Size and tpi for hub motor shaft?

[Crash Machine]

I'm trying to figure out a way to switch to a rear motor/dual drive but I still need to use my BOB trailer. Biketrailershops has one set of Bob nutz that have a hole through it that may be used to pass wires through. The thread is 10.5 mm x 26 threads per inch for use with the Sturmey-Archer hub. I'm just wondering what the size and thread per inch for a hub motor is?

 

[justin_le]

I'm trying to figure out a way to switch to a rear motor/dual drive but I still need to use my BOB trailer. Biketrailershops has one set of Bob nutz that have a hole through it that may be used to pass wires through. The thread is 10.5 mm x 26 threads per inch for use with the Sturmey-Archer hub. I'm just wondering what the size and thread per inch for a hub motor is?

Just about all the ebike hub motors fall into two axle standards. One is 12mm x 1.25mm pitch, the other is 14mm x 1.5mm pitch, in both cases ground with 10mm flats. Most rear hub motors these days (ex. eZee, BMC, Nine Continent, Clyte 5300 series) use the 14mm standard, though a few like the Crystalyte 400 series are 12mm.

You might be able to drill and re-tap the 10.5mm sturney archer nut to fit over a 12mm axle, but there's probably not enough metal there to do that with for a 14mm.

Justin

 

[Tiberius]

Just to add to what Justin says, they are usually metric threads, but beware they aren't the standard M12 or M14 type.

When people say M or Metric threads they usually mean Metric Coarse. Motor axles are the same OD but finer pitch. I'd be careful about calling them Metric Fine, because not everyone agrees what is Fine, Super Fine, etc.

For instance, M12 Coarse is M12 x 1.75 mm and I've seen M12 Fine listed in different places as M12 x 1.5 mm and M12 x 1.25 mm. Its better to quote the actual pitch.

Nick

 

[Chalo]

I'm trying to figure out a way to switch to a rear motor/dual drive but I still need to use my BOB trailer. Biketrailershops has one set of Bob nutz that have a hole through it that may be used to pass wires through. The thread is 10.5 mm x 26 threads per inch for use with the Sturmey-Archer hub. I'm just wondering what the size and thread per inch for a hub motor is?

Why not use another kind of trailer instead? Your conversion is going to cost money anyway. With a bigger trailer, you can even put your batteries in there while keeping equal or better cargo space.

Another option is to make a hybrid of a BOB and one of those trailer kidbike things, grafting the hitch and front arm from the trailer bike onto the cargo platform of the BOB. That would probably handle better anyway on account of the trailer pivot being forward of the rear axle.

 

[Crash Machine]

Another option is to make a hybrid of a BOB and one of those trailer kidbike things, grafting the hitch and front arm from the trailer bike onto the cargo platform of the BOB. That would probably handle better anyway on account of the trailer pivot being forward of the rear axle.

Good idea I've actually got one lying around(kid trailer) with bad axle bearings. I may just get the baddest front motor I can find. I like my front hub. X5 maybe...Thanks for all the info guys.

 

[justin_le]

Just to add to what Justin says, they are usually metric threads, but beware they aren't the standard M12 or M14 type.

When people say M or Metric threads they usually mean Metric Coarse. Motor axles are the same OD but finer pitch. I'd be careful about calling them Metric Fine, because not everyone agrees what is Fine, Super Fine, etc.

For instance, M12 Coarse is M12 x 1.75 mm and I've seen M12 Fine listed in different places as M12 x 1.5 mm and M12 x 1.25 mm. Its better to quote the actual pitch.

Nick

What Nick says here is very true. I have some pretty useless M14 x 1.25mm and M12 x 1.5mm tap sets in my toolbox now for having made the same mistake!

Few off-the-shelf metric tap and die sets from hardware stores will have the correct thread pitch in them, you usually need to go to more of a specialty shop.

Justin

 

[Tiberius]

Justin,

You need a lathe with a metric leadscrew.
I had a device earlier this week with an M6 x 0.5 mm thread - the simplest solution was just to make something to fit.

Nick

 

[fechter]

Nice to see you Justin! Long time, no post.

I found some nice extra beefy nuts at my local auto parts store. They are lug nuts for a Chevy Suburban or something (14mm-1.5). The extra thick threaded section of the lug nuts makes them less prone to stripping the threads.

 

[justin_le]

Nice to see you Justin! Long time, no post.

Hey Fetcher, yeah, it's good to be back in the sphere! I thought I'd take time out from 'public' life this year in an attempt to better focus on some things, but that was a mistake. Glad to see so many good faces still around and contributing so. But sad to see no NutsAndVolts ??

I found some nice extra beefy nuts at my local auto parts store. They are lug nuts for a Chevy Suburban or something (14mm-1.5). The extra thick threaded section of the lug nuts makes them less prone to stripping the threads.

Yeah I remember Lowell actually using and suggesting these as a source. They are apparently also useful as foot pegs when you're doubling up with a girl or two on the rear rack.

 

[Mammalian04]

Holy Thread Revival Batman!!!

Anyone figure out how to make the Bob Yak work with the 14x1.5 axles? I found a good deal on a Yak and didn't even think about verifying that mounts exist.

An expensive option would be to use the Chevrolet lug nut nuts and have them turned down on a lathe to fit the Yak trailer but that seems $$$.
Another idea is to have a plate fabricated to mount Bob Nutz to the brake caliper mounts, though that sounds expensive too.

Any other solutions?

 

[d8veh]

Two plates with a 14mm hole for the axle and a 6mm hole for the trailer pins, which will sit just behind the axle.