semcycle cranks and cotter pins

[Mr G S Walker]

I'm not too sure what type of crank nut semcycles have, but if the discussion is
about a cotter pin for the crank then merely tightening up the nut as much as
possible will be insufficient to tighten your cranks.

The nut is just to retain the cotter pin and does not add extra tension to it.
To tighten a cotter pin, the pin should be tapped with a small hammer from the
opposite side to the retainer nut. The nut should then be tightened (taking up
the slack). Then tap the pin in again and tighten the nut, Repeat until the pin
can no longer be tightened.

If the discussion was about a different crank nut then I'm sorry for this
erroneous explaination, but hey people with cotter pins will at least know how
to tighten them up. Assuming I've been able to explain this clearly.

I remember a not too distant posting asking about the difference between
cottered cranks and cotterless cranks and which was the best to buy. A
cottered crank has a cotter pin fixing the crank on, where as a cotterless one
doesn't (well thats a surprise). Hmm, how to tell if the uni has a cotter pin
is a bit difficult to describe and depends on how familiar you are with bikes
etc. (I'm not).

Just wanting to verify my terminology (I know what I'm talking about but do
you?), the pedal is attached to the crank which is fixed to an axle which
connects to the other peddle. The cotter pin can be clearly seen (if it exists)
on this axle just after the crank. It's a small metal rod going through the axle
with a nut on the other side.

Surprisingly enough a cotterless crank possess no such pin. The crank is affixed
to the axle by a hexagonal fixing or so I believe, but I'm sure there are many
of you out there will put me right if I'm wrong.

It is commonly believed that cotterless cranks are better than those with cotter
pins because cranks without cotter pins are less likely to slacken. Personally
I've had no problem with the cotter pins on my first unicycle (a Pashley, boo
hiss) which went through much abuse, and I suspect that people may dislike
cotter pins because they were unaware of how to correctly tighten them. However
I dare say my defence of cotter pins would dramatically change if I ever had a
unicycle which had ever loosening cranks. I guess what I'm trying to say is that
its a personal choice if you want to avoid cotter pins. Personally I've had no
problem with them.

Hope this was of some help.

Cheers

GAV

[Bill Gilbertson]

>
> I'm not too sure what type of crank nut semcycles have, but if the

Both Semcycle models have cotterless cranks.
>
> The nut is just to retain the cotter pin and does not add extra tension to it.
> To tighten a cotter pin, the pin should be tapped with a small hammer from the
> opposite side to the retainer nut. The nut should then be tightened (taking up
> the slack). Then tap the pin in again and tighten the nut, Repeat until the
> pin can no longer be tightened.

The pins are very easy to shear off from over tightening. I pound on the pin
while applying slight pressure to the wrench turning the nut.
>
> Just wanting to verify my terminology (I know what I'm talking about but do
> you?), the pedal is attached to the crank which is fixed to an axle which
> connects to the other peddle. The cotter pin can be clearly seen (if it
^ should be crank
> exists) on this axle just after the crank. It's a small metal rod going
^ This sentence is wrong
> through the axle with a nut on the other side.
^ should be crank A cottered axle has a single flat spot on each
end and no threads. A cottered crank has a round hole where it
mounts on the axle.
>
> Surprisingly enough a cotterless crank possess no such pin. The crank is
> affixed to the axle by a hexagonal fixing or so I believe, but I'm sure there
> are many of you out there will put me right if I'm wrong.

The axle has a chamfered square surface where the crank arm slips on. The axle
is threaded on the end and uses a large 14mm nut. The cotterless crank arm has a
chamfered square hole in the same plane as the pedal hole.
>
> It is commonly believed that cotterless cranks are better than those with
> cotter pins because cranks without cotter pins are less likely to slacken.
> Personally I've had no problem with the cotter pins on my first unicycle (a
> Pashley, boo hiss) which went through much abuse, and I suspect that people
> may dislike cotter pins because they were unaware of how to correctly tighten
> them. However I dare say my defence of cotter pins would dramatically change
> if I ever had a unicycle which had ever loosening cranks. I guess what I'm
> trying to say is that its a personal choice if you want to avoid cotter pins.
> Personally I've had no problem with them.

Cottered cranks are superior mechanically. It depends on a persons needs re
weight and riding style. Cotter pins are soft, provide only one surface to bear
the entire twisting torque, and tend to elongate the crank arm hole over time.
On my big wheel, I have to replace my cotter pins at least every month.
>
Selecting a uni is like anything else you buy. You need to ask how are you are
going to use it and if you can appreciate a good one. If you are the type that
would buy a $130 bicycle at Kmart, then a <$100 uni will probably do you just
fine. (The $65 price someone quoted for a CyclePro is a steal as they are
selling for $90 here.) No one serious about unicycling would buy such a uni
except as a novelty just like a serious biker would never buy a $130 bike. You
get what you pay for. Every unicycle I would recommend has cotterless cranks.

> Hope this was of some help.

Bill Gilbertson Another kind of nut