Chain drops down the cassette when pedaling back - Help!

boofont

Hi all. Having a mare with my Ransom. When I pedal back whilst the chain is on the middle ring and on the lowest on the rear my chain drops down one or two gears. I've changed the rear hanger and gear cable. The indexing is set up and works perfectly. I've got a SRAM cassette with X.0 mech, Shimano chain.

Anyone got any ideas?

supersonic

Don't pedal backwards lol.

Sometimes happens because of the chainline, or a slightly sticky freewheel

andrewjoseph

or sticky jockey wheels.

boofont

supersonic wrote:

Don't pedal backwards lol.

Sometimes happens because of the chainline, or a slightly sticky freewheel

It's not a sticky freewheel, I did wonder about the chain line as it is quite an angle change from the crank to the cassette, as the chain rides on to the cassette you can see how tight the angle is. It's almost like the wheel needs to come forward on the left hand axle, obviously this is not possible.

Can anything be done? It's not that I pedal backwards but you know sometimes you need a quick spin back when tackling those nadjery technical bits to stop a pedal from clanging something.

supersonic

Without altering the chainline, not muich I am afraid. You nay find it diminishes with fresh unworn kit.

bikaholic

There are a couple of things you can do to alter the chainline depending on your bottom bracket type:

- Square taper, ISIS, or Octalink BB w/ a fixed shoulder on the driveside (non driveside has a lockring) ---> grind off the shoulder so that the BB can be screwed inwards, flush with the driveside BB shell. The non driveside lockring will portrude out by the same amount that the DS was screwed in.

- External bearing cups ---> put the driveside spacer on the NDS. If no spacer is present, then remove a small amount of material by facing the DS a bit more; add a spacer to the NDS to account for the removed material.

If there is enough clearance between the rear dropout when the chain is on the smallest cog, then you might also be able to shift the cassette outwards by putting a spacer under it. You'll get about 2mm of adjustment depending on clearance and how much threading there is on the cassette lockring.

Another minor solution is to use a cassette with a smaller tooth count for the 2 biggest cogs.

I believe an SRAM chain might also help as it's slightly wider (although I never measured one), but within tolerances to be compatible with Shimano cassettes.