Disadvantages of front wheel drive for ebike?

I'm considering making a front wheel drive system by installing a hub motor in the front wheel of a bicycle. I see that most, but not all, hub motors are in the rear wheel.

I'm wondering what the pros and cons of putting a hub motor in the front wheel would be?

Always fit the motor in the back wheel if you can. A front motor looks simpler and if done properly, it can work quite well, but if not done properly, it can be very dangerous and expensive.

As a general rule, front motors should only be fitted in steel forks, except that low power ones are OK in aluminium forks as long as the drop-outs have some meat around them, and I'd always fit at least one torque arm.

Even when properly installed, you can feel the difference in the handling. It makes the steering heavier and less responsive. Also, traction isn't as good. Even low power ones start to slip and spin on loose surfaces and steep hills, which is not only a bit worrying, but it wears out your tyre quickly.

Lastly, only a minor point, you have to route the motor wire past the moving suspension and round the moving steering head. It's not good to keep bending copper because it has very low fatigue resistance.

If you finally decide to go ahead with a front motor for whatever reason (normally hub gears), ask how to do it properly.

Just had an after-thought. Front motors always sound much noisier than rear ones too.

As a general rule, front motors should only be fitted in steel forks, except that low power ones are OK in aluminium forks as long as the drop-outs have some meat around them, and I'd always fit at least one torque arm.

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Another general rule is to not fit front hubmotors on bikes with front suspension, although like with the above rule a low power motor and a good fork would likely not be a big problem.

Main disadvantage to me is the ramification of a major problem is greater with a front installation, although that was my first conversion and it worked extremely well (steel Surly fork and Grin torque arm).

Disadvantages:

1) Less traction, due to the power being put where ~33% of the rider weight is. Same problem with a rear wheel drive truck, where the motor and rider are in front, but the power is applied to the back.
2) Only safe scenario is with a steel fork because front dropouts are typically weak on forks ( due to them taking a minority of the weight VS. the rear )
3) Induces strange steering feel, depending on how heavy the motor is.
4) More often that not, a front motor will send vibrations up through the handlebar or at least be audible and annoying. The rear is less prone to this.

Advantages:

1) Don't have to be creative with rear gearing - or can preserve a, existing non-standard rear gearing system such as an IGH.
2) The bike can have more of a balanced weight distribution if using dual motors, and also overall better traction since this is AWD.

Most forks really aren't set up to handle high-powered hubmotors, so any front hub would need to be on the lower-powered end of the scale. Of course, some forks are stronger than others. I would suggest that it's a given that you should have a strong torque-arm. If using 1,000W or less, a strong fork (steel) coupled with a strong torque-arm might allow using just one. Sometimes a cheap torque-arm and a strong one "look" similar, but their strength can vary widely, so...always get a good one.

If you are using less than 1,000W and you live on fairly flat land (only occasional mild hills), then a front hub can be a great option. They are the easiest to install, and the easiest to change a flat tire.

The biggest disadvantage (as far as I'm concerned) is on a steep uphill. The slightest bit of sand or water on the road, and it will occasionally spin-out right when you need it most.

I don't recommend them for steep uphills or high power. I still like them very much for certain extreme conditions where a 2WD would be appropriate...and of course for low power on flattish land.

I would always be mindful of the fact that power should probably be very limited anytime you're going around a turn.

I don't recommend them for steep uphills or high power. I still like them very much for certain extreme conditions where a 2WD would be appropriate.
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I actually looked into doing this with an EZIP Trailz. I was going to leave the RWD system intact, and install a 250-350 watt front hubmotor for quiet cruising on the flat (FWD) and extra climbing power on severe hills (2WD). At the time I didn't see any geared front 24V motors that were reasonably priced, so I never tried it.

I have a two hub drive and most of the time I use just the front .It's lower power than the rear wheel motor and draws less battery and gets better mileage . One has to be careful when cornering in gravel over pavement but that's about the only con with a lower power bike I see .

spinningmagnets said:

Most forks really aren't set up to handle high-powered hubmotors, so any front hub would need to be on the lower-powered end of the scale.

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I would say "many", perhaps "most", but not "any"; there have been a number of higher-powered front hubs, including my old CrazyBike2, with about 2kW front (and antoher 2kW rear).

Kinda broke all the "rules" with alloy fork, that's also suspension, and 2kW of power on a DD hubmotor with regen braking too. But it did use two torque arms (wrenches), and the dropouts had a tight fit on the axle flats, and I also used nordlock washers on the axle nuts (though I don't know if that had anything to do with the effectiveness of the system).

First of all, if your bike has 7 or 8 gears in back, it is not in any way easier to do a front hub, vs a rear.

Because of much better traction when the power is in back, in almost every case a rear motor is better. And if you have an aluminum shock fork in front, it gets very technical to make a hub motor work safely. Some shock forks can be used, but they lock up and become rigid when the motor is pulling.

But there are exceptions, which make a front wheel just about the only way. The typical adult trike is the biggest user of front hubs. They have rear drive trains and axles that usually make using a rear motor impossible, or at least a need a welder type situation.

Beach cruisers with a coaster brake, have no brakes at all if you change the rear wheel to a motor wheel. Those can usually be adapted to have other brakes fairly easy though. Might take a welder to do a nice conversion to disk.

Others just have internal gear shifter hubs, and want to keep that, because they loathe derailleurs.

And lastly, the really exotic bikes, belt drive, shaft drive, and so forth, can never use a different rear wheel.


Other type beach cruisers can be a good ride with a front motor, when they are the type with a 7 speed rear gear and rim brakes. They are the one type bike that tends to have a very strong front fork. And you won't be riding it much in dirt, so the traction situation is not a big problem. The only two bikes I'd really recomend a front motor for, are the schwinn trikes and the 7 speed cruisers.


FWIW, I rode about 5000 miles on front hubs, and my main reason was wanting to keep my rear gears on that particular bike. I even built a 50 mph, very high power front hub racing bike. It was fun to learn to power slide the front wheel, and extremely dangerous. But today, all my front hubs gather dust, everything I have runs a rear hub.

Five years later, I implemented what I proposed above: an old EZIP Trailz step-thru,
with a 500 watt front brushless hubmotor that claims 500 watts. Actually, after breaking it in,
I'd say it does manage 500 watts. Not much torque, but plenty of power from the mid-range on.
After having trouble with both parts and installation, the bike is now 2WD, with a
500 watt brushless drive in the front wheel, and the OEM 450 watt
external brushed motor with chain drive in the rear - albeit
over-volted to 36 volts, 800 watts. That little once-450 watt brushed motor really
screams, now. It will hit 24+ MPH indicated, with the stock gearing.
The front drive is almost silent, and has cruise control. I can run both drives
simultaneously, so I can (and do!) use the front drive to set a speed, which it will
hold until squeeze the right brake lever. It will provide a MPH reading and
available propulsion power even after I take over with the rear drive,
and the cruise will remain engaged until that brake lever is squeezed.
That means I can ride effortlessly in FWD mode, adding power from the
rear drive as needed to climb hills, for more speed. Issues with the
new derailleur aside, I'm quite pleased with it. I even managed to get
the front rim brake to provide very adequate stopping force. The bike
actually perfforms better than I had hoped...

I'll post a photo or two later.









;

lol I remember this post when I was researching my fwd conversion. The only bad thing after 4 years with it is nothing to do with fwd itself but the lack of torque sensor and too much power. On flats I end up pedalling like flinstone because gearing isn't enough to keep up with motor, but on hills you don't have that torque like from a mid drive. But all this is just due to it being a DD motor lol.

My rule of thumb never on an aluminum fork never on a suspension fork only on an old chromoly steel for with two torque arms. For about 22mph tops.

Ok you don't want to putt a cristalyte 5303 on a front aluminum fork. @ 35mph.

First ebike 14 years ago. Day 6/Bionx RWD, nice ride, decided to build my own RWD (never seen a Harley with FWD) and built 3 bikes with RWD. Balance sucked (lead era) and issues with everything else on the rear wheel were fussy. My butt also!
Accidentally ran into a guy that had a 26" FWD hanging in his garage which he bad mouthed as wrong thinking and gave it to me. Put it on a free bike (Schwinn Jaguar step thru) which helped the balance. Noticed that there is a difference between being pushed by RWD and pulled by FWD. Prefer being pulled after gaining experience. Went on to build several more FWDs. RANS V2 recumbent with FWD is an incredibly nice ride and FWD has been beyond perfect. As my kid says "awesome!"
Then I Thought about tricycles, what I call pickup trucks. Chalo calls "granny trikes" for me "Geezer Glider" 'cause I'm a guy - I think. Put FWD on 23 Schwinn Meridian 26" Trikes and a couple of 24" Gomiers. Sold them on Craigs list and have kept 3 for my personal use.

Torque arms are not an issue with the Meridian. I have steel forks, strong dished drop outs, and C washers. Never had an issue and have stopped using TAs except on one trike that I have two TAs, hot rodder by nature.
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I love it you have a stable of those things how fast do they go or how fast do you go on them top speed

TricycleMichael said:

First ebike 14 years ago. Day 6/Bionx RWD, nice ride, decided to build my own RWD (never seen a Harley with FWD) and built 3 bikes with RWD. Balance sucked (lead era) and issues with everything else on the rear wheel were fussy. My butt also!
Accidentally ran into a guy that had a 26" FWD hanging in his garage which he bad mouthed as wrong thinking and gave it to me. Put it on a free bike (Schwinn Jaguar step thru) which helped the balance. Noticed that there is a difference between being pushed by RWD and pulled by FWD. Prefer being pulled after gaining experience. Went on to build several more FWDs. RANS V2 recumbent with FWD is an incredibly nice ride and FWD has been beyond perfect. As my kid says "awesome!"
Then I Thought about tricycles, what I call pickup trucks. Chalo calls "granny trikes" for me "Geezer Glider" 'cause I'm a guy - I think. Put FWD on 23 Schwinn Meridian 26" Trikes and a couple of 24" Gomiers. Sold them on Craigs list and have kept 3 for my personal use.

Torque arms are not an issue with the Meridian. I have steel forks, strong dished drop outs, and C washers. Never had an issue and have stopped using TAs except on one trike that I have two TAs, hot rodder by nature.
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Top speed 30 mph, normally cruise under 20.