Is there any reason I should do a front/rear hub road/gravel bike instead of a mid drive road bike or hybrid/mtb

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uhmwpolyethylene

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Question here, was thinking of doing the usual hybrid bbshd build, but uh, if I had a somewhat lightweight bike, probably not much lighter than the hybrid ubless its very high end, but maybe i could secure a 15-20 lb instead of a 25-28 lb hybrid, could I get away with a q75 250w front hub, or a 750w, 1000w, etc. On the HD I needed like 1200+ to get uphill super easily but with a smaller overall weight with less battery and more of a road bike etc, maybe I would need 750w or less? Get more range? Is a front hub better because it doesn't interrupt your back drive from pedaling, or is a rear huh as efficient.
 
Front hub drives on swift road/ gravel bikes are not ideal. Front hub-drive is never ideal, except on trikes.

You sound like a good candidate for a rear hub drive, since you are wanting a bike for road riding(?)

Mid drives are great. I ride a horse of mountain bike with a Bafang BBSHD mid drive so I can climb steep off-road hills.

You seem to be on another path. Don't search out a lighter "hybrid" bicycle. When you add a motor and battery your need a sturdy bike to support the higher speed.
 
The motor simulator at ebikes.ca and the bike simulator here should tell you what power you need for a certain speed and certain grade at any given weight.

I'm trying to add some electrification to my gravel/road bike as well, and I am currently looking at the BikeOn system. It's similar to a small geared hub motor (Bafang G310 etc.), but without the need for a wheel modification or new wheel.
 
I have an unassisted gravel bike and an assisted MTB. The effort to pedal the gravel bike is about the same as my MTB with the power on level 1, which is about 120w. That's pedalling uphill at the same speed. Downhill, the gravel bike gains from its lower drag, so is quite a lot faster. In summary, you'd gain about 10% range using a gravel bike compared with an MTB. That's for a relatively low power application - say 48v up to 20 amps.

Front motors are generally unsuitable for gravel bikes because the forks are not strong enough and you cannot use high power. Also, you can't get good traction because of the thin tyres. Something like a rear Bafang G370 is a good motor for a gravel bike if you don't want too much power. The Q128C/AKM128C would be better if you want decent power. For that one you should should get the 328 rpm 48v version run at 22 amps, which gives a cruising speed of around 22 mph and really good climbing power. If you want more speed or power, a mid-drive would be better, but your 120w advantage from the gravel bike would then be unnoticeable.
 
d8veh said:
I have an unassisted gravel bike and an assisted MTB. The effort to pedal the gravel bike is about the same as my MTB with the power on level 1, which is about 120w. That's pedalling uphill at the same speed. Downhill, the gravel bike gains from its lower drag, so is quite a lot faster. In summary, you'd gain about 10% range using a gravel bike compared with an MTB. That's for a relatively low power application - say 48v up to 20 amps.

Front motors are generally unsuitable for gravel bikes because the forks are not strong enough and you cannot use high power. Also, you can't get good traction because of the thin tyres. Something like a rear Bafang G370 is a good motor for a gravel bike if you don't want too much power. The Q128C/AKM128C would be better if you want decent power. For that one you should should get the 328 rpm 48v version run at 22 amps, which gives a cruising speed of around 22 mph and really good climbing power. If you want more speed or power, a mid-drive would be better, but your 120w advantage from the gravel bike would then be unnoticeable.
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Here's a question, do rear hub motors interrupt the drivechain of a nicer bike that's equipped with ultegra etc? Also if you do want less weight, they say geared ones weigh less but do they suck more in the 250/500/750w range? And is it very difficult to lace to carbon rims or spokes or not really
 
Other than the fact that both are turning the rear wheel, the pedaling drivetrain and hub motor are independent. One won’t affect the other, except that you may end up shifting less when you have assistance.

Do you care about sound/noise at all? I like my ebike to be silent, so that’s pretty high on the priority list for me. The noise will vary depending on what motor you go with and the controller you end up using.
 
E-HP said:
Other than the fact that both are turning the rear wheel, the pedaling drivetrain and hub motor are independent. One won’t affect the other, except that you may end up shifting less when you have assistance.

Do you care about sound/noise at all? I like my ebike to be silent, so that’s pretty high on the priority list for me. The noise will vary depending on what motor you go with and the controller you end up using.
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But can you mount any size (11/12 sprocket) cassette on most hub motors, or do they restrict what size and type of cassette hub they allow/contain?
 
Gruesome said:
But can you mount any size (11/12 sprocket) cassette on most hub motors, or do they restrict what size and type of cassette hub they allow/contain?
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The ones made for cassettes have a normal freehub. There can be space restrictions depending on the width of the hub used. Ones that accept a freewheel are generally restricted to 7 speeds or less, and limited by the available options. You may shift less with a hub drive, since it’s not necessary as it is with a mid drive. Except for occasionally realigning my derailleur, I probably have only shifted twice in the last couple of years. I only use my highest gear. I pedal a lot; just don’t shift.
 
E-HP said:
The ones made for cassettes have a normal freehub. There can be space restrictions depending on the width of the hub used. Ones that accept a freewheel are generally restricted to 7 speeds or less, and limited by the available options. You may shift less with a hub drive, since it’s not necessary as it is with a mid drive. Except for occasionally realigning my derailleur, I probably have only shifted twice in the last couple of years. I only use my highest gear. I pedal a lot; just don’t shift.
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When you pedal, are you using pedal assist or not?
 
As above, don't worry about the number of gears with a cassette because they're not as necessary with a motor. You can procure individual gears and construct whatever range you desire (and have less weight).
 
I use PAS if I’m riding a long stretch of road, but pedal with throttle otherwise. I have the PAS set to increase assistance when cadence increases, so when I used to pedal on hills with PAS I could shift down and the assist would increase while climbing. Nowadays, I just pedal with throttle, and just apply as much assist as I need. Coincidentally, I may switch to using PAS again since I’m about to make some custom buttons to replace the crappy Grin ones I use to control PAS levels. I’m sure I’ll also use it more when I get around to installing my torque sensor.
It’s sad that a set of buttons could be a deterent to using PAS but twisting the throttle is an easy/lazy substitute, if you have good throttle control.
 
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2old said:
As above, don't worry about the number of gears with a cassette because they're not as necessary with a motor. You can procure individual gears and construct whatever range you desire (and have less weight).
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It’s the case with both hubs a mid drives. A lot of folks rearrange/restack their cogs so that the 3 or 4 they actually use have the best chain line for their mid drive.
 
Some good input, I guess if you did rear hub you'd be losing your expensive rear analog hub on a used classy bike at least but eh. The q75 250w direct drive front hub motor is only 1.4 kg but only supports caliper brakes. As far as rear hub motors go, is a geared one truly lighter in a 250/500/750/1000w config, is a direct drive worth the extra weight with heat efficiency etc... I feel like perhaps if I scooped up a 16 lb road bike maybe I could get away with a 500w/750w lightweight hub motor and a medium/large battery with very long range, with the BBSHD I'll probably end up with two 20ah batts or a 40ah triangle batt, etc. I've also to be honest been aggressively dieting , I tested the bbshd at 250lb and needed I'd say 1200watts+ to get uphill, 1500w to make it trivial, but dropping another 50 pounds will probably make a large difference. Average 700x38 bikes I've seen are round 28 lbs.
Maybe even 250w could be swingable but powering up steep coastal highway roads would be probably mission critical at some point.
 
Another thing was like, the mid drive needs a metal frame ideally, whereas the lightweight bike market shifted to carbon and it's more trivial to scoop up one of those than a 5/10,000$ touring lightweight rigid "90s mtb for gen z" bike that still weighs like 23 lbs. The bbshd 12? Lb weight is not bad and it has the internal permanent magnet rotor , but some hub motor around 4-8 lbs is again some decent weight savings. Those 12,000$ specialized s works creo mid drive bikes aren't even really light even though the mid drive is only 5 lbs 250w, I think because the big downtube for the wimpy 1000$ proprietary 12ah internal battery adds weight. Doing up your own with a 250/500w hub motor would probably make sense , plus you get to use your ultegra bottom bracket etc. Then there's the rotational weight to consider vs mid drive obv
 
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Unrelated question, for those of you who commute and tour on trails; tubeless latex or Schwalbe Marathon plus ? I wasn't aware the latex acts like super slime, and unsure of the Weight between the two, but the rolling resistance of Mplus, the most reliable Schwalbe, is really poor. I have however met a guy who did multiple tours across America, probably on road, who only changed his flats on Mplus once per 3 months.
 
uhmwpolyethylene said:
Here's a question, do rear hub motors interrupt the drivechain of a nicer bike that's equipped with ultegra etc? Also if you do want less weight, they say geared ones weigh less but do they suck more in the 250/500/750w range? And is it very difficult to lace to carbon rims or spokes or not really
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You shouldn't want to use a direct drive motor with a gravel bike. They're too heavy. A small or medium sized geared hub-motor would be fine. They come in two versions: freewheel motors for up to 7 speeds; cassette motors for 8+ speeds. The spline on a cassette motor is the same as any freehub spline, so you can keep your gears.

Don't focus too much on whether a motor is 250w, 500w or 750. The power that any motor makes has little bearing on those numbers. The actual power is determined by the controller, not the motor. The motor only needs to be able to handle the power. Most 250w hub motors can manage 1000w from the battery, which would be about 750w output power at the wheel.
 
One thing to keep in mind is that with a mid drive and decent rims and hubs, it's going to coast a lot further

and faster per power applied than any hub motors. Will be lighter and the center of gravity will be better too.
 
Is there something in the class of weight like the q75 but supports disc brakes and rear hub besides proprietary shit like the mahle x20, I wonder if one could overvolt a smaller direct drive like that
 
For lighter weight, how about going with a friction drive?
endless-sphere.com

Kepler Friction drive comes of age.

Many here are probably aware of my ongoing love hate affair with friction drives. My latest design has been tested over 5000km of commuting and has been been documented on this thread https://endless-sphere.com/forums/viewtopic.php?f=6&t=74269 After discussions with US interests, I have...
endless-sphere.com endless-sphere.com
 
uhmwpolyethylene said:
Is there something in the class of weight like the q75 but supports disc brakes and rear hub besides proprietary shit like the mahle x20, I wonder if one could overvolt a smaller direct drive like that
Click to expand...

Try a shengyi SX2 from ebikes.ca.
500-750w rated, light, quiet, and very efficient for it's size. Good for 25mph duty.
AFAIK the best geared motor out there right now.
 
E-HP said:
For lighter weight, how about going with a friction drive?
endless-sphere.com

Kepler Friction drive comes of age.

Many here are probably aware of my ongoing love hate affair with friction drives. My latest design has been tested over 5000km of commuting and has been been documented on this thread https://endless-sphere.com/forums/viewtopic.php?f=6&t=74269 After discussions with US interests, I have...
endless-sphere.com endless-sphere.com
Click to expand...
That's not something you can buy, or is it? Please post a link.
 
My 500W Q128c rear hubmotor has lasted 7 years and well over 70,000km run at the stock specifications of 48V at ~12A - and still going strong, so I have absolutely no complaints about these motors. lol I'd be more active in these forums if I could get my stuff to break. My first Q128c only lasted a year when run at ~900W, so I suspect they are rated close to the max they can take in terms of thermal tolerance, plus no temperature sensor in the ones I purchased make it hard to tell what is going on inside. I suspect the geared motors just don't have the metal mass to dump and shed all the heat and the nylon gears melt easily. I have no experience with the smaller Q75...
 
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