Front vs. Rear Hub Motors

[ekline309]

Up until 2 days ago I always thought rear hub motors were the obvious choice (albeit a month ago I thought chain drive was the best thing since sliced bread). Anyways, Sanyo's new release uses a front hub motor, they say they chose this to decrease pedal resistance, and balance power between both the front and rear wheels.

It now seems that front hub motors might be the smart way to go. Anybody have experience with one versus the other???

 

[AussieJester]

(albeit a month ago I thought chain drive was the best thing since sliced bread).

I still do LoL..can't help on the hub motor havent owned one never would...

 

[dogman dan]

I really like my front hub, but that opens a whole can of worms, especially if you want suspension. It depends a lot on how you use the bike. What I really really really,,,, really like is the way you can stick both wheels to the road by putting power on both wheels. Cornering with the motor off feels sketchy to me now that I'm used to the frontie pulling me through the corner. But if you want suspension, it's take your chances with alloy forks, or settle for cheezy steel ones. For me, street riding, 40 mm of travel and no oil or air in em is usually enough to smooth out moderate road cracks. But when I get on my peadle mtb, that has just barely better suspension than the wallbike, it's like night and day with 80mm travel.

My bike feels pretty balanced, with 15 lb motor up front, and 15 lb battery on the back rack, so that is nice. A big ol x5 up front might be just too heavy, but I don't know without trying it. Another thing you definitely lose is ability to jump the front wheel over a curb. I'm just not strong enough to do that with 15lbs on the forks. My city has lots of wheelchair curb ramps where I need em, so It rarely affects me if I'm riding legaly.

Riding this bike on dirt trails is suprisingly nice. The wheel does spin sometimes going up a really steep hill, but it does that at about the same point that I have a really hard time controlling wheelies on the peadle bike, so in a way, the heavy wheel helps out when I need it. But with the cheeze front forks, I bottom out endlessly on downhills, and have to go real slow on them, unlike the peadle bikes forks that just eat up the bumps. Again, you can find it hard to pop the front over an obstacle, but no trees grow here, so I don't need to hop logs across the trail.

 

[docnjoj]

Long, well damped suspension travel and low unsprung weight is what makes the world go round smoothly! A light geared hub, and light batteries in the middle triangle would make even Fisher proud! Now THAT would be a formidable trail bike!
otherDoc

 

[Wile E. Coyote]

I switched from front (eZee) to rear (BMC) because the front wheel skidded to much, causing some white knuckle moments. The skidding happens on uphill grades when the road is wet (or loose sand/gravel). If you live somewhere dry and flat, you may not experience this problem.

 

[mer]

i have both rear and front . The front one is a golden motor , the rear is a bafang .

I prefer having my motor on the rear. My front wheel skidded as well , but since I got a fat front tyre with aggressive knobbing and soft compound it is less much pronounced , although it still skidds . Even if it didnt skid , I still prefer having my motor on the rear

 

[Toshi]

I live in Seattle, where it is known to rain. Even on steep hills I rarely have a problem with losing traction with my front hubmotor setup. All it takes is avoiding manhole covers and using a bit of common sense and throttle modulation. Overall I'm happy with my choice of a front hubmotor as it allowed me to balance the bike better (my 15 lb 48V 12Ah LiFePO4 pack lives in a pannier on the rear of the bike) and it also allowed me to use an internally geared Shimano Nexus rear hub in lieu of a derailleur setup.

See the link in my sig for much more.

 

[dogman dan]

Hmm, only skids I ever had were on extreme steep dirt hills, even on wet roads. I don't have an x5 though. Musta learned something about riding in 50 years. I definitely am aware of crosswalk stripes. I don't even know I'm doing a lot of the stuff I do, but there is a lot to it. I've seen a lot of guys buy a motorcycle, ride it a month and park it. Definite advantages to both front or rear, for different reasons. Make the choice based on the riding you will do. I'll be putting a rear gearmotor i'm buying soon on my trail riding bike. Skidding may be much more of a problem with a tourqey gear motor like the ezee. My motor has some tourqe, but it's nothing compared to what I can do with the peadles.

 

[Anonymous]

.

 

[snowcrow]

One more thought If you plan on going with regenerative braking now, or in the future, a rear non gears hub, would be your best option.

Blessings, Snow Crow 8)

 

[ekline309]

Why is rear the best option for regen?? Sanyo's uses a front hub motor.

 

[snowcrow]

Why is rear the best option for regen?? Sanyo's uses a front hub motor.

For starters, rear wheel braking is used 2/3 more than front wheel braking at any given time, under most riding conditions. I know of no one applies the front brakes, before appling back brakes :wink:

The next issue is the strength of the fork ? The constant pulling and pushing will cause a fork to fail, unless it's one piece.

Personally, if something is going to go wrong, I would rather it happen be behind me, than in front of me, allowing me to steer out of it If something happens up front, most time, your just along for the ride with effect on the outcome :?

The choice is yours!!! 8)

Blessings, Snow Crow

 

[Link]

Why is rear the best option for regen?? Sanyo's uses a front hub motor.

For starters, rear wheel braking is used 2/3 more than front wheel braking at any given time, under most riding conditions. I know of no one applies the front brakes, before appling back brakes :wink:

Seriously? I rarely use the back brake. Probably because it's garbage with my yet-untrue rim and can't come close to comparing with the front BB7, though...

I'd go with rear regen. You'd be sacrificing more stopping power if you put it on the front.

 

[dogman dan]

For more on what snowcrow says, see the spun front axle thread. Wow, what a suprise that must have been.

Did some higher speed riding on a dirt road, today, seeing if I could get some skidding to happen with the front motor. Sure enough, with the loose surface, and flooring it in corners, It skidded quite a lot. Being so comfortable with the same thing on the rear tires of motorcycles and bicycles for decades, it was pretty easy for me to get used to, and even sorta enjoy the feeling. But since it is up front, I can see how much more scary it must feel to most people. I just allways felt on motorcycles, If you weren't sliding sideways, you weren't having fun at all. It's much more fun to make a left turn by pointing the handlebars right.

 

[vanilla ice]

I'll take the weight imbalance if it means going with rear drive. Its personal I guess, but having a heavy front hub just seems wrong. If its a light one I could go for it tho, none of the 10-30 pounders. Those go out back.

How much force does a coaster brake put on a frame? Reason I ask is, why the hell do hub motors even have these not-round axles to spin out. Just give me a round axle and two big stand offs poking off of the hub.. to bolt on to the inside of the frame in the same way a coaster brake does it.

 

[bbushwacker]

I wanted to go front, as of the balance. Ah, and cost. With the availability of rear disc/motor combos (ebikes.ca, Justin had two ezee's) I am quite satisfied. The batteries will have to go somewhere onto the center frame. But, the handling is much more intuitive if you are used to fossil fuel (FF)-bikes. On trials you don't want the front wheel to stick, but it needs to be movable. So far I am convinced that the trouble of putting the battery into the frame outweighs the installation hassle. On a different note, soft metal front forks (particularly those nice 20mm through axle) appear inherently troublesome without appropriate torque control. And the axles don't fit. In the rear dropouts, a 14mm axle sits flush, flat and happy.

In the end, I think we can sacrifice most gears on the rear, keep three, add disk and great motor. Reason: Riding a fast, heavy bike on mud/ in rain/ urban traffic is more fun if you know that you can stop it, as you bike better. Discs are the way to go (commuting in Vancouver, getting dirty in the pacific spirit park).

 

[voicecoils]

Why is rear the best option for regen?? Sanyo's uses a front hub motor.

For starters, rear wheel braking is used 2/3 more than front wheel braking at any given time, under most riding conditions. I know of no one applies the front brakes, before appling back brakes :wink:

That's completely wrong. Backwards if anything.

As you brake the deceleration (m/s^2) & your mass (kg) will generate a forward force (kN) that will unload your rear wheel and force your body weight forward. The front wheel does most of the braking. Look at superbikes, they have two giant hydraulic disc brakes on the front wheel and one tiny one on the rear wheel.

I've gone for a front hubmotor (in my avatar photo) because like Toshi, I wanted to keep my internal gear hub (8speed Shimano Alfine) on the rear wheel.

 

[dogman dan]

Superbikes are usually ridden by superriders too. Too much front brakes scares the shit out of a lot of people, just like the slip on a front hub does. I like to hit the back brake first, and then the front, since my crappy front shocks will bottom out if I hit the fronties first. But indeed, nothing much happens till I hit the front brakes. Years ago I had a honda with nonfunctional front brakes, and learned how to steer a skid reall good with the rear locked up. It was amazing how you could thread the bike through the cars that stopped in front of you with the rear tire laying rubber. Now I sometimes still do that on the ebike, locking the rear, and braking with the front, just short of losing steering on that wheel. Never lock the front wheel, you'll be commited to a straight line by then. Or over the bars!

 

[pwbset]

locking the rear, and braking with the front, just short of losing steering on that wheel. Never lock the front wheel

Word. On my downhill commute I lock up the rear all the time as a matter of practice. It's a great way to deal with pea gravel, downed trees, squirrels, elk, bears, deer etc. Allows for a lot of side to side control and makes me feel like a kid on a BMX again . Front brake on 15% downhill gravel is suicide IMO. On dry paved flats... 50/50 for emergency stopping otherwise mostly rear also. .02

 

[MidniteTweeker]

When I began riding recumbents I became a lot more aware of the difference in dynamics between front and rear wheels with regard to going over a bump. When the front wheel encounters a bump, basically for an instant the whole bike wants to slow down momentarily. To exaggerate it, imagine it is a really large square cornered bump maybe 6 inches high. Before the wheel actually goes over the bump a lot of weight transfers to the front wheel as bike and rider slow down. The additional weight on the front wheel aggravates the situation even more.

When the rear wheel goes over the same bump, the bike and rider still try to slow down and the weight still shifts forward, but doing so unweights the rear wheel which makes it easier for it to go over the bump.

Of course, having a front suspension greatly helps. But fundamentally, the more weight on the front wheel (sprung or unsprung) you have, the harder you hit the bumps. This may or may not make a difference to you. It's one thing if you're light and wiry; something else if you're heavy and pack a lot of batteries and cargo. I'm in the latter category and therefore do whatever I can to minimize the amount of shock delivered to the frame. For me, this eliminates a front motor.

MT

 

[JinbaIttai]

balance power between both the front and rear wheels.

I never noticed a power imbalance riding a bicycle with no motor. This statement just doesn't make sense to me.

One reason I am grateful for having a rear hub motor is that it is easy to walk the bike on its back wheel in order to store it in my tiny apartment.

 

[Mark_A_W]

I can't believe people think that the back brake does anything....


My front disc makes my eyeballs pop out.

The rear disc brake is good for skids, but no slowing down.


As for front versus back motor....neither is better and they are both a PITA.

Front is a PITA for suspension forks and disc brakes - although I worked around that with my triple clamp bombers.

Rear is a PITA for gears. A total PITA to try and squeeze a motor, disc, and 7 speeds in 135mm. Even if you get it working you are stuck with rubbish (and hard to replace) screw on freewheels. And I'd like 9 speeds instead of 7.


Choose your poison...but be wary...1100w on the front wheel does wicked burnouts in the wet or dirt...sometimes when you least expect it.

 

[dogman dan]

I agree there, my front hub is only 600 watts so that explains why I don't mind all the slipping, what slipping? And it doesn't weigh like a front x5. Front brakes stop you much better, but rears add controll, in my opinion. My old ski bug, years ago had manual brake adjusters and rear studded tires. I would set it up to have tight rear brakes so the rears would start grabbing first, and on Ice I could just give the brakes a tap and straighten right out anytime I needed when nice Suv's were spinning into ditches. I get the same kind of feeling on the bike by just grabbing the rear a hair ahead of the fronts. It feels to me like a lot more controll compared to hitting the front first. And if I do need to lock it up, I can steer with the rear locked up, but lock up the front, and you just go straight. You can gain a lot more stopping room if you can do a crooked line, and maybe just skid to a stop between two stopped cars instead of kissing bumpers. I did that many many times on the ol honda.

On the power balance, as you become better at riding, you can definitely feel a difference between a wheel grabbing traction and one that is not. I love the feeling of cornering with the rear tire grabbing from all the peadling I can give and the front grabbing with all the throttle I have. Of course, you won't be feeling that if you still use brakes while cornering instead of throttle. It seems backwards, but use the brakes on the straightaway, and floor it in the corners.