Front Vs. Rear Drive

[hoss10]

I'm really new to this. I'm planning on build an E bike for my son to commute to school with, he is just over 200 pounds and we will be using SLA batteries (at least for now), with a direct drive hub motor. The front wheel drive kit looks easier to install and would distribute the weight better. Is there any downside to a front drive (except finding a steel fork) or advantage to a rear drive. We will most probably be using an Amped Kit.

Thanks in advance for the help.

 

[jonathanm]

One major advantage is safety. I went with rear mainly for this reason. If you've ever locked up a front wheel at speed you'll know what I'm talking about. Rear wheel lockups are a lot easier to manage. Front wheel lockups - unless you're already anticipating it with your weight far back.... you're going down...hard...

 

[dogman dan]

True, but that problem is not so common. I found it quite easy to go over the bars many other ways. :lol:

Rear drive is easier to handle on anything slick, loose sand on the road, etc. Being a highly skilled two wheel rider, I found front hub nice on pavement. But others freak out on it, especially if not really a biker to start with. Rear for sure for dirt riding.

One thing for sure, if you build a bike with rear hub, then stack 30 pounds of sla on the rear rack, it will handle so bad it's unbelievable. So go rear hub if you can, but you must find a way to carry the batteries in the frame of the bike, up front. If your bike choice has no space for batteries up front, then go front hub.

 

[Pure]

One thing for sure, if you build a bike with rear hub, then stack 30 pounds of sla on the rear rack, it will handle so bad it's unbelievable.

You know, this is one thing I see said on here all the time, but honestly for street use, I can't really even tell the weight is back there. Sure the bike is very top heavy wile I'm pushing it out of the car port, but as soon as I get on it, my 250 pound on the pedals pretty much nixes any effect the battery weight has being up that high. Maybe on a single track trail where you are needing to make sharp fast turns, it makes a difference, but like I said, on the street I can't tell any difference in it's handling. And for the record, I rarely slow down for turns. To do so would mean I have to pull more amps to get back up to speed so I try to keep my turns at 20+mph traffic allowing of course.

Perhaps, since that is all I know, I don't know any difference? Even still handling is not an issue.

 

[etard]

First off let me say, "in my day we had to pedal both ways up hill in 5 foot snow..." :lol:

Go rear hub and DON'T go SLA, he will learn to hate this ebike and it will never get used. Also make sure to get a decent kickstand for parking it at school and home.

 

[Ykick]

I started with front wheel DD's but have riding a rear DD for several months - each have their pros & cons. Safety is important but install things correctly and use good judgement front wheel DD seems fairly safe to me.

During winter snow storms I actually prefer front wheel drive just because I would rather be pulled than pushed in those situations where the snow is deep. I'm also a fairly advanced rider and know better than to use too much power during a turn on slick surfaces with any front motor bike. Just like being careful with the front brake during a lean you need to be mindful of power too. But, when in a straight line on slick surfaces I still prefer to be pulled rather than pushed.

Rear motor spokes do suffer more of a beating but it's nice to have a light front end that can be more easily lifted when riding over curbs and chunky stuff. Spread weight as evenly as possible - you're more than doubling the weight of the bike and it will be averaging much higher speeds than originally intended.

 

[liveforphysics]

Rear hubs are for straight folk.

If you're thinking about lead, just abort the project and save yourself the trouble.

 

[FMB42]

I agree on the "lead is not the way to go" comments.

I'm also wondering just how your son is going to secure this ebike while at school.

 

[dogman dan]

Must be the extra 80 pounds up front balancing your bike compared to me. Rear hub and rear battery is more rideable with 15 pounds of lifepo4 back there. But 30 pounds makes it pretty bad to me. Not that it can't be ridden, just doesn't feel good, or safe. I start feeling the frame flex like crazy for one, and steering is sketchy with the front wheel so light.

 

[USAEBIKECO]

Dont go sla.. Your spokes will pop with that much weight. Trust me sla is not worth it.

 

[Gordo]

True, but that problem is not so common. I found it quite easy to go over the bars many other ways. :lol:

Rear drive is easier to handle on anything slick, loose sand on the road, etc. Being a highly skilled two wheel rider, I found front hub nice on pavement. But others freak out on it, especially if not really a biker to start with. Rear for sure for dirt riding.

One thing for sure, if you build a bike with rear hub, then stack 30 pounds of sla on the rear rack, it will handle so bad it's unbelievable. So go rear hub if you can, but you must find a way to carry the batteries in the frame of the bike, up front. If your bike choice has no space for batteries up front, then go front hub.

I just built a bike using a "Montana" frame if that is even the proper name? 1KW 24" rear drive with 48V x 12Ah LMP battery pack on the rack. I did not like it, so I put the system on a Giant with front suspension. Feels better, but still don't like all that weight on the rear. Battery in the frame sounds a lot better to me, but I'll ride it for a while to see how it feels. Next build is a 750W 36V 8Ah front wheel drive with the battery in the frame. Then I will be able to decide on what feels best to me.

SLA is not worth even thinking about. And I have lots of free 40Ah mobility scooter batteries. On a utility trike for short commutes, it is an acceptable plan. On a bike, nobody has ever been happy that I can find.

 

[ZOMGVTEK]

I used lead for my first build, mostly since it was cheap. It worked out great for the first few cycles, but noticeably lost capacity as time went on. It ended up lasting only a few months before my 18AH pack would give me 2-3AH, and thats with a TON of voltage sag. It maintained about 3AH for quite some time, but thats pathetic capacity for a 18AH pack that gave 11-13AH new. After winter, the batteries were absolutely dead and worthless. I looked around, and attempted to find new lead for cheap, but it did not exist. For some reason, after a little over a year, the prices nearly doubled. For the cost of a lead pack now, you can honestly almost get comparable 'useable' capacity in Turnigy LiPo... I went with LiPo and its been running dandy since.

I dont even see why anyone would ever go with front drive, thats just silly.

 

[Green Machine]

I gravitate towards front wheel drives because i like IGH (internal gear hubs) for shifting in the back. Once you ride with a igh its hard to go back to derailers.

On pavement they spin out only on take off...but i notice people unfamiliar with electric bikes crash a lot more on the front wheel drive bikes. But once you get use to the concept it is fine. Awful climber in dirt however but then you got to rely on your legs to get the back tire moving

Bike feels much lighter when weight is balanced.

 

[MikeFairbanks]

This is my setup (there are other threads on it), and I'm thrilled.

First, my commute is 4.5 miles each way to work, all on pavement, up and down fairly significant hills and flats.

Secondly, it's SLA and front wheel drive. Neither is an issue.

Details:

A. The battery is a 48-volt SLA, but is only 9ah, which makes it relatively light. The battery pack is 23 pounds. The same in Lifepo would be less than half that weight, but because the pack is in the frame (and very secure) it doesn't affect handling at all. It has low range, but I don't need a lot of range. I get lighter battery in exchange.

B. The front wheel, when the throttle is engaged, will spin a bit when I go over bumps (tree roots in the pavement), but only a fraction of a rotation. I can hear it, but it's not affecting handling.


All-in-all, it is extremely fun and comfortable, and I don't have a single issue with the battery being SLA. It pulls me to work just fine, even up big hills, without lagging much. I don't have to pedal (although I usually do). I'm maintaining 26mph on the flats and about 16-20 on the hills with pedaling. Without pedaling I drop to about 11-13mph on the hills in my town.

It corners well, rides very smoothly (the seatpost has adjustable suspension), and is just a dream to ride around town and to work and back.

The reason this setup is working so well is for a few reasons: First, the weight in the front is actually making the ride a bit smoother. Secondly, the battery is in the frame. Thirdly, the whole bike sits low to the ground. So I'm very satisfied with what I have for my situation. It's a Trek Pure (which is almost exactly the same as an electra townie). The secret is the low center of gravity. Being up high on a regular road, mountain, or hybrid bike is good for hill climbing and muscle efficiency, but that's about it. For commuting, this Trek Pure is like driving a luxury sedan: low and smooth. If you want a jeep, electrify a mountain bike. A hybrid isn't much different than a road bike. But a low-riding beach cruiser, particularly the pedal-forward designs, are smooooth.

As time goes by and the battery runs down I might even consider the exact same battery again. Jason at EbikeKit.com put it together for me, special order, and it's great. 23 pounds behind the seat would be a bummer, but it's not an issue on this bike, and the original kickstand works great.


So, SLA is a bad decision most of the time, but in my case, with my particular bike and frame, it's not a problem. Even the guys at Trek all rode it and love it.


Note: This photo is a bit warped, making the bike look taller than it really is.

I hope none of the above sounds arrogant. I don't mean it like that. I'm just really enthusiastic about this build. It's been a joy. I can honestly say that in my situation the only advantage of a lifePo battery is range. My bike can only do about 8 miles unassisted. The farthest I've gone is nine miles. But like I said, my commute is 4.5 miles and I'm averaging 23mph throughout the trip. It takes me 15 minutes to get to work by Ebike, and 15-20 by car. So unless it's raining or brutally cold, it's a no-brainer. I ride to work, plug it in, and ride it home. It's fun, economical, and handles great. It's actually very relaxing. I'm sitting straight up (not hunched over) and actually feel like I'm reclining while riding, because the pedals are forward. It feels like a chopper.

 

[Pure]

Must be the extra 80 pounds up front balancing your bike compared to me. Rear hub and rear battery is more rideable with 15 pounds of lifepo4 back there. But 30 pounds makes it pretty bad to me. Not that it can't be ridden, just doesn't feel good, or safe. I start feeling the frame flex like crazy for one, and steering is sketchy with the front wheel so light.

It probably is, 80 pounds isn't a little bit of weight.

I should have also mentioned, I do really hate having my batteries back there, but it isn't because of handling issues. My frame has zero room for batteries. If it weren't for the design of my bike I would have moved them a long time ago. I hate the stress the battery put on my seat post. My battery isn't little. I drilled the seat post and the cargo mount and installed a bolt through them to help support the weight. So far no cracking, and my frame doesn't flex, but it still worries me. I do have plans to move it, but it's going to involve some heavy fabrication and splitting my pack in 2.

To the OP, don't bother with SLA it really isn't worth the hassle if you want any kind of range, and if you pull any kind of real amps from a low AH (9Ah) pack it won't last long at all. I killed a temp 48V 9Ah SLA pack pulling 30 Amps in less than 40 miles. That was a hundred bucks tossed down the drain. Oh well live n learn.

 

[dogman dan]

Mikes new bike is a great example of how to do it right, provided you are using a bike with a frame space there. That bike would be great with the motor wheel on either end. If you are going to have to carry lead, that's the place for it. Once you go to lithium, batteries seldom weigh less than 15 pounds.

I do have one bike with rear motor and rear rack, a FS mountain bike. It rides fine with 8 pounds of lipo back there, but put 16 pounds of lifepo4 and the frame starts flexing a lot, and steering is not so solid. You end up leaning on the handlebars hard, leading to hand fatigue on a ride longer than 5 miles.

30 pounds of lead on that bike would be nasty. As the others say, lead is a poor choice. But affording a good lifepo4 pack now can be impossible. Just don't expect that lead to still be good next summer, unless your ride is extremely short. Mike again, has that. He can use lead and never discharge deep enough to damage em. 3-4 miles then charge is about the max for lead to last.

 

[jtdiode]

If you want to be able to remove your front wheel easily in order to throw your bike in the back of a car then I recommend a rear drive motor. Good luck and happy cycling!

 

[etard]

I love when people post up a question and get plenty of response and then don't pop in to say thanks or follow up on what they decided to do.

 

[dogman dan]

Don't you love it even more when guys like me will NEVER shut the hell up? Some are just shy, some are waiting till two weeks later when they get on to the internet again, at the library or whatever.

 

[DrkAngel]

Ebike (Electric bike) vs EAbike (Electric Assist bike).

If you are going to run as an electric motorcycle, then you will want to go with a rear drive!
Especially with a high power front hub, you are liable to spin during heavy acceleration.
Losing traction with your front tire is extremely dangerous.
Dirty, even wet surfaces, are liable to put you down.

So why would anyone ever want a front wheel motor?

A front drive Electric Assist bike is capable of supplying All Wheel Drive.
A reasonable motor up front, combined with pedal assist to the rear, gives awesome traction and performance.
Skill is required! Possibly, restraint, is a better term.
Front throttle must be matched to road, or trail, conditions!

Spinning the rear tire can be considered fun, on the other hand, spinning the front tire is called OUCH!

So beginners, "lead foots", etc. ... go rear motor.
More advanced, skilled, of if you want to enhance your own performance ... front drive can be awesome!