Front Hub Motor with Steel ebike Fork on Dual Suspension?

[OverflySportsmanXY]

Hi,
I have a dual suspension mountain bike that I’d like to electrify with a 36V 350W front hub geared motor with a compatible steel ebike fork. Granted, the removal of the front suspension fork makes the bike a soft-tail, but I only have a front hub motor, and the real strength of this particular bike lies in its rear suspension and gearing, etc., so I’m willing to sacrifice the suspension fork for power and plan to use a 2.4 inch tire to help smooth out the front end.
I plan to purchase a triangle 36V 500W 10ah battery bag and use a separate controller case and mated controller display. I want to do this build so I can enjoy riding some relatively technical singletrack with typical rocks and roots and sharp hills without destroying my lower back while giving me that slight power boost the front hub motor will provide.
Has anyone out there tried this? Did it help with powering through difficult sections and sharp hills on the trail? Any thoughts, advice or suggestions would be greatly appreciated.
Thanks!!!

 

[kmccune]

You sound pretty serious, beware of the handling difference, other wise it should work out pretty good.

 

[Catalyzt]

Didn't do it with a full suspension, but I mounted a 250 Watt kit on an old Trek 900 with no suspension and I love it! I did add a suspension seatpost and suspension stem, which was better than nothing... a lot better.

However, I'm riding mostly on bad pavement with occasional light single track, gravel or trail use, not using MTB tires, more like hybrid or gravel bike tires-- and not doing rock gardens or roots (on that bike.)

It's really hard to predict for your application. Generally, I found I had greater traction with all-wheel drive-- e.g., I could go up hills that I couldn't before because either the front wheel would lift up or the rear wheel would spin... but again, this is on asphalt or briefly on trails.

On fire-road type steeps with a sandy covering, I did find that while I was doing some stuff I couldn't do unassisted, I was getting some front wheel spinning, and keeping a good balance between front and rear tires was tricky.

Another thing I found was that with the 250W front hub motor, the Trek's balance was perfect. The cornering is insane-- before the motor, I sometimes felt like it would fold up on sharp turns, but a little added weight in front made the bike more stable, and with all-wheel drive, I can pull myself through hairpins the same way I can on a front wheel drive car-- corner much faster.

However, with a 500, the front end might be heavier and/or applying just the right amount of power could be tricky.

 

[fauconnier]

Don't do that it's not a good idea. A front hub motor is a good choice only on paved road. The weight of a front hub on the trail, bumps and hills will be disturbing and traction will be very limited. A hub motor has a fixed gearing. Buy a mid motor to make your motor benefit of your rear cassette gearing. Your bike will climb a lot steeper hills.

 

[m@Robertson]

Unfortunately, you don't see front-hub trail bikes for a reason. There's also a reason *quality* emtb's meant for singletrack vs. groomed trails are mid drives. The hub is the wrong tool for the job if its alone.

The weight of the hub is not such a big deal, assuming you don't go bananas on the size. Assuming you do it right and use a geared hub, you will have an underpowered motor thats singlespeed. I *guess* thats livable, but only barely so. What you need to do is ride a hub on singletrack with very low power (I have found 250w output using pedal assist is about right) so you gain a traction benefit without creating a risk of the wheel popping up over a root, and then coming back down pointed in an unfortunate direction and off you go. Either faceplanting or off an edge where you need a parachute to stay out of the hospital.

Doing trails with a powered front wheel takes a fair amount of skill, and *is* rewarding once you know how to do it right. But... I would never do it as the sole mode of power. This is the realm where a pedal-only mid drive really shines.

BTW when I say I wouldn't do a front hub alone this is where I'm coming at that statement from:

Dual Motor AWD Electric Bikes – Case Study: Fat Trail and Hill Climber

Built to conquer the weakness of twin hubs in hills – and eliminate the damage a mid drive does to an ebike’s drivetrain. The bike I call 2Fat did all that.

talesontwowheels.com

and this

 

[PDoz]

Why sacrifice the suspension fork?

If you consider the braking forces going through a 200 mm disc with 4 pot hydraulics - the forks cope with stopping a lot harder than a 350 w motor can drive. Surely most of the modern 36 mm and above forks would be strong enough for a motor? Trying to tune the dampening for that unsprung weight might be interesting.....

Looking at the forks on this thing, they don't look a lot more robust than most emtb's are running https://ubcobikes.com/au/2x2-adv-bike/

 

[JRA]

I'm with PDOz in why not use a sus fork? As long as you use a solid type of torque arm setup the dropouts should be just fine. I have thousands of miles on a rigid carbon fiber fork bike with a 1000w 9c hub motor with no issues.

That said I set up a gentleman with a setup as you are eyeing years ago and he loves it to this day. He has a rather arduous uphill off road journey home from work in a wet climate and really likes the 2 wheel drive aspect, although he gets his rear drive via manual pedaling.

I think the 350w you are looking at is all the power you will need and would suggest the geared Bafang G31x motor. If you spend the money on the right parts you can get a decent torque assist system but a simple throttle based system would work but be fiddly for trail work. I mainly ride varying road surfaces on my front hub bikes and use throttle only but rely heavily on my controller/display cruise control function as I can set it to whatever watt output I desire.

But at the end of the day I do prefer my TSDZ2 mid kit motor that has a decent torque PAS for primarily off road use and the cost to set up is about the same as a hub if you count in a decent controller and torque system.

 

[RunForTheHills]

Holy necro-thread!