Velonews: Technical Faq: Wide Gear Ranges, Mixing Drivetrains, And More


Jan 3, 2005
Despite not being rated to do so, the Ultegra RD-6870-GS long-cage rear derailleur will cross-chain with a 36-tooth large cog and a 50-tooth large chainring. Photo: Lennard Zinn |
Wide gear range on Shimano 11-speed
Dear Lennard,
I want wide gearing as I age but still want to go steep on occasion. My Campy triple shifting on the front has never been good enough. The 1996 Record double on my old bike shifts better. Your columns about Di2 shifting with wider gearing are very interesting.
And my Campy-pattern wheels with appropriate 11-speed clusters should work with the Shimano gruppo. Campy’s largest-range cogset is 11-29. A recent check at the IRD website shows Campy-compatible cogsets, 10-speed to 11-32 and 11-34, also 11-speed to 11-32. Also Shimano 11-speed up to 11-36.
They are heavier and maybe not as well-made as the original [parts], but they work. So I could use my several Campy rear hubs with new 11s cogsets on the Di2 group and use the current cogsets on the older bike.
If I can give up the 53-39 in the front for 52-36 or 50-34, I can get to 1:1 or even lower for exotic travel without the XTR.
But before I make an expensive jump, would you hazard a guess as to the shifting quality of the Di2 GS6870 rear derailleur on an 11-34 or an 11-36 rear cogset? Maybe you and your older, heavier customers could try it since you already have bikes with Di2!
My mid-length Campy racing triple rear derailleur handles the 30-tooth OK, maybe even a little better if its [b-screw] isn’t turned all the way. It is the front triple that is aggravating. What I read about Di2 sounds so much better.
— Eric
Dear Eric,
I have tried an 11-36 on my 11-speed Di2 ’cross bike with Ultegra Di2 GS6870 long-cage rear derailleur, and it shifts fine. When I switch from my 11-28 cogset, where I have the b-screw almost all the way out, to the 11-36 cogset, the chain really bumps along on the 36T cog. But when I tighten the b-screw until it is most of the way in, it runs smoothly.
And, for those of you with a short-cage Shimano 11-speed rear derailleur wanting more gear range, I have found that to work fine with an 11-32 cogset. To smooth it out, I also tightened the b-screw in quite a ways.
As you said, IRD offers 11-speed Campy-compatible cogsets only up to 11-32. However, IRD goes to 11-36 in 10-speed Campy-compatible, and in 10-speed Shimano-compatible, it goes to 11-42! Perhaps that means down the road it will make that much range available in 11-speed cassettes as well. I would expect that if I were to turn the b-screw around on my Ultegra 6870-GS Di2 11-speed rear derailleur, it would handle more — maybe even to 40T.
Yes, the spacing of 11-speed cogs (the cog pitch) is essentially the same on Shimano, Campagnolo, and SRAM, and their cogsets work fine on each others’ drivetrains. So you can run that 11-32 Campagnolo-compatible IRD 11-speed cogset on your wheels with an Ultegra Di2 11-speed shifter and 6870-GS rear derailleur. However, if you wanted to run an 11-34 or 11-36, depending on what wheels you have, you may be able to interchange the Campagnolo freehub body for an 11-speed Shimano-compatible one, and then run an 11-36 on it.
― Lennard
Aligning a front derailleur cage
Dear Lennard,
When checking the setting of the cable with the plastic gizmo, what should be the position of the front derailleur cage?
— Mark
Dear Mark,
With a Shimano 11-speed front derailleur, the outer cage plate should be flush with the face of the outer chainring before installing the TL-FD-90 or TL-FD68 (the “plastic gizmo”) cable-angle alignment tool. Use the inner limit screw to get it there (if the cable is already connected and you’re using the TL-FD68, you can use the cable tension to get it flush). Shimano recommends holding a hex key against the face of the ring to check that the cage is flush. Of course, the outer cage plate should also be parallel to the chainring; use the support bolt on a braze-on derailleur, and the clamp bolt on a band-type derailleur, to line it up.
― Lennard
Mixing 10-, 11-speed setups
Dear Lennard,
With the current interplay between 10- and 11-speed systems, it is expensive for riders who have lots of older 10-speed wheels who want to switch over.
I just thought I’d share my experience that 10-speed wheels (and cassettes) can work on an 11-speed system (at least for Shimano—we haven’t tried it on Campy 11 or SRAM 11). I and a couple of friends in our riding group have been experimenting with this on several bikes and wheels. So far, we have tried:
— Zipp 404 (pre-Firecrest)
— HED Jet disc wheel
— Custom-built wheels with Novatec hubs
— Shimano wheels (pre 11-speed)
These have been tried across several bikes:
— Parlee
— Cervelo S3 and P5
— Bianchi Infinito
Of course, it doesn’t work perfectly — in particular, the smallest cog (the 11 or 12) usually requires two shifts to go up to the next cog, and shifting at the 17-19 cogs isn’t very good either. But other than that it works perfectly well. I’m told by some of the others in my group that careful adjustment of the derailleur limit screws mitigate the problem somewhat. One of them found it good enough to race ITU triathlons at a national level, so it’s certainly not horrible.
In conclusion, don’t throw out your 10-speed wheels and cassettes. They will play with the 11-speed system, just not perfectly. But it’s more than good enough to get by.
To clarify, these are 10-speed cassettes (e.g. 6700, 7800 series cassettes) on 10-speed freehub wheels with 11-speed systems (shifters, derailleurs). 11-speed cassettes can be fitted to a 10-speed freehub by dropping out one cog and one spacer. It also works as with an 11-speed system.
— David
Dear David,
Thanks for the tip.
― Lennard
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