Derailleur compatibility questions? Lennard Zinn...

Technical FAQ: Shifting compatibility with different cassettes

Lennard Zinn answers questions about how you can run a mix of different parts and gets a tip on how to help out a weak derailleur.

Dear Lennard,
With all the wide-range cassettes and drivetrains people are setting up, I thought I’d share a good modification I’ve found to put a little more cog into a given derailleur. A thin washer — I get stainless ones from the hardware store for 15 cents — between the hanger and derailleur can add enough clearance for a few more teeth. It moves the shift plane of the parallelogram out a little bit, putting the guide pulley a little lower at any given cog. I figured this out by trying to make a thin hanger work with a normal cassette and a cheap, under-sprung derailleur, but it works as well on a high-end road bike. I fit a 32-tooth cog on a Bianchi Infinito with a short-cage derailleur with no cog-pulley contact, and it helps with the 42-tooth cassette adapters, too. Chain wrap isn’t ideal, but it works, and customers appreciate a $1 solution to a $100 problem.

I hope your readers find this useful.
— Tim

Dear Tim,
That’s a great, creative solution. Thanks for sharing it with us.

By the way, that is a method that I have also used with success on a drivetrain that was sluggish in getting the chain to the smallest cog. The derailleur spring can be too weak to overcome the resistance in the cables with an old or cheap derailleur, or with continuous cable housing from front to rear like on some older, internally-routed frames, or with tandems, or with sharp cable bends in the system. The hardest shift will be to the smallest cog, because in that position, the derailleur spring is closest to its relaxed state (except with a Shimano Rapid Rise or low-normal rear derailleur).

By putting a spacer between the derailleur hanger and the derailleur, you effectively tighten the spring in every position.
― Lennard

Dear Lennard,
In the last Tech FAQ, a reader asked about using Campy shifters with a Shimano cassette. It does work — and well. I use it on my CX bike. I am using Campy 11-speed shifters with an older XTR Rapid Rise rear derailleur that has 10-speed pulleys. You have to clamp the cable a bit differently but it works well … you get 10 speeds. The reader didn’t specify (or I missed it) if he was trying to use the Campy rear derailleur or not.
— JC

Dear JC,
I made the possibly erroneous assumption that Reggie was using a Campy rear derailleur with the Campy shifters. But now when I re-read the question, I see that, as you stated, he doesn’t actually specify. Interesting how I can read something like that and picture in my mind exactly the setup I think that he has, and then on later review, I discover that the letter never mentioned some of the parts that I pictured so clearly in my mind … Another reminder to read more carefully without preconceptions!

I assume you’re doing the “Hubbub Shimagnolo” conversion by clamping the derailleur cable farther back around the cable-fixing bolt on your XTR 8- or 9-speed derailleur, rather than in its standard groove below the bolt. This decreases the derailleur movement with each click of the shifter.

The 11-speed Campagnolo Ergo Power shifter pulls 2.6mm of cable with each shift click, and the shift-actuation ratio of a (non-Dura-Ace) 6-, 7-, 8-, or 9-speed Shimano rear derailleur is 1.7. Multiplied together, that gives a lateral derailleur movement of 4.42mm for each click. However, the cog pitch of a Shimano 10-speed cassette is 3.95mm (center-center distance between adjacent cogs), so you need the derailleur to move less far with each click. (By contrast, a Shimano 10-speed road STI shifter pulls 2.3mm of cable with each shift click.)

As it says here about the Hubbub conversion on Sheldon Brown, “To get the indexing to match the sprocket spacing, you will have to check and readjust the place where the cable attaches.”

Over time, non-standard cable-clamping locations tend to fray and break the cable strands, so check for that frequently so you don’t end up far from home with a broken cable.

That’s cool you’re using a Rapid Rise rear derailleur; I’ve never seen a setup with a Campy shifter where operating the shift paddle moves the derailleur to a smaller cog, rather than to a larger one!
― Lennard