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Did a cassette swap over the weekend...(5 posts)

Did a cassette swap over the weekend...joekm
Apr 21, 2003 5:23 AM
Pretty easy task nowadays, the Shimano Ultegra cogs only go on one way so there are no issues with lining up the ramps. Went from 11-23 to 12-27 so I could spend some time working on climbing. Did a 25 mile test ride the following day (in hills of course) and it appears I'll have to tighten the thumbwheel about a 1/16 to 1/8 turn but that's about it for deraillure adjustment. Given the rather dramatic change, I'm kinda surprised at that.

Other than that, I just need to work out my new shift strategy with the new cassette. Basically, I've got a 7-speed 12-21 with two "bailout" gears that I should only use from the small chain wheel.
this might helpDougSloan
Apr 21, 2003 6:19 AM
Did you need to lengthen the chain?duckstrap
Apr 21, 2003 8:47 AM
to accomodate the larger rear cogs? I want to go from a 12-23 to a 12-25. Thanks much.
Sould not have to. . .Mike P
Apr 21, 2003 8:57 AM
I have an 11-21, 12-23, 12-25, and 12-27 I swap out between two wheelsets. Lately I have not even had to adjust the deraileur upon changing cassettes.

Did you need to lengthen the chain?joekm
Apr 21, 2003 9:05 AM
My understanding is that you set the new chain length based upon the lower chainwheel and the smallest cog. Therefore, you should not have to change the chain length for that swap. However, some people do advocate keeping the chain and cog together so that they wear together. However, YMMV.

In my case, I did swap the chain. However, my smallest cog went from 11 to 12 and that 27 that was going on there was going to cause a lot of movement on the idler pulleys.