dcombs

I wanted to build a decent flat bar road bike, and started buying stuff. Started with a Raleigh Cadent 5.0 frame. My question is, I bought a set of Shimano SL-R770 flat bar road shifters. The specs say it will work with all Shimano 10 speed rear deraileurs, will it also work with the SRAM Foece rear deraileur I just bought? Or did I screw up? Is all SRAM and SHimano stuff compatable, or does that just apply to cassettes, chains, etc.?

doggy

i read that campy shifters will shift a sram derailer!
https://velonews.competitor.com/2008/...-why-not_73404

DieselDan

No. SRAM derailleurs have a different cable pull ratio then Shimano. Exchange the Force derailleur for 105.

JanMM

Generally, SRAM RD's require SRAM shifters with 1:1 cable pull.
Shimano shifters are 2:1, as are some SRAM shifters. Always check the specs.

DaveSSS 

No, it will not work. For the record, SRAM road shifters are not 1:1 and Shimano is not 2:1. Campy shifters are also a poor choice for a SRAM road RD.

SRAM road shifters pull 3 or 3.1mm of cable per shift, depending on who you want to believe and that cable pull is uniform. To be 1:1, the cable pull would have to be the same 3.95mm as the cog spacing. SRAM's own literature is confusing. Uniform pulls and 1:1 are not the same thing.

Campy 10 shifters pull an average of 2.8mm, but the real pulls are 2.5mm 5 times, 3mm twice and 3.5mm twice. A Campy shifter hooked to a SRAM RD should be far behind in cable pull after those first five.

Shimano 10 pulls are also nonuniform and average only 2.3mm per shift.

operator

Not according to zinn:

https://velonews.competitor.com/2008/...-why-not_73404

DaveSSS 

I've read Zinn's article long ago, but I don't believe in fairy tales or magic. If you have a Campy 10 bike available, it is easy to verify that the first 5 shifts will pull very close to 12.5mm of cable. The SRAM shifter needs at least 12mm to make 4 shifts and 15mm to make 5, so the mismatch seems to be quite large - off by a whole shift - quickly. In general, an undershifting setup (which this should be) is not as tolerable as the opposite setup where the RD overtravels. That's why many people think that Shimano cassettes with a Campy drivetrain work OK.

Sometimes you can get the chain to shift onto the desired cog, but the RD will be running out of alignment, which should cause noise, friction and premature wear. There are few mismatched combinations that truly work out very well.

Here's one that Shimano 9 users can try - a Campy 11 shifter with a Shimano 9 drivetrain. The average 2.6mm cable pull is just a little more than the 2.5 average Shimano 9 cable pull. A setup like that actually makes some sense, although it will slightly over travel.

dcombs

Thanks for the replies, and sorry for the stupid question. I did alot of reading last night after I posted this and realized I screwed up with the Force derailleur. I ordered a Ultegra RD-6600 Short Cage to replace it. I was tempted to get the new SRAM flat bar shifters that weren"t available when I started gathering parts for this build, but I'm already sinking too much cash into this bike.

operator

Normally I would agree with you about shift quality but this isn't joe hack mechanic writing about it. This is from a guy who has written a book on bike maintenance. I will test this when I get back to work tomorrow as it is very interesting. What do you think your error on _your_ measurements are?

DaveSSS 

I measure the cable pull using the most accurate machinist scale that you can buy - a Starrett with .01 inch increments. I place a piece of masking tape on the shift cable, about 1 inch ahead of the cable stop on the rear chainstay. I adjust the tape so the sharp edge aligns exactly with some even increment like 1.0 or 1.1 inches, then go through all 9 shifts, one at a time, writing down the position of the tape after each shift. Do this at least 3 times and compare the values to insure that they are accurate and repeatable.

I get .10 inch for each of the first five shifts which is very close to 2.5mm. There should be no doubt at all that 5 shifts fall far short of the 15-15.5mm cable pull required for 5 shifts of a SRAM RD. The even bigger issue is Campy pulls are nonuniform while SRAM's are supposed to all be the same.

J-tek makes a shiftmate to improve the mismatch between the two shifters, but all it can do is increase the average cable pull. That will make the first five better and the last four worse.

I respect Zinn, but his cable travel measurements do not agree with mine or SRAM's claimed 3mm per shift. I started doing precision measurements in a machine shop in 1971 and worked in the manufacture of precision machined minature mechanical components for many years. I know what I'm doing.

To do a more precise measurement, I'd set up a 2 inch travel dial indicator to monitor the travel in .001 inch increments, but that's a lot more work. A setup like that would be precise enough to show the very small errors between each shift. You'd also find not every shifter to be exactly the same. Everything has a tolerance range.