was doing that and it turned out to be the top of a tooth broken off of the gear. In fact, two of the middle gears had teeth broken off. New freewheel solved the problem.