which motor for BMX

[tomchester999]

Ok guys I think I am going to build a bmx, I'd like to use a rear hub but are there any that would have suitable windings for the small bmx wheel.

Im going for about 2.5kw ideallly

I was going for the 9C 9x7 for my project but now I've decided to use a bmx frame.. or is this a bad idea.

It's just going to be for fun and bombing round town no long distances comfort required!

thanks

Tom

 

[dogman dan]

Look at Ebikes-ca for the right motor winding 9c for 20" wheels. You could use the 9x7, if you wanted slow and better hill climbing. But for bombing around town, I assume you want speed? So for that use the faster windings offered at Grin.

 

[Ypedal]

http://www.ypedal.com/eBMX/BMX.htm


I love my BMX,small bike, big fun, !

The X5 was a bit overkill * (unless you like that kinda thing ) but at 2000w or so a 9C is a nice pick, for max grin factor check with Methods for a 6x10 and run it at 100v in that 20" ! :wink:

 

[Ypedal]

also, remember that the rear frame on a BMX is not 135mm like a regular 7 rear speeds bicycle frame, it is narrower with a single speed freewheel so using a front wheel motor works easiest... :wink: *( might have to skip the chain )

 

[tomchester999]

thanks for the info ypedal!

I guess a chain is not essential but is there any easy way of doing it (without re-engineering the rear dropouts/frame)

right I am almost buying my battery.

I have asked for 100A normal discharge current (although i will use a 45a controller) as I may wish to use the battery for something else later..(lifepo4)

Is there any problem with running a high discharge rated battery with a smaller controller? probably a sill question..

thanks

Tom

 

[wdwrkr51]

Hey, dude.

Given the inherent strength of the typical steel BMX frame and forks, a front mount motor works well - the batteries on a rear rack tend to balance out the load. You can keep the chain drive and help out on the hills or starting off as needed. See the gocarlite website for a writeup about using an AMPED BIkes 9C 9x7 motor at 36 volts in a BMX build. I'm strongly considering doing the same. Already have the bike and have planned for Hobby King Turnigy battery packs to keep it light. That would be my 3rd ebike build, and my fourth is just about as far along.

wdwrkr51

 

[Arlo1]

I would build it for easy upgrades!!! SO I would start with a 9c or x5 in the rear and just up the power and the cooling and beef up the drop outs as you feel the need for speed!!!
I dont like front drive bikes my front wheel is in the air to much to bother driving it!!!
But seriously the 9c is a nice wheel and good for lowe power like you want but if you might want higher power one day then a x5 might be in need.

 

[Arlo1]

You can also consider a rc type motor they have some big advantages!! Incl weight reduction and gearing changes!

 

[def215]

rc motor might be the best bet for that. i put a brushed unite motor on my bmx and its not the greatest thing in the world. but with wahtever route you take, hub or rc, it should end up being fun.

 

[FMB42]

Also keep in mind that excessive spoke angles can sometimes be a problem with the smaller BMX wheels (especially with the larger diameter hub motors).