Adjustable or disposable?
Dear Lennard,
Can you tell me if the bottom brackets on the two-piece style Shimano cranks have adjustable bearings, like those used in a hub or pedal or are they a non-adjustable sealed cartridge, like that used in the current Octalink bottom brackets? I don’t see separate bottom bracket bearings being sold for the new style cranks, so I’m guessing they are adjustable rather than disposable, but it’s just not clear. I need new mountain-bike cranks, but I chew through the Octalink bottom brackets pretty quickly, so a non-disposable bottom bracket would probably make the new two-piece cranks worth the extra bucks.
Steve Dear Steve,
It’s not adjustable; the same thing applies to all of the integrated-spindle/external bearing designs. With the Shimano and others with pinch bolts on the left arm (see photo), you can’t adjust the bearings, but you sure can mess them up on installation by putting too much torque on the little threaded cap that pushes the left arm on, thereby sideloading the bearings and greatly shortening their life. Truvativ’s GXP design pinches the (smaller) left bearing between the left arm and a shoulder on the spindle (this one you do tighten the left crank on to high torque), thereby isolating the drive-side bearing from axial loads, since it has more radial loading already due to the chain being on that side. The left bearing takes some axial loading, but since its radial loading is less, the bearing wear is more even on the two sides. In the photo, notice the shoulder just below the splines. You don’t find separate bearings for integrated-spindle cranks for sale because you can’t remove them from the cups; now the cups with the bearings installed are disposable and not adjustable.
Lennard

What’s in a name?
Dear Lennard,
My local bike shop cleaned my chain as a free service. I usually clean it myself, but who is it that turns down a complement? Anyway, I notice that they removed the chain and reattached it with a link marked “KMC.” My chain is a Campagnolo Ultra 10 speed chain. Campy recommends that one uses the four link replacement chain and other riders I know use the Super Link III on their Campy Chains. Are you familiar with this link? Should I be worried? I can change my own chains. So, if this is a hazard, I’ll just pop it off and put a new chain on.
Jack

Dear Jack,
It’s a perfectly reasonable thing to do, if they wanted to replace the chain without having to dispose of a perfectly good chain. KMC is a respectable chain brand that has been including master links in its bicycle chains for some time. I would not worry about it.
Lennard

A lighter shade of pin
Dear Lennard,
Are the pins used to fasten Shimano pins the same across all chains? I noticed that the Dura Ace pins are a different shade of grey (lighter) than some off the lower end chain pins (darker). The reason I ask is I tried using the darker pins (obtained free from a bike shop) on my Dura Ace chain and experienced some binding problems.
John

Dear John,
No, they are not. There are three different versions, in order of decreasing length: 7/8-speed, 9-speed and 10-speed.
Lennard

Dear Lennard,
I'm an intermediate cyclist. I recently bought a LeMond Arrivee Ti bike with Ultegra components (59cm frame, I'm around 6 foot 2). I loved it. The first long ride I took (75 miles), I encountered a problem I'd run into 10 years ago (the other time in my life when I've ridden such distances) - Achilles Tendinitis. I rested until the pain went away and then got back on the bike. It came back, and I noticed a direct correlation between the amount I rode and the level of pain in my heel. I got frustrated and sold the bike.

I was sad to do it, and I was sad about my prospects for future adventures by bike. However, I was on your website yesterday reading about your cycling primer book, and I got to thinking...

My question: Do you think that there is at least a decent chance that my tendinitis issues are predominantly related to bicycle fit? I know that I should consult my physician about specific physical problems, but I'm simply curious if you've run across these types of stress-injury problems before and found that in a lot of cases they can be addressed with the right bike and the right fit.
Jason

Answer from cycling sports medicine guru Andy Pruitt

Dear Jason,
Achilles tendinitis is rare from cycling but if an anatomical variant exists then the bike can aggravate it. He mentioned his heel, which makes me think that his "tendinitis" is really retro-calcaneal bursitis. He needs an appropriate x-ray and exam to see if it is really the tendon. In either regard he should move his feet as far forward as possible and lower his saddle.
Andrew Pruitt
Director, Boulder Center for Sports Medicine

New group, bad shift
Dear Lennard,
I am on my second bike with the current version of Shimano's XTR Group. For whatever reason neither has shifted well in the rear. In fact I would go as a far as to say my current XTR is by far the worst shifting Shimano group I have ever owned and I’ve owned plenty, including older XT and XTR groups as well as Dura Ace 8-, 9- and 10-speed road groups.

The main issue is that even after the rear derailleur is perfectly adjusted in the stand, the cable moves on the trail and the shifting is horrible. I have spoken to other XTR users and some have had similar experiences. I noticed the barrel adjusters at the shifters have indents on them, but the shifter bodies do not. As a result they do not "engage" each other to stay in place like all other barrel adjusters. I have found that the barrel adjuster moves several turns in a given ride and that is often the cause of the poor shifting.Do you have any thoughts? I would have just locked it out and used the one on the rear derailleur, but BIG S decided not to put one there. Should I try Loctite on the adjuster? SRAM? Help!
CJ

Dear CJ,
If you can establish that it actually is turning, by marking its position with paint or a marker, then by all means, try blue Loctite. Loctite expands and makes rotation of the threads more difficult, but still possible for adjustment. It sounds like you think you have eliminated these possibilities with both of your bikes, but I strongly recommend checking for sticky cables and housings, stiff chain links, alignment of the rear derailleur hanger, sufficiently tightened cogset locking, and adjustment of the b-screw. All of these things can lead to poor shifting and can sometimes be disguised as something else.
Lennard

Finally, regarding cutting carbon handlebars and steering tubes
Dear Lennard,
I don't often have to cut carbon, but when I do, I use a pipe cutter to start, and then a hacksaw to do the majority of the cutting and to finish. The pipe cutter provides a even cut line to follow. It seems that I have accidentally found a way to avoid both of the problems you have noted.
Gary

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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.