Saturday, May 21, 2011

Wheelbuilding

















This week I was unlucky enough to have yet another crash (my third in 3 months), and while the resultant damage to my body was not too bad this time (just some minor road rash), the damage to the bike was, whilst visually small, very tricky to repair. See that hairline crack along the hub body in the above photo? It may not look like much, but it does in fact make the whole wheel loose, as well as rendering one of the spokes useless.


















Now, obtaining a replacement hub for a Corima wheel in Hong Kong might sound like a bit of a tough task, but it was in fact quite easy, courtesy of the fact I have a spare Corima Winium rear wheel in the spare room. This is a left over from another crash where I wrote off the front wheel a couple of years ago in a minor collision with a car (the driver paid for the replacements). What proved to be much less easy was the process of getting the actual hub off the old wheel and re-lacing the new.




















Given Mrs bikesandbuildings was off for a long yoga session and it was raining outside I thought a solid couple of hours wheelbuilding should do this. Little did I appreciate quite how much longer carbon wheels take to deal with. The all internal spoke nipples mean you can't see what you're doing, the hub requires the removal of the axle to remove the spokes, and the mix of radial and 3 cross lacing took a good 15 minutes of moleskin sketching to work out the lacing pattern and sequence.

















Lastly, upon dismantling the existing deep section Corima, I discovered that none of the spokes really want to leave the rim. I managed to get the outer half of the two cross off in order to remove the hub, but in actual fact the re-lacing was a mix of rim to hub with the more conventional hub to rim.


















I got there in the end with the lacing, but to use a car analogy, I tend to think of replacing a hub as a bit like replacing an engine, and replacing a Corima would seem a bit like replacing a rotary wankle engine. OK, I should probably stop writing about embedded nipples now...



4 hrs later, I still wasn't there with the tensioning of the spokes, and I must admit I'm not 100% confident I'll be able to produce a well tensioned wheel, as it'll be my first attempt at a 24 spoke carbon wheel, but nothing ventured nothing gained. And, if nothing else, I feel I have a better understanding of my equipment. Of course, there's something quite satisfying about building wheels, and any excuse to take something apart jn the living room and put it back together is always quite welcome in my book, if not the wife's.