The limits of that braze-on
Dear Lennard,
I just purchased a new compact Campy Centaur crank and front derailleur.I had a local bike shop install these on my steel frame bike and with thederailleur lowered all the way to the bottom of the braze-on we still havea gap of more than 8mm between the outer cage and the large chainring.It seems to shift okay but is there any spacer or part made that willlower this down to the 2mm spec called for by Campy or will it be finethe way it is? I tried the old derailleur and it installed with the suggested2mm of spacing. So I assume there is something in the size of the new compactderailleur that is shorter.
EddieDear Eddie,
You’re seeing one of the many reasons why those of us who make frameshave gone away from installing front derailleur bosses and have gone backto clamp-on front derailleurs.If riders want to vary the size of their chainrings, then a braze-onplaces a limit on the vertical adjustment of the derailleur. That obviouslyprevents you from fully accommodating significant variations in chainringdiameter.Yes, getting to a spacing of 1-2mm between the cage and the top of thechainring will improve shifting. If you can’t get there, then you’ll justhave to live with the 8mm gap. You can maybe get a millimeter or two byfiling the braze-ons slot downward a bit with a round file, bit you can’tremove too much there.I know of no adapter to do what you want, and I can’t even imagine howsuch a thing could be designed, since it would certainly have to push thederailleur back in order to make space for an alternative clamping system,which would also compromise shifting.Your best performance will come from filing off that braze-on and replacingit with either a band-clamp front derailleur or with a band-clamp adapterto which your braze-on front derailleur can attach. I know it is a hideousthing to propose, and it is not a good idea due to the high risk of filinginto the seat tube itself, but that’s what it would take to get the derailleurto the specified location relative to the chainring.
LennardCutting carbon?
Dear Lennard,
I am thinking about switching to a rise carbon handlebar such as EastonEC70 Monkey Lite bar on my mountain bike, but all rise carbon bars thatI could find are 26" wide and it's too wide for me. In the past with alloybars, I could just shorten the width with a hacksaw or with a pipe cutter.Can I do the same with the carbon bars or is there other cutting methodthat you would recommend for the carbon handlebar? Are there any safetyconcerns?
AlDear Al,
Cutting carbon is something you need to do carefully. For starters,don’t use a pipe cutter, as it will shred the inner layers of carbon whenit has cut down to those layers.If you do opt to use a hacksaw, don’t do it with a single cut. Cut halfwaythen go around cutting from other sides to avoid peeling back the outerlayer of carbon.
LennardDental work
Dear Lennard,
I have a 9 speed Shimano XTR RD-M953 rear derailleur that the 11-toothupper jockey wheel is missing a tooth. I also have a 9-speed Shimano 105RD-5500 that I no longer use. It, too, has an 11-tooth upper jockey wheel.Can I use the upper jockey wheel from the 105 derailleur to fix the XTRderailleur? The XTR derailleur is shifting fine with the missing tooth,but I would like to have it complete. Please let me know if this can bedone, or if I should worry about it.
RobertDear Robert,
The 11-tooth 105 9-speed upper jockey wheel assembly should work finein place of the 9-speed XTR 11-tooth upper jockey wheel assembly.
LennardErgo ID follow-up
Dear readers,
I recently shot off ananswer about the apparent year of a Campagnolo Ergo Power 9-speed lever.Well, I was wrong. Fortunately, I have friends like Peter to keep me honest.
LennardDear Lennard,
For this-if your Record Ergo Power 9-speed lever does not have a littleoval hole on the inboard side of the lever body for the button on an ErgoBrain computer, you have a 1999 version.Actually, 1999 was the first year the levers were designed for ErgoBrain, although it didn't come out until later. 1998 didn't have the holes,bumps and had a different back plate and through-bolt.Must be tough to field this type of question. Without seeing it, hardto diagnose. We get calls like this all the time.
Peter Chisholm
Vecchio’s Bicicletteria
Boulder, Colorado
 

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Technical writer Lennard Zinn is a frame builder (www.zinncycles.com), a former U.S. national team rider and author of several books on bikes and bike maintenance including the pair of successful maintenance guides " Zinn & the Art of Mountain Bike Maintenance" and "Zinn & the Art of Road Bike Maintenance."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.