which size rear derailleur do I need please?

daffyavfc

Hi

I've got a 2009 GT GTR series 4 road bike and the rear mech got damaged in the car!!
I'm going to get a 105 mech as the one on it at present is a Sora shimano.

It's 16 speed and has a 50/39 chainset and an 8 speed rear cassette 12-25.

What size cage rear mech do I need for this set up please ?

thanks

http://www.evanscycles.com/products/gt/gtr-series-4-2009-road-bike-ec016380

Mike67

One of these:

http://www.ribblecycles.co.uk/sp/road-track-bike/Gears-Rear-Road-Shimano-105-Silver-5700-10-Spd-Rear-Gear/SHIMGRRR520

Should do you.
It's a short cage you need (SS) for info.
If you had a triple up front and/or larger gears at back you would need a medium cage (GS).

You may find it cheaper elsewhere as you have to spend over £50 to get that price

Mike

oldnslowcp

Short cage rear derailleur is what you need. 105s are on ebay:- http://cgi.ebay.co.uk/Shimano-105-5600- ... 379wt_1139 for a very good price. Although I doubt you'd notice any difference using a Tiagra http://cgi.ebay.co.uk/Shimano-Tiagra-45 ... 2325wt_905