Rear Mech

Bazzowmb

I'm aware of the following ball park guidance:

3 Chain rings - long cage, 2 Chain rings - medium cage etc.

But whilst doing a bit of research before I replace a busted rear mech I came across the following in a review about the Sram X9;

'Many XC racers and riders who understand how their gearing really works prefer to use mid, or preferably short cage rear derailleurs, as they allow riders to use a slightly shorter run of chain, with less of it flapping about in the wind. They're also lighter at 212g for the short cage (as opposed to the 230g of the long cage) and less likely to catch on twigs, rocks or narrow rut edges.'

The above comments seem to make sense but I'm wondering if there are technicial issues.

Basic question is does this mean I can purchase a medium or short cage derailleur for my 27 gear setup and if so what are the pros and cons?

Cheers for your help.

:?:

nicklouse

only if you try and use a ratio that will not fit and then you are eith stuck in a gear or something brakes.

ride_whenever

So it is fine as long as you don't cross the chain in large large. The thing to do is to instead of wrapping the chain round the large and large, wrap around the large and middle, that will result in a shorter chain but you will lose some easier big ring gears, which you shouldn't really use anyway. You then just have to be careful!