Yesterday I did the first test ride on my Schlumpf geared unicycle,
for getting used to it. Wheel diameter 29" (with Big Apple 2.35"),
crank length 170 mm. The seat post can barely get low enough, but I
won’t cut it shorter because I will probably revert to shorter cranks
later on.
It took some time to get used to the feel of the gear. Initially I
couldn’t ride at all, but after a couple of minutes I could ride,
although it was with quite a few decelerations and accelerations, and
a bit of swerving too. Not only is the gear making all your
corrections less effective, but the torque arm exerts forces on the
frame. That makes the ride less significant than on a Coker. All of
that is quite predictible though, it’s just a matter of getting used
to…
Once I could ride a bit more relaxed, I tried freemounting in geared
mode (static mount). I got it on my third try, and subsequently about
half of the attemps succeeded (in the sense that I rode 5 revolutions
or more). More than with an ungeared uni, the wheel tends to run away
from you during a static mount. So you have to jump up and forward
more “on your own”, rather than using the uni as a pivot. Also, apply
more pressure on the back pedal. And then once you’re up there, start
accellerating. This is slower than normal, so it was not uncommon for
me to fall off in the first revolution or so, because there’s little
speed yet to work with in correcting any imbalance.
I tried shifting down, at low speed. Unsuccessful so far. You use the
back end of your shoe to push the shift button (that runs through the
hub). So that means that af the moment of shifting, your cranks are
about horizontal. Then the cranks disengage from high gear, and rotate
through up to 30 degrees with respect to the wheel to re-engage in low
gear. During that time you have no control whatsoever (unless you can
coast which I can’t). At the same time, the wheel moves on as well.
The two effect combined meant for me that I regain control in low gear
close to ‘dead position’, i.e. with vertical cranks. I’ll have to
practice more. Maybe I should try to rotate the cranks backward in the
unengaged period? Or not rotate them, let the wheel catch up?
I heard some “krk” noises coming from below during most of the ride,
and I thought that something in the hub was not right. It turned out
though that I was picking up gravel and dirt, and since the seat post
was only about 3 mm above the tyre, the gravel hit the seat post.
Pfffft.
The exact ratio of the high gear is one to 17/11, I determined through
some counting and calculating. That’s 1 : 1.54545454. The wheel’s real
diameter is about 29.20" (unloaded). That means that the wheel’s
virtual unloaded diameter is 45.13", or 114.6 cm. What that converts
to in road distance covered per revolution depends on your weight,
tyre pressure, wobbliness and more.
My test ride was 10 km, mostly on tarmac, about 1 km on easy
singletrack (gravel). Max speed on tarmac was 19.9 km/h (from the GPS
but credible in view of the overall speed profile). The uni has a lot
more speed potential, even with the 170 mm cranks, but I haven’t
really tried to go fast yet.
Oh and my hub serial number is 00006. Cool!
Klaas Bil - Newsgroup Addict
“erectile function trumps public image - David Stone, commenting on the importance of seat comfort”
