Hi All, I have just noticed that my crank arms seem to have a little bit of movement when riding, especially noticed while idling.
Upon examination, I found that my right pedal was loose. I tightened it and thought it was fixed. Didn’t notice the problem for a few more days.
Now, last night, I noticed the slight movement again. Pedals are tight. However, it feels like the cranks more slightly, instead of being rigid.
The Schwinn 24" has the original cranks (from around 1976) still on it. I do not know the name of the parts, but they look to have a smooth crank arm sticking out fo the hub. Then the end of the crank has what looks like a headless but tapered bolt sticking through the end of the crank arm, secured with a nut.
How do I tighten these? How do I check to see if they are worn out? Can I get replacements? Thanks in advance. --chirokid–
Cottered cranks use a cotter pin to keep the crank from spinning on the axle.
Cotterless cranks have a tapered square hole in the crank.
I don’t have a real clear picture that shows how a cottered crank fits on a unicycle hub. There are some pictures that show the parts, but the pictures don’t show how the parts fit together. Hopefully these pictures will be enough to allow you to identify if you have cottered cranks.
If you have cottered cranks you may want to take it to a bike shop and see what they can do. Cotter pins can be very finicky to get tight. There are several different sizes of cotter pins. If the hub has too much wear on the flat area where the cotter pin squeezes it may be impossible to keep the cranks tight.
If it’s a 1976 (Bicentennial!) Schwinn, it’s cottered. Cotter pins come loose from motions such as idling and general riding. They hold a lot better on one-way bicycles.
Here is the low-science method my friends and I used, back in the days when we were stuck with cotter pins [DISCLAIMER–use hammer with care!]:
Learn to detect the feel (or sound, on cotterless and splined) of loose cranks. Or pedals. Riding with either one will wear away important threads.
Apply hammer to cotter pin. Hard rubber mallet is better if you have one, but if the cycle is assembled with air in the tire, the shock will be reduced. Bang bang bang. Careful what you’re hitting.
Tighten the nut on the other end. If it has a flat washer, replace with a lock washer. Do not overtighten, as cotter pin metal is Soft! Intentionally softer than crank and axle metal.
Repeat steps 2 and 3 until the nut doesn’t tighten any more.
For better pounding results, rest the crank on a block of something hard, so the tire doesn’t bounce away the force of your blows. Make sure the bottom end of the pin is not resting on your block, of course.
If the cotter pin extends out the bottom beyond the threads, that pin is done. Use a punch, if necessary, to pound it out from the bottom, and take it to the bike shop. You need to find a shop that still has cotter pins, which may take a few tries. Bring the whole unicycle, and see if they have pins that are slightly bigger, or have less of a cut on them.
If step six is unsuccessful, there are two choices:
a. Low budget repair: Weld the cranks on. This is a one-way trip!
b. Hang cycle on wall or in garage. Buy new unicycle with cotterless or splined cranks.
Your question has already been answered but I feel obliged to reply as a fellow owner of a “Bicentenial Schwinn”.
I tried to remove my crank a while back, the cotter pin was so stuck I couldn’t drive it out to save my life. Seems it is as good as welded for now. Its currently on loan as a trainer, will be interesting to see if use will loosen it.
Thanks for responding UniBrier. I started to try and remove mine last night, but then decided to wait until I get to Unicycle.com tomorrow. My motive was thinking they might have a trick for removal :D, but I’ll just wait and see.
I do plan to buy two new cotter pins and a new original tire while I’m there. --chirokid–
Cotter pins are the invention of the devil. 'Orrible things. They work loose at inopportune moments, then snap when you try to tighten them.
To remove a stuck cotter pin, get a punch or use a small tommy bar as a drift. Line it up straight with the axis of the cotter pin at the threaded end of the cotter pin (after removing the nut and washer…) then strike the punch/drift sharply and hard, with follow through. Most people use hammers ineffectually; the follow through is important. usually, one good thwack in the right place will fire the cotter pin out of the hole, whereas 124 tappity taps will just leave it there grinning at you.
You also might want to get more than one set of cotter pins. I used to use quite a few of them on my first uni. Of course, I didn’t know what I was doing back then, but it doesn’t hurt to stock up (and besides, they’re the cheapest thing to replace on a uni).
