Do mid drives hurt your knees after a while?

[TranslucentGold]

I read a thread that said that the TSDZ2 and BBS02 mid drive motors both caused the rider to spread their feet too wide and that caused them knee damage over time.

Intro guide to TSDZ2 & BBS02 (updated 2021)

Before buying all these motors I would have appreciated the info I'm about to give here and that's why I'm posting this. I own a couple of TSDZ2 (all broken by now, see below), two BBS02 and 1 BBSHD mounted on touring, mtb and city bikes. TS=TongSheng 02=BBS02 HD=BBSHD Shared traits ++ The...

endless-sphere.com

Has anybody else experienced this?

I'd like to get a good torque sensing mid drive but am considering getting a hub motor if this is the case. Are there any good hub motors that go 40+km/h 25mph?

 

[gromike]

That's not been my experience. It all depends on your personal geometry.
There are torque sensing hub motor installations, and yes they go 25mph and beyond. Their weakness is climbing steep hills.

 

[docw009]

I suppose the width of the pedals might bother some people. Doesn't bother me, as I don't pedal hard enough to hurt my knees. I've currently got three mid drive ebikes, one BBS02 and two TSDZ2.

If you're looking for 40 km/hour with motor reliability, you have to forgo the torque sensing and go with the BBS02B, It just works better. We (wife/I) ride our Tongsheng bikes at 20-25 k,/hour, and we get a lot of exercise out of them that wwe don;t with the hubmotors.

 

[Epithemeus]

I've not found the q factor/pedal distance to be an issue with my CYC photon however I am only at about 600km total. The other option I was considering was a GMAC hub with a torque sensing bottom bracket from grin. Any of the hubs they sell can be used with the torque sensing bottom bracket.

 

[calab]

I read a thread that said that the TSDZ2 and BBS02 mid drive motors both caused the rider to spread their feet too wide and that caused them knee damage over time.

Intro guide to TSDZ2 & BBS02 (updated 2021)

Before buying all these motors I would have appreciated the info I'm about to give here and that's why I'm posting this. I own a couple of TSDZ2 (all broken by now, see below), two BBS02 and 1 BBSHD mounted on touring, mtb and city bikes. TS=TongSheng 02=BBS02 HD=BBSHD Shared traits ++ The...

endless-sphere.com

Has anybody else experienced this?

I'd like to get a good torque sending mid drive but am considering getting a hub motor if this is the case. Are there any good hub motors that go 40+km/h 25mph?

What is the terrain like that you will be riding?

 

[Chalo]

All the mid drives I've seen come with goofy flared cranks. I fixed mine (for me) by substituting "square" unicycle cranks.

I like wide Q factor on my own bikes, and my feet tend to wander off to the outer ends of the pedals if the tread width is narrow. But Bafang mid drive is wide even for me.

 

[neptronix]

I think that comment was all from me, consider i have a twist in both of my hips, so my alignment is not good to begin with, but i am a capable ( if lower power ) cyclist and never had cycling pain until the bbs02.

 

[TranslucentGold]

What is the terrain like that you will be riding?

Riding fast on the grass to overtake people using the sidewalk/mixed use paths. Higher speeds on paved surfaces.

I suppose the width of the pedals might bother some people. Doesn't bother me, as I don't pedal hard enough to hurt my knees. I've currently got three mid drive ebikes, one BBS02 and two TSDZ2.

If you're looking for 40 km/hour with motor reliability, you have to forgo the torque sensing and go with the BBS02B, It just works better. We (wife/I) ride our Tongsheng bikes at 20-25 k,/hour, and we get a lot of exercise out of them that wwe don;t with the hubmotors.

I do like torque sensing but for large distances and high speeds, I imagine cadence sensing might be more practical. Thanks for sharing your experience.

 

[docw009]

For high speeds, it's not that cadence sensor is more practical. It's about the TSDZ2's lower power. Mine only pulls about 12A max, according to my wattmeter. The same measurement will give twice as much current on my BBS02B. Current x voltage is watts, so that's twice the power.

Torque sensing is really a fine way to ride a ebike. It doesn't overboost you at low speeds like a cadence sensor. Still, I cannot pedal either of my TSZ2B bikes hard enough to reach 40 km/hour, SOmeone else could, but not me.

 

[richj8990]

That's not been my experience. It all depends on your personal geometry.
There are torque sensing hub motor installations, and yes they go 25mph and beyond. Their weakness is climbing steep hills.

The question is: does the torque sensor couple to a geared or direct drive hub motor. Geared hub motors can climb steep hills, assuming downhill (in this case uphill) tires and low enough gearing for the rider to help out.

 

[richj8990]

All the mid drives I've seen come with goofy flared cranks. I fixed mine (for me) by substituting "square" unicycle cranks.

I like wide Q factor on my own bikes, and my feet tend to wander off to the outer ends of the pedals if the tread width is narrow. But Bafang mid drive is wide even for me.

If you don't mind me linking a different site about this topic: Bicycle Q Factor Definition - Ebike Mid-Drive Motor Q Factor List

• Yamaha PW-X Q Factor Length: 168 mm
• Shimano E8000 Q Factor Length: 175 mm
• Brose Drive T, TF, S Q Factor Length: 179 mm
• Bosch Performance Line Q Factor Length: 180 mm

Considering that modern non-ebike q-factors are now usually 170-185mm (including boost), the brand-name complete ebikes have a normal Q factor. It's generally only the DIY mid-drives that are out to 200mm q or more. And it's a bit puzzling for the DIY ones that they simply don't stretch out the motor mounts a couple more inches so that more traditional narrow-stanced pedals don't hit the back of the motor. I don't understand why the motor has to be so close to the bottom bracket. If people can put the motor in the triangle, they can certainly move it further up the down tube with longer motor mounts.

Eventually I will try again with a normal 181q crankset to do this with my mid-drive that has a q of around 200mm and is VERY offset to the right. What's holding me back is mainly the battery still being attached to the downtube, so no room to properly attach heavy-duty exhaust muffler brackets to hold the front of the motor in place. Have a battery bag now, waiting for more time in the Winter to try. Then try to use a generic tray (see below) and hopefully link everything up solid. I think I actually threw away the one tray I had because it didn't fit the carbon frame, DOH! Has to be used on aluminum or steel (or titanium) 68/73 frame and no extra room on either side of the bb (tray in image is below the engine and to the left of the controller). If you can attach the BACK of a mid-drive motor to the very front of a tray like this, there is a decent chance the pedal cranks will miss the motor and it would be doable. It will be close and you'll need to offset the right pedal with spacer(s) to the right as much as you can, then offset the motor to the left as much as you can. Because with mine, the motor is offset to the right of the frame 15mm, and the q factor is 200 mm; you are shooting for around 180mm q total so the motor needs to be going to the left (centered) and the right pedal a bit to the right so that the chainline can actually work (regardless of 1 or 2 chains).

 

[Chalo]

Considering that modern non-ebike q-factors are now usually 170-185mm (including boost), the brand-name complete ebikes have a normal Q factor. It's generally only the DIY mid-drives that are out to 200mm q or more.

Brand name e-bikes also use proprietary frames, which is one of several major reasons not to buy one.

I don't have an issue with the width of the motors and mountings of DIY mid drives; those widths have practical reasons behind them. It's the dumb flared cranks that add extra Q factor for no reason that I think are a problem.

 

[Saracen]

I read a thread that said that the TSDZ2 and BBS02 mid drive motors both caused the rider to spread their feet too wide and that caused them knee damage over time.


THE CRAP YOU READ lol

 

[neptronix]

I read a thread that said that the TSDZ2 and BBS02 mid drive motors both caused the rider to spread their feet too wide and that caused them knee damage over time.

THE CRAP YOU READ lol

'the crap you read' was my 6 months of physical therapy, the loss of a job ( i needed to be able to stand ), and spiraling depression out of the shock of not being able to walk without severe pain at the age of 35.

What happened was that my leg muscles became imbalanced from the 15mm offset on one leg and it resulted in me walking funny after riding funny. This lead to kneecap issues.
Official diagnosis was chondromalcia patella - a condition where the kneecap doesn't track at an even angle, rubs too hard on one side, and that can lead to extreme inflammation that results in knee cartilage basically disintegrating. The pain is severe and crippling.

People can actually get this from running too if their leg muscles are disbalanced or they are stepping wrong.

Please don't make light of / fun of anyone's injuries on this forum.

 

[UtahPete]

Yes, so I stopped hitting my knees with it and voila...problem solved

 

[riding_on]

Brand name e-bikes also use proprietary frames, which is one of several major reasons not to buy one.

I don't have an issue with the width of the motors and mountings of DIY mid drives; those widths have practical reasons behind them. It's the dumb flared cranks that add extra Q factor for no reason that I think are a problem.

So, I ride a Priority Current ($3,200.00 from the company site without discounts, or any upgrades). They've got the best customer service in the business, I can vouch for that rumor being true, now that I'm on the subject -- but that not withstanding, I'd call them a brand name. My mid-drive from them is a rebranded Truckrun motor (a Chinese company with little or no brand recognition). The motor is a 500w that puts out nearly as much power as a Bafang 1000w, from my anecdotal comparisons, and suits me just fine.

My knees have never been too far apart on either my old unidentified Bafang 750w (1000w peak output) hub drive, or my 500w Truckrun/Priority mid-drive. I do have to state that I believe Priority claiming a 140nm output for their Current is bullshit though, and I have no idea how nobody's called them on it yet. Great bike, great customer service, but that particular bit of marketing is just bullshit IMHO.

 

[Hillhater]

So, I ride a Priority Current ($3,200.00 from the company site without discounts, or any upgrades). They've got the best customer service in the business, I can vouch for that rumor being true, now that I'm on the subject -- but that not withstanding, I'd call them a brand name. My mid-drive from them is a rebranded Truckrun motor (a Chinese company with little or no brand recognition). The motor is a 500w that puts out nearly as much power as a Bafang 1000w, from my anecdotal comparisons, and suits me just fine.

… OK, but what is the “Q” factor, and is it a regular frame with an aftermarket motor, or a “special” frame to suit the motor ?

 

[Chalo]

… OK, but what is the “Q” factor, and is it a regular frame with an aftermarket motor, or a “special” frame to suit the motor ?

Priority Current has a tumor instead of a bottom bracket shell. So that answers your last question.

 

[riding_on]

Priority Current has a tumor instead of a bottom bracket shell. So that answers your last question.

I can't vouch for that information, but I can certainly tell you that my ebike is not growing a neoplasm that threatens the host -- can you explain your use of the word "tumor" to me? Remember, I've only been cycling a few months now.

I haven't caught on to what the Q factor is, but it seems to be slang for the width of the entire crank assembly...? The measurement that you need to know in order to strap a mid-drive motor to the frame?

Priority is a brand name. I'd be happy to answer your questions, but I didn't engineer it the way many here would have. I'm not a good source for this information.

 

[Chalo]

I can't vouch for that information, but I can certainly tell you that my ebike is not growing a neoplasm that threatens the host -- can you explain your use of the word "tumor" to me? Remember, I've only been cycling a few months now.

Here's a bottom bracket shell. This kind has been supported with various cranks for over 100 years, and will still be supported 100 years from now:

This is the same part of a Priority Current bike. It only takes the one kind of motor that's in it, which can't be replaced with anything else, and which may become unavailable at any time:

I haven't caught on to what the Q factor is, but it seems to be slang for the width of the entire crank assembly...?

Q factor stands for "quack factor", short for how much your bike makes you pedal like a duck. It's the side-to-side width across the cranks where the pedals attach.

 

[richj8990]

I do have to state that I believe Priority claiming a 140nm output for their Current is bullshit though, and I have no idea how nobody's called them on it yet. Great bike, great customer service, but that particular bit of marketing is just bullshit IMHO.

The 140 Nm is a pretty common top-end figure that 'could' be possible in some more extreme circumstances, like going about 3 mph up a very steep hill. If you play around with different variables, put on a smaller chainring and huge cassette in the back, and then put the bike in the lowest cog and climb a 15% hill, the torque will theoretically be around 140 Nm for a bike that's 750-1000W.

The more the (usually internal) gear reduction, the smaller the chainring, the larger the cassette in back, the more torque it can have in the smallest cog. On a practical level, it's probably doing more like 50-70 Nm up a steeper hill, because to me 3 mph with an e-bike is just plain silly. 4-6 mph on a mid-drive is more realistic offroad on steep hills, and a little more than that on pavement. But yes a decently powered mid-drive 'can' have 140 Nm of torque; it's just not usable 99% of the time.

 

[richj8990]

'the crap you read' was my 6 months of physical therapy, the loss of a job ( i needed to be able to stand ), and spiraling depression out of the shock of not being able to walk without severe pain at the age of 35.

What happened was that my leg muscles became imbalanced from the 15mm offset on one leg and it resulted in me walking funny after riding funny. This lead to kneecap issues.
Official diagnosis was chondromalcia patella - a condition where the kneecap doesn't track at an even angle, rubs too hard on one side, and that can lead to extreme inflammation that results in knee cartilage basically disintegrating. The pain is severe and crippling.

People can actually get this from running too if their leg muscles are disbalanced or they are stepping wrong.

Please don't make light of / fun of anyone's injuries on this forum.

Sorry to hear about that. You do have options, unfortunately they are not DIY. There are some pretty cool brand name mid-drives out there for around $3500 starting. And good riders are making the most of them offroad. I just rode up a technical hill and got the best time ever personally, but my time was still only 8th out of 18 riders (most of them if they name the bike have 250W mid-drives, peak torque is around 70-80 Nm). The GPS numbers and average mph up the hill tells me these brand-name mid-drives are pretty good. Yes a lot of those guys are better climbers than me but I was using more watts and still finished in the middle of the pack. Don't underestimate a bike that's been QA/QC tested by a company that has money. I'll eventually get one of those when I'm older and can't ride an acoustic bike like I can now. Until then, my e-bikes will be for casual fun and comparing times just for interest/information and not any real competition.

You however should seriously look into one of these bikes if you have that much pain on a wider q-factor bike. No conflict of interest to be a DIY moderator and get a complete e-bike that's comfortable.