MTB rear dérailleur with a road cassette

[anth73]

I'd like to get some lower gearing on my cyclocross bike for when I am on the trails and am looking at SRAM's new Apex 10 speed cassette. The rest of the groupset is Shimano 105 5600. What MTB dérailleur could work with the 105 so that I can fit an 11 - 32 cassette?

[biker jk]

Shimano XT or LX. I believe XTR doesn't have a barrel adjuster.

[il padrone]

I believe XTR doesn't have a barrel adjuster.

Surely no barrel adjuster means no indexed shifting, unless you have exceptional cable-setting skills??

[alchemist]

I'm presuming the new 10speed Dyna-Sys stuff will work.

I have a SRAM drive train on my CXer and I went the other way & went for a mtb double ring crank set up the front. The lowest gear is now a 28:28 which I found was low enough.

[anth73]

My CX'r also serves as my commuter and wet weather training bike. When doing so it runs 28mm slicks and a 12-25 cassette. Hence why I'd like to keep my 34/48 crank but have the option of running an 11-32 cassette when needed.

[jules21]

IWhat MTB dérailleur could work with the 105 so that I can fit an 11 - 32 cassette?

any shimano or SRAM one would with a long cage, i would say. the only compatibility issues for derailleurs are:
1. lever ratio (i believe shimano and SRAM run the same ratio across the range)
2. cage size
3. mounting (dunno if these vary)

don't believe that BS about "10 spd compatible" or similar - derailleurs have no idea how many gears the cassette or shifters work on.

[Uncle Grumpy]

Surely no barrel adjuster means no indexed shifting, unless you have exceptional cable-setting skills??

Barrel adjuster is at the shifter on XTR shifters. Just like a front derailleur when you think about it, they don't have adjustment at the derailleur either.

Bit difficult if you want to pair them with road levers unless you have a good inline barrel adjuster and a bit of time to get the initial cable tension close to the money.

SRAM MTB derailleurs are the same, no barrel at the derailleur.

Grumps

[il padrone]

don't believe that BS about "10 spd compatible" or similar - derailleurs have no idea how many gears the cassette or shifters work on.

+1

I run an old Deore DX rear derailleur from the 80s (the days of 6 and 7 spds) on my MTB tourer. It shifts perfectly well with a 9 sp casstte.

[ironhanglider]

IWhat MTB dérailleur could work with the 105 so that I can fit an 11 - 32 cassette?

any shimano or SRAM one would with a long cage, i would say. the only compatibility issues for derailleurs are:
1. lever ratio (i believe shimano and SRAM run the same ratio across the range)
2. cage size
3. mounting (dunno if these vary)

don't believe that BS about "10 spd compatible" or similar - derailleurs have no idea how many gears the cassette or shifters work on.

According to Leonard Zinn whilst Shimano and SRAM cogsets are interchangeable, the SRAM levers pull the same amount of cable as Campag ones. This means that a SRAM derailleur won't move far enough with each shift to use with Shimano levers in this scenario. The cable response ratio for Shimano rear derailleurs hasn't changed since the advent of STI (with the exception of 8 speed Dura-Ace). This means that any decent Shimano long cage derailler less than about 20 years old will work. I'm using a "rapid rise" XT derailleur with 9spd Dura Ace levers on the tandem at the moment (long story) and a SRAM 9spd cassette. The biggest problem is with changing gears in the wrong direction by mistake. http://www.bicycles.net.au/forums/posti ... c26a54c5e9#

As previously mentioned, not having a barrel adjuster doesn't preclude XTR, most STI levers have a barrel adjuster at the down tube anyway.

Cheers,

Cameron

[jules21]

ta for that

[GMech]

According to Leonard Zinn whilst Shimano and SRAM cogsets are interchangeable, the SRAM levers pull the same amount of cable as Campag ones. This means that a SRAM derailleur won't move far enough with each shift to use with Shimano levers in this scenario.

Just a little more detail on the above. It is true that MTB-SRAM (since the introduction of the X Series) uses a 1:1 cable pull ratio (cable pulled = movement of derailleur) whereas Shimano uses a 1:2 cable pull ratio. This means it's impossible to pair any Shimano shifter with a SRAM rear derailleur and vice versa.

I'm not too sure about Road-SRAM. Anyone any ideas?

[jacks1071]

I'm presuming the new 10speed Dyna-Sys stuff will work.

I have a SRAM drive train on my CXer and I went the other way & went for a mtb double ring crank set up the front. The lowest gear is now a 28:28 which I found was low enough.

The Dyna-Sys won't work - the cable pull ratio's are different. The poster just needs an old 9sp like XT or LX unit would be fine. They will work with 10sp no problem.

[Baalzamon]

I'm going to follow down this path with my cyclocross with the Sram Apex PG-1050 11-32 cassette. Will require the Sram Apex 10 speed rear derailleur mid cage. That isn't too pricey, but then I need the SRAM Apex double tap shifters and they are pricey, but I know that this combination will work 100%. Shame that c r c don't sell the 11-32 cassette as it isn't that much dearer to fork out for the whole groupset and sell off bits that I can't use ie the brakes.

[trailgumby]

I'm presuming the new 10speed Dyna-Sys stuff will work.

Unfortunately not. Different cable pull ratio. Shimano's MTB stuff is no longer compatible with their roadie groupset from what I read.

The new pull ratio was overdue - my XT groupset is not as tolerant as SRAM of mud in the cable system and I've had to take extra measures to keep the crud out.

A mate has just bought a new Reign with the Dynasis groupset, so I'll get to have a test ride in a couple of weeks. Just from trying out the shifters at the LBS, the action is a lot lighter and more positive than 9-speed - my reasons for preferring Dual Control over standard have just been dealt a mortal blow.