SRAM E-Matic 2 speed hubmotor

[Warren]

I hope this is the right spot to ask about this. Someone on ES must know about this motor. It is a 36 volt, 2 speed, geared, rear hubmotor, which SRAM apparently showed last year. It is showing up on several bikes at Eurobike this week, including the Electra Townie Go model. From photos, it appears very small, and is controller limited to 15 mph. Probably no more than 250 watts.

I recall Justin mentioning working on a similar idea. Justin have you pursued your design? I am sure it would be much better than SRAM's wimpy version.

 

[Miles]

http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=34258

 

[Warren]

Thanks Miles! Too bad it has an internal controller. SRAM says it only assists to 15 mph in the US version. That makes it pretty worthless for me. I wonder if the controller would handle 48 volts? That would get it to 20 mph, and make it a useful setup.

[edit] that info came from an e-zine. I just checked SRAM's site. They offer a 15 mph 200 watt version, and a 250 watt, 20 mph version. Clearly, the 250 watt, 20 mph version is for the US. I ride several light, single speed roadbikes. This is looking good.

[second edit] 135 mm spacing. It would work on one of my single speeds, which is built up from an old steel hybrid frame, converted to drop bars. But the other two have 120 mm single speed spacing. I could cold set them to 135 mm, but then I couldn't switch it back to the stock wheel.

Again, Justin's version would be way better, no doubt.

 

[Miles]

Not a very positive report here.. : http://www.pedelecs.co.uk/forum/electric-bicycles/12547-eurobike-2012-a.html

I'm working on a non-hub version.

 

[Warren]

Miles,

I'm not sure what kind of single speed riders these guys are. I have no problem starting, standing up on double digit grades. They are talking about the motor kicking in at 2.5 mph. That is like two pedal strokes. Not a problem for me. And it really saves watt hours, as motors draw huge amps at standstill. Humans produce huge torque, jumping up on the pedals. I don't mind jumping on the pedals to start the climb. Its the two miles after that that starts to drain me.

 

[Miles]

Yes, not a big deal..

It would be great if Justin developed his one, especially with his own controller.. I seem to remember some information about it in the video of a lecture he gave. I'll see if I can find it..

Edit: http://www.endless-sphere.com/forums/viewtopic.php?f=30&t=34972

 

[Warren]

The other thing that would have to go is the rear rack battery mounting. That would need to go in a bracket bolted to the water bottle bolts on the down tube. Interesting that they show the battery in the triangle in their patent drawing!

 

[adrian_sm]

Links to Installation manual:
http://cdn.sram.com/cdn/farfuture/Wsc1TbpSBDuPaq3BA0FWsDJ2mYYemzwBWDFYbViQhA8/mtime:1336490920/sites/default/files/techdocs/gen.0000000004181_rev_a_ematic_frame_fit_specifications.pdf

User Manual:
http://cdn.sram.com/cdn/farfuture/1DMrSJy_oUrIfld8a1J9MILPpIPoJiN--tjugVF67Hw/mtime:1336149469/sites/default/files/techdocs/95-3015-000-000_rev_a_ematic_low_res_for_web.pdf


P.S. I think a lot of the OEM manufacturers are going for motors with integrated controllers since it works well at 250w power levels, and makes for a much cleaner installation on the bike, meaning more eBike makers will go for it.

 

[Toango]

just read about this hub and it looks interesting. here is a bicycle about to be releaseed with it.


The OHM Urban XU450
It will be available in four sizes and retail for $2,899.

http://www.bicycleretailer.com/nort...merican-e-bike-market-new-model#.UUs3_xfbMVA