C'lyte 3540 in 20" BMX rim, spokes?

[Kabbage]

I am thinking of putting my big crystalyte 3540 into a 20" BMX rim to make a little fun electric farm-bike for my nephew.

I have used the calculator on Ebikes.ca, and recon it is still capable of 40kph at 48v and 30 odd amps; hopefully some good torque in the 20" rim.

Any advice about spoke arrangements? 1 cross, or straight out zero cross? They're gunna be short spokes - I am worried 1 cross will make them enter the rim at too-large an angle....

Was thinking 11/12 double butted spokes from JRH... Any other advice

In Melbourne, aus.

 

[voicecoils]

I am thinking of putting my big crystalyte 3540 into a 20" BMX rim to make a little fun electric farm-bike for my nephew.

I have used the calculator on Ebikes.ca, and recon it is still capable of 40kph at 48v and 30 odd amps; hopefully some good torque in the 20" rim.

Any advice about spoke arrangements? 1 cross, or straight out zero cross? They're gunna be short spokes - I am worried 1 cross will make them enter the rim at too-large an angle....

Was thinking 11/12 double butted spokes from JRH... Any other advice

In Melbourne, aus.

I've built zero cross and 1 cross wheels with the the 35XX motor (and others the same diameter) in 20" BMX wheel and using the same 11/12G butted spokes.

Zero cross is very high maintenance no matter how thick or thin spokes you use. You'll be truing, tensioning and replacing spokes regularly. It does work, but just barely.

1-cross is just possible by drilling the rim spoke holes out till the point where the spoke nipple can sit at the necessary angle. But, that angle is extreme and makes the wheel build super tedious, particularly if you use a double wall rim.

Alternative is to use a 17" rim (the Holmes MMP rear is a good choice) and then you can get 1 cross with good spoke angles, build the wheel up much more smoothy, better rim strength and fit a moto tyre that will last ages. It's at the expense of extra weight but all the other positives overcome that in my view.

 

[Tench]

+1

I have just built a 17" moped rim onto an HT3525 motor, one cross with nice strong spokes all sat at comfortable angles. There are areas where I have tried hard to save weight but with a heavy hub motor the rim and tyre is not one of them.

 

[Kabbage]

Alternative is to use a 17" rim (the Holmes MMP rear is a good choice) and then you can get 1 cross with good spoke angles, build the wheel up much more smoothy, better rim strength and fit a moto tyre that will last ages. It's at the expense of extra weight but all the other positives overcome that in my view.

Nice answers guys, Thanks.

So, recommendations for where to buy these 17" rims and moto tyres from? Those spokes are going to mighty tiny in a 17" rim though, aren't they?

Also, since I am not in the business of building my own wheels, who would I get to do this sort of thing? LBS? or would they freak out? Are there moto mechanics who do this sort of thing? May have to find a youtube video about how to do it. And re-read the sheldon brown info...