Support road.cc

Like this site? Help us to make it better.

forum
road.cc bike forum

Shimano Tiagra - Expanding Cassette??

by Walshinoz
Thu, May 20, 2021 14:38
4

Hi,

I have a 10 year old roadbike that is kitted out with a Shimano Tiagra groupset. It is 50/34 on the chainwheel and 11/28 (10spd) on the cassette. It is in pretty good nick but  don't really want to spend lots of money upgrading ( I would rather put that towards a new one when the time comes). I have a trip coming up with a few tasty gradients over a few days. So question: Is there any way I can expand the rear cassette to incorporate a bigger granny cog, say a 32t (or a 30t), without having to buy a new groupset / lots of new parts? Is there something similar to the 'oneup' system where I can take one sprocket out of the current cassette and replace with a 32t sprocket in the cassette? Or can I replace with an 11/32 cassette only (if I can get one) withut buying a new shifter/derailluer/chain etc? I understand the issue with the cage length, but if I only used a new 32t sprocket whilst in the 34 chainwheel upfront (and adjusted tbe B screw) would that work? Or am I just barking up the wrong tree?? Just trying not to spend a lot of money.

Many thanks in advance

Cheers, Jason

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

Add new comment

4 comments

Avatar
Secret_squirrel | 3 years ago
0 likes

This thread has a number of suggestions a secondhand 5701 RD being the main one.

https://www.cyclechat.net/threads/shimano-4600-shifters-with-which-rear-...

Avatar
gmac101 | 3 years ago
0 likes

If it’s a RD-4600 the largest cog on the back is a 30 tooth according to the Shimano spec sheet.  Though you can sometimes push the shimano spec I haven’t done it with this item. Maybe others have. https://productinfo.shimano.com/download?path=pdfs/archive/2012_SPECIFIC... - page 85

Avatar
Stef Marazzi replied to gmac101 | 3 years ago
0 likes

I tried 32 tooth on a short cage Tiagra and although it vaguely worked, it definitely wasn't happy. Changed to the proper long cage and no issues.

Avatar
Podc replied to Stef Marazzi | 3 years ago
0 likes

Stef Marazzi wrote:

I tried 32 tooth on a short cage Tiagra and although it vaguely worked, it definitely wasn't happy. Changed to the proper long cage and no issues.

Same here. I think the frame geometry/mech hanger set up has a significant impact - what works on one bike may not work on a different make or model.

Latest Comments