Friday, May 07, 2010

"My right shifter is noisy."

Customer presented us with a Specialized Roubaix Elite, about two years old. I didn't do the check in. On the tag it said the bike needed a tune up and the right shifter is noisy.

The owner of the bike is a competitive Nordic skier, although a health problem has limited her competitive activities for a while.

I've noticed something about skiers, whether cross-country or downhill. They tend to beat their bikes to death. They spend so much time on equipment with almost no moving parts that they forget to do any maintenance. At first glance this seemed to be the typically under-lubricated, road grimy bike, sticky with spilled energy drink. But the shifter noise was atypical and intriguing. It was a sort of grindy squeak.

On closer inspection I discovered that the shift cables had worn into the bottom bracket cable guide deeply enough to allow the cables to begin to saw into the fat down tube. They hadn't gone too far. I could easily fix it by pulling off the BB cable guide and replacing it with a thicker one. It's just held on with a single screw or bolt.

I worked slack into the cables and unscrewed the cable guide. The screw turned stiffly but never withdrew. I tried coaxing it out with a little cautious prying as I turned the screwdriver. That did no good. Clearly I would have to remove the crank and bottom bracket bearings to see what the other end of the screw or bolt looked like, rather than continue to pry or twist.

Getting the FSA SL-K crank off was another treat. The left crank arm is held on with an alloy bolt torqued to 36 foot-pounds. You're just as likely to strip out the hole in it as you are to break it loose after it has been sealed in with thread locker and then ridden in all weather. I got it out mostly intact. I may not put the same bolt back.

Inside the BB shell I saw that the cable guide is held with a bolt into a threaded insert in the BB shell. This insert has broken loose. The bolt can't be removed BECAUSE THE THREADS WERE NOT GREASED WHEN THE BIKE WAS ASSEMBLED.

There are no unimportant parts. I get a certain amount of crap for my meticulous assembly procedures, but then something like this proves my point. It's not even a rare occurrence.

I won't know until I get further into it tomorrow what I will have to do to graft on the new cable guide. Without it the cables will cut deeper and deeper into the carbon fiber, ultimately leading to failure.

4 comments:

Rantwick said...

Steve A is going to take issue with you on the whole skiers are hard on bikes thing... he skis and seems pretty uptight on the proper care and feeding of his bicycles.

[prighant]

cafiend said...

There are always exceptions. A ski instructor I know, who teaches both Nordic and alpine, lives an entirely car-free life. And our shop owner is very sensitive to issues with his bike.

Maybe it's New England. Most people ski around here and the majority of people everywhere neglect bike maintenance. As a mechanic I only get to see equipment when it's acting up.

Steve A said...

Most people who go around on skis, as most people who go around on bikes, are hard on the equipment and are unfeeling troglodites, so I can see why cafiend reaches that unwarranted conclusion.

I may not be very good or elegant at either pastime, but the standard is abysmally low so it isn't hard to be far above average. It's amazing what a minimal amount of education can do to raise any of us above the hoi polloi.

One of my fond memories from my first season snowboarding was rescuing an elderly skiier who'd wandered into deep snow and gotten stuck. Said he, "no snowboarder has ever been nice to me before, I didn't know such a thing was possible."

I didn't have the heart to tell him I was really a skiier learning to be bilingual. And NO, I don't ride goofy foot, though I later learned how to do it when needed.

[machagr]

Steve A said...

Speaking of skiing. I've noticed that when one wants to damp down expectations, it works well to tell people "we're from TEXAS!" When we want to appear serious, we note we're from Washington, visiting our sister who works at Breck. It's nice to be able to go either way...