semcycle cranks and cotter pins

semcycle cranks and cotter pins

Post by Bill Gilberts » Thu, 14 Sep 1995 04:00:00


Quote:

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

Both Semcycle models have cotterless cranks.

Quote:

> 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.
Quote:

> 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
Quote:
> exists) on this axle just after the crank.  It's a small metal rod going

          ^
     This sentence is wrong
Quote:
> 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.

Quote:

> 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.

Quote:

> 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.

Quote:
> Hope this was of some help.

                                  Bill Gilbertson
                                  Another kind of nut
 
 
 

semcycle cranks and cotter pins

Post by Mr G S Walke » Thu, 14 Sep 1995 04:00:00

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