Freewheel (kiddie) stoker
09-08-17, 10:28 AM
#1
Senior Member
Thread Starter
Freewheel (kiddie) stoker
I didn't found a lot of info on that online so I'll share what I did to arrange a freewheel stoker crank for my almost 4-year old daughter. The set up uses front drive with a left side sync chain and a BB mounted high on the seat tube.
I machined some left-hand freewheel threads on the crank shoulder using a lathe. Since the cast crank is a bit irregular it was tricky to mount in the chuck and the threads aren't perfectly centred (but it's pretty close).
I then used a left hand freewheel (used for left-hand drive on some BMXs) and fabricated a chainring adapter. You can also get LH flanged freewheel + adapters on https://www.staton-inc.com
img_20170908_085517-2.jpg
I also considered using a right-hand tread freewheel crank (used on e-bikes and trial bikes). But on the left side they freewheel the wrong way so you need to mount it backwards, but then it'll unscrew under torque. So I bolted a flange to prevent the freewheel from coming off (pretty tricky to do; not a lot of room and small threads are a pain to tap). Alternatively you can use loctite. It should work fine given the low torque of a kid.
img_20170908_085615-2.jpg
In hindsight I think it would be much simpler to use a right side sync chainring in lieu of the third front drive chainring (I have never needed it so far) combined with a regular freewheel stoker crank. You can easily find those and the freewheel + adapters.
I machined some left-hand freewheel threads on the crank shoulder using a lathe. Since the cast crank is a bit irregular it was tricky to mount in the chuck and the threads aren't perfectly centred (but it's pretty close).
I then used a left hand freewheel (used for left-hand drive on some BMXs) and fabricated a chainring adapter. You can also get LH flanged freewheel + adapters on https://www.staton-inc.com
img_20170908_085517-2.jpg
I also considered using a right-hand tread freewheel crank (used on e-bikes and trial bikes). But on the left side they freewheel the wrong way so you need to mount it backwards, but then it'll unscrew under torque. So I bolted a flange to prevent the freewheel from coming off (pretty tricky to do; not a lot of room and small threads are a pain to tap). Alternatively you can use loctite. It should work fine given the low torque of a kid.
img_20170908_085615-2.jpg
In hindsight I think it would be much simpler to use a right side sync chainring in lieu of the third front drive chainring (I have never needed it so far) combined with a regular freewheel stoker crank. You can easily find those and the freewheel + adapters.
