Clamping power
Dear Lennard,
I am hearing that disc brakes can cause the axel to shift within thedropouts when paired with standard quick release skewers causing alignmentproblems in the rotor/caliper interface. Is this true? If so, is movingto a beefier mechanism (such as a new Marzocchi QR20 fork) the only fix?Is there a difference between steel and titanium skewers in this respect?I am thinking of making the change to discs and need to know how much hiddencost there is, new fork, hub, etc.
BlairDear Blair,
Yes, that’s true. Indeed, the clamping force is definitely less withsome skewer designs than with others. Titanium skewers offer less forcethan do their steel counterparts, even with the same head design. We oncedid a study of this for a VeloNews magazine article more than tenyears ago.The foolproof way is with a through-axle, but that can be expensive.At minimum get the strongest skewers you can for your front wheel, becausethe leverage when applying the disc brake hard can, in some cases, yankthe wheel right out of the dropouts. You see, when the caliper grabs thedisc, that point becomes the fulcrum, and the force on the front axle dueto the rotational inertia of the front wheel with all of your momentumbehind it is directed almost straight down, out of the dropout. On therear, the braking leverage tightens it into the dropouts, so it’s not sucha concern there.
LennardUpgrading that wheel?
Dear Lennard,
A few years back, I purchased a Mavic Cosmic Carbone rear wheel torace on. The wheel was 8 speed and Campy specific. I have since gottena new bike and changed to Shimano components and 9 speed. I wouldlike to still use this wheel, but I don't know what to do to convert it.A Shimano cassette will not slide onto the hub. I suspect the hubmust be changed, and am wondering if this is something that is practicaleconomically and otherwise.
RyanDear Ryan,
I figured we should go straight to the manufacturer on this one.
Lennard
A response from Mavic:

Dear Lennard and Ryan,
The old ED 8-speed bodies are the same width as Shimano's 8- and 9-speed bodies, so this conversion can be done with available parts. The freehub body is M40082 and axle halves are M40237 + M40064. Because the width of the body is unchanged the wheel will not need to be re-dished.Good luck!
Christopher Zigmont
Senior Idea Guy
Mavic, Inc.

Getting it straight
Dear Lennard,
My wife has just recently been reunited with her 1980's Andersen steelroad frame (out of the Bay Area I think.) It's a pretty nice frame, andwe'd like to turn it into a town bike.Here's the problem. I put a spare 8-speed Ultegra built rear wheel intothe frame and it fits, but doesn't line up - the wheel is off center byabout 0.5 to 1cm - but it still clears the stays. I then tried the 7-speedwheel from her current road bike (I admit it; I married a retro’ type)and it has the same problem. She swears it was previously a seven-cog cassettebike. Her dad shipped the frame out when he was clearing out many yearsof junk from his garage, and I think it may be somewhat bent. Is therean easy way to put the frame on a jig and check alignment? Since it's steel,can it be cold worked? We're not too concerned about performance as thegoal is just to make a usable town bike.
PeterDear Peter,
Yes, it can be cold set (a wonderfully fancy word for “bending”) bya frame builder or a qualified shop with the proper alignment equipment.
LennardIs 10-speed the same in all cases?
Dear Lennard,
Can I use my Dura-Ace 10 speed crank with Campagnolo Chorus 10-speed drivetrain? Thank you.
JoeDear Joe,
Yes you may.
LennardRegarding the Jump Stop
Dear Lennard,
I installed a Jump Stop chain watcher on my Bianchi Eros equipped witha Campy Mirage triple setup. (See "Technical Q&A" from March 8) After following many instructions for checksand adjustments to solve the problem of chain drop (including those inyour book "Zinn andthe Art of Road Bike Maintenance"), I resorted to the Jump Stop.Prior to installation I suffered routine chain drops at the most inappropriatetimes. With the Jump Stop, I have not experienced a chain drop inover two years since installation.The Jump Stop offers adjustment of both vertical and horizontal positionrelative to the small chainring. It is easy to install, stays inplace, and is very durable.Aside from the excellent product, the customer service was impeccable.I called Nick up one evening. We discussed the problem, landed onthe proper size for my seat tube, and he sent a Jump Stop out. Itarrived in a couple of days. I installed it and tried it out.Only after I was satisfied did I have to send him my $10 (included shipping).No one wants to have to install a chain minder, but if you need one,this is the one to get. I am surprised that this product has notbeen picked up by a larger manufacturer or is not found in the catalogs.I suppose the upside is that it remains an inexpensive, high quality productwith great support and free shipping.
JimA follow-up on powder coating
Dear Lennard,
Maybe I can help a bit the guy who asked questions about powder coatingthe Shimano 105 cranks.I think it's unlikely he'll ruin them by powder coating.I don't know what alloy they are made, but 20 minutes is a short time comparedwith typical heat treatment times for aluminum. If possible I'd suggestto use as low temperature as possible.Aluminum alloys get their strength from "aging." Aging increaseswith time and temperature, and it is typically effective only ifyou first "solutionized" the aluminum, which means to get rid from badeffects of
casting or forging. The potential problem of heating up the cranksduring powder coating is "over-aging," which actually reduces the strengthof the crank.If the Shimano 105 cranks are not solutionized or aged, then over-agingis not much of an issue in most alloys. If they are solutionized,the heating time should be short compared to the heat treatment from thefactory. Many alloys for casting are aged 2-5 hours at 300 F; fromwhere I guess that 20 minutes at 300 F will not be much of a factor.Alloys for tubing of the 7XXX series require even longer times, of theorder of 8 to 24 hours at 250F. I'd love to know what allow thosecranks are made of.
Patricio
Department of Metallurgical and Materials Engineering
Colorado School of Mines

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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.