BMX left hand drive

I have a brushless RC motor which I setup for no.25 drive on a scooter, but the first time I took it out, I broke the fork.

I also happen to have a no.25 sprocket which I machined onto a 16t freewheel many years ago (I made it not freewheel anymore).

I noticed my 24" bmx bike has threads on both sides. I'm assuming that's for flipping the wheel around, not a left hand ebike drive

Is there some way to thread that sprocket on the left hand of the rear wheel and get it to stay?

metal re-enforced epoxy...
look at dp-460
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.Xdp-460.TRS0&_nkw=dp-460&_sacat=0

This looks like a one way solution?

you could blow torch it off....

but its a option for gluing on an adapter on threads that are not favorable to left side drive.

fitek said:

I noticed my 24" bmx bike has threads on both sides. I'm assuming that's for flipping the wheel around, not a left hand ebike drive

Click to expand...

Have you actually checked that both sides have R.H. threads? Dual drive BMX hubs (RH drive plus LH drive) used to be available: https://endless-sphere.com/forums/viewtopic.php?f=28&t=9342&start=70

The most common double threaded BMX hubs are those with 1.37"-24 RH threads on one side and M30x1 RH threads on the other. There were a scarce few in the mid-1990s that had RH and LH threads in the same size, and you can still find 16 tooth LH freewheels for them.

Some Currie e-bikes had RH/LH threaded hubs, and last I checked there was an EV parts seller still offering them. They're not very nice quality, but equivalent to what you'd find on a cheap 21 speed MTB with a freewheel. They are rebuildable and can easily be respaced to 110mm for your BMX bike.

Staton-inc.com has nicely made but poorly designed RH/LH hubs that can't easily be respaced. I mention them in case you're handy enough to consider making a different axle, because their axle is both the wrong width for your bike and flawed by design.

All these options presume that you can buy or make a LH threaded sprocket for your bike. But there is another option that doesn't.

If you get a fixed/free track bike hub (normal freewheel thread on one side, fixed gear thread with LH threaded lockring on the other, common these days), then you can attach a track sprocket or any other comparable thickness RH threaded item and lock it in place with a track lockring.

Back in the day, I made a big 144t #25 chain sprocket that clamped onto a 16t LH freewheel with an 8-bolt pattern that meshed between the teeth. That was the left side motor drive for my own first e-bike.

.

A couple of RH/LH drive BMX hubs that I bought when they were still available.

Those DK Dual Drive hubs were the ultimate. M30x1 RH and LH threads, plus 1.37"-24 RH and LH collars that threaded on over the metric threads. You could use any available single freewheel on the same hub. I wish I'd had the foresight to buy some while they were around. (But I always wondered whether the threaded collar would stay with the hub or the freewheel when you took off the freewheel.)

I did bag a couple of Specialized RH/LH hubs that were drilled for 36 spokes-- very convenient, given that most BMX hubs in those days were 48 hole.

The DK hub guards weigh almost half as much as the hub itself..

FWIW, the Grubee hub still seems to be available: http://www.pistonbikes.com/product-p/gruhdak.htm That's 135mm O.L.D.

Those older ones being highly adaptable sound awesome, but I can't think for much need of all that, and what about the cost vs (example) $30 shipped joytech 32-36h?

If you get a fixed/free track bike hub (normal freewheel thread on one side, fixed gear thread with LH threaded locket on the other, common these days), then you can attach a track sprocket or any other comparable thickness RH threaded item and lock it in place with a track lockring.

Click to expand...

[strike]If you have to lock the left side in place with lockring, doesn't that mean it's LH thread?[/strike]
Never mind I was confused- my fixie has matching RH 1.37x24 thread on each side, and the fixie portion is smaller LH thread for the 'fixie' nut.

I would have preferred a disc flange on left, but the bearing/race dimensions and 1.37x24 on rightside were key.
Good hub and flange. It's what I designed my dual FW adapter with 3rd bearing around. ~30$
http://www.ebay.com/itm/JOYTECH-32-36H-Fixed-Gear-Rear-Flip-Flop-Hub-for-Fixie-Track-Single-Speed-Bike-/161218916127?var=&hash=item2589656f1f:m:mYbzTqaGNqnUfx1fmfCVjwg

I know there is a temptation to try and find some holy grail "silver bullet" solution, but...consider spending an extra $100 to add a jackshaft to the middle of the drive, and that opens up a whole new world of options.

Right-side primary reduction, then a left-side chain to the rear wheel, freewheel somewhere on the jackshaft. Just a thought...

Yes I'm thinking I should leave this wheel alone. The bike is a Haro Pro 24 in excellent condition https://www.harobikes.com/race/bikes/2015-race/pro-24-2015
Too nice to hack up.

I was going to put my RC motor on a Downtube folder (I even had mated a no.35 sprocket to the 8 spd Sturmey Archer wheel) but I left the bike up in PDX when I was there for a bit last year, though I still have the wheel since the massive go kart sprocket didn't fit in the bag I checked in for the flight (I hastily threw on a coaster brake steelie which disintegrated going up a hill on day 1, sheesh).

I found a 20" bmx frame by the side of the road but it's missing quite a few pieces, rear wheel included, however the Sturmey Archer is too wide for the drop outs. Since the bike was free and is in fair condition, I'm thinking I use a torch and bend those chainstays so it fits.

A mid drive would be cool, but I remember it being kinda complicated when that approach was being pioneered here years ago w/ RC motors (which is about when I checked out of making ebikes).

If you run a jackshaft, it is typically for extra reduction and/or to combine crank and motor power into one chain going to wheel, right?

Besides added weight/complexity/cost/upkeep, neither of those things appeal to me as you lose benefits of parallel like redundancy and I would assume all pedal gears.

If I got the facts strate, maybe it would be more appealing with higher power than a hub or motor FW can handle, and/or for a high kv motor, and/or for no pedals or one pedal gear.

(i guess you coouuld use a roloff or front deraileur to get some bike gears w/ jackshafts? Tho that wouldn't appeal to me either because of either high cost or space.)

Originally I had wanted to build an RC powered bike that didn't need two stage reduction. I figured I could get close by using go kart sprockets and a small wheel.

The first scooter had a very small wheel... Like six inches. The reduction wasn't much but you don't need much with a wheel that size. It was a torque monster with a top speed limited by the controller shutting down at high current. Top speed was probably 10mph. It was next to impossible to ride though because unless you had a very light touch it would buck you off.

So I adapted it for a scooter with something like a 12 inch wheel. Unfortunately I tried to bunny hop it after about ten seconds and the fork broke when I landed.

I was able to muscle the sturmey archer wheel into the drop outs but the axle is way too small. I think I'm best off retrieving my down tube frame from Portland. Unfortunately that won't be till July.