An old wives tale ???

[Camac]

I've read a number of discussions/reviews on the merits of hub versus mid drive motors.

One of the oft quoted disadvantages of a mid drive layout is that the drive puts more strain on the chain making it prone to breaking. When you think about it it will take say X kw (or Xhp) to move a bike and rider weighing Y kg, 100 yards up a 20 ° slope. On a mid drive AND a non-electric bike that X kw will be applied to the chain ring, to the chain, to the rear wheel. That power on the mid drive will be via the motor and the legs, on the non-electric bike by the legs alone.

I don't see any reports warning of regular bikes breaking chains. funny that !!

 

[slomoshun]

My old wife said you might be a troll.

 

[rich c]

I’ve yet to get my chains measured for stretch, but I have 2 Haibikes with over 2,000 miles on each. On original chains still.

 

[Camac]

My old wife said you might be a troll.

I don't believe I have met your 'old' wife so how would she know .

No this sudden outburst from me was prompted by reading a review which claimed to be "a useful analysis of hub vs mid drive setups". There was a number of long paragraphs extolling the virtues of the hub drives and very little on the mid drives. It mentioned a problem of breaking chains which got me thinking. (dangerous)

( for the last 15 months I have ridden a Bulls MTB)

 

[Reid]

Bike chains of decent construction cannot break, period. That would require either the shearing of a solid pin (impossible!) or the drifting-out of an unriveted pin (impossible in a properly made chain.)

If a chain is "broken" by pressing-out a pin, and that same pin is re-pressed in but not riveted-over, it might be subject to drifting out. In which case, the chain did not "break"; it parted in compliance with physical law of drifting pins; it had to.

9S-and-above-chains have truly riveted, rather-hardened pins. They are NOT meant to be displaced and then pressed back in to stay. They cannot! And they cannot be re-riveted because they are hardened steel. Only single-speed chains can be broken and the rivet pressed back in again and re-riveted. You cannot rivet the hardened steel of multi-speed bicycle chain!

SNAP, goes the riveted portion when breaking such a chain.

SNAP, when breaking a chain, tells you it was a hardened rivet. A hardened rivet cannot be re-riveted! You gotta use a master link when re-joining such a chain, or in the case of a Shimano chain, a master pin of UNhardened, deformable steel.

 

[AlanDB]

Well, I am no bike expert and not a scientist, but I think your point is valid when comparing a mid drive motor to a conventional (pedal only) bike. To propel x amount of weight up a y degree incline takes the same amount of torque and strain on the drive/gear/chain mechanism whether the motor or muscle is providing the power. But, on a hub drive, the motor is providing the power directly to the axle mechanism, not the chain. So it is easier on the chain ... harder on the motor. Again, this is from a novice in both e-bikes and physics, so take my analysis with a "grain of salt".

 

[Deleted member 18083]

I don't see any reports warning of regular bikes breaking chains.

Camac ...
I agree with the comment that you were trying to make in your post #1 above: mid-drive ebikes are no more prone to breaking chains than regular bikes - a point which is stated far more clearly in your later post #11 below.

These days I can climb hills on my ebike at the same rate as I did on my road bike a decade ago: the power transferred through the chain by older me + mid-drive motor combined is essentially the same as was once supplied by younger me alone; therefore, no increase in the risk of chain failure when comparing mid-drive ebike and road bike.
... David

 

[Chris Hammond]

When you think about it it will take say X kw (or Xhp) to move a bike and rider weighing Y kg, 100 yards up a 20 ° slope. On a mid drive AND a non-electric bike that X kw will be applied to the chain ring, to the chain, to the rear wheel. That power on the mid drive will be via the motor and the legs, on the non-electric bike by the legs alone.

You seem to be misunderstanding how a hub drive motor applies power to the wheel. It does not use the bikes drivetrain at all. The simplest way to show this is by looking at an ebike with a FRONT hub motor or take the chain off a rear drive, you can still power the bike with the throttle. Clearly it is not using the bikes chain or cassette to apply power to the wheel. The power is applied via the hub to the spokes ane then the wheel.

A mid-drive clearly has to use the chain to apply power to the wheel.

You can read plenty of reports of people that went to high power mid-drives (>2000W) with broken chains and cassettes.

The degree to which a 250-500W mid-drive causes increased wear is open to debate. However, a hub drive actually reduces the load on the drivetrain, thus as long as maintenance is done, hub drives will clearly have less drivetrain wear.
The trade off is the stress placed on the spokes with a hub motor.
There is no free ride either way. Putting power to the ground will add stress somewhere, hopefully the design engineers did their job well on your bike, if so a good routine maintenance schedule will provide most people with thousands of mostly trouble free riding.

 

[Ann M.]

Breaking would be the wrong word to use; mid drives can do something called "chain suck" where the chain is jammed on the small drive gear if the motor is not disengaged during a shift. Most quality mid drive motors have shift sensors now which helps to prevent this issue. Chain wear can be an issue on a mid drive system particularly if the rider doesn't clean and lube the chain regularly.

 

[Alaskan]

Given that there is more strain put on the chain by a mid drive, I want a mid drive motor on my bike (which I do have) Every review and commentary on the relative merits of mid versus hub drive highlights that the mid drive is way better on hills as it uses the mechanical advantage of the gear train or transmission rather than just simply turning the wheel at the hub. If the added stress on the chain makes it more subject to stretching and/or breakage, use a higher quality chain or better yet a carbon fiber belt drive system to overcome the superior assist on hills made possible with the mid drive. Problem solved.

 

[Camac]

You seem to be misunderstanding how a hub drive motor applies power to the wheel. It does not use the bikes drivetrain at all. .

I am well aware of how a hub drive motor applies power to the wheel but read what I said. I am not talking about hub drive motors. I am simply pointing out reviews usually bring up a breaking chain possibility when the same amount of power will be applied to a chain/drive train by someone riding a non-electric bike. I don't see any reports warning of regular bikes breaking chains.

 

[harryS]

As a casual rider, I've don't look at chains as maintenance items, but there are roadies that claim to replace their chains every few 1000 miles because of chain stretch. So it stands to reason that a heavily used mid drive will wear the components. So what? If the gauge says your chain is stretched, spend the $22 and replace it.

These same roadies say they use cassettes because they blow up the weaker freewheels.. Well, they probably aren't lying, but who else does 100 mile weekends at 25 mph.

So I don't discount the fact that a mid drive ought to be harder on the running gear, but it's a minor thing for most riders unless they really are running hard.
.

.

 

[Nova Haibike]

roadies say they use cassettes because they blow up the weaker freewheels

Off topic to the discussion at hand, but cassettes are better not because freewheels are weaker and "blow up." Rather, the placement of the right side wheel bearings in a freewheel hub means there is uneven loading, resulting in axle bending and breakage.

 

[jazz]

myth

 

[Ebikefevercure]

Chains are cheap and easy to replace. Keep one in the tool box when you go to the trails. Cassettes too.... Bike shop said he replaces chains every 1,000 miles and has never broken one. "CLEAN the chain, cassette and sprockets well. Lube well and don't shift like a fool in the power band" is what he said verbatim. He has a Topnotch Haibike for himself... My mid-drive Voltbike Enduro is 39miles away in Chicago, ugh waiting delivery.....

 

[J Miller]

I am well aware of how a hub drive motor applies power to the wheel but read what I said. I am not talking about hub drive motors. I am simply pointing out reviews usually bring up a breaking chain possibility when the same amount of power will be applied to a chain/drive train by someone riding a non-electric bike. I don't see any reports warning of regular bikes breaking chains.

While a sufficiently well-made chain shouldn't be breaking even under motorized stress, I've had plenty of maintenance issues with my regular bike drivetrains - gear teeth wear out, chains stretch, crank bolt works loose, derailleur catching, etc. Particularly as I ride in all weather. In fact, I've had more incidents with drivetrains than I've ever had with flat tires, most of which are so slow leaking as to not matter until I get home thanks to sealant.

I also really hated the whirring noise and delayed engagement mid-drives had, so I put a lot of research in alternatives, and it turned out that sufficiently powerful DD hubs are fine for non-offroad hills in the right setup, especially with regen on the downslopes.

 

[Mr. Coffee]

Well, I haven't exactly seen a chain snap, which would be spectacular and possibly injury-causing, but I have seen multiple cases where the chain got bent and often hopelessly mangled. From a practical standpoint the effect is the same: expect to walk home unless your field repair skills are up to snuff.

My personal suspicion is that the thinner chains used with bigger 11 and 12 speed cassettes are more prone to failing. I'd guess/speculate that combined with the increased torque of a mid-drive motor that on one of those thinner chains might increase the rate of chain mangling.

 

[ebikemom]

The simplest way to show this is by looking at an ebike with a FRONT hub motor or take the chain off a rear drive, you can still power the bike with the throttle

Today my son's chain fell off on an incline that was steep enough I thought it'd be hard to work on the bike. I said "walk it up here where it's flat." He sat on the bike and throttled it up the hill. It seemed to me like magic!

 

[TForan]

Today my son's chain fell off on an incline that was steep enough I thought it'd be hard to work on the bike. I said "walk it up here where it's flat." He sat on the bike and throttled it up the hill. It seemed to me like magic!

Which is not really a characteristic of a bicycle but a scooter. But, I absolutely loathe throttles on bikes.

 

[JimFMB]

It is not advisable to dismiss the purchase of a mid drive over a concern about chain stretch, wear or strain.