Electric Bikes - Brushless Hub on Shocked Front Wheel

I've been told not to put my Wilderness Energy brushless 36V hub on the front of my Giant Cypress because it has front shocks. I can't remember why I shouldn't do it, so I did it.

What will happen to me and/or my bike?

By the way the 48 km commute is a lot smoother now I'm running with the shock.

"Our hub motor is not recommend for bike with front shock forks or bike with front aluminum fork. Please click here to view the dimension of the fork requirement that must fit a 26" rim. Shock fork can flex too much and aluminum fork is generally not strong enough to handle the hub motor torque - breakage can occur" Warning found here (http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2039) also here (http://www.ecrater.com/product.php?pid=62403)

I have no technical expertise on the subject but I would not think a front shock would be designed to handle the force put on it by a hub motor. I'd be worried about it snapping the shock eventually depending on it's design or at least wearing it excessively.
I used to have a front suspension fork on my bike. It is nice if you don't have alot of hills. I had alot of climbing and I couldn't lock it out so it sucked. I didn't enjoy pogoing up a hill.

Edit: A number of electric scooters have hub motors and use shocks both on the front but I don't know if they design the suspension with that in mind, i'd hope so if it were neccessary.

The reason that you're told not to do this is that forks in the first place aren't really meant to take any torque on them. The front fork holds your front wheel, but the rear axle is normally where the torque is applied when riding. Adding a system that then generates a considerable amount of force at that point can be acceptable for strong front forks, but most suspension forks may eventually give into the stress.

If you had an aluminum fork, i'd just suggest removing the hub, dont risk it. The danger of your front wheel coming off during riding is much more significant than a rear wheel oriented accident.

If steel, or another high strength setup:
My suggestion would be to check your fork regularily and make sure your lowers aren't becoming bent or weakened, understand the increased risks. Also understand that you may eventually permanently damage your front fork. Use some strong nylon capped bolts and a locking compound to make sure it doesn't come loose in there.

If you absolutely have to use a front drive kit, here is a suggestion:
Pedal first, or use a PAS instead of an immediate start throttle. The biggest threat to the integrity of your fork is right when you start. Not using the motor at that moment will make a world of difference.

The fork can definetly handle having the motor on there at cruising, its starting thats the issue.

Now the initial scrum has died down, let's think about the real issues here:

Wheel spin (Hall effect)
Aluminum vs Chromoly forks
Shock failure


To address the first issue that the hub may come loose and separate from the fork; please be aware that my fork has a notch for the hub to fit into. As long as the bolts are tight, and the wheel does not come off the fork, that will not be an issue. I have 7 months experience on a non-shocked Giant Cyress and I know these bolts never came close to being loose. Myth busted!

The aluminum/Chromoly issue rages on. The real concern for the manufacturer is that there be enough space for the fork to accept the hub. Aluminum doesn't like being bent. You can pry open a chromoly fork to fit a hub and have no failure. Myth busted!


Ah, shock failure! you may have me there as I have no idea if my shocks might fail, but I'm not sure that a spinning wheel will make them fail. One writer suggested it might be okay with a pedal first system. That's what I have, and other than the extra weight on the front wheel (that a pannier may also incure), I don't really see why a pedal first hub would add so much stress.

Oh, never mind.

Now the initial scrum has died down, let's think about the real issues here:

Wheel spin (Hall effect)
Aluminum vs Chromoly forks
Shock failure


To address the first issue that the hub may come loose and separate from the fork; please be aware that my fork has a notch for the hub to fit into. As long as the bolts are tight, and the wheel does not come off the fork, that will not be an issue. I have 7 months experience on a non-shocked Giant Cyress and I know these bolts never came close to being loose. Myth busted!

The aluminum/Chromoly issue rages on. The real concern for the manufacturer is that there be enough space for the fork to accept the hub. Aluminum doesn't like being bent. You can pry open a chromoly fork to fit a hub and have no failure. Myth busted!


Ah, shock failure! you may have me there as I have no idea if my shocks might fail, but I'm not sure that a spinning wheel will make them fail. One writer suggested it might be okay with a pedal first system. That's what I have, and other than the extra weight on the front wheel (that a pannier may also incure), I don't really see why a pedal first hub would add so much stress.

Oh, never mind.

I'm kinda curious. Were you replying to someone who had their post deleted, or mine in particular?

The reason I wouldn't suggest aluminum in that situation is that with the motion created by the motor, it encourages the fork to flex for a moment during initial acceleration. Something which over time, is not great. Once again, that could be avoided with pedal-first or PAS.

One thing is that suspension forks are simply not made to be bent open. It doesn't matter if its steel, aluminum, carbon, magnesium, whatever. Your pieces are designed for maximum strength during motion when they're all in perfect alignment, changing that alignment could mean that your lowers are at a slightly different angle from the rest of the fork now. Attempting to do so on an aluminum or magnesium fork would likely permanently ruin the fork just from installing the hub. With the others, I just don't think it would be a good long term plan.

As for it coming off the fork on its own accord, no. As long as your bolts were tight and proper, bolts don't care if they're on a suspension fork or not, they work all the same. Still, keep them tight or you'll face problems, same with anyone else :)

I read now that you are indeed using pedal first. So long as you can get your hub on without bending the fork, it should work out fine for you. I was able to mount a front hub on my girlfriends system without doing so simply by removing some paint, trying that might work out for you if you have trouble but its only a very slight amount of space you need.

Well, the handful of fork failiure reports I've read over the past few years related to destroying the fork's dropouts from losenuts/spinaxle, something preventable and that wouldn't happen with proper torque arms. Even then, they happenned while starting from a stop. Also I know Velectris (http://www.velectris.com/) has been selling/retrofitting bikes like that for quite a while now, hardly a peep on their forums about problems with this setup, loosenuts/spinaxle. No sweat.

yes, my first set gave way on startup right where the axle bolts, so i replaced the lower part of the shocks and now i pedal first and avoid putting my axle under too much load. i can't bear to think of no suspension, the ride is too nice, however, when i upgrade i am going to go for a mid mount motor, a fair while off though.

I have a 5303 running 36 volts on a cheap walmart front suspension CCM bike...no problems at all,just had to tighten the fork when i got it as it wasn't put together very well :S

Original Poster here!

I've put about 1000kms on the bike since the conversion. I have to say that I haven't had any issues with the forks. I didn't have to bend them to fit the Wilderness hub. The hub is pedal first, so I haven't had the torque issues.

I have been checking the bike every week to make sure everything is tight. Last week the front bolts required some tightening. This is the first time ever I've had to do that. Always a good idea to do the check.

This is going to be my primary bike for the winter. The full commute is 48 kms a day. I'm locking a beater to a fence near the furthest subway station just in case I can't do the full distance in the snow. I'll let you know.

Surf enough of the ebike forums and you will come across quite a few aluminium fork failures, let alone suspension forks.
Use rigid steel forks if you care for your health or stick the hub in the rear and keep the suspension fork up front.
Pedal first will certainly help but whether it will stop the eventual fatigue?
Unfortunately if enough people manage to hurt them selves on e-bikes they will tighten the restrictions further, other than that fact it is your life, if you don't care why should anyone else.

the reason that its not recommended to put a hub motor on the front of the bike relates more to directions of force. As the bike is pushed along normally, the shocks act to absorb bumps on the same axis as their travel. There is also a slight angular force due to rider weight. Putting a hub motor on the shocks has the effect of drastically increasing the forward force - putting strain on the shocks, which they most likely will not be designed for. Secondary to this is the force that breaks the droupouts. If you are going to put a motor on the front i would highly recommend a very strong torque arm made of steel that could potentially support the whole bike if your dropouts do break for some reason.

Surf enough of the ebike forums and you will come across quite a few aluminium fork failures, let alone suspension forks.
Use rigid steel forks if you care for your health or stick the hub in the rear and keep the suspension fork up front.
Pedal first will certainly help but whether it will stop the eventual fatigue?
Unfortunately if enough people manage to hurt them selves on e-bikes they will tighten the restrictions further, other than that fact it is your life, if you don't care why should anyone else.

Dangerous words. I like you, value life. We may disagree, but don't flash the "L" card.

Take a deep breath, and think about what you post.

Since it seems that some of you folks out there are really super cool geniuses...maybe you could put your heads together and come up with a fork mod that would take the torque? The reason why some of us want to do this is to simplify making a hybrid - motor and pedal - yet without sacrificing our lives or our ability to father children.

Since it seems that some of you folks out there are really super cool geniuses...maybe you could put your heads together and come up with a fork mod that would take the torque? The reason why some of us want to do this is to simplify making a hybrid - motor and pedal - yet without sacrificing our lives or our ability to father children.

http://www.thudbuster.com/products.html

:) This is what you need to father children properly. A front fork is only really needed if you're running poor passive suspension, or you ride bad roads.

That said, i'd still say that front suspension, installing properly, using pedal first/pedaling first would work out fine. My girlfriend hasn't had any problems on hers yet.

Piece of cake put the motor in the rear wheel with a 7 speed cluster a triple on the front and a suspended front fork.
Makes a hybrid.
Lets see what else, cyclone drive, BB drive, offside rear chain drive.
I have used all except the cyclone, the BB drive is great in severly steep terrain and legal direct drive hubs suck on the same.
If you want kids buy a recumbent, same strategy as the top for a 2 wheeler or tadpole trike, delta trike power one rear wheel with the pedals and the other by any of the above methods or pedal the front and power both rear wheels.
Oh and the thud-buster is meant to be great a friend swears by them.

Thanks! Yes, powering the rear wheel is a common option but my reason for wanting the front wheel powered, as well as many other threads I have read (sorry, I hope I am not hijacking this thread) is that not all of us have bikes that have cassettes on the rear to work with so that there would only be room for the motor and I want to move some of the weight forward to improve handling. Also some people don't want to use hub motors and also don't want to have to mess with extra freewheels, etc on the rear end to get the power of the motor transmitted to the wheel. I have ridden many different kinds of ebikes and one that I most enjoyed riding was one with a mid mount motor and a battery directly behind the seat post. This puts about 80% of the total weight of bike, motor, battery and rider in the middle third of the bike. I found handling the bike was very enjoyable. If I had the $$ I would take modify a frame and do the same thing but I don't have the $$ so my objective is to try to spread the weight more evenly across the bicycle. Also originally I was trying to find a way to squeeze more distance out of the batteries and was hoping that by using a hub gear up front with a gear motor I could increase the range. I have heard mixed thoughts about this though, and am not sure which setup would be most efficient.

The front fork holds your front wheel, but the rear axle is normally where the torque is applied when riding. .

What torque? A derailleur/single speed/fixed drive does not apply any torque to the axle, apart from the trivial amount caused by friction in the bearings. (Bearing friction would cause a similar trivial torque on the front axle also). The torque from the drive sprocket is applied to the wheel without the axle being involved.

In cases where the axle does have significant torque applied (coaster brake, drum brake, Rohloff 14 speed hub) there is a "torque arm" which is attached to the frame. This transfers the torque to the frame and prevents the axle from rotating in the dropouts. Three speeds don't generate much torque and so the flatted axles suffice.

"Our hub motor is not recommend for bike with front shock forks or bike with front aluminum fork. .

Sounds like a load of BS or lawyer CYA stuff to me!

The forces applied to the fork during hard braking will be greater than or equal to the force applied by a motor. When you brake the fork is being shoved backwards. A motor would shove the fork forwards. Different direction but I expect that a typical shock and/or fork would be equally strong in both directions.

If the motor torque is a concern (and it should be) this should be resolved by using a torque arm attached to the fork/frame similar to a coaster or drum brake.

If the motor torque is a concern (and it should be) this should be resolved by using a torque arm attached to the fork/frame similar to a coaster or drum brake.

Is it possible to buy a torque arm or must one be made?

its not an issue of if the force is high when braking- its an issue of the direction of forces AND the high force on the front fork. When you brake the direction of force is different to the TWISTING motion of the axle in the dropouts. Once the dropouts brake, away goes ur front wheel (unless your torque arms are strong enough to support your bike.

Ditto suspension forks. They are designed for high forces travelling up their length towards the rider's head, and to a lesser extent backwards. High powered motor pulls the fork forwards, moving it in a direction it wasn't designed for.

My friend rode my bike eariler in the week, (rear 408 motored at 2950w fully charged). the motor popped out of the rear dropouts while moving due to the forces. Don't think these are piddly forces on the frame (and shocks) they are real and potentially dangerous. The rear dropout failure (they flexed enough to let the axle out) resulted in a (luckily low speed) ejection of the rider onto the road in the direction of traffic ! lucky!

always use massive torque arms that can support the motor even if there were no dropouts! better safe than reconstructive surgery / funeral.

There is only one front fork torque arm that i've seen that would fill me with confidence with riding a front motored bike. - mark_A_w on endless sphere.

There is only one front fork torque arm that i've seen that would fill me with confidence with riding a front motored bike.

Too bad for you

http://i181.photobucket.com/albums/x25/coutujean/imgp0733yh0-1.jpg
Full res: http://i181.photobucket.com/albums/x25/coutujean/imgp0733yh0.jpg


With 2.95Kw in, you're likely getting ~2.13Kw out. That's ~1.5X the max for a moped, this isn't relevant to ebikes. What I take from your experience is that trying to build a motorcycle out of a bike is rather a bad idea.

Its not a case of the torque, but rather what happens immediately as a result of. The angles on your fork are *designed* to be very strong where needed when breaking, the force moves right down, in tandem with the suspension and the tubing and is absorbed with maximum efficiency.. They are simply not designed as the propulsion point of your bicycle. Its simply my suggestion that anyone not wanting to exceed the safe design limitations of their setup work around that.

" There is only one front fork torque arm that i've seen that would fill me with confidence with riding a front motored bike. - mark_A_w on endless sphere."

Please...please....please tell me where to get that torque arm...or how to make one!!! :)

Too bad for you

With 2.95Kw in, you're likely getting ~2.13Kw out. That's ~1.5X the max for a moped, this isn't relevant to ebikes. What I take from your experience is that trying to build a motorcycle out of a bike is rather a bad idea.

No - thats not correct. The reason the extra power is there, is for assistance climbing some rather crazy hills in my area. The high voltage is also designed to allow higher speed cruising. One of the problems i find with the electric bikes i've ridden, is that you're still often doing bicycle speeds. ie at 36v 35a (1260w) I found that the motor and me peddling wouldn't maintain 30kph up a hill. While i can't do that on the road bike, the Average speed i'd be commuting at on the roady was almost the same as the electric. I wanted to be faster! I would be averaging 40kph on the flat on the roady - thats a mean feat for an ebike (ie requries 48v+ in a hub motor with decent hill climbing abilities)


I'm sorry but higher power motors etc, do put higher strain on the dropouts yes, and you're more than welcome to consider my bike a motorbike, (its not), but it does show an indication of what long term use can do to a set of front forks, even at lower power levels.


Thankyou soo much for that picture (esp the high res version), its now my background on the laptop. Is that your e-bike? it is absolutely BEAUTIFUL! there needs to be more pictures of bikes taken like this!

" There is only one front fork torque arm that i've seen that would fill me with confidence with riding a front motored bike. - mark_A_w on endless sphere."

Please...please....please tell me where to get that torque arm...or how to make one!!! :)

http://endless-sphere.com/forums/viewtopic.php?t=1533&highlight=
^ ^ ^

http://endless-sphere.com/forums/files/reinforcements_191.jpg

Heya BiGH,

On ES you claim to get ~45kph top speed on the flats. And sure 200w isn't much and it's one thing to have extra power for hills, but the power level you've mentionned here would be ~1000% the max for something to be an ebike in your neck of the woods, and that much power also pushes your vehicle over the hill as a moped in most parts of the world. Also if you take a quick look at commlaw.gov.au (http://www.comlaw.gov.au/ComLaw/Legislation/LegislativeInstrument1.nsf/0/CDDA6B83D99AEBD0CA2570D50008BC08/$file/ADR+Definitions+%5BFINA+FRLI%5D.pdf) you'll see that your vehicle dont fit as ebike, but snug as a bug as moped:

4.2. Two-Wheeled and Three-Wheeled Vehicles

4.2.1. PEDAL CYCLE (AA)
A vehicle designed to be propelled through a mechanism solely by
human power.

4.2.2. POWER-ASSISTED PEDAL CYCLE (AB)
A pedal cycle to which is attached one or more auxiliary
propulsion motors having a combined maximum power output not
exceeding 200 watts.

4.2.3. MOPED - 2 Wheels (LA)
A 2-wheeled motor vehicle, not being a power-assisted pedal
cycle, with an engine cylinder capacity not exceeding 50 ml and a
‘Maximum Motor Cycle Speed‘ not exceeding 50 km/h; or a 2-
wheeled motor vehicle with a power source other than a piston
engine and a ‘Maximum Motor Cycle Speed‘ not exceeding 50
km/h.


Have you taken a look at geebee's bike? Even something with a strictly Aussie legal 200w through the gears goes quite a ways, and something like a plain road bike would be hella faster for it. But reading you complain that ebikes go bicycle speeds says a lot, because for said vehicle in question to stay a bicycle seems to be a cornerstone behind ebike regulations worldwide... Who'd a guessed.



The Triban isn't my bike, It belongs to one of Velectris'es clients, the Triban series in road version seem to be a pretty popular choice. Either that or Triban owners like to show off their bikes more.

There's a lot of them in their forum's guest book:
http://www.velectris.com/forum/f16-Livre.html


I dig the looks overall, but the elevated chainstays and trunk make it stick out, also they did the classic mistake of using different colord rims front and back, this seriously hurts the overall looks. I'd prefer it with out the trunk and with a set of drop bars, more comfort for longer rides, better aero, better looks. Though it does have bar ends, but they seem angled to far up to be comfy. The clean chainline given by the nexus 8 is nicely put in accent by the raised stays, and the mudguards fit in well with the hybrid tires, though the rear one needs to be ajusted... But the bike's overall proportions seem to compliment each other nicely (if you ignore the trunk). I appreciate the attention payed to details on it, it's very well done for an ebike. You'll notice the colors are well matched, right down to the bit of red on the tires with the red stripe on the saddlebag, sticker on front toptube and the reflective tape/ light in the back. It also looks as though attention way payed when choseing the lights, cyclocomputer, rack & lock. A good job overall.

Unfortunately it wouldn't be a practical bike for me. Even if I used a real lock like an abus or kryptonite, I'd still be stuck having to partially disassemble that bike (lights, seat, battery, anything in the trunk, etc) and haul a bag full of misc parts with me anytime I'd park it downtown. For what it's worth I'm better off with a low-key steel bike, and that's what I got. Though I guess it could be worse, I've seen some Tibans with disks... Ouch. May as well put a neon sign that says "Steal me!".



Anyways, compare to the triban5 trail, to me it just looks wrong:

http://www.casimages.com/img/070222081124343339.jpg





And here's another really nice bike with front hubmotor:

http://perso.numericable.fr/~bposte/photos/veloctris/PICT2681small.jpg

http://perso.numericable.fr/~bposte/photos/veloctris/PICT2678small.jpg

i take your point as to what the law is (i'm fully aware of what it is, and how much power i'm running in comparison). I've re-checked hte speed, its max 55 - which puts me just out of moped too, however to me it still feels like a bicycle, as i peddle along with it, just means i run in a higher gear when on the flat - i'll be putting a road bike front tripple chainring on for this purpose. I don't run the bike at 55kph usually, but its nice to hvae the extra power if needed. usually sit on about 40-45kph which would be too hard to maintain on teh road bike.

for comparison, i commuted the 25k to work today, had to go to a different campus (another 10k) then to the g/f's place (18k) in each leg i averaged ~30kph (as stated by my heart rate monitor), that was on the road bike. Max for the day was around 60kph all with no motor, so maybe you can see that i'd want to have the advantage of the extra power.

I've ridden a road legal 200w front hubbed bike, but i have to say i didn't really enjoy it - it was "kinda cool" but it wouldn't keep up with me on the road bike. For the price i'd rather just build a very light flat bar road bike (with no electric assist). I would like to ride an elation or cyclone ebike, however i just haven't had the opportunity to.

I can see this turning into a heated debate so i'm happy to say that we just disagree, i think what we are after our machines is very different.

Thanks for the extra pictures.

just found this:

http://endless-sphere.com/forums/viewtopic.php?t=14

torque arms are important! its a thread from old on endless - but shows the importance of strong forks

just found this:

http://endless-sphere.com/forums/viewtopic.php?t=14

torque arms are important! its a thread from old on endless - but shows the importance of strong forks

He was also running his kit pretty far out of bounds from where you're still riding an e-bike. I don't understand this fascination people have with building 40kph+ systems, all it does is:

1. violate the law. And when the e-bike laws in many places are new and soft, you're risking not only your liberty but those around you by blatantly violating them.

2. endanger yourself and others. Let me put this simply! Bikes are designed to exceed speeds like 40kph.. For a moment of downhill or a sprint. World class athletes who ride at these speeds or greater for prolonged periods of time are riding *world class bikes* on predictable terrain. What many people do with these bikes is just honestly *stupid*. Bicycles can't stop in nearly the same amount of time as a motorcycle. They can't handle nearly as well at the same speeds, and they're *not* built standard with components that will survive such use over extended time. Using a bicycle as a moped or a motorcycle is a design mismatch.

Anyone wanting to build some kind of high speed ride, when you're exceeding the intended design of just about every component on your bike, the law and (often) your electric kit, its probably time to pony up and build a bloody moped or e-motorcycle instead. Besides, you're killing your max range :)

My stance on front suspension/hub motor hasn't changed. While its often a design mismatch, the only real design abuse here is initial pull. As long as you're installing your motor onto something decent, not bending/abusing the fork to fit it in, then your only worry should be in eliminating the first moments of tug from the motor, something that would be easy to do by using pedal assist/pedal first.