Showing posts with label cassette body. Show all posts
Showing posts with label cassette body. Show all posts

07 October 2011

Doing An Involuntary Track Stand





Eight blocks from my apartment....Up to that point, it had been a routine ride home.  But, suddenly, my rear wheel stopped dead.  My feet locked in an involuntary track stand:  I couldn't push the pedals forward or backward.   


Fortunately, I skidded only a few feet and teetered only slightly to one side.  Pulling my left foot out of my pedal, I set it down on the pavement and kept myself from falling.  I had just passed through an industrial area of Long Island City where, at that hour, there was no traffic.  So, I lifted the rear and looked at the rear wheel in the middle of the street, where the lights were bright enough that you could have read the instructions in a Rema patch kit. 


What I saw puzzled me at first:  It looked like a four-or five-centimeter gap behind the locknut on the right side of my rear wheel.  I pulled the bike over to the truck bay in back of one of the buildings.  Even though the trucks were gone, the loading docks and driveway were lit by large kleig lights, which allowed me to see my problem clearly:  The locknut on the drive side had unscrewed from the bearing cone, which tightned against the bearings so that the wheel could not spin.  


Of course, I didn't have the tools I needed to remedy the problem.  (Do you carry cone wrenches on your daily commute?)  So, I had to lift the rear wheel and roll the bike on its front wheel for a bit less than a kilometer to my apartment.


When I got home, of course, I hoisted the bike onto my repair stand and took the wheel off.  The latter task proved difficult, as the wheel had wedged itself even more firmly between the dropouts, which made it difficult to unscrew the quick release skewer.


But once I got the wheel off, I discovered the problem:  The cassette shook from side to side as I moved the wheel.  Once I took off the cassette, I saw that the cassette carrier was very loose on the hub.  


On most Shimano rear hubs, like the one I was riding (It came with the bike), the cassette carrier (what you slide the cogs onto and screw the lockring into) is held onto the hub body with an allen-head bolt that takes a 10 mm key.  


The hub originally came with a seven-speed body; because seven-speed cassettes are becoming more difficult to find, I decided to swap the body for one that is compatible with 8, 9 and 10 speed cassettes.  If you ever do such a thing, remember that the bolt has to be tight!  Otherwise, you will have a mishap like the one I had.  When the body loosened, it wobbled.  And when it wobbled, one of its edges probably caught the edges of the locknut, which caused it to unscrew from the cone.


If that ever happens to you, you won't be able to pedal, even if you use the smallest chainring on your TA Cyclotouriste crank and the largest cog on one of those old SunTour freewheels!  


As I fixed the hub (I cleaned it, packed it with fresh grease and replaced the ball bearings, for good measure), I thought of the time, years ago, when I was riding home from Bear Mountain.  I was pedaling along the long flat stretch of Route 9W just south of the state line to the George Washington Bridge.  In those days before indexed shifting and cassette hubs, I rode a Regina CX freewheel on my racing bike.  It was one of the lightest freewheels available and, being Italian, it seemed like just the thing to ride on a Campagnolo hub. 


Anyway, as the day was mild and the air was calm, I had little trouble in keeping up a high rate of RPMs, even though I had already ridden close to a hundred miles.  Suddenly, I had no choice but to keep on pedaling:  The ratchet mechanism inside the freewheel broke, which meant that I couldn't coast.  And I couldn't stop because, behind me, about a hundred other cyclists were riding at high RPMs and I didn't want to start a pile-up, especially if I would end up at the bottom of it!


Well, I made it home, but not after riding about ten miles on what was, to my knowledge, the world's only bike with twelve fixed gears!


At least the problem I had last night wasn't a complicated fix and didn't require any expensive new parts.  My Regina freewheel, on the other hand, was toast.