Everyone who owns a Semcycle, please raise your hand.
Everyone who does NOT need to carry along a toolkit with you anytime you ride
more than a mile, put your hand down.
How many of you still have your hands up?
I’m more than a little frustrated over two mechanical problems I have been
having with my recently aquired 20" Semcycle. After having been away from the
sport for several years following the theft of my Schwinn back around 1989 (who
the hell steals a unicycle?!), I bought the Semcycle in August from the Juggling
Capitol in Washington, DC. It was delightful to discover that I still knew how
to ride, and nostalgic to remind myself how much my crotch hates unicycle seats.
So what are the hardware problems I am having?
Number one is a slow leak. Over a two mile ride I can lose as much as 3 PSI in
the tyre. It also loses air when I am not riding, but I do not know at what
rate. As much as 10psi over two days of not using it has been observed. It
basically means that I have to inflate the tyre every single time I am going to
use it, even for the return commute home in the evening when I’d just ridden it
in ten hours earlier.
The other problem, much more frustrating, is with the left crank. The retainer
nut loosens up, eventually enough so that the crank loosens up on the axel and
gets progressively worse, the point where it can just be pulled off. I thought I
had this problem licked when I really tightened down the nut so much that I was
afraid of stripping the threads. It was further down (ie, tighter) on the bolt
than the right crank. This worked fine for maybe a dozen miles, but just two
nights ago, in the middle of my commute, it went from rock solid to completely
off in less than half a mile. This was especially annoying as I couldn’t even
put it back on and tighten it up because not only had the dust/retainer cap
fallen off, but the nut had also come completely off the axel and was lost.
This weekend I intend to get to hardware store and find a new nut, and probably
thread lock it as a prophylactic against this happening again. But still, even
with such a solution at hand, it bothers me that I have been having these
problems. What are your opinions?
>Everyone who owns a Semcycle, please raise your hand. > >Everyone who does NOT need to carry along a toolkit with you anytime you ride >more than a mile, put your hand down. > >How many of you still have your hands up?
I just got a 26" Semcycle a couple of months ago and haven’t started carrying a
tool kit yet. I have done some agressive riding out in the dirt over 7-8 miles
with no problems while on the trail.
That is not to say I haven’t had any problems. My tire seems fine still even
though I’ve ridden it over some dubious ground in the desert. Just last week
though, I had problems with the left crank. It started coming loose so I
immediately stopped riding and walked until I could tighten it back up. Luckly
it wasn’t too far a walk to my tools. I have heard how bad it is to ride on a
loose cotterless crank so by stopping quickly I hope I have avoided any further
problems. (I’ll find out later today when I go out for another long ride.) I
think my crank might have come loose from letting a friend attempt learning my
particularly high seat. He wasn’t too stable and sent it down hard.
_ _ Doug Borngasser
(o)(o) San Diego CA db db@ucsd.edu \__/ You know you're a
unicyclist when walking feels strange.
Semcycles are fine unicycles. You should not have those problems.
The loss of air on the tire really has nothing to do with the rest of the
unicycle. Check the adjustment of the valve on your tire and your inner tube for
slow leaks. The worst that could happen is that you change the inner tube which
is not a major investment.
The left crank should not loosen up if you have a lefthanded crank there. The
more you pedal the tighter it should get. Maybe you got two righthanded cranks
by mistake. The lefthanded crank tightens counterclockwise. The pedal, of
course, should also be lefthanded.
> This is probably a silly question, but how do you change the tyre? I’ve been > look at my 24" SemCycle and couldn’t see how I could remove the wheel. Do I > need any special tools? I know I’m not very handy, but changing a tube should > be within my abbilities.
Undo the main bolt that holds the forks to the stem. The forks will then come
apart and you can change the tyre.
Now the bigger problem…
Loosening of cotterless cranks is a common problem, but it can be solved or
(even better) avoided completely in the following ways:
don’t ride if the cranks are loose not only does the axle eat into a loose
crank and make it almost impossible to get it to fit well ever again, but the
jarring of the loose crank against the axle greatly increases the chance of
the axle shearing off completely!
seat the crank well on to the axle use a rubber hammer if you can to avoid
damaging the thread so that extracting the crank will be easier. Once the
crank is seat firmly in place the contact between all of the faces of the
axle and the crank should be so secure that the nut should not have to do
much work.
make sure the the nut doesn’t start to work loose once a nut has developed the
habit for working loose it is much harder to stop it. The best solution we
have come up with so far is thread tape, which you can wrap around the thread
on the axle before you put the nut on.
if the parts are damaged, replace them nuts are cheap. Worn ones are not worth
the bother. If riding with a loose crank has caused damage to the crank, and
filing the faces of the hole in the crank does not make a tight fit on the
axle possible, then get another crank. This is greatly preferable to breaking
the axle and having to rebuild the whole wheel.
don’t assume that because the uni is new, the cranks are well fitted
These lessons are the fruit of years of bitter experience both from my own uni
and those of my team-mates. The main point is that prevention is better than
cure and if you get it right first time you never need to have a problem.
Peter
Peter Philip of the LUNIs - London's Unicycle Hockey Team Coordinator of UNICON
VIII - The World Unicycling Convention 1996 +44 181 341 7587 peterp@foe.co.uk
<a href="http://www.foe.co.uk/foe/staff/peterp">http://www.foe.co.uk/foe/staff/peterp</a>
I have had my Semcycle XL for 6 months or so and have not had any troubles with
it. Nothing has ever come loose. I do know a friend (Paul Halter) who got a
Semcycle XL maybe 5 months ago to learn on and he has the loose crank problem. I
learned on an old Schwinn then bought the Semcycle.
> The loss of air on the tire really has nothing to do with the rest of the > unicycle. Check the adjustment of the valve on your tire and your inner tube > for slow leaks. The worst that could happen is that you change the inner tube > which is not a major investment.
This is probably a silly question, but how do you change the tyre? I’ve been
look at my 24" SemCycle and couldn’t see how I could remove the wheel. Do I need
any special tools? I know I’m not very handy, but changing a tube should be
within my abbilities.
As a follow-up to removing cottered cranks. If the key doesn’t come out easily,
put the nut (or better yet, an old spare) back on the key leaving it a few turns
loose. You then can bang on the nut instead of the threads of the key, avoiding
damage to the threads on the key.
>Loosening of cotterless cranks is a common problem, but it can be solved or >(even better) avoided completely in the following ways:
>* seat the crank well on to the axle use a rubber hammer if you can to avoid > damaging the thread so that extracting the crank will be easier. Once the > crank is seat firmly in place the contact between all of the faces of the > axle and the crank should be so secure that the nut should not have to do > much work.
Instead of a rubber hammer, one can use a block of wood and a good sized (24
oz.) regular hammer.
When pounding a crankarm onto a cotterless axle, put a (second) block of wood on
the floor, placing the other end of the axle on top of the block. Now the
pounding force will be transmitted through the axle to the wood rather than
through the spokes, which can be stretched out of true otherwise.
The nut or bolt that screws on the axle is not meant to tighten the crankarm,
but simply secure it in place so it does not come loose. This is particularly
true for unicycles, since torque can be applied in both directions, making it
quite easy for crankarms to come loose!
One should take care not to pound with really excessive force, since that may
possibly cause the crankarm to split or damage other parts of the unicycle. Use
just enough force to get a tight fit; in my experience, it does take quite a lot
of force; I’ve never damaged a unicycle by appling too much force; I’ve never
split a crankarm.