What crank will I be able to fit in a Schwin Cruiser?

[Skylark]

I recently got a Schwin Cruiser, with a coaster hub/pedal brake, so simple so much fun for cruising around.
But unfortunately the build quality is 100% Pnp special level, absolute garbage spec parts and poor build quality on the frame, sad but there doesn't seem to be much else to choose from in the Cruiser segment. Anyway the cranks use some weird small thread spec for the pedals so none of my normal pedals will fit or anything decent for that matter.

My question is what cranks can be fitted to these frames that use normal pedal threads?
The BB is cup and cone and the shell is 68mm wide, ideally I'd like to use a Shimano Hollowtech MTB crank but the BB has no threads so probably not possible. I'm assuming something like old cup and cone MTB or BMX cranks will be a straight fit?

 

It's a bike like this:

Edited February 27, 2023 by Skylark

[droo]

BMX pedals will probably fit. Standard pedal threads are 9/16", but BMX threads are 1/2".

Otherwise any cranks should fit - if the BB is square taper just get a set of cheap and cheerful square taper cranks and off you go. You say the BB has no threads, so I'm guessing it's a 1 piece - if this is the case you'll need to bin (or donate) the cranks and BB and replace the whole lot.

The 68mm BB shell should be a 1.37" BSA thread which will fit any English threaded BB, so you'll be able to fit whatever cranks you like - as long as the chainline is correct.

 

[Skylark]

45 minutes ago, droo said:

BMX pedals will probably fit. Standard pedal threads are 9/16", but BMX threads are 1/2".

Otherwise any cranks should fit - if the BB is square taper just get a set of cheap and cheerful square taper cranks and off you go. You say the BB has no threads, so I'm guessing it's a 1 piece - if this is the case you'll need to bin (or donate) the cranks and BB and replace the whole lot.

The 68mm BB shell should be a 1.37" BSA thread which will fit any English threaded BB, so you'll be able to fit whatever cranks you like - as long as the chainline is correct.

 

Ok that would explain the weird pedal thread size, do modern BMX cranks still use 1/2" threads?
The existing BB is unfortunately cup and cone with no threads that I can see, could the cups possibly be screwed in?
I was hoping to chuck on a MTB crank, you can get decent ones in the classifieds 2hnd for around R500 and then I can use all my existing chainrings and pedals but without threads on the BB even octolink probably won't work. Are there any options to convert a thread-less BB to threaded, something like those BB30 adaptors to allow threaded GXP or Shimano BB's

[droo]

If there were no threads, how would the BB stay in? And how would you adjust a cup and cone system?

Take the thing out, you'll find the threads.

[Skylark]

40 minutes ago, droo said:

If there were no threads, how would the BB stay in? And how would you adjust a cup and cone system?

Take the thing out, you'll find the threads.

I took the crank out to check the bearings/regrease it and it's old school tech, looks like an old one piece BMX crank from the 80's - the cone nut tightens onto the one side of the crank and that's where you set the preload. Like I mentioned in the op these Schwin cruisers use bottom of the barrel parts.

Edited February 27, 2023 by Skylark

[Skylark]

It's a crank/BB like this:
https://www.parktool.com/en-us/blog/repair-help/bottom-bracket-service-one-piece
 

Edited February 27, 2023 by Skylark

[droo]

5 minutes ago, Skylark said:

I took the crank out to check the bearings/regrease it and it's old school tech, looks like an old one piece BMX crank from the 80's - the cone nut tightens onto the one side of the crank and that's where you set the preload. Like I mentions in the op these Schwin cruisers use bottom of the barrel spec parts.

Ah. I'd forgotten about these. Start looking for 1/2" threaded pedals then.

[droo]

When in doubt, Sheldon has the answer:

https://sheldonbrown.com/gloss_n-o.html#opc

[Skylark]

I had a dig on Google and it seems modern BMX 3 piece cranks still use cup and cone and will work and Truvativ sells an American-to-Euro BMX Adapter that means I could use any BSA thread MTB crank, getting that in South Africa might not be too easy though but it's on Amazon.

https://www.amazon.com/Truvativ-00-6415-027-000-American-To-Euro-Bmx-Adapter/dp/B000VT550K