Would a 250W mid drive be worthwhile for me - a 'reasonably' fit cyclist?

[JES2020]

A 1000w hub motor will feel nothing like traditional cycling. He'll need something with a torque sensor to get that feel.

Umm, excuse me but, I have rode literally dozens of "traditional" bikes. What you state is not true in my experience.
Other than a few more pounds my Trek Mountain Track rides the same as it did pre 1500w motorized !
And it's w/out a "torque sensor".
I think you forget there are many options of how much PAS to set.

 

[m@Robertson]

it’s critical that the bike still ride like a bike with the motor off or on a very low setting, and critical that you can tune the output based on speed and torque.

You made a point of saying this is your advice, but I want to use that personal opinion as a springboard for a rant of my own. This is what you want and thats fine. Its critical to you but not necessarily to the next guy or gal doing the riding. By way of example, these three stated criteria absolutely require a small motor, low power, a small battery and a torque sensor. But thats the wrong choice for a lot of use cases. In my case its three wrong choices. But thats for me.

I build both geared hubs and mid drives, although in recent years I have left the former behind in favor of the latter. While like all of the other posts here, this is just my opinion, but all of the arguments above against speed, motor size, battery size and (gasp!) torque sensing can be countered and either overcome or replaced by a superior alternative - as far as I'm concerned.

Build a bike with big gears (50T in the front and 11T in the back in my case) and you can pedal the bike faster than the motor can carry it. So you can always work hard and *never* have a bike that outruns you. Dialing pedal assist down is the easiest way to accomplish this though. Some bikes (Sondors in particular in recent years) dial pedal assist way up so even on low settings the bike outruns you. But the settings can be changed in the display (for the Sondors, at least) and problem solved. So this is not a universal trait of hub bikes or even powerful motors. It just requires some effort to dial to your preference.

Big speed means big brakes and strong wheels. And a good helmet/gloves etc. Incumbent on the responsibility you took on when you build the fast bike (or the fast car or fast anything). 30 mph seems like a lot when you think you are riding a bicycle. But as I said before an ebike is a bicycle-shaped-object. and not a bicycle. Use it for utility and transportation and, in order to make it practical if your distances are not short, speed and acceleration - up to a point - is essential to creating that practical automobile replacement. For a recreational bike not so much but if the bike has an actual job its a necessary evil. Couple the speed to the gearing and settings mentioned above and you have practical transportation that gives you a strong workout with none of that 'motorcycle' business in the picture.

As always, it depends on what you want to use the bike for, with your experience as a rider and as a builder (or knowledge of what components to specify to your shop) factored in.

The only absolutes are personal opinions on what it is you want your bike to be and do.

As an aside, I completely agree with the relative speed points above: As a commuter I am safest when the closing rates between myself and the 2-ton boxcars surrounding me are slow. As crazy as it sounds, I prefer rush hour driving as the cars slow down to my speed and for sure I can see drivers having more awareness of me on the road with them. Plus I have an extra second or so to react thanks to those slower closing rates. Normal traffic speeds here are 40-60 mph and they slow to about 30-35 in the rush hours. The difference in safety is very much noticeable just on cars overtaking, for example.

 

[JES2020]

You made a point of saying this is your advice, but I want to use that personal opinion as a springboard for a rant of my own. This is what you want and thats fine. Its critical to you but not necessarily to the next guy or gal doing the riding. By way of example, these three stated criteria absolutely require a small motor, low power, a small battery and a torque sensor. But thats the wrong choice for a lot of use cases. In my case its three wrong choices. But thats for me.

I build both geared hubs and mid drives, although in recent years I have left the former behind in favor of the latter. While like all of the other posts here, this is just my opinion, but all of the arguments above against speed, motor size, battery size and (gasp!) torque sensing can be countered and either overcome or replaced by a superior alternative - as far as I'm concerned.

Build a bike with big gears (50T in the front and 11T in the back in my case) and you can pedal the bike faster than the motor can carry it. So you can always work hard and *never* have a bike that outruns you. Dialing pedal assist down is the easiest way to accomplish this though. Some bikes (Sondors in particular in recent years) dial pedal assist way up so even on low settings the bike outruns you. But the settings can be changed in the display (for the Sondors, at least) and problem solved. So this is not a universal trait of hub bikes or even powerful motors. It just requires some effort to dial to your preference.

Big speed means big brakes and strong wheels. And a good helmet/gloves etc. Incumbent on the responsibility you took on when you build the fast bike (or the fast car or fast anything). 30 mph seems like a lot when you think you are riding a bicycle. But as I said before an ebike is a bicycle-shaped-object. and not a bicycle. Use it for utility and transportation and, in order to make it practical if your distances are not short, speed and acceleration - up to a point - is essential to creating that practical automobile replacement. For a recreational bike not so much but if the bike has an actual job its a necessary evil. Couple the speed to the gearing and settings mentioned above and you have practical transportation that gives you a strong workout with none of that 'motorcycle' business in the picture.

As always, it depends on what you want to use the bike for, with your experience as a rider and as a builder (or knowledge of what components to specify to your shop) factored in.

The only absolutes are personal opinions on what it is you want your bike to be and do.

As an aside, I completely agree with the relative speed points above: As a commuter I am safest when the closing rates between myself and the 2-ton boxcars surrounding me are slow. As crazy as it sounds, I prefer rush hour driving as the cars slow down to my speed and for sure I can see drivers having more awareness of me on the road with them. Plus I have an extra second or so to react thanks to those slower closing rates. Normal traffic speeds here are 40-60 mph and they slow to about 30-35 in the rush hours. The difference in safety is very much noticeable just on cars overtaking, for example.

We finally agree !

 

[EMGX]

I'm just getting familiar with mid drive kits and curious if a 250w motor on a road bike would be worthwhile for me. I'm somewhat fit but I'd like to have that assistance when needed and that nice feeling of moving along at a nice pace. I am a solo rider just calorie burn type rides, no training plan, no goal just cal burn.
It's mostly flat around here with a couple of small to everyone else hills (2% grades). On a good day I'll average 21mph, but usually its around 19.7-20.1 mph.

Would that 250w motor do much for my riding?

thank you

As usual on this web site the replies have gone off the rails. mschwett gave a good and reasoned reply that seems to have addressed your query as a recreational rider content with ~20mph on recreational/fitness rides. The others addressing heavy, high speed and commuter ebikes - not so much. I ride purely for recreation/exercise and personally wouldn't bother with an ebike if the area that I ride in was relatively flat like you describe because I prefer a lighter bike. But I live on a mountain and ebikes have opened up riding opportunities that I wouldn't have with a regular non-assist bike. So for me the weight compromise is worth it and my bikes (that include a Yamaha 250w nominal mid drive powered gravel bike as well as the Tongsheng mid drive conversions) deliver. Almost certainly a 250w motor, mid drive or hub, will make for an easier ride allowing for longer routes, if that is what you want, maybe not much higher average speed though. And there is the weight penalty to consider, as well as the cost/added complexity which can detract from the simple pleasure of riding a bicycle. Make no mistake, a mid drive torque sensing motor will provide a more natural riding experience than a cadence hub drive system. I'd thoroughly ignore the advice about reprogramming a tongsheng - it works great right out of the box, similar to the Yamaha PW-SE on my gravel bike - and not too many people seem to complain about Yamaha functionality.

 

[rich c]

Umm, excuse me but, I have rode literally dozens of "traditional" bikes. What you state is not true in my experience.
Other than a few more pounds my Trek Mountain Track rides the same as it did pre 1500w motorized !
And it's w/out a "torque sensor".
I think you forget there are many options of how much PAS to set.

I didn't forget. It's not how much PAS, it's how smoothly and how quickly. If there is a cadence sensor involved, the disc has to rotate before the motor comes in. With a torque sensor, as soon as a crank moves you have power. No magnets have to move past a sensor to get the power.

 

[mschwett]

But as I said before an ebike is a bicycle-shaped-object. and not a bicycle. Use it for utility and transportation and, in order to make it practical if your distances are not short, speed and acceleration - up to a point - is essential to creating that practical automobile replacement. For a recreational bike not so much but if the bike has an actual job its a necessary evil.

in general i agree with mu

...But as I said before an ebike is a bicycle-shaped-object. and not a bicycle. Use it for utility and transportation and, in order to make it practical if your distances are not short, speed and acceleration - up to a point - is essential to creating that practical automobile replacement. For a recreational bike not so much but if the bike has an actual job its a necessary evil. Couple the speed to the gearing and settings mentioned above and you have practical transportation that gives you a strong workout with none of that 'motorcycle' business in the picture.

As always, it depends on what you want to use the bike for...

i strongly agree with your basic premise - it depends what the bike is for. but in this case, the OP clearly stated what the bike was for - exercise, recreation, and he describes himself as a "reasonably fit cyclist." all the rest of the stuff you said has no bearing on that situation. totally agree that for many people a "car replacement" eBike is a different animal. again, not what OP is asking about. i stand by my point that for exercise and riding for "fun" for a reasonably fit cyclist, a light bike with a relatively low-powered mid-drive on a torque sensor with flexible power levels is the most appropriate answer.

 

[JES2020]

I didn't forget. It's not how much PAS, it's how smoothly and how quickly. If there is a cadence sensor involved, the disc has to rotate before the motor comes in. With a torque sensor, as soon as a crank moves you have power. No magnets have to move past a sensor to get the power.

The you forgot part is, if you set the PAS lower than the force you pedal at, you have control over torque as in a normal bike.
Also you have torque control,(as you stated) before the magnet kicks in, this can be adjusted too, in my case I have it set to 1/4 turn of the crank.
If you are having jerky PAS that's a totally different problem, try a 12 magnet disk and or adjust (if you have the option) the amount of power you give the PAS.
A torque sensor (IMHO), is a high price to pay for the complexities, and possible stranding weak points, of a mid drive motor. Especially considering you get a natural torque sensor with a hub motor. IE your leg muscles.

 

[tomjasz]

We finally agree !

A remarkable achievement.

 

[rich c]

The you forgot part is, if you set the PAS lower than the force you pedal at, you have control over torque as in a normal bike.
Also you have torque control,(as you stated) before the magnet kicks in, this can be adjusted too, in my case I have it set to 1/4 turn of the crank.
If you are having jerky PAS that's a totally different problem, try a 12 magnet disk and or adjust (if you have the option) the amount of power you give the PAS.
A torque sensor (IMHO), is a high price to pay for the complexities, and possible stranding weak points, of a mid drive motor. Especially considering you get a natural torque sensor with a hub motor. IE your leg muscles.

If your legs are your torque sensor, why not make them your motor too? I ride some pretty technical single tracks. If I have to wait for 1/4 turn of the crank, I'm on my ass or worse. There are cases where I am balanced on a rock or roots, climbing a tight switchback. If I have to make a 1/4 turn with no assist, then the assist kicks in, it would make for a need for rapid adjustment. At 69, I don't need the extra challenges!

 

[AHicks]

A 1000w hub motor will feel nothing like traditional cycling. He'll need something with a torque sensor to get that feel.

As somebody that's spent a great deal of time with a 1000w (+) geared hub under me, I struggle with this idea (needs a torque sensor). IMHO, it IS about the controller -but- it is NOT necessarily the with or without torque sensor. There are power based controllers available, mostly on the aftermarket, but also commonly found in Bafang mid drives (I have a bunch of time on both). If you set up the controller correctly for your riding habits and the areas you ride most often, you can control how much assist is available - and it's NOT going to make one bit of difference how fast you go. You want more power/assist, raise the PAS level. Less, just lower it. THAT ALSO gives a pretty workable solution. So torque assist -OR- power based PAS.

Who cares about "traditional" cycling anyway. We're talking about e-bikes here! It's about what works, and what doesn't, as regarding e-bikes......

 

[JES2020]

If your legs are your torque sensor, why not make them your motor too? I ride some pretty technical single tracks. If I have to wait for 1/4 turn of the crank, I'm on my ass or worse. There are cases where I am balanced on a rock or roots, climbing a tight switchback. If I have to make a 1/4 turn with no assist, then the assist kicks in, it would make for a need for rapid adjustment. At 69, I don't need the extra challenges!

"If your legs are your torque sensor, why not make them your motor too?"
You have to make up your mind if you want a standard or an ebike !

"If I have to wait for 1/4 turn of the crank,I'm on my ass or worse"
You still can power your bike before the motor kicks in, have you ever ridden a hub drive ebike?

"If I have to make a 1/4 turn with no assist, then the assist kicks in, it would make for a need for rapid adjustment. At 69, I don't need the extra challenges!"
Simple, if your legs are not up to the task of launching you on your bike, use a throttle.
Like I already mentioned, you can set how much power your PAS has (if you have that kind of controller).

 

[tomjasz]

I have 2 BBS02B 36V 250W and 2 36V 350W. My 350W have been in use since 2014.
All I need. I no longer want or need more than 20mph.
I’m very happy. Drag is minimal without motor running.

 

[PedalUma]

I am about to walk from a bike for the first time. I will give the owner a free $15 tube for their trouble. The last person to work on it over tightened a hex bolt with red Loctite on the non-dropout side. That's correct. On the drive-side which is single speed there is no dropout! You must remove the end of the frame to drop the rear wheel. The bike is a 2,000W, 81.8 pound hub drive. The huge battery is way up high for poor handling. There is no way to put it in a bike stand. It does not have a seat post to grab onto and it has a bunch of crap on the handlebar so you can't just flip it. The last guy to work on it charged them $60 to fix a flat. I will let them take the monster back to him. He did the overtightening. I agree that there are different styles of riding and different types of bikes to accommodate these preferences. I am good with that. I like riding bikes. This 'bike' is not for me. Legally it is an illegal motorcycle. The pedals are decorations and the crank arms are like the arms of a T-rex, an afterthought. Normal crankarms are 170-175mm. These are 115mm. https://super73.com/products/super73-rx

 

[JES2020]

I am about to walk from a bike for the first time. I will give the owner a free $15 tube for their trouble. The last person to work on it over tightened a hex bolt with red Loctite on the non-dropout side. That's correct. On the drive-side which is single speed there is no dropout! You must remove the end of the frame to drop the rear wheel. The bike is a 2,000W, 81.8 pound hub drive. The huge battery is way up high for poor handling. There is no way to put it in a bike stand. It does not have a seat post to grab onto and it has a bunch of crap on the handlebar so you can't just flip it. The last guy to work on it charged them $60 to fix a flat. I will let them take the monster back to him. He did the overtightening. I agree that there are different styles of riding and different types of bikes to accommodate these preferences. I am good with that. I like riding bikes. This 'bike' is not for me. Legally it is an illegal motorcycle. The pedals are decorations and the crank arms are like the arms of a T-rex, an afterthought. Normal crankarms are 170-175mm. These are 115mm. https://super73.com/products/super73-rx
View attachment 95724

Well put together, not my style of bike, but I do like the two piece fenders. 2000w on such a heavy bike, I bet top speed is not astounding. Especially with those heavy fat tires and 960w battery. Range is overestimated IMO, unless by "eco pedal assist" they mean pedal your ass off : )
for that price I could build 4 1500w geared hub bikes.

 

[m@Robertson]

in general i agree with mu


i strongly agree with your basic premise - it depends what the bike is for. but in this case, the OP clearly stated what the bike was for - exercise, recreation, and he describes himself as a "reasonably fit cyclist." all the rest of the stuff you said has no bearing on that situation. totally agree that for many people a "car replacement" eBike is a different animal. again, not what OP is asking about.

Fair enough. I got triggered and lost sight of the original scope. My bad.

On point: The OP asked about a 250w motor on a 'road bike'. I'll offer this: For that kind of hardware a low-current motor (notice I did not say low wattage) is all he should consider. The chain- and seatstays on a road bike that wasn't made to have a motor are too spindly to take on anything powerful. I have seen BBS02s on bona fide older road bike frames be a big success, after they have had their amperage dialed back and the rider took the 'bicycle shaped object' designation to heart and spent time working over the PAS settings so they are in their personal Goldilocks zone.

I know of a couple of old-school fit-but-mid-curious riders who have fallen in love again with their 1990's chromoly road bikes, resurrected from the garage ceiling. Key word: "Back it off".

So... its not a question of whether its good for riding, its all about what a frame like that can handle. I'd back it off to 15a tops, work over PAS and watch it like a hawk to see if amperage needs to be dropped some more. I'd also use a higher powered motor (750w BBS02 or Tongsheng with the OSF firmware) as again the amps are what matters and the higher powered motors have upgraded controllers that, once dialed back, should last forever no matter what.

I would think this sort of minimalist build is right up @PedalUma's alley.

Both of the road bike riders I know used bigger batteries. One a Wolf pack and the other a Shark.

 

[PedalUma]

Fair enough. I got triggered and lost sight of the original scope. My bad.

On point: The OP asked about a 250w motor on a 'road bike'. I'll offer this: For that kind of hardware a low-current motor (notice I did not say low wattage) is all he should consider. The chain- and seatstays on a road bike that wasn't made to have a motor are too spindly to take on anything powerful. I have seen BBS02s on bona fide older road bike frames be a big success, after they have had their amperage dialed back and the rider took the 'bicycle shaped object' designation to heart and spent time working over the PAS settings so they are in their personal Goldilocks zone.

I know of a couple of old-school fit-but-mid-curious riders who have fallen in love again with their 1990's chromoly road bikes, resurrected from the garage ceiling. Key word: "Back it off".

So... its not a question of whether its good for riding, its all about what a frame like that can handle. I'd back it off to 15a tops, work over PAS and watch it like a hawk to see if amperage needs to be dropped some more. I'd also use a higher powered motor (750w BBS02 or Tongsheng with the OSF firmware) as again the amps are what matters and the higher powered motors have upgraded controllers that, once dialed back, should last forever no matter what.

I would think this sort of minimalist build is right up @PedalUma's alley.

Both of the road bike riders I know used bigger batteries. One a Wolf pack and the other a Shark.

Yes, those Chromoly frames from the 70's, 80's and 1990's were sweet and make for great conversions. The frame is the soul of the bike. Everything else can be swapped out. I will be doing a 750W TS for a Cop next with a 48V 7Wh battery and will have it limited to 16Amps. The 750 motor is the same weight as the 350W, so why not. It is just the battery that is a little heavier, yet is still the diameter of a standard water bottle so it can be covered by one.
The guy with the Super 73 is pissed I did not fix it. The last guy to work on it is many miles away. I am just not going to risk sheering off the head of a vital bolt.

 

[PedalUma]

The bolts on the Super 73 are made out of cheese. In contrast, the Mecian is a 1972 bike and still holding up.

 

[stw]

Fair enough. I got triggered and lost sight of the original scope. My bad.

On point: The OP asked about a 250w motor on a 'road bike'. I'll offer this: For that kind of hardware a low-current motor (notice I did not say low wattage) is all he should consider. The chain- and seatstays on a road bike that wasn't made to have a motor are too spindly to take on anything powerful. I have seen BBS02s on bona fide older road bike frames be a big success, after they have had their amperage dialed back and the rider took the 'bicycle shaped object' designation to heart and spent time working over the PAS settings so they are in their personal Goldilocks zone.

I know of a couple of old-school fit-but-mid-curious riders who have fallen in love again with their 1990's chromoly road bikes, resurrected from the garage ceiling. Key word: "Back it off".

So... its not a question of whether its good for riding, its all about what a frame like that can handle. I'd back it off to 15a tops, work over PAS and watch it like a hawk to see if amperage needs to be dropped some more. I'd also use a higher powered motor (750w BBS02 or Tongsheng with the OSF firmware) as again the amps are what matters and the higher powered motors have upgraded controllers that, once dialed back, should last forever no matter what.

I would think this sort of minimalist build is right up @PedalUma's alley.

Both of the road bike riders I know used bigger batteries. One a Wolf pack and the other a Shark.

Would you (and/or @PedalUma) say this advice for building/converting a steel frame bike applies to a hub-motor conversion too? Or is does the advice to limit the amps/current apply mainly to a mid-drive conversion where the motor is pulling the chain and yanking hard on chainstays and bb not built for the extra power?

I can see a lot of power through a hub-drive could also de-stabilize a flexible steel road bike, but perhaps it does it more symmetrically than a mid-drive and without trying to fold the frame in half (which is how a lot of power through the off-set chain drive functions).

 

[stw]

Well put together, not my style of bike, but I do like the two piece fenders. 2000w on such a heavy bike, I bet top speed is not astounding. Especially with those heavy fat tires and 960w battery. Range is overestimated IMO, unless by "eco pedal assist" they mean pedal your ass off : )
for that price I could build 4 1500w geared hub bikes.

If 2000w is marginal on such a heavy bike (with hub-motor), it must be limiting for steep climbing / sustained climbing even more than it limits top speed or range(?).

 

[m@Robertson]

Would you (and/or @PedalUma) say this advice for building/converting a steel frame bike applies to a hub-motor conversion too? Or is does the advice to limit the amps/current apply mainly to a mid-drive conversion where the motor is pulling the chain and yanking hard on chainstays and bb not built for the extra power?

I can see a lot of power through a hub-drive could also de-stabilize a flexible steel road bike, but perhaps it does it more symmetrically than a mid-drive and without trying to fold the frame in half (which is how a lot of power through the off-set chain drive functions).

I think with a hub motor you have limits, but for different reasons. With a mid drive, the mid pulls like hell on the chain, which pulls the chain and seatstays with it unless they are strong enough to resist. Duck soup for an emtb rear triangle. A road bike with Columbus tubing? Too big of an ask as we described above.

A hub motor is a different animal. It powers the bike thru the axle. That means in addition to it being a single-speed assist independent of the drivetrain (with the associated implications on hill climbing) it is putting rotational force on the dropouts in order for it to be able to spin forward. Just like the lightweight stays were not designed for a kilowatt of oomph, neither are the dropouts expecting to get enormous twisting forces applied to them, and if they are steel they will spread so they are no longer parallel, at which point the frame is literally ruined. If its an alloy frame, then the dropouts just snap instead of bending/spreading because aluminum.

The above is the worst case scenario. You counteract that unintended force with something known as a torque arm. And there are good quality ones and crappy ones. But either way a donor ebike is a more suitable donor if it has beefy parts on it. A proper old school lightweight road bike is not that, and as such you should limit it to a lower-power solution. And still do torque arms because there is (unless you have a frame building shop and jigs+brazing tools+spare dropouts) *no* coming back from dropouts that have spread past parallel and let the axle spin.

So short answer is yes I would go low power on a hub motor too if the donor is a quality road bike. Given my druthers I would do a dialed-back BBS02. Like I said I know of two hard-core cyclists who have done it and they were in love when they had it all dialed in.