Swapping cranks

I have a suzue hub from about 2004 and I need to change the cranks. I don’t know how universal these things are.

Would I be able to swap the cranks I have on a Schwinn purchased in 1999 onto the suzue?

Thanks.

I would think so… try it out!

A 1999 Schwinn should have cotterless cranks. If you look at the axle between the hub flange and the crank (it’s kind of hard to see it because it’s a tight spot when the cranks are on there) the axle should have a square cross-section at the end If you pull off the cranks it’s easier to see the square, tapered cross section at the end. All cotterless cranks have the same square taper and are interchangeable.

The Suzue hub from 2004 certainly fits cotterless cranks.

An older Schwinn will have cottered cranks. The cranks have an obvious pin running through them right up close to the axle. The pin has a nut on the other side. The end of the axle is round with with a flat cut into it to accept the cotter pin.

If they are both cotterless the cranks should be held on by 14mm bolts that thread into the axle. You may need to remove dustcaps that are covering the bolt at the axle. There is the possibility that the caps are an 8mm allen key bolt too. In this case there would be no dustcap.

Regardless of the bolt, you’ll really want (i.e. need) a crank puller to make the swap. Make sure you get one that does what most bike shops will refer to as square taper. Without the tool it will be an incredibly frustrating experience.

Square taper and cotterless are the same style. The nomenclature developed to square taper when ISIS came along.

Overall, square taper (or cotterless) cranks are pretty cheap). It is probably worth it to just buy a new set rather than borrow from the other uni.

One last thing to note After swapping or installing new square taper cranks, be sure to check the crank bolts for tightness REALLY frequently. UPDs will cause them to loosen very quickly. Carry the proper wrench with you.

After a while they should settle in, but if they get loose and you ride them loose, you’ll be in the market for a new set of cranks!

Based on knowuni’s encouraging if not overly informative post, I did in fact “try it out”. It worked.

Greg on matters mechanical you are to my knowledge never wrong and your post gave me a great deal of confidence that I had made the correct choice.

Unigoat, I did take it out for a 9 mile ride and brought along the tools for tightening, which I did not need but will use to keep things tight before my next ride.

I thank you all for your assistance.

What happened is that the right pedal loosened in the crank and no tightening would keep from slipping. Since I am very sure I had the cranks and pedals on the proper sides, I’m guessing that after about 2,000 miles it was time for something to wear out. Every mechanical failure is an opportunity to pick up a new skill. I don’t particularly like the pedals that came with the Schwinn on the 29"er, so at some point I’m going to have to figure out if the threads on the crank or the pedals got stripped or both.

Glad to hear it worked!

The pedal interface shouldn’t wear out for a long, long time- if ever. In the grand scheme of cranks and pedals, 2000 miles isn’t that far. In the case of unicycling, one of the most common causes of pedal loosening is riding backwards (assuming the cranks are on the proper sides to start). We’ve had riders in the gym nearly completely unscrew their pedals when practicing riding backwards.

Overtightening can be a problem too. When checking the crank bolts or pedals, make sure they’re tight, but don’t tighten them if they are. Sorry if this sounds like common sense, but I’ve seen people ruin things by ham-fisting them.

That being said, if something is stripped, it’s most likely the threads in the crank- the steel on the pedal axles are typically harder than the threads in the steel or aluminum crankarms.

In these matters I am always reminded of the narrator’s friend in Zen and the Art of Motorcycle Maintenance. It is said of him that he knew nothing of motorcycle maintenance choosing instead to buy pricey and supposedly reliable BMWs on the assumption that nothing would go wrong and his ignorance wouldn’t be an impediment to riding.

I have always tried to buy the best equipment I could sort of with the same mindset.

But as we know, something always goes wrong, and I am just now catching up and trying to develop a bit of self-sufficiency.