rear mech

[fred_dillon]

Hi, I have a shimano set-up (unknown name), with 52/42 on front and 8 speed cassette 11 - 30 on the back, the existing mech is a long cage, but it rests almost horizontal to road. pointing backwards, and does jerk and snag in highest gear.

as the mech is a bit tired, I thought change it for a tiagra or similar, and the chain, which does appear to be too long! On an 8 speed double should be a short cage, but the Shimano web site says maximum cog on rear is 27.

Any advise welcome

thanks

 

[jpembroke]

If you are changing the chain - which I agree sounds too long - then change the cassette as well as they wear at the same rate. You are right: a short cage mech is recommended for cassettes where largest sprocket is no more than 27t but in practice you can go up to 28 (I have this on my 'cross bike: 105 short mech and 11-28t 8 speed SRAM cassette). Personally, I'd go for 12-27 on the back and get a 38 or 39 small chainring up front. That'd give you a better range of gears. It's all personal preference though.

 

[jpembroke]

but perhaps start off by just shortening the chain by a couple of links.