deepakvrao

Did a search and came up with this, where on page 2 someone mentions that you dont need an XX, now you could even use a X9 or X7 RD with a mountain cassette and road shifters.

https://www.bikeforums.net/showthread...oad-bike/page2

My wife rides a road bike with Red shifters. We are planning some really steep climbs and wanted to get her an MTB cassette and RD.

Thought of the X9 10 speed RD, or even the X7 10 speed RD

https://www.chainreactioncycles.com/M...?ModelID=55243

and a 12-36 10 sp cassette PG1070

https://www.chainreactioncycles.com/M...?ModelID=55198

Will this work? Would I need a long cage or medium cage RD? Would the cable routing be a screw up?

SRAM website says that for 2*10 medium cage, and for 3*10 a long cage. So, as she is on a SRAM compact double, would a medium cage be correct?

deepakvrao

Strangely SRAM does not give the wrap capacity on their website, but I found this on Performance Bikes website:

CAPACITY: 39T (Medium), 47T (Long)
COMPATIBILITY: SRAM 10-speed mountain and road shifters
MAX. COG: 36T (Long)

So, if she has a 50/34 and a 12-36, that should need a wrap capacity of 40, and I should get away with the medium cage right?

adriano 

ive exceeded the wrap by one tooth but not three. id say its worth a try, but be prepared to go back for the long.

deepakvrao

Capacity is 39 for the medium, and my requirement would be 40. Just one over, or am I missing something?

RoboCheme

I use a Rival mid-cage RD with a IRD 11-34 cassette with no problems.

deepakvrao

I think I might want to put in the 12-36. Don't think the Rival midcage would handle it?

adriano 

i apologize with my math fail. id say itll work. you might have to play with the chain length and front derailleur placement quite precisely.

Kind of Blued

I'd get the long cage, medium cage if you were only going to 32 in the back (according to what I've read). Worst case scenario, your long cage RD will be more capable than you need it to be. I can't think of a drawback except it'll weigh a few more grams.

deepakvrao

Shifting is supposed to be better with the medium cage right? Not sure medium/long has anything to do with number of teeth of largest rear cog.

deepakvrao

Some sites say that the wrap capacity of a medium is 35 teeth, so does that mean that I will get away if she avoids the small chainring/small cog combination, and maybe the small chainring/last few small cog combinations?

I <3 Robots

David Millar ran a 36T XX cassette with an XX RD in the Giro.

https://www.theroaddiaries.com/2011/0...3-giro-2011-2/

https://www.velonation.com/News/ID/85...mountains.aspx

deepakvrao

^^^I know that, but he has only 10 teeth different in front. Still, any idea whetehr this is a medium/long cage?

deepakvrao

OK guys, taking my chances with the mid cage and the 12-36. Will post how it works out. Saw this very informative post. She might just lose the use of small chainring with last two small cogs, or maybe even not that if the wrap capacity is a bit conservative.

https://forums.mtbr.com/drivetrain-sh...ur-284688.html

This site gives capacity of the medium cage 10 speed RDs as 39, and my need is 40. Should work.

https://www.bti-usa.com/public/quicks...?page=1#GS2732

deepakvrao

Works great with the medium cage. Had to cut a new housing for the cable where it goes from chain stay to RD, but have kept the inner cable its original length to be able to easily go back to the original RD.

Complete cross chaining and small, small also is OK and the RD takes up the chain slack without any issues. I had thought that the last one or two cogs might be unusable from the small chainring.

Best part is that I learnt a fair bit too as to how to set up an RD from scratch :-)