Electric Bikes - whats better a front brushless hub or rear?
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im just about to order my kit and was wondering whats better a front hub or rear hub. its just i see allot of
front wheel hubs and not allot of rear ones.
12-10-07, 03:11 AM
Well, i'll provide some input here:
As far as performance is concerned, there is little or no difference. Both orientations will provide pretty much the same output and efficiency.
The largest differences are in the nuances:
1. Weight: The weight of the front hub is easier to balance than the weight of a rear one. Thats not to say that a rear hub can't end up being well balanced, but its much easier to find/buy a decent and reliable rear rack than a front one, and easier to work out weight balance. If you're popping the money for a lighter battery though, a good frame bag isn't hard to come by.
2. Traction and control: generally, front wheels are a bit more manageable if you tap the throttle accidentally. However, they also have a harder time climbing loose terrain, as less of your weight rests on the front wheel than the rear. This isn't noticeable unless you're say, climbing a muddy or wet hill, and it typically still gets you up the hill, just with some wheel slip. Not overly big differences here.
3: Compatibility. I think this is really the important part, one that people often overlook. Basically, its a lot easier to work certain components into a rear wheel mix than a front wheel one. Disk brakes are available for rear wheel systems, whereas they are not for front wheel ones - there's no room. Things like hub dynamos obviously can't be used with a front hub motor either. Suspension is a subject of controversy. Some people will tell you that its a bad idea, others won't. From what i've experienced, and from my research, a decent quality front suspension system works just fine with a moderate hub motor, but packing on the power is a bad idea, as is carelessness with maintenance in this regard.
The only thing you really lose in compatibility in regards to the rear wheel is the ability to use cassette system gearing. That means no 9-10 speed. Freewheels are typically 7 speed, although some 8 speeds are out there. If you can't find a compatible one for your dérailleur and shifter though, getting a rear hub also means getting a whole new rear shifting system. One final thing too, is that for setups where you pack a lot of weight on the rear wheel (Xtracycle, other load bearing utility bikes), the rear wheel often takes a lot more punishment.
Crystalytes are 36 spoke for instance, which is a strong configuration, but a front hub would let you use a touring wheel or a tandem wheel instead on the rear. This is something most people won't need unless they're packing 100+lbs of gear.
Honestly, both types work quite well. I have an appreciation for the front hub system simply due to weight distribution, and the ease in using a stronger rear wheel for load bearing. That said, if you're wanting disks, suspension, or a hub dynamo setup, go with rear drive without a doubt. Oh, and if you're going to be building one of those silly 60v+ e-motorcycle bicycles, go rear.
lol no ill leave the default 36volts. thanks for the info. rear hub sounds just about right for my needs. it works out my rear
has bad hub bearings anyway.
12-10-07, 02:04 PM
Interesting post, pretty much sums up what I have found. I had a rear Crystalyte on my G'friends bike, when it had problems I changed over to 2 front hubs, but it is an agressive setup: 4011 hubs with 72Volts. I was thinking that my real world use of this is probably quite a bit different than what most others want to achieve – because I’m in the mountains and vertical is my main challenge, thus the need for the torque. I have to bear in mind that I went to the front because a pretty good trial of the rear system with the 409 did not appear like it would meet the challenge of the steep hills. Then there was the issue of getting the bike on the car, the weight distribution, etc. So the way I see it, I have no other option than to continue and achieve the end goal of getting a front end that can deal with the torque. Even if I can find steel non suspension forks, it seems I will still need to modify them.
I've already stripped out a cheap pair of steel dropouts:
and I'm going to have to fabricate a real fancy set of acel retainer torque arms something like this:
I've also built 2 NiMh 36 V battery packs at a total cost around $1,000.00 and neither of them work!
The biggest challenge with Front Hubs is stabilizing your dropouts, hopefully once that is achieved, it will be worth it.
12-10-07, 02:43 PM
Actually, thats really interesting to see a front hub with a disk brake. Do you know which make that one is?
On the subject of your motor, a 4011@72v is a massive amount of torque. The fabricated torque arms are probably a *really* good idea in this case. With these motors, typically the bolts and washers on the axle themselves are designed to take the force and need to be as tight as possible to avoid the axle transferring punishment to the dropouts in a prying manner.
The ones that Crystalyte sends out with their kits are only adequate for moderate voltages. I would try giving http://www.ebikes.ca/contacts.shtml These guys a call, last time I checked they have oversized/overstrength washers and nuts for the 4 series motors. At least, I think that's where power in motion gets them from. They cover more surface area on the face of your dropouts, take up more thread on the axle, and have an internal nylon section to prevent them from coming loose. I would give it a shot.
12-12-07, 09:20 AM
I met mark (the guy who owns the bike above) on wednesday last week. He had to custom fit the brake to the motor. His info can be found on this thread: http://endless-sphere.com/forums/viewtopic.php?p=40219#40219. His disc brake is drilled directly into the side of the hub motor. and then fitted from there. there wasn't a lot of spare room to run the brake, and he also HAD to use an 8" rotor, otherwise he wouldn't have been able to fit the caliper over the disc.
His torque arms are great, they can support the bike without the use of the dropouts themselves (ie if they fail but the torque arms don't then the bike will still work. 4011 on the front as abnetcat said is MASSIVE.
12-12-07, 02:47 PM
I just read on this bike, he's done some very neat additions. Looks like a well planned out machine with a lot of effort into it!
12-12-07, 06:24 PM
i would try rear wheel with a good torque arm i have seen many post where those front wheel ones get ripped out.
TSellers-- it's not clear to me why you went for front hubs. The fact that a 409 rear hub was too weak explain to me why after that, you got a different type of front hub, rather than getting a different type of rear hub.
12-17-07, 07:56 AM
Why 4011 on front? Balance, transport: ability to remove front wheel and therefore put it on roof rack on car, ability to keep rear cassette, all wheel drive on hills as opposed to just rear wheel drive, ability to convert bike back to regular ride easily. Why massive torque, to climb the 18% road grade on some of the fire roads. Our welder is going to help me make up a set of fork stabilizers similar to those above that will disperse the torque and take the full weight of the bike in the event of a failure. I imagine that as Crystalyte makes the 4011 in this configuration 1: they must have intended it to be used, 2: therefore I must not be the only one in the world using it.
12-17-07, 01:10 PM
Well, I would think that the 4011 would be paired quite well with a vehicle like an upright delta trike, that would be my ideal application for such a motor. Balance desire though, thats understandable, i've just finished putting together my Xtracycle - and while I don't have a battery right now, put the motor on to test out the balance. If that motor was on the rear, the thing would be *ungodly* weighted towards the rear end, especially loaded with gear! The front motor keeps it a little more even.
Personally, i'll be switching to a frame mounted motor utilizing a P5 Cargo sometime down the road, but for now the 408 on the front end provides good balance.
Personally, it seems like a 4011@72v is overdoing it. My 408@48 goes up those grades with some pedal input quite well, but it all depends on how much input you want to be doing personally I suppose!
Balance desire though, thats understandable, i've just finished putting together my Xtracycle - and while I don't have a battery right now, put the motor on to test out the balance. If that motor was on the rear, the thing would be *ungodly* weighted towards the rear end, especially loaded with gear!
an xtracycle that is not loaded down actually has a lot less weight on the rear wheel than a regular bike... owing to the fact that the rider remains close to the front wheel but is further from the rear wheel (than he would be on a standard bike).
12-18-07, 02:28 PM
Yes, that part is quite apparent, thanks.
I wasn't talking about weight applied to the wheels, rather the fact that an Xtracycle has a fat butt, weight wise. Packing on 9lbs of Freeradical, 15lbs of Crystalyte, and 10lbs of battery is a gain of 34lbs on the rear end, already. Not counting gear I want to carry on the 'X.
The front wheel configuration will take advantage of what is normally one of the front wheels weaknesses, not enough weight for traction over some surfaces. At the same time, it'll let me use a tandem grade wheel for the rear. A rear wheel would work quite well as well, but the front wheel is actually a stronger competitor on an Xtracycle than it is on a normal bicycle. I'll pack the 15lbs of Crystalyte onto the front, 10lbs of battery in the middle, and the X, with the standard gear of lock/tire maintenance and so on, will nearly perfectly balance the load throughout the vehicle.
Of course, then comes along the 150lbs of junk i'll pack onto the 'X :D
12-24-07, 04:07 AM
Another application where the rear hub won't be suitable:
12-24-07, 09:47 AM
What the heck?
12-24-07, 04:25 PM
Another application where the rear hub won't be suitable:
Wow! that is just soooooo teeerrrific :D
Have you seen this one? (not mine unfortunately).
12-31-07, 03:51 AM
Now there's someone that must stay up late. Looks rather out of place without snow!
01-02-08, 07:36 AM
awesome! I want one...do you think it will go up stairs? but yat gonna have to add skis to the front wheels before it will handle in snow.
01-02-08, 06:42 PM
Those wheels are too small to effectively climb most stairs. Rather than skis, I would personally go with a pair of Marathon Winter tires on the front. Tried those out on my friends bike today, grips nearly as good as my Ice Spikers (nearly), but rolls more easily and has reflective sidewalls. Sweet tires those are!
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