Front or rear wheel drive, or . . .

[sdrio]

Any thoughts on the pros/cons of front and rear wheel drive?

I know there's crank drive too, but that doesn't seem popular.

Also, out of curiosity, carrying a ton of batteries aside, has anyone ever made a 2 wheel drive bike? Seems pretty simple to do, even just taking a rear wheel drive bike and adding a kit to the front.

 

[flecc]

Crank drives are very popular with those who have to tackle steeps hills, due to the advantage of the motor driving through the bike's gears. The Panasonic one has been a major market player for over a decade now, the Bosch one is dominant in Germany's high quality e-bike market and there are two other German makes as well. The Orientals are now fighting back with crank drives, one from Pacific Cycles of Taiwan and at least two more coming soon from China.

With hub motors, Front drive has the advantage of two wheel traction, pedals driving rear and motor at front, useful in poor road conditions. It has the disadvantage of less comfortable ride due to the "throw" of the motor weight on bumpy surfaces. Suspension forks alleviate the effects of that to some extent. Traction can also be lost on poor or slippery surfaces with a powerful motor when pulling a trailer uphill. The extra weight in the front wheel can also affect handling a little.

Rear motors have the advantage of greater comfort, no ill effect on handling and better trailer control. The disadvantages are poor weight distribution, usually much of the weight at the rear, and often gearing limitations. For example, no hub gears possible, and derailleurs limited to using freewheel sprocket clusters. These are much more limited in range than cassette systems and are weaker as well.

There have been many two wheel motor drive e-bikes and member OldTimer has created one. Obviously they aren't usually within the law on power limits, but if that is ignored all sorts of combinations are possible. The photo below shows one with a Panasonic crank drive for the rear wheel, with it's own battery. There's a Heinzmann motor in the front wheel and a tiny generator on the carrier. This can run with either motor from the battery, or both motors together with the generator motor running:

 

[SportRider]

I've tried both front and rear wheel drive, and to behonest I think it's just down to personal preference. My car is rear wheel drive, and I'm a motorcyclist, so I guess I just naturally prefer being pushed around instead of pulled!

As for 2WD, take a look at this: index

 

[Cyclezee]

Hi sdrio,

The pros of a front motor conversion are easier installation, more even weight distribution between front and rear, no alteration to gearing is required and in effect 2 wheel drive, i.e. front electric and rear pedal power, the only solution if you have hub gears.

Cons, steering is marginally heavier and traction not quite as good on loose gravel and off road.

Pros for a rear motor, traction is better for off road riding and on loose gravel, the installtion and the steering is not effected.

Cons, the bike will be heavier at the rear, gearing may require alteration, cannot be used with hub gears, a Freewheel will need to be fitted adding to the cost, only one wheel drive.

We have not done a front and rear conversion, I would question the need for such a configuration.

I think Banbury Frank may be your man to advise on a front + rear conversion, you can find him here index

In summary, it real is a case of personal choice and what you want to use the bike for.

 

[Deleted member 4366]

In my experience, for a 250w motor, it makes little difference whether the motor is front or rear, both have advantages and disadvantaches which tend to cancel each other out. Rear motors seem to be generally quieter than fronts. I'm not sure why!.
I'm building a two-wheel drive at the moment. You can do it with one (strong) battery, but you need two controllers, and, if you want to power both motors equally (more or less), you need to make a double throttle by taking the hall sensor out of one and installing it in tandem with another. Some people have had moderate success with one throttle with a split signal, but they often start glitching. Alternatively you can power the motors seperately - like having one on a throttle and the other on a switch as a boost for hills, but you don't get so much efficiency that way, which is no problem if you have a big enough battery to cover the waste. There's loads of stuff on Endless Sphere about 2 wheel drive, but most of it is for higher power direct drive applications, so ignor what the nay-sayers say. Most of the advocates have used low powered geared motors, which give the most advantage.

 

[morphix]

Any thoughts on the pros/cons of front and rear wheel drive?

I know there's crank drive too, but that doesn't seem popular.

Also, out of curiosity, carrying a ton of batteries aside, has anyone ever made a 2 wheel drive bike? Seems pretty simple to do, even just taking a rear wheel drive bike and adding a kit to the front.

It's a question that gets asked constantly and you'll always get different thoughts on this..but here's my take on it..

The decision as to whether to go front or rear drive should be considered in the context of where you plan to mount your battery/controller, and what your arrangements or requirements are for gears...

Certainly a front-wheel mounting is a lot simpler and doesn't require any changes to gears, however the downside is that it makes the bike more obviously electric, as a rear drive is more discrete. That could be an important factor if you plan on leaving your bike outside as the less attention you draw to it the better.

The other thing to consider is the battery/controller mounting as I mentioned...it probably doesn't make sense to have a front-wheel drive if you're planning to mount everything at the back of the bike as you'd have cabling going across your frame..and same applies if you plan to do a handlebar bag mount but have a rear drive motor.. you'd have less cabling visible if you have the mounting next to where the motor is.

I've only ever ridden a front wheel drive so I can't say how it compares to a rear drive, but I've seen it said some people say the rear drive motors seem a little less noisy, but that could just be peoples perceptions of course, because with the motor in front you're more aware of it. From the front-wheel drive prospective, I found it made no difference at all to steering, braking or handling.

 

[sdrio]

Interesting. I'm glad to know there's not a huge difference between front / rear, as I'd hate to have to pare down an already rather short list of possible bikes to buy!

Now, what we need to do is get hold of one of Franks two wheel drive monsters, and get a crank drive fitted. Then all you'll need is a towball fitted to take the caravan.

 

[jazper53]

I have a FWD bike, and find no problems with the handling ability. A definite pro if the battery is at the back with FWD there is a better balance of weight spread through the bike, which makes it less awkward to manhandle the bike, plus you have two wheel drive, IMHO.

 

[flecc]

The lower noise from rear wheel motors has several reasons. It's behind the ears so from a less aurally sensitive direction. It's being left behind in the airstream flowing around the bike, the consequent Doppler effect lowering it's frequency and reducing the range of the upper odd harmonics that electric motors produce. In many riding positions the soft body mass between motor and ears absorbs and damps sounds.

 

[jazper53]

The lower noise from rear wheel motors has several reasons. It's behind the ears so from a less aurally sensitive direction. It's being left behind in the airstream flowing around the bike, the consequent Doppler effect lowering it's frequency and reducing the range of the upper odd harmonics that electric motors produce. In many riding positions the soft body mass between motor and ears absorbs and damps sounds.

Interesting point, but what if you have a 30mph following wind, would this not be reversing the doppler effect?

 

[Deleted member 4366]

I forgot to mention that if you have more powerful motors running at more than 20 amps. then a rear motor is more favourable because you start to lose traction on steep hills with a front motor especially if there's gravel, so I'd say 25 amps is the max unless you only ride on smooth tarmac. Also you can get other problems from torque on the forks above that.

 

[flecc]

Interesting point, but what if you have a 30mph following wind, would this not be reversing the doppler effect?

If the wind was overtaking you, yes. Either that or you'd be belting along at 45 mph plus wearing a huge grin!

 

[Cyclezee]

The image below shows a bike with front and rear motors used by eZee for testing.

It is not for sale, but would not be too difficult to reproduce

 

[Deleted member 4366]

Do you know any more about it. Does it have a dual-channel controller or too separate ones? Does the throttle drive both motors at the same time?

 

[banbury frank]

Hi hear is a duel speed controller From crystalyte Belgium


Crystalyte Europe :: Controllers :: 48 Volt 20A Dualspeed controller

Frank

 

[Cyclezee]

Do you know any more about it. Does it have a dual-channel controller or too separate ones? Does the throttle drive both motors at the same time?

Hi d8veh,

The bike in the photo was being used by Justin of ebikes.ca whilst I was at the factory for testing various eZee motors, setups and components.

The motors are not run in tandem, so it is really a bit of a hoax as far as dual drive is concerned, but quite feasible to create.

 

[eddieo]

I have had both rear and front and find nothing in it to be honest, except front motor bikes tend to be better balanced.....

To so flippantly dismiss the superior centre drive/crank drive systems is laughable. Just try a few you will be very pleasantly surprised.

 

[jazper53]

If the wind was overtaking you, yes. Either that or you'd be belting along at 45 mph plus wearing a huge grin!

At 45mph, I doubt if it is a huge grin that i would be wearing

 

[sdrio]

I have had both rear and front and find nothing in it to be honest, except front motor bikes tend to be better balanced.....

To so flippantly dismiss the superior centre drive/crank drive systems is laughable. Just try a few you will be very pleasantly surprised.

Maybe I didn't put that properly.

It seems to me that crank drive is not as common as either front or back wheel motors. I may be wrong, that's just my impression. Maybe they tend to be on more expensive bikes (and I could be wrong again).

I don't mean they're not liked, or that they're inferior.

So far I haven't seen a crank drive model that I can afford, or like the style of.

But on the bright side, there are lots of alternatives!

 

[sdrio]

At 45mph, I doubt if it is a huge grin that i would be wearing

Same here, and the following wind wouldn't necessarily be caused by atmospheric conditions . . .