Technical Q&A with Lennard Zinn: A problem with spacing
Your books have helped me to be a pretty decent wrench for my bikes over the years. Here’s an issue that I haven’t seen covered anywhere:
I just purchased a 2005 Cannondale R5000 frame (CAAD8) after a roof rack incident (my fault, unfortunately) left my old 1996 C-dale R400 frame unrideable. I upgraded all my componentry over the years so that the only thing that was original was the frame. I was assuming I could just swap all the 9-speed Ultegra componentry from the R400 to the newer frame. However, I’m having a hard time getting my rear Mavic Open Pro into the new frame. I can get it in if I muscle it, but the rim ends up off-center to the drive side. (Just for kicks I turned the wheel around and slid it in with the cogs on the non-drive side and the rim still ended up off-center to the drive side.)
The frame dropouts are 123mm apart, the Open Pros are 129mm wide. (I can’t measure the distance between dropouts on the old frame as it was the drive-side seat-stay that was mangled so the dropout distance is now narrower than it originally was.)
1) Is this because the 2005 R5000 was built to accept a 10-cog setup, or is the width of a rear wheel with 10 cogs the same as one with 9?
2) There seem to be spacers on both the drive and non-drive side of my Open Pros. Can one or both of these spacers be removed or do they need to be there for safe operation?
That 2005 frame is screwed up. It should be 130mm spacing. Both 9-speed and 10-speed road wheels are 130mm spacing.
It sounds like the left chainstay and seatstay are bent inward toward the frame’s central plane. That’s why the wheel ends up off to the right, no matter which way you flip it.
Even if the spacing is a defect in the frame, it’s too old, I suspect, to raise a warranty issue. Unfortunately, you will have to get a new frame. Bending a heat-treated aluminum frame is not a good idea.
You can mix and match cogs, but not shift ramps
I have two 10s Campagnolo cassettes – an 11-23 and a 13-29. Since each gear is separate, is it safe to mix and match them to create an 11-26 or an 11-29? I’m running old 10s Daytona shifters and derailleurs – I’m not sure if that would make a difference or not…
Assuming your cogs are not riveted together, you can do it, but it won’t shift very well. Shift ramps on cogs are designed to work with the adjacent cog. The shift ramps will be in the wrong places if you put a different size cog next to a cog intended for a certain pairing different from the one you’ve now created.
Saving the base tape
I want to remove my tubular ’cross tires and replace them with a beefier tread tire. The current tires have some life left in them so I want to keep them in good condition as backups. Could you describe the process for removing tires delicately that keeps the base tape intact? I used the 4/2 layer gluing technique you described in another post.
Push up the edge of the tire with your thumbs on both sides until your thumbs are so tired you can’t do it anymore. If before they lapse into exhaustion you’re able to peel the tire over the centerline of the rim with your hands only, then great. Just continue peeling.
Very likely, however, your thumbs will be blistered and sore before you can get the tire off. Then, in a place where you’ve gotten the edge lifted from both sides a bit, slide a thin screwdriver under the tire and out to the other side of the rim. Do this carefully, working the screwdriver blade back and forth a bit in order to not point-load the base tape in such a narrow strip across that you tear it. Once the screwdriver is through, grab the handle and the tip of the blade and carefully pull toward you, rolling the screwdriver’s shaft under the tire to separate the tire from the rim. Work back and forth if it ever acts like the base tape wants to tear. Once you get an inch or two of the tire separated from the rim, you can generally roll the screwdriver along with more impunity, since the danger of tearing the tire will be behind you. And once you have rolled the screwdriver under the tire for a foot or so, you should be able to just grab the tire and peel it the rest of the way off.
The way you tear a tire’s base tape (which wrecks it, as there will be a bulge there), is by prying too vigorously with a screwdriver. Just be careful, and don’t try to pry the tire off with the screwdriver. Do only the minimum to get it under the tire and through to the other side of the rim, and then roll it carefully; don’t pry it.
The remnants of a tubular
Just removed some Tufo Extreme tape from a Zipp 303. It left a very thin layer of tacky adhesive behind. I’m going to be gluing a set of ‘cross tires up. Do I need to use acetone or something else to get that last layer off, or use it as first layer of glue in the glue process?
You can leave that layer on, as long as it is smooth and not folded over or wadded up. But make sure all of those other clear plastic layers of the Tufo Extreme tape are peeled off; glue will not stick to them.
Tick, tick, tick
My Zipp 404 tubular wheel makes a ticking noise with every revolution while I’m riding it, but when I spin it when I’m off the bike, it makes no noise. And when I sprint uphill out of the saddle, the ticking becomes a louder, popping noise. It really ticks me off. I have a number of other pairs of Zipp wheels, from 808s to 303s, and none of them do it. How do I make it stop?
I’m willing to bet that it’s your valve extender clicking back and forth in the valve hole. Perhaps because the valve comes out at more of an angle on some tubulars, or perhaps the tire’s stitching is more pinched near the valve stem, some valves can move just slightly when the wheel rolls over it with weight on it. This movement against the valve hole can cause the ticking noise that you can hear while riding but not while spinning it without weight on it. And this is a problem that can plague any deep-section carbon wheel, not just the ones you have.
To fix it, take a piece of electrical tape about 4cm long, and cut a slot down the middle maybe 2.5cm (an inch) long. Pull that slot around the valve extender where it comes out of the rim, and stick it down all around the valve extender to hold it in place. I’ll bet the sound will go away.
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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 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. Zinn’s column appears here each Tuesday.