VeloNews technical writer Lennard Zinn is a frame builder, a formerU.S. national team rider and author of several books on bikes and bikemantenance. This marks the beginning of Zinn's weekly VeloNews.com columndevoted to addressing readers' technical questions about bikes, their careand feeding and how we as riders can use them as comfortably and efficientlyas possible. Readers can send brief technical questions directlyto Zinn. We'll try to print a representative sample of questions eachThursday.Question: Do you have any advice for correcting leg lengthdiscrepancies?  I have undergone an Xray which revealed an 8mm discrepancy. Speedplay recommends shimming 1/2 the discrepancy.  Tom Kellogg saysto shim only if the difference is at the tibia.  The initial reportdid not say whether the discrepancy is femoral or tibial.  Any helpis appreciated. -- Matt

Answer: On leg length, High Sierra Cycle Center makes customcranks with the chainrings offset as well as pedals, one of which is droppedrelative to the spindle and the other is raised. They also work with shimson the shoe sole under the cleats. You can e-mail them at hscc@qnet.comor call 800/438-4399.

Dr. Andy Pruitt at Boulder Center for Sports Medicine also works withleg-length discrepancies.  You can see their web site at www.bch.org/sportsmedicine or  call 303/544-5700. -- Lennard

Question:  I also have a question about Q-Factor (thelateral distance between the left and right pedals) and knee injury. Ihave an ongoing but manageable problem with IT Band Syndrome in my rightknee.

I borrowed a bike during a recent trip that appeared to have widercranks (higher Q-Factor?).  Over several rides I experienced lessirritation in my right knee riding this bike using a position that was"as close as I could possibly make it" to my own road bike.  Thisbike also has longer cranks than my bike, which I feared would aggravatemy knee.  I know my perception of this is highly subjective, so Iwas wondering if there has been any research as to whether a higher Q-Factoris beneficial for some body types or knee injuries.  Also, I noticedthat Look now makes a pedal with adjustable Q-Factor.  Is this featurerelated to injury treatment or prevention theories?

Answer: Having suffered myself from IT band syndrome, I can relate.Since the IT band attaches above the hip, spreading the legs would seemto decrease the tension and hence the pain. Spreading your legs is theopposite of the stretching routine physical therapists give you to makethe IT band longer.

I don't see how crank length would affect it one way or another. --Lennard

Question: I have a new Bianchi SL Light frame.  I swappedmy Dura-Ace 7700 components over from another bike to this one. Now, however,I have a tick in the bottom bracket area that I can't get rid of. I've tried a new bottom bracket, I have a new chain, cogs, I've tried differentwheels and pedals.  The only thing I haven't tried are new chainrings($100 for new DA chainrings...sheesh).

The tick is always in the same spot, when the left crank arms is about even with the down tube.  It's intermittent in that it ticks about 75 percent of the time.  Under heavy load, out of the saddle, it ticks on the left and right side.

But...sometimes it ticks when I'm soft pedaling, sometimes it's quietwhen I'm pushing a big gear.  But again, when it does tick, it's alwaysat the same spot.

I can't believe it's the frame; it's pretty beefy looking down there.But do you know of any of these types of problems with recent Bianchi frames?Could it be the chainrings, I've used chainrings for a long, long timeand haven't had any problems and these aren't very old. Could the alignmentbetween the cogs and the chainrings cause a tick? Is there something aboutmy new Bianchi frame I should know?

I'm stumped and frustrated. -- Phil

Answer: I would approach the problem in this order:

1. Grease the snot out of the bottom bracket threads and theinside of the cup that comes free where it fits over the cartridge, andre-install the BB. This prevents noise from parts moving relative to eachother, like slop in threads or fit of the cup over the cartridge.

2. Switch pedals and shoes to eliminate those as possibilities.Put your MTB shoes and pedals on and ride it.

3. Remove, grease, and tighten the chainring bolts.

Of course, I assume you have already inspected your frame for cracks.

Good luck. -- Lennard

Question: Here's a question from one tall rider to another:I am wondering if you can recommend a tall stem for a road bike, one withthe long quill (+200mm) and long extension (+12cm). I am 6'9", rebuildinga big old frame, and trying to get the bars up as high and out as far aspossible. Having a hell of a time making this thing fit. Someday when Ihave more cash I'll have to order a Zinn Project Big frame! The biggestI've been able to find so far is the Nitto Technomic, (non-deluxe) 25.4Clamp 225 mm quill atRivendell. -- Nick

Answer: Sad to say, that's about the biggest one I know of, nowthat Salsa doesn't make custom stems anymore. Anyone else have any suggestions? -- Lennard

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VeloNews technical writer Lennard Zinn is a frame builder, a former U.S. national team rider and author of several books including the pair of successful maintenance guides "Zinn& the Art of Mountain Bike Maintenance" and "Zinn& the Art of Road Bike Maintenance."