Wanted Spiderless square taper cranks?

[tenbikes]

Warning!! It might depend on the model of Bafang mid drive ,but...

When I fitted Middleburn cranks to mine it off set the pedals by quite a long way. 20mms or so.

You need Lekki Bling cranks which are asymmetric off the bike, but balance everything out when fitted. Cost c £120 new.

My motor is the hd type for 100mms fat bike bb.

You might be ok with other models of Bafang but my expectation is that all models will have the same issue.

 

[Mickeyspinn]

Warning!! It might depend on the model of Bafang mid drive ,but...

When I fitted Middleburn cranks to mine it off set the pedals by quite a long way. 20mms or so.

You need Lekki Bling cranks which are asymmetric off the bike, but balance everything out when fitted. Cost c £120 new.

My motor is the hd type for 100mms fat bike bb.

You might be ok with other models of Bafang but my expectation is that all models will have the same issue.

Very true....I dont have experience of the 36v bafang mid drive but do with bbshd....to get a good chainline....a sensible tread width and most importantly equal tread between left and right can take a bit of effort!
I've managed to get my tread to 198 and equalised l to r and get Bob on chainline on a sturmey..
Yes you can just fit em...but nothing really lines up! Worth doing tho great motors I've had zero reliability problems .

 

[ishaw]

I've got a set of xt ones which I've already pinched the spider from. I forget the model, m750? Got them cheap so don't want a lot for them.

 

[grey-beard]

I've got a set of xt ones which I've already pinched the spider from. I forget the model, m750? Got them cheap so don't want a lot for them.

I'll keep that in mind, thanks.

 

[FluffyChicken]

A quick look at the motors and it looks like you'll be wanting stuff that is the super low/low profile design as they'll just stick the pedal further out?
You need something designed, in old terms, for 122.5mm bb's
?
Grab some old MT-60, M730's and chop and grind the spider down to make it good?

I could be wrong and looking at the wrong motors, or you don't mind having pedals further apart.

 

[grey-beard]

They really do need to straight, low profile but not too low, as they can hit they motor in the nondrive side. I've some specialized strong arms on the way and possibly Middleburn rs7, I'll post some pics when I get a chance.

 

[Mickeyspinn]

As fluffy chicken has pointed out early cranks are your most likely way of fitting or go with lekki cranks....what motor are you fitting? If your going with a bbshd then you'll be ok modifying cranks as your not really applying much torque through them if any really other than at a high cadence!
But I wouldn't recommend modding lightweight cranks or CNC cranks.

These are cranks from a 122.5 BB...a tiny shave was taken just to keep the gap equal over the motor...gaps about 2.5mm.....you won't apply enough grunt to flex them to touch the motor.
Standard bafang crank that gap would be around
8-10 mm...and boy those cranks are soft mushy junk!

 

[FluffyChicken]

If you want a small amount of profile (just low profile in Shimano terms, XTR/737 style are super low profile), then Suntour MicroDrive cranks are in between.
Again you'll need to modify the spider to loose loose it, aka saw.

 

[grey-beard]

It is a bbshd that I'm using. It is wide compared to the lower powered version, which can cause clearance issues.

 

[Mickeyspinn]

It is a bbshd that I'm using. It is wide compared to the lower powered version, which can cause clearance issues.

Great choice bbshd so 48v? my advice is to fit the motor to the frame before thinking of cranks and get measuring. I don't know what gearing your thinking of but essentially you don't need many gears! Get it right one is all the motor needs however peddling becomes impossible then! I'd personally recommend leaving derailleur gears behind for longevity of chains sprockets etc. Your now dumping torque a moped could only ever dream of from zero rpm through a bicycle gear train.....it doesn't last! The issues you'll have will be chainline using the standard chainring at 46 tooth,clearance to chainstay and then equalisation of tread.