# Bicycle Mechanics - Cane we make a sticky about Shimergo?

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Mark Kelly
11-21-11, 03:34 AM
Can we make a sticky about Shimano / SRAM / Campagnolo gear spacing and interchangeability? I would like it to include the following information:

Gear spacing____Campagnolo____Shimano

6 speed__________N/A_________5.50
7 speed__________N/A_________5.10
8 speed__________5.00_________4.80
9 speed__________4.55_________4.35
10 speed_________4.15_________3.95
11 speed_________3.85_________N/A

Cable pull_____Campagnolo___Shimano___SRAM

6 speed__________N/A_________3.2______N/A
7 speed__________N/A_________3.0______4.6
8 speed__________3.6__________2.8______4.4
9 speed__________3.3 / 3.0*____2.6______4.0
10 speed_________2.8_________2.3_______3.6
11 speed_________2.6__________N/A______N/A

To use these tables: For the rear derailleur you propose to use, divide the gear spacing by cable pull to obtain actuation ratio:

Campy New 1.5, Campy old 1.4, Shimano 1.7, SRAM 1.1

If using Jtek shiftmate, multiply or divide by shiftmate ratio
Type 1=1.04, 2=1.07, 3=1.2, 4=1.13

Multiply the final actuation ratio by the cable pull of proposed shifter to obtain new derailleur mechanism actuation.

If this is within 0.5mm of an available cassette it will shift very well. If it is within 0.1mm of an available casette, it will shift OK. Greater errors make worse shifting, you can always try it to see if it's tolerable.

Use a 9 speed chain for anything 9 speed or less. Use a 10 speed chain for 10 speed. Campy 11 is Campy 11, don't use it unless you need it.

Match the derailleur pulleys to the chain used - conversion pulleys are easily available. If going large to small, a washer under the head of the pulley bolt will stop the end of the pulley bolt protruding too far in. If going small to large check that enough threads engage on the pulley boilts.

Worked example:

Say I have old Campagnolo (1st generation 9 speed) shifters and I need to replace the derailleur with something available from the LBS which carries Shimano and SRAM.

If I choose SRAM 10 speed, with an actuation ratio of 1.1 and use a Jtek type 1 I get a derailleur action of 3.3 x 1.1 x 1.07 which is 3.88 mm. The nearest suitable spacing for Shimano / SRAM is 3.95 mm (10 speed), the error or 0.7 mm per shift will result in acceptable shifting.

If I use a Jtek type 4 I get 3.3 x 1.1 x 1.13 which is 4.10 mm, the nearest suitable spacing for Campagnolo is 4.15 (again 10 speed). The 0.5 mm error should result in good shifting.

In both cases I will only be able to use 9 of the 10 speeds because the number is set by the indents in the shifter mechanism.

Mark Kelly
11-21-11, 03:35 AM
Err, that was "Can we make..." but I can't edit the title

HillRider
11-21-11, 08:20 AM
Good information but I don't understand the "match the derailleur pulleys to the chain used" comment. I've had no problems using an 8-speed Shimano rear derailleur (RD-1056) with a 9-speed chain and a 9-speed Shimano rear derailleur (RD-6500) with a 10-speed chain.

Ex Pres
11-21-11, 08:21 AM
Why reinvent the wheel?

DaveSSS
11-21-11, 06:09 PM
A SRAM RD is never suitable for use with the other brands of shifters because it requires a uniform cable pull (3mm for road bikes). Campy and Shimano values that have been listed are an average value. The actual pulls are significantly different. For example, although Campy 10 shifters average 2.8mm of pull, the actual pulls are 2.5mm five times, 3mm twice and 3.5mm twice. If mated to a SRAM RD, the pull would be way behind after the first five shifts - about a whole cog's worth. Lennard Zinn started this poor advice and failed to measure the individual pulls.

Also, there's rarely any need to match RD jockey pulleys with the number of speeds being used. With Campy, there have been a few changes to the RD's acutation ratio. 2001 and newer 9 speed is not the same '97-'00. 11 speed RDs have a slightly larger actuation ratio than 10 speed, but a 10 speed RD can be modified slightly to work with 11 speed. I ground the cable clamp bolt down to the root of the threads (about .140 inch diameter) in the area where the cable contacts the bolt, to shorten the lever arm and increase the actuation ratio. It works just fine with 11speed and no change to the jockey pulleys is required.

The small increase in actuation ratio between Campy 10 and 11 seems to work OK, when an 11 speed RD is used with 10 speed. Once again, the jockey pulleys are not a problem.

rdtompki
11-21-11, 08:02 PM
A SRAM RD is never suitable for use with the other brands of shifters because it requires a uniform cable pull (3mm for road bikes). .....
Dave, do you have any data on the new SRAM RD (Exact Actuation)? The actuation ratios are clearly different than the previous versions. For whatever reasons and FWIW it's been my experience that the Campy 10spd ergo shifters worth with both the mtn and road new SRAM RD with Shimano cassettes. I just had a new single set up this way with a Rival RD and the shifting is excellent, albeit superior with KMC chains. I would still classify such a setup as an "experiment" with not an absolute guarantee, but in my experience it does work and on our daVinci I use every cog in each of the four chainrings when I get lazy.

AEO
11-21-11, 08:39 PM
J-tek shiftmate is cheaper than buying an SRAM RD.

Al1943
11-21-11, 09:28 PM
Try this: http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946

DaveSSS
11-23-11, 04:38 PM
Dave, do you have any data on the new SRAM RD (Exact Actuation)? The actuation ratios are clearly different than the previous versions. For whatever reasons and FWIW it's been my experience that the Campy 10spd ergo shifters worth with both the mtn and road new SRAM RD with Shimano cassettes. I just had a new single set up this way with a Rival RD and the shifting is excellent, albeit superior with KMC chains. I would still classify such a setup as an "experiment" with not an absolute guarantee, but in my experience it does work and on our daVinci I use every cog in each of the four chainrings when I get lazy.

I have no data on SRAM, since I only own Campy. I have asked others to measure the SRAM road bike cable pull and got answers that support the claim of a uniform 3mm per shift. It's not hard to measure the cable pull. I put a piece of masking tape on the cable, along the chainstay and use a precision machinist's rule to measure between the cable stop and sharp edge of the masking tape. Take several reading for each shift and the total to reduce errors.

If the actuation ratio is different with the "exact actuation" models, then the cable pull can't be the same 3mm per shift. It always irritates me (as a mechanical engineer) when brands like SRAM use terminology like exact actuation, but fail to explain what it really means. That makes it marketing BS.

The main point is that SRAM RDs are supposed to a have a single actuation ratio that works with uniform cable pulls, while the Shimano and Campy RD's don't have a single actuation ratio. The ratio varies as the RD move from the smaller cogs to the larger ones and more pull is required toward the larger cogs. If you mix the two, the results won't be as intended.

There's just no way that a Campy shifter should work well with a SRAM RD since it pulls only 12.5mm of cable and 15mm is required for five shifts. The lag would be nearly a full cog by then.

dddd
11-25-11, 02:42 PM
Perhaps just another way to phrase some of what has been said here, but I've found that those numbers, 1.4, etc., for the actuation ratios, are only approximate. Some test-calculations with the data in those charts bears this out.
So, I wouldn't use those particular numbers to verify anything.

On a related note, and I offer no explanation, but I have seen a local rider whose 10-speed bike uses Ultegra shifters with a Rival rear derailer. I recalled reading that this could not possibly work and I really looked it over. The guy says it works fine, and I noticed no Jtek and no weird hookup with respect to the cable pinch bolt.
It's sorta been bothering me ever since. That rider didn't seem to be tech saavy himself, and offered no explanation beyond that it worked fine.

DaveSSS
11-25-11, 05:27 PM
Perhaps just another way to phrase some of what has been said here, but I've found that those numbers, 1.4, etc., for the actuation ratios, are only approximate. Some test-calculations with the data in those charts bears this out.
So, I wouldn't use those particular numbers to verify anything.

On a related note, and I offer no explanation, but I have seen a local rider whose 10-speed bike uses Ultegra shifters with a Rival rear derailer. I recalled reading that this could not possibly work and I really looked it over. The guy says it works fine, and I noticed no Jtek and no weird hookup with respect to the cable pinch bolt.
It's sorta been bothering me ever since. That rider didn't seem to be tech saavy himself, and offered no explanation beyond that it worked fine.

Shimano shifters with a SRAM RD could not possibly work, since Shimano 10 shifters only pull 2.3mm of cable (on the average), which isn't even close to the required 3mm. There is no magic to cable shifting systems. The cable pull is either matched to the RD's requirements or it won't work well.

As an example, I've used a Campy 10 RD with 11 speed, but it required a modification to the RD. The difference in the actuation ratio is quite small, but it was easy to install the RD without the chain and watch the RD lag the cogs, reaching it's worst mismatch when the RD was shifted to the largest cog. Grinding the cable clamp bolt down to the root of the threads shortened the lever arm enough to increase the actuation ratio and correct the problem. Users who select an 11 speed RD to use with 10 speed, find the slight overshifting to be tolerable.