Mid drives vs Hub drives ???

[tomjasz]

To add to "Mass Deduction"'s deconstruction, one other section about the eBikes.ca "Why Hub Motors" could be misleading when taken out of context:



The article is totally accurate when talking about older mid-drive kits, but only about kits. Otherwise, the opposite tends to be true. Mid-drives from the major manufacturers (Bosch, Brose, Shimano, Yamaha, and derivatives such as the motors from Giant and Specialized) always have integrated torque sensing, and that torque sensing has been tuned over time. Thus, the torque sensing worked well with every mid-drive that I tried when I was investigating which bike to buy. On the other hand, torque sensors with hub drives tend to be an afterthought. I had tried two, and one (Stromer ST1) was smooth, the other (Raleigh Misceo iE) was less so. Also, there have been reports on the forum of external torque sensors (i.e. those not associated with mid-drives) going bad over time.

Thus, while torque sensing isn't exclusive to mid-drives, it does tend to be one of mid-drive's main advantages.

As always, it is best to ride any bike before you buy to see how it behaves. The proof is in the pudding.

Yes completely out of context with the subheading, “ Why don't you carry the Bafang BBSXX mid-drive kits?”
Which the article is largely responding to. Funny how the guy supporting and trouble shooting BBSxx motors finds little to quibble about...

 

[Ken M]

The debate between mid and hub drives will always be a bit distorted because DD hubs (unless high power) tend to be poor low speed performers where most people get their "perception" of performance. Even the 250w mid drives and and gear hub drives at 500W or higher will have good low speed acceleration and power especially if the person riding knows how to take advantage of the drive train gearing (ie starts out in the lower gears from a stop or when climbing stays in lower gears).

To me the only thing everyone should understand is that DD and geared hubs do very well at higher speeds which may be very common when the ebike is being used as a tool for transportation / urban mobility / commuting (what term you want to use for riding other then just around the neighborhood for fun).

I just don't think most ebike riders have had the experience of riding a 1000-2000W Direct Drive hub motor at a cruising speed of say 25-35mph - at higher cruising speeds they simply excel and are very efficient. Since I'm pretty capable of putting in the few seconds of effort it takes to get a bike to 15+mph when urban riding this is where I "perceive" performance to be important. I fully understand that there are many that love to just cruise around at 10-15mph but when commuting (where time is pretty much the same as money) the higher average speeds can be a huge benefit.

All the drive and brake wear that can be reduced and the little bit of regeneration possible with with a DD hub is just icing on the cake, not the prime decision factors for most because most riders are just too slow to even consider that in the equation. Sorry to call most riders slow but that is just the way it is. I've been hammered for suggesting that riding above 20mph with assist is a good thing - it's like some consider it a felony.

 

[tomjasz]

Sorry to call most riders slow but that is just the way it is. I've been hammered for suggesting that riding above 20mph with assist is a good thing - it's like some consider it a felony.

Maybe something I've been guilty of. In my defense, I sees many builders putting 35MPH motors on bikes that most LBS won't even do minor repairs on. The Walmart and Big Box series are terrifyingly dangerous builds. I sold my personal BBSHD motors, not wanting to upgrade beyond BB7 disc brakes.
All my newest bikes are 36V. I've actually gone backwards. BUT I do have a 1500W grocery hauler that runs wide open at 25-28. Regen brakes are a dream on that bike. I have may commuter customers that build safe bikes and do ride and choose to safely ride at 25-35MPH.

Great food for thought Ken!

 

[tomjasz]

I pedal unpowered more than 2/3 the distance so I don't want a draggy mid drive.

Hi Joe!

I wonder, which mid drive has been a drag on pedaling?

Thanks!

T

 

[AHicks]

Ken, your riding habits are pretty much a perfect example of where the DD works best. That's why I say they should not be totally discounted. The gear drive hubs, and even the mid drives, are going to have trouble stacking up here, especially when it comes to simplicity. They are way more at home at the lower speeds, where the direct drives, even big ones, struggle.

 

[Ken M]

Maybe something I've been guilty of. In my defense, I sees many builders putting 35MPH motors on bikes that most LBS won't even do minor repairs on. The Walmart and Big Box series are terrifyingly dangerous builds. I sold my personal BBSHD motors, not wanting to upgrade beyond BB7 disc brakes.
All my newest bikes are 36V. I've actually gone backwards. BUT I do have a 1500W grocery hauler that runs wide open at 25-28. Regen brakes are a dream on that bike. I have may commuter customers that build safe bikes and do ride and choose to safely ride at 25-35MPH.

Great food for thought Ken!

Thanks Thomas. I understand that a 50-80lb kit ebike based on a Wamart platform or maybe even a good frame with old rim brakes may be a bit un-nerving to consider a safe ebike but most non-ebike riders have some experience at speeds up to 35mph (at least when going down a long hill) so I consider it a "?safe?" speed for the most part. I'm certainly not in the camp of putting 5000W DD hubs on old bikes and to out and ride at 50mph - I think that is just inviting Darwin into your life.

The debate between mids and hubs tends to be an argument that one is better regardless of application and you and I know that is simply not the case. I mainly ride DD hubs because I find them best for my commuting - I did spend a significant % of my rides over 20mph and I didn't feel like I was a law breaker because I didn't have a Class 3 sticker on my ebike.

 

[Ken M]

Ken, your riding habits are pretty much a perfect example of where the DD works best. That's why I say they should not be totally discounted. The gear drive hubs, and even the mid drives, are going to have trouble stacking up here, especially when it comes to simplicity. They are way more at home at the lower speeds, where the direct drives, even big ones, struggle.

100% agreed on this statement....

 

[Ken M]

Forgot to add that humans are actually pretty efficient at the 0 - 15mph range...especially if only need to get the ebike to 15mph and assist is effective at the higher speeds. That is where the simplicity of a hub simply shines the brightest but it just seems that opinions are so influenced by the constant mid drive marketing machine. I like mid so I don't mean to diss them....but their strengths just don't seem to fit best when an ebike is used as a tool for transportation. Customers just need to be aware of the strengths and how they plan to use their ebike. Buy two ebikes if you plan to do serious mtn biking and serious commuting....

 

[tomjasz]

I mainly ride DD hubs because I find them best for my commuting - I did spend a significant % of my rides over 20mph and I didn't feel like I was a law breaker because I didn't have a Class 3 sticker on my ebike

I'm big on CHOICE and the freedom to chose. Wear helmet but argue against laws, ride at speeds above legal limit, but encourage most to ride at speeds under 20MPH. Support kits and suggest most buy finished bikes. Support mid drive kits but converting two rides to geared motors. I agree with Justin and support BBSxx drives. A walking conundrum? Nah, just an eBike fanboy, without exceptions. There's a ride, a kit, a complete bike for everyone. Sorting which is best for each of us is the fun. It's hard to make a mistake if we use due diligence.

 

[Alex M]

I wonder, which mid drive has been a drag on pedaling?

All of them.
Early Bafang models had quite a notable drag. Recent versions are better. Expensive mid drives like Yamaha are better yet, though technically they all have motor-induced resistance when un-powered. You can't trick physics laws.

 

[tomjasz]

All of them.
Early Bafang models had quite a notable drag. Recent versions are much better. Expensive mid drives like Yamaha are better yet, though technically they all have motor-induced resistance when un-powered. You can't trick physics laws.

Interesting. I have two 2014 BBS01. Maybe the higher power BBS02 750W were worse? My 1500W hub is impossible for me to pedal.

 

[GregGritton]

thing everyone should understand is that DD and geared hubs do very well at higher speeds which may be very common when the ebike is being used as a tool for transportation / urban mobility / commuting (what term you want to use for riding other then just around the neighborhood for fun)...

I've been hammered for suggesting that riding above 20mph with assist is a good thing - it's like some consider it a felony.

The view on speed is probably a major factor in the debate.

In countries where bicycling is commonly used for transportation (i.e. urban mobility), for example, Netherlands, Denmark, and Europe to a lesser degree, and I believe China, speeds do tend to be low. It isn't uncommon to be riding at 10mph in Europe. E-bikes bump this up a little, but not always dramatically. Thus, motors with good acceleration, but low top speeds, often work well in those situations.

US cities tend to be more spread out than European ones and there is much less bicycle only or bicycle/pedestrian paths, so there is more demand for high speeds. This is reflected in part in the typical 20mph (32km/hr) assist levels in the US compared to 25km/hr in Europe, and the fact that class 3 and beyond bikes are more common here.

However, bicycling in the US is already much riskier than bicycling in Europe, and higher speeds increase risk further. Some are fine with that and are happy to ride at 25mph or even 35mph. But 35mph is getting into motorcycle speeds. I wouldn't want to crash at that speed without the protective equipment motorcyclists wear. Others see the value in e-bikes even if the assist stops at 20mph. I find myself in that camp. Personally, I tend to cruise un-aided at about 12mph, so a boost to near 20mph is definitely helpful, but I would rather not take the risk of exceeding 20mph frequently even though it is fun to do occasionally.

 

[Ken M]

You are correct but there are some legal loop holes that allow speed pedelec riders to "take out" the slower riders - it's important to keep our sidewalks and bike path clear for the faster riders. Just kidding of coarse but the reality is that the more crowded any mode of transportation gets the slower the speeds tend to be....I guess that's why I can get around Denver on my bike faster than I can in a car most of the time. I can commute the 18 miles to work faster on my bike than sitting in interstate I25 traffic jams. I don't think many people realize just how effective an ebike can be for transportation.

Note: the higher assist speeds will really only help some riders increase their average commute speeds somewhat. It's not really about hot rods being idiots in most cases.

 

[Mass Deduction]

While I have some general agreements with the article, I find some glaring misrepresentations in your response.

Many heavy duty, EBike designated chains, Connex Whipperman for example, won’t run on narrow side chainrings popular with mid drive users.

I didn't even know Whipperman had e-bike chains. I was referring to KMC's heavy duty e-bike chains, which work fine on narrow/wide chainrings in my experience (dozens installed successfully on a variety of bikes).

Front drive hub motors have very safe and practical applications.

They do, and if you read my reply again, I acknowledged as much. What I am concerned with is front hub conversion kits, which is what the article was referring to. Front forks aren't warrantied for front hub motors, so front hub conversion kits are a problem. I've personally seen forks that failed from conversion kits. However, as I acknowledged in my original post, a bike built, engineered, and warrantied around a front hub motor is a different thing entirely.

Broken spokes are rare in properly built wheels with quality rims and spokes. I’ve seen a fair number in mid drives. And never any unusual rates with proper hub builds.

What do you define as a properly built wheel? I regularly see broken spokes in a variety of hub motor applications. BionX, Rad Power, Pedego, you name it. What is improper about these builds?

I think you miss the point regarding power levels. Justin pointed to the advent of 3000W mid drives. They are hard on drive systems. Very hard.

I agree. They're also illegal to use on anything other than private property, so would presumably be a niche application?

BIONX is an example of one regenerative braking system. My steel fork, front DD using a Grin controller and CA3 is extremely effective. As a Grin user you may have utilized that feature. BIONX is no longer available and maybe not a good representation of how it should have been implemented?

Perhaps not. The fact remains that the article talked about regenerative braking wear as if it were a one-sided thing. It's not, it's a two-sided issue (disc pad wear on one side, motor wear on the other.

Visit a forum with higher voltage mid drives and read about disc pad wear. Significant for some unless upgraded to high end systems.

Would these be street legal? I only have experience with street legal class 1 and class 3 mid-drives, and my comments were only for street legal e-bikes. I believe that disc brake wear is negligible on a lightweight and street legal mid-drive. And potentially less costly than the motor wear of a regenerative system.

Higher end bikes fo have great performance and are fabulous bikes, but pretty anemic for much of the market. Bafang popularity clearly demonstrates that.

I think it's hard to parse Bafang's popularity. I think part of it is more power, and part of it is a lower price. Which does it lean more into? I can't say. I just ordered a bike with an OEM Bafang mid-drive myself, so I'm not closed off to Bafang as a brand.

Your post is a great counterpoint, but I think you make judgements that leave many holes and exceptions. Some, like front hubs glaringly narrow. Front drives can be very successful build methods. Albeit limited, low power dual torque arms and steel forks, but still no reason to pitch the baby with the bath water.

Again, re-read my comment about front hub motors. I dismissed hub motor *kits* for quality and safety concerns. A frame is likelier to handle a rear hub motor than a fork is to handle a front hub motor. You might get lucky in either case, but in both cases they're not engineered for that application when you're doing a conversion. I can only again point to the fact that I acknowledged their potential validity for an OEM build, though.

 

[Mass Deduction]

I've owned 2 drive wheels with hub motors. Neither has broken a spoke over about 4000 miles. I broke one schwinn spoke 20 years ago. The 1000 W 48 v DD hub motor cost $189 with controller, throttle, brake handles, freewheel. The 1200 W 48 v geared front hub cost $221 with controller, throttle, PAS sensor, brake handles, brake calipers & disks. I like having weight on the front, the unpowered MTB's I rode previously threw me over the handlebars on my chin thrice after the wheel whipped sideways on obstructions. I prefer the geared hub for many short steep hills, up to 15%. People in areas with long steep hills should buy DD hub which shed heat better. DD are grade capable but use more electricity on them than geared hub. I pedal unpowered more than 2/3 the distance so I don't want a draggy mid drive.
I changed to IGH (SA 8 speed) before the electric conversion, and that added 15% to my elapsed time over derailleur. You spin all those planatary gears all the time. With the front hub motor I can have 8 speeds on my cassette (11:32) that came with the bike instead of 7 speed (14:28) that came with the DD drive. No 8 speed freewheel on the DD motor would fit the dropout.

Anecdotal evidence isn't hugely useful in debates like this. We all probably know someone who has ridden for decades without a helmet and never got hurt, and we all probably know someone whose life has been saved multiple times by wearing a helmet. But those stories aren't as useful as actual research into the subject, or at least anecdotal evidence with a much larger sample size. Similarly, I would expect responses like yours from people who've had the good fortune to never get a broken spoke on a hub motor, and people who've never had a broken chain on their high torque mid-drive. I'm in the latter camp, but didn't bother to say so as my anecdotal experience doesn't prove anything by itself. Having a high torque mid-drive doesn't guarantee a broken chain, and having a hub motor doesn't guarantee a broken spoke, but in each case it does increase the odds of it.

I'm not someone who owns a mid-drive and is now trying to justify that purchase. I'm actually an LBS owner who gets his e-bikes provided to him for evaluation and changes them on a whim. I've spent hundreds of hours on 4 different e-bikes so far in 2019, and have my eye on another one. My bike shop also sells muscle bikes, but we've been selling e-bikes since 2003 and that is increasingly our focus. We've sold mid-drive OEM, and we've sold rear hub motor OEM. We've sold mid-drive kits, and we've sold hub motor kits. Over 16 years of selling this stuff, we've seen a lot of broken spokes on hub motors, but haven't seen a corresponding rash of broken chains on mid-drives. We do see standard chains on mid-drives wear out more quickly than is ideal, so we recommend people go with a hardened e-bike chain for mid-drive use as they've been standing up very well.

Over time we've focused in on OEM mid-drive as we see far fewer problems with them, our mechanics much prefer working on them, and they're vastly lighter weight presuming similar range and hill-climbing ability. Maybe we were selling the wrong hub motors, or maybe hub motors have gotten a tonne better in recent years. But since someone appeared to insult me by saying "Why do you waste your time Tom?", I thought I'd give more context to my response. I'm no fanboy, and come to this forum to learn and to share what I've learned. I appreciate those responses that I got that were polite, like Tom's. Let's all be a little less quick to judge, shall we?

 

[AHicks]

<<<What do you define as a properly built wheel? I regularly see broken spokes in a variety of hub motor applications. BionX, Rad Power, Pedego, you name it. What is improper about these builds? >>>

Regarding the Rad's, they are pretty well known for loose spokes. Hard to assume this is a well built wheel.

 

[Mass Deduction]

The view on speed is probably a major factor in the debate.

'Tis true. Unless I specify otherwise, my comments are always limited to street legal e-bikes that fall neatly into one of the three classes of the 3 class system.

 

[tomjasz]

I didn't even know Whipperman had e-bike chains. I was referring to KMC's heavy duty e-bike chains, which work fine on narrow/wide chainrings in my experience (dozens installed successfully on a variety of bikes).

Good to know, I'd nt run into them. Off to find....

Front forks aren't warrantied for front hub motors, so front hub conversion kits are a problem. I've personally seen forks that failed from conversion kits. However, as I acknowledged in my original post, a bike built, engineered, and warrantied around a front hub motor is a different thing entirely.

I don't think any kit builders look for warranty on an installation. But certainly there are MANY front conversions, when done thoughtfully and with proper torque arms are safe and sane

What is improper about these builds?

IME it's a quality controller issue. Cheap labor and poorly calibrated robotic wheel builders are the issue. NOT hub motors in wheels.

I dismissed hub motor *kits* for quality and safety concerns.

It's not fair to dismiss all front kits as doomed to fail. There's hundreds if not thousands of safe, sane, and successful front kits. Suspension forks and alloy forks are the first disqualifying parameters.

EDIT OK now I see. You are an LBS. As an LBS I wouldn't install a kit, any kit, on any bike. Liability would run me off instantly!

That said I have dealt with literally thousands of support emails since 2015. I just don't hear about the spoke failures you do. I've never seen a failure on a Grin wheel or any from the LBS I have used and have suggested others use. A little 250W-350W geared hub motor as a front or in a 2wd is quite the nice conversion. Again, a steel fork with dual torque arms, motors up to 750W is typically what those with a decade of building experience suggest as a limit. Having done support for the largest and the smallest of kit sellers, my experience isn't in line with yours. Reading about failures is, as you pointed out to Joe, largely anecdotal and limited typically to some idiot imagining himself smarter than design engineers.

We'll have to generally agree to disagree as regenerative braking is applied to eBikes. My experience is very positive and in thousands of miles of daily use.

Thanks for the great discussion! We need more insight into how LBS approach the business. My view is admittedly myopic given I have no LBS experience other than supporting mechanics doing BBSxx repairs.

 

[Mass Deduction]

<<<What do you define as a properly built wheel? I regularly see broken spokes in a variety of hub motor applications. BionX, Rad Power, Pedego, you name it. What is improper about these builds? >>>

Regarding the Rad's, they are pretty well known for loose spokes. Hard to assume this is a well built wheel.

A well built wheel doesn't always stay that way. How often is the wheel trued? How frequently are people hopping off curbs? A tonne of variables there. The torque emanating from the hub through the spokes doesn't so much create problems, it more exacerbates existing problems. If you have a quality wheel, watch for potholes, don't hob off curbs, and true it regularly then you may never get a broken spoke. But is that level of fastidiousness the norm? I think it probably isn't.

 

[Mass Deduction]

Good to know, I'd nt run into them. Off to find....

They're awesome, and reasonably priced. Typically available in 8spd through 11spd.

I don't think any kit builders look for warranty on an installation. But certainly there are MANY front conversions, when done thoughtfully and with proper torque arms are safe and sane

IME it's a quality controller issue. Cheap labor and poorly calibrated robotic wheel builders are the issue. NOT hub motors in wheels.

It's not fair to dismiss all front kits as doomed to fail. There's hundreds if not thousands of safe, sane, and successful front kits. Suspension forks and alloy forks are the first disqualifying parameters.

There are millions of people who smoke, and don't get lung cancer. I don't necessarily think that a high proportion of front forks with motors fail. But I have seen several failures, so it makes me uncomfortable. The most recent one was on a steel fork too (though, admittedly, a cheap one, not a high-end chromo one).

EDIT OK now I see. You are an LBS. As an LBS I wouldn't install a kit, any kit, on any bike. Liability would run me off instantly!

We've installed rear hub BionX kits many times in the past. We've more recently assisted a customer in installing a Bafang mid-drive, and last summer did a Pendix mid-drive install too. We're not against kits in theory, and have done it several times. In practice, though, we find the end product with conversions isn't as good as a purpose-built alternative.

[...]
We'll have to generally agree to disagree as regenerative braking is applied to eBikes. My experience is very positive and in thousands of miles of daily use.

Not necessarily, I acknowledged my experience was limited to BionX and that leaves the door open to something newer and better.

Thanks for the great discussion! We need more insight into how LBS approach the business. My view is admittedly myopic given I have no LBS experience other than supporting mechanics doing BBSxx repairs.

I'm learning a lot here, and I appreciate both your responses and your politeness!