Technical Q&A with Lennard Zinn – Rim remnants and the great mix-and-match debate

By Lennard Zinn

Ridding the rim of remnants
Dear Lennard,
I have some carbon tubular rims that I glued Vredestein Fortezzas into, and when I removed them there were parts of the casing stuck to the rim (I think it might have been latex that covered the casing but it wasn’t able to be removed before mounting). Is there a safe way to remove this substance from a carbon rim?
Jared

Dear Jared,
It’s not particularly safe for you or the environment, but acetone will get that off without damaging your carbon rim. And of course, if there are base tape fibers stuck in the glue, scraping them off with a screwdriver is required.
Lennard

Can I put SRAM Force shifters on my bike but keep the Campagnolo drive train? Or do I have to also change the front & rear derailleur to Force, and still use Campy’s rear cassette, being I have a few wheel sets that are Campy. I’d like to know what options are able to be done so as I can make the change without attracting much attention from my wife’s radar.
Rick

Dear Rick,
The front derailleur is not an issue. The rear derailleur will work, but not as well as if you were to get a SRAM rear derailleur and cogset (or Shimano cogset). I’ve already written a bit about what to expect.

Of course, if you were willing to go to the lengths of the author of the following letter, you could dial it in to work fairly well.
Lennard

That poor horse
Dear Lennard,
To officially beat a dead horse to death, I wanted to share an idea that I had and successfully implemented this past week. I recently changed from Shimano 9 to Campagnolo 10 and I wanted to use up some cassettes that I have.

I wanted to make the Campy 10 group shift the Shimano cassette for a while. I have been aware of the Jenks method for Campy/Shimano hybrid shifting, and I decided to try and make it work for my problem. Effectively, the Jenks solution is just changing the attachment point of the RD, so that the throw is adjusted for the different spacing. It just so happens that rotating the clamp washer is a convenient way to get the correct offset right.

For my modification, I basically removed the cable clamp washer and replaced it with a flat washer, so that I could move the attachment point of the cable to the rear derailleur, which adjusts the throw of the derailleur for each click. I then adjusted that point by trial and error until I found the correct point. Next, I used a hacksaw to cut the cable groove in the washer and reinstalled. It definitely works, and I figured that I would pass this your way, since I have never heard of someone doing this exact technique before.

The good news: a small change in the attachment point makes a big difference, so the cable angle is very close to the original (no excessive rubbing)

The bad news: a small change in the attachment point makes a big difference, so it is very difficult to get it just right
Jamie

Dear Lennard,
I currently have a bike with an Ultegra SL gruppo. However I like the feel of SRAM levers more. For the sake of my bank account, I am wondering if I could switch only my cassette, rear derailleur and shifters to SRAM while keeping my Shimano SL crank and front derailleur? Would the front shifting work at all or suffer with a Shimano SRAM mix?
Matthew

Dear Matthew,
It would work fine.
Lennard

Dear Lennard,
I’ve read about some compatibility issues that you have written about and would like your opinion on using the new super record rear derailleur with my record 10-speed cassette and front derailleur. Does the new rear super record “care” that my 10-speed older ergo levers would be moving it?

I was hoping the 10 notches or stops are in the handles and that the rear would just pivot up and down. I would really like to put one on my bike.
Dan

Dear Dan,
The clicks are indeed in the Ergopower lever and not in the derailleur. I have not tried it, but the only reason I can see why it wouldn’t work would be that the cage is slightly narrower and could perhaps drag on the fatter 10-speed chain.
Lennard

Dear Lennard,
Are the new 2009 Campy Centaur 10-speed shifters compatible with my older 2007 Centaur drivetrain and if not and I need to replace it, can I at least keep my older Centaur carbon crank.
Ted

Dear Ted,
Yes, they are compatible.
Lennard

Do you know if this requires an adaptor that allows the standard BB cups to be inserted in to this BB shell, or is it not even possible? Sadly, I did see that SRAM is offering a BB30 crankset for ‘09, but too little, too late.
Jeremy

Dear Jeremy,
I think that SRAM Red BB30 crank is available now. That would be the best solution. Otherwise, yes, you can press a threaded bottom bracket insert into a BB30 shell and install a standard threaded crankset.
Lennard

Dear Lennard,
I am trying to confirm whether a Cannondale Hollowgram crankset will work in a Tarmac SL frame. Will this work and are there any items to be aware of?
Greg

Dear Greg,
The BB30 standard is the same in both frames. The cranks are interchangeable.
Lennard

I wouldn’t normally bring something like this up, but I was interested to hear if this could possibly damage a frame. I would think not considering the low amount of weight, I could only imagine the seat to snap/break away, but if that was the case I wouldn’t even trust that seat to ride.
Ryan

Dear Ryan,
Oops. Guess I didn’t read that too well! I always get the hanging from the wheels question, and I guess I didn’t even notice that this was a different question!

No, hanging it from the saddle will not hurt the frame. It’s probably not great on some saddles, though.
Lennard

I got a lot of mail about the no automatic gear selection by the Dura-Ace electronic shifter. Most of it was along the vein of this first letter, but perhaps the second letter sheds a bit of light, too.

Dear Lennard,
I wanted to follow up on your post to Jon’s question about electric Dura-Ace, as I thought it excellent question. It seemed to me that Jon was asking not about automatic transmission, but rather smarter gear selection that might be available with this system. When shifting to a larger (harder) gear, the rider will usually simply select a smaller rear cog OR will switch to the large chainring. The rider less commonly shifts both, even though doing so might lead to a smaller change in gear ratio. For example, if I were riding 53/39 up front and 11/23 in the back, if I wanted to shift to a bigger (harder) gear while riding the 53/19 combination (gear ratio 5.6), the next larger gear ratio is found in the 39/13 (ratio 6.1) and not the 53/17 (6.3). I think Jon was asking if this could be made automatic with the electric system. That is as the rider I would simply use one gear selector to “go up” or “go down” and the system would select the next harder or easier gear, which may require the system to make either a single or double shift.
Topher

Dear Lennard,
Regarding the question about “smart” auto-shifts, what Shimano nor you will say is that there would be an obvious “Legal Component” to automatic shifting by the equipment.

It’s not hard to visualize a racing wanna-be dude launching over the bars or such in the wrong gear and then going for a big pay-day – ditto personal injury lawyer.
Sal

These go to 11
Dear Lennard,
The only time that I have seen a chain get sucked between the small and large ring even with the correct chain is when the inner chainring has been installed inside out.
Rudy

Dear Lennard,
First of all you are the man! As far as the 11-speed chain and cassette go and the 10-speed crank, the problem with his jamming the chain has much more to do with the adjustment of the front derailleur than the chain issue. If you measure the distance between the chainrings its not possible for the chain to fit into that gap, unless one or both rings are deflected from each other creating a space large enough to fit the 11-speed chain. This could be done with compact 110 BCD cranks but most likely not a Dura-Ace 39-53 combination.

It would depend on the chainrings, and how stiff they are, but basically he didn’t get the chain over far enough, it hung up on the outside plate of the new 11-speed chain and was forced into the space and jammed due to the rider’s own power. I am sure a quick adjustment of the front derailleur would fix this situation. And a reminder to all your readers: not all mechanics are created equally.
James

Dear Lennard,
For what it’s worth, regarding the campy 11s chain that got “stuck” in the 10s crank; I too have been riding a “minimal” Campy 11-speed setup to see what works; this means 11-speed shifters, chain and cassette only with SRAM red crankset (177.5 CT, which campy doesn’t make) and Campagnolo 10-speed derailleurs; I’ve used this about 1200 miles with great results; it shifts as fast and clean as another bike which I use as a “baseline” which has full campy super record 11s and which also has been ridden for about 1100 miles.

One of the issues I’m trying to evaluate is the long-term viability of riding the 11-speed without using an 11-speed crank or derailleurs; ie, do the SRAM 10s chainrings or the campy 10-speed derailleur pulleys “wear” the 11s chain pematurely or lead to failure? To date, the system works fantastic, and even better than a pure 10-speed system.
David Zimbelman
Salmon Cyclery
The Dalles, Oregon

Dear Lennard,
Our demo Moots has a Record 10-speed compact cranks and otherwise 11-speed Chorus group and it works just fine. We’ve had no issues at all.
Peter Chisholm
Vecchio’s Bicicletteria
Boulder, Colorado

Technical writer Lennard Zinn is a frame builder (www.zinncycles.com), a former U.S. national team rider and author of numerous books on bikes and bike maintenance including the pair of successful maintenance guides “Zinn and the Art of Mountain Bike Maintenance” – now available also on DVD, and “Zinn and the Art of Road Bike Maintenance,” as well as “Zinn and the Art of Triathlon Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.”

Zinn’s regular column is devoted to addressing readers’ technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Readers can send brief technical questions directly to Zinn. Zinn’s column appears here each Tuesday.