29er ground clearance on mtb?

[monkeyra]

Hi all. Been reading up on mid drives, must say it floats my boat. I'm thinking of adding a mid drive to my full suspension 29er which I use for mountain biking only. Ground clearance looks slightly compromising though, anyone here use the same setup? Is ground clearance adequate or is there a chance of striking the motor?
I also do a lot of wet, muddy riding. Are these things capable of withstanding that?

Thanks

Nick

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[Deleted member 4366]

It depends on the shape of your frame around the bottom bracket. Many modern ones go horizontal for a few inches before going up to the steering head. That horizontal bit forces the motor down . If your frame goes up directly from the BB, the motor can be positioned much higher behind the downtube.

Best would be to show a picture of your frame.

 

[Nealh]

I have 26" wheeled Cube FS with BBS01 no ground strikes unless you try and go over a 6/8 inch obstacle. Pretty much waterproof, I don't shy away from mud or water when off road. In fact it was pretty well wet and boggy on my Surrey Hills ride today, the bike, motor and me got well caked.

 

[Kinninvie]

My Trek 6300 and Cannondale MTB both have BBSHD fitted and never had a problem on any trails in Hamsterley Forest.
My BBS02 regularly goes through a ford where the water is over the top of the motor and never been a problem in almost 3 years of use.
As D8veh says it depends on the shape of the frame immediately in front of the BB.

 

[monkeyra]

Cool, good to know, thanks. The frame I've got is a carbon one, assume no issues with that and mounting the motor? Let me see if I can add a photo...

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[monkeyra]

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[Nealh]

Be careful there;s not much leeway for fitting BBSxx with carbon BB if there is too much material thickness.
A brief look at your pic seems to suggest you will be alright.

 

[Deleted member 4366]

The BBSxx motors are for standard BSA/Shimano bottom brackets. You'll have to make Some adaptors for yours.

As said, you also need to check the thickness from the theoretical 35mm diameter to the thickest part of the frame around it. IIRC, 6mm is the max. You might have to file away some of the frame and patch it from inside the bottom bracket.

When I fitted one of those motors to a carbon fibre frame, I also had to grind off two webs behind the bearings to get the 35mm for the shaft to pass through.

Finally, you need to think about anti-rotation of the motor. If you rest it against the frame, it could wear through, so you'd need a reinforcing plate. The motor has a clamp that clamps on the BB to stop it from dropping down when the power is off, but you can't do that because your adaptors will rotate in the frame and carbon fibre isn't strong enough to take a clamping force anyway. That means that you'll need to think of a way to stop the motor falling down. I used a custom plate that went up to the suspension pivot point and was fixed there.