ad5at

Hello all. This is my first actual post here. I have read tons of great information in these forums in the past, but could use some help in clearing up an idea I have.

Rather than swap out my 53/39 front setup with a 50/34 Compact Crankset, I would like to instead go with an 11/32 rear cassette and long cage 10 speed derailleur. The main reason is that it looks to be more cost effective. I live in the moutainous areas of Northwest Arkansas, and although do a signficant amount of climbing and get by ok with what I have, I just get blown away by the climbers who are using the Compacts. After a 50-60 mile ride that might include two or three decent climbs, my legs are just wiped out. I feel as if though I might get by a little better later in the stage of the ride if I could spin a little more up the hills. It just looks like from what I have studied so far, more could be lost on the flatter areas as far as higher gear options with the compact, than with staying with the standard front and making the ratio change at the rear.

I guess my real question is this; Has anyone done this, and if so, will a 10 speed long cage derailleur work with double front chainrings? The models I have looked at keep referring to a triple front setup. I need it to be compatible with my 10 speed Ultegra STI levers and front chainrings.

Thanks for any and all replies.

capwater

What are you running as a cassette now? 12-27 ought to work fine with your existing short cage RD. Gotta get stronger on the climbs, no magic mechanical bullet.

HillRider

A long cage rd will work with the 53/39 crank and 11x32 cassette if you make sure the chain is long enough to allow big-big (53-32 in this case). The total wrap required is 35 teeth and even Shimano's road long cage rd's will handle that. Eg. the 105GS has a capacity of 37 teeth.

What may not work is a road rear derailleur with the 32T large cog. Shimano says their road rd's are limited to a 27T largest cog. Experience says they will usually work with a 30T and sometimes a 32T. but not always. To be sure, you will need an MTB rear derailleur.

ad5at

Thanks for the advice.

My 12/27 does work just fine with the Dura Ace rear. I am just looking for a little lower gear for the climbs without sacrificing the higher options that I have for the flatter sections I currently ride.

Hillrider, I think you may have answered my question. I was just trying to get clarification on whether or not the MTB long cage rear needed for an 11/32 cassette, would be compatible with the road set up that I have in the front. It sounds like it would be a good fit.

Thanks again for taking the time to respond.

Little Darwin

The cable pull for Shimano rear derailleurs is the same whether it is a mountain or road derailleur.

Many tourers use mountain rear derailleurs. although they also tend to use 9 speed and bar end shifters...

There are also reports in the forums of people using 9 speed derailleurs successfully with 10 speed cassettes and chains, so you should be good to go. Just be sure that you don't get a rapid rise derailleur or it will reverse your rear shifting.

johnny0

i just did this except on a tiagra bike. i swapped out the tiagra RD for a deore SGS cage and swapped the 11-25 to a 11-34. also required a new chain. I have a compact front.

the things you need to watch out for:
-the road RD will definitely not fit 34, may slightly fit 32.
-RD capacity in terms of chain slack. https://www.parktool.com/repair/readhowto.asp?id=26
-right shifter has to be 9 speed unfortunately. the mountain RD's and cassettes are only 9 speed. you might be able to use a 9 speed RD with a 10 speed cassette, but you sure as hell cant use a 10 speed shifter with a 9 speed cassette.

rmac

IRD sells an 11-34 10sp cassette.

A lot of tandems use 10sp brifters with 9sp wide-range cassettes.

demoncyclist

The RD doesn't have speeds. Any current Shimano MTB derailleur will work, from XTR on down, with a 10 speed cassette, chain and shifters

cyccommute 

I use an XT rear derailer on two different road bikes with STI. No issues. One of the XT derailers was stock on the Cannondale T800.

ad5at

Great! it sounds as if though I may even have more options on components than I originally thought.

Right now, my plan would be to use my current 53/39 up front with the Ultegra FD, 10 spd levers, and an Ultegra Long Cage RD with the 11/32 cassette. I really like the way the ratios work out with that set up.

Just a bit lower gear for the hills, without the huge change in ratios on the flats from switching to a compact.

Thanks for all the help.

cyccommute 

You may have issues with the Ultegra rear. If you have the derailer, try it. If you have to buy it, XT would be a better choice with less hassles.

ad5at

You may have issues with the Ultegra rear. If you have the derailer, try it. If you have to buy it, XT would be a better choice with less hassles.


Advice taken!