It's been quite a few years since I last attempted to build my own wheels,
with varying degrees of success. Anyhow, since I had a pair of nasty, wobbly
Mavic CXP14s on decent Chorus hubs, and didn't want to ride my Scirrocos
through winter, I thought it was about time I gave wheel building another
go.
I found an online spoke length calculator, based on a database of rims and
hubs and the length formular from Jobst Brandt's 'The Bicycle Wheel', and
used that instead of doing the calculations myself. Plumping for a pair of
Mavic Open Pro CD's, I ended up needing 16x 295mm, 16x 293mm and 32x 296mm
spokes, to build a standard 3X partern, front and rear.
Disassembling the old wheels was easy enough. Most spokes unscrewed readily
using my electric screw driver. Others were not going to budge, as I had had
to crimp them in place to prevent them from slackening off. Note that these
wheels were not constructed by me. These obstinate spokes were dispatched
with a pair of wire cutters, once the tension had been sufficiently reduced
by the removal of the spokes that were easy to remove.
After a good cleaning of the hubs on Tuesday evening, I sat down in the
middle of the lounge floor, 'The Bicycle Wheel' by my side for reference,
and began inserting the first of the 14/15g DB stainless spokes in the rear
hub. I was a bit dubious about the spoke lengths at first, as the first two
sets of pulling spokes seemed to be prouder than the first of the pulling
spokes. This was on top of not actually finding the correct rim in the spoke
length calculators database, so I chose another Open Pro and hoped that the
effective diameter wasn't different between the two models. I needn't have
worried, for as I screwed all the nipples down until the spokes began to
emerge from the threads, everything began to become tensioned.
After bedding the spokes down against the hub flange and manually improving
the spoke line, I inserted the wheel into the rear triangle of a hack bike
on my workstand, and began tensioning and trueing. I used a pencil between
the top of the rim and the seat stays to help me judge radial throw, and
held the same pencil against the seat stay at brake pad height to detect
lateral variances. When I was happy with the first pass, I checked the wheel
against my dishing tool, which showed a gap of 4mm. As the use of a dishing
tool magnifys the error by a factor of four, this meant that I had to pull
the rim over to the cassette side by 1mm. It took me two more passes to
reduce the dish error to zero. With stress relieving, final lateral tweeks
and having one eye on the tv, the whole rear wheel took three hours to
complete.
I had all Wednesday to myself, so I built the front wheel. This went just as
well, although my workstand is not as well balanced when working on the
front wheel. When finished, I mounted a new pair of 23c Continental 4 Season
GPs on the wheels and pumped them up to 8.5 bar. Pity that I had planned a
lot of house work to get through, but I had to make headway on that or else
anything pleasurable, like a cycle ride, would have been spoilt by guilt. So
the first ride would have to wait.
I'm on jury service right now, and have been spending all the time waiting
to be selected. They weren't starting any new trials on Wednesday, which is
why I had the whole day free. Today (Thursday), I nearly got selected for a
jury in the morning, but was left as one of the spares. We got to 1 o'clock
and then they decided that no more cases were to start today, and probably
not Friday either, so we were sent home. Cue opertunity for first ride.
I swapped the new wheels for the Sciroccos on my Sirius cyclocross bike,
which is in general road riding guise, with SKS Raceblade mudguards and full
light set. As I got on, there were a few spoke pings, as residual torsion
was released under my weight. I took the shortest route out to the country
lanes from the estate, and headed for a straight run along the A5. As I had
expected, the ride was as smooth as any other. There were no more pings, and
there were no issues even when I struch the odd pothole. I had intended to
take it steady, but with the trucks and the smooth run along the A5, I
couldn't help but up the gear and inject a little pace. I wanted to be back
before rush hour got crazy, so I only did 1.5 hours. I put in a good climb
to the end, a good test for wheel build quality as the old wheels would have
deflected onto the brake block under torsional load. The new wheels?
Nothing - no touches even with the block set close.
Me - one happy bunny.
David Lloyd