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Technical Q&A with Lennard Zinn: Of G-springs, cranksets and those little plastic bushings

By Lennard Zinn

Crunch time
Dear Lennard,
I have Campagnolo record 10-speed shifters. In fact the componentsare all campy record, except the wheels. I have been having a terribletime with the front shifter. It gets hung up and won’t shift or is veryhard to shift and then it makes a terrible crunching noise. I have theCampagnolo triple front derailleur. Two different mechanics have lookedat it, without taking the levers apart, and nether has been able to diagnoseit or fix it. Any suggestions?
DebbieDear Debbie,
That’s the beauty of Campagnolo Ergo Power; you can fix it if somethinggets jammed inside. Following the instructions in Zinnand the Art of Road Bike Maintenance, take the lever apart and replaceany worn-out or broken parts. I would guess that one of the G-springs isbroken. The G-springs engage the ratchet and click into the appropriategear and hold it there. You might as well get a couple of G-springs aheadof time; they’re pretty cheap. If your bike shop doesn’t stock those, wedo.
LennardTwo questions, a single answer:
Dear Lennard,
I have a 2003 Specialized Allez Compe with an Ultegra-9 group, andam considering changing the triple crank to a compact double 34-50, pairedwith my 12-25 cogset. Is there a compact crank, such as those byFSA (though not necessarily carbon), which will enable me to keep the restof my Ultegra-9 drivetrain and STI’s intact, and still shift smartly?Furthermore, could I at some point change the rear derailleur to anUltegra or DA-9 short-cage, even if I might ultimately change the cogsto 13-27?I know you’ve answered a boat-load of compact related questions overthe past year, but I haven’t seen my particular issue addressed.
CharlesDear Lennard,
Can a Shimano FC-R700 compact crankset be used with a Dura Ace 9-speedgroup? If yes, what chain works best?
BobDear Charles and Bob,
You can switch to any compact on the market, and you will get decentshifting performance. Obviously, you will have to reposition and readjustyour front derailleur, and a triple FD will be a hair more sluggish thana double FD, but it will work fine. The tiny spacing difference betweenchainrings will be a non-issue.It’s probably best to run a Shimano 9-speed chain.
LennardGreat question. Wait for the answer
Dear Lennard.
I understand from bike literature that the new oversize, outboard bottombracket bearing systems create approximately four percent more frictionthan a standard internal bearing system from Campagnolo or Shimano. Ridersare attracted to them, partly, because they are claimed to increase performancevia lighter weight/increased stiffness. Is it possible to measure the performanceimprovement of the lighter/stiffer crankset against the four-percent frictionloss? Are these new systems are, in fact, an improvement?
BillDear Bill,
Look for my column on that very topic in the upcoming print issue ofVeloNews. We tested a bunch of bottom brackets, square-taper, ISIS,Octalink, integrated-spindle/external-bearing, and ceramic-bearing. I can’tdivulge the results until it’s published.
LennardComing up to speed
Dear Lennard,
I’d prefer to run a Campagnolo 9-speed cogset on my ‘cross bike.The Campagnolo 9-speed components have become somewhat scarce (and pricey),but I have ready access to newer Record and Chorus 10-speed shifters, andfront and rear derailleurs.I know that a 10-speed front derailleur will work just fine ina 9-speed set-up. But, what about the rear? Assuming I switchthe index gear in the RH shift lever to a 9-speed version, will the 10-speedrear derailleur shift properly or, will I need to find an older 9-speedversion of the rear derailleur? Conversely, switching to a 10-speed cogsetmay be a simpler, albeit less attractive option, assuming I make the aboveacquisitions. In that case, will a 10-speed cogset fit on an older,9-speed Campagnolo hub? Similarly, do 10-speed Shimano cogsets fiton older, 9-speed Shimano hubs? And, lastly, how well do Shimano10-speed cogsets work with Campagnolo 10-speed shifter/derailleur set-ups?
JWDear JW,
If you switch the index gear and ratchet ring to a 9-speed inside theright Ergo Power, it will shift fine with a 10-speed rear derailleur, andyou can run a 9-speed chain just fine, too. And 10-speed Campagnolo cogsetsfit on 9-speed Campagnolo freehub bodies. A Shimano 10-speed cogset doesnot work even marginally well with a Campagnolo 10 setup.
LennardFollow-up and feedback
Dear readers,
Here is some feedback on last week’s column, on “The sounds of suffering,”regarding squealing Mavic hubs. Many readers wrote in about it with a numberof different theories. Here is a sample of each theory.
LennardDear Lennard,
The problem described by the reader with the Mavic SL wheels is thedreaded “death squeal” of Mavic’s hub design.The plastic bushing Mavic uses as the inboard bearing in theirfreehub design wears out, and when the cassette body becomes loose, itstarts to make that howling sound when freewheeling at high speed.
Tightening the cassette body helps at first, but the noise quicklyreturns.A longer-term fix is to replace the cassette body, but becausethe aluminum-bearing surface on the hub that the plastic bushing rubs againstalso wears, it’s a short-term fix that will repeat itself more and moreoften as the hub wears out.I have no idea why Mavic thought it was feasible to use a plasticbushing instead of a real bearing in their cassette hubs, but there itis. Friends of mine who’ve tried to contact Mavic about this issue as apossible warranty item have been told it’s “normal wear and tear”.
IanDear Ian,
I thought I’d jump in and explain about that inboard plastic bushinginstead of a real bearing. I got the scoop on it when I was up at a Mavic2007 MTB product intro in Whistler in July and wrote the following aboutit as part of a longer article for the VeloNews print magazine:Mavic has a solution for high freehub wear rate. The FTS-X freehub systemretains the bushings so often complained about but reduces wear on themwith harder pawls.Mavic points out that its two-pawl FTS system is a very good freehubsystem only in need of a bit of tweaking. It’s efficient and stiff, beinga part of the hub body supported by bearings near either end of the axle,rather than being a separate part with correspondingly inboard bearingsupport. It is extremely simple to disassemble, clean, maintain and reassemble.The bushing on the inboard interior end of the freehub body that riderswho have had problems assume is a cheap substitute for a bearing is actuallyfar superior to a bearing and is not the cause of freehub failure at all,according to Mavic. Loaded up to 400 kg under the pedaling force of manyriders is no problem for it, as it can withstand almost a ton of load withoutdistorting, whereas a bearing can be damaged with a 300 kg load appliedto it. It’s 40 grams lighter than a bearing, and when freewheeling, thereis no load on the bushing and hence no friction (and it’s as slick as Teflonto boot).So what’s been the problem? Over the years, Mavic has upped the hardnessof its freehub bodies without increasing the hardness of the pawls, whichcan wear away and generate fine steel dust capable of grinding down thebushing. Furthermore, the thread-in axle stub can loosen up. And finally,the chain can drop onto the chainstay when freewheeling because the frictionof the freehub is so high, not due to bushings or bearings, but due toa sticky lip seal.In going from the current FTS-L system to FTS-X, Mavic has made thepawls of harder steel and applied threadlock (good for six disassembliesbefore applying new Loctite) to the axle end screw threads. The new pawls,being so hard, could not be forged with the little tabs to hold them inplace, so those tabs are now on snap-on plastic pieces. Mavic has alsocreated a new lip seal made of softer material with a slick surface treatmentto reduce frictional drag by 50 percent.All of these changes are compatible with current Mavic freehub bodies,but the upgrade parts will not be available for until late next seasonwhen Mavic gets over the production hump for the 2007 wheels, all of whichincorporate the freehub changes.
LennardDear Lennard,
I had a similar noise that came from my Mavic Ksyrium freehub whilecoasting down the Simplon Pass last May. As you know, there are a numberof tunnels on the way down to Domodossola. In the confined area of thetunnels the screeching was so loud that it sounded like my bike was goingto explode! The problem turned out to be an almost dry freehub. Removingthe axle and applying a little synthetic chain lube (I did not have themineral oil that the Mavic web site recommends) inside the freehub eliminatedthe screeching sound and gave me a much quieter coast. When one does thisrepair, one should be sure to keep an eye on the pawls and springs! (Editor’snote: You should really clean and lube the pawls as well. Youcan find instructions for Mavic freehub overhaul in either ” Zinnand the Art of Mountain Bike Maintenance” book or DVD,and “Zinnand the Art of Road Bike Maintenance.”)
JimDear Lennard,
The problem with the Mavic SL is from the small rubber gasket in thefreehub that requires occasional lube. It makes a screeching noisewhen freewheeling or backpedaling. The maintenance for this can be foundon the Mavic website.
MichaelDear Lennard,
That screeching sound is often the spring beneath the pawls in thefreehub getting free and rubbing against the inside of the freehub body.I have only experienced this with the Mavic Ksyrium SLs.
DeanDear Lennard,
It’s probably broken pawls in the freehub mechanism. I had aset of original Ksyrium SSCs. While going down a 45 mph descent lastwinter, they began to screech. Soon it started doing it while coastingdown less steep hills, and then it progressed to making the noise whilecoasting on the flats at high speed.My local bike shop diagnosed the problem as a broken pawl. Thepawls were replaced for about $15, and the wheels has been fine ever since.
TrippFeedback on 29er gearing from last week:
Dear Lennard,
I have a theory on the issue of 29’er wheels and the fact that the11-percent higher gear does not seem to bother people on climbs.Since the 29-inch wheel has a tendency to “smooth out” surfaces andimprove traction a bit, small ruts, bumps and other impediments that canprovide extra resistance to a smaller wheel may have less effect on the29-inch wheel, allowing it to roll (even uphill) a bit more easily.For example, a small bump on a climb tends to increase the effectivegrade that the wheel is climbing, as it not only is tractoring up the (say,10%) grade, but also then has raise up the extra height of the bump.Without getting into the calculus of it, that one-inch-high bump will hitcloser to the “normal” contact patch of the tire, temporarily making thewheel feel that it is climbing a steeper gradient. On a 29-inch wheel,that same bump will hit the leading edge of the tire a bit farther away,and it will tend to make the wheel increase the angle of climb a touchless. Even though the wheel will still climb that one-inch-high obstacle,it does it over a slightly longer distance, which is equivalent to a lowerpercent grade. It will also drop a bit less into a small rut or dip,requiring less effort to “climb back out of” that same depression.
ScottFeedback on “chain issues” from last week:
Dear Lennard,
I’ve experienced similar issues as Bob has in trying to run a Shimanocompact crank with a 9-speed drivetrain, and thought I’d pass this alongin case it’s helpful: My local shop suggested trying to use a (Shimano)10-speed chain, and it has helped a little bit (I gained 1 extra cog onthe back without chain rub) without any compatibility issues. Sincethen, SRAM has come out with their 10-speed chain, and I’m told it’s slightlynarrower still (on the outside), so I may try that when this chain wearsout.
Walter


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,” now available on DVD, “Zinn & the Art of Road Bike Maintenance,” 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.

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