Front Hub Motor with Shimano Mid Drive Advice

I have an eMTB with the Shimano Steps system with a 250w Mid Drive Motor (Shimano DU-E8000). From what I've been able to find researching there is not a way to add a throttle to this system. The bike is used for short commuting as well as MTB trails. During commuting a throttle would be nice with the ability to have power assist beyond 20mph. I think bike would function as stock for riding until there were long straight paths, then I could throttle up the front hub motor and cruise along. Anything from 25-35 mph would be fine. The battery for this system is as 36v, 14ah (Shimano BT-E8010) in a Shimano case that is semi-integrated into the bike frame. If possible I would like the Hub Motor to be powered off of the existing battery. I assume I would have to integrate a controller for the hub motor (unless built into the front hub). My main focus would be a motor as light as possible that still can cruise once the mid drive shuts off at 20mph. Torque for the hub motor isn't much of a factor as I think the mid drive has that covered. Any other ideas or thought I've missed are welcome!

-Bob

The difference between 25 mph and 35 mph is huge, in terms of power.

Depending on your size and your bike's setup, you need about 1000W to run at 30 mph. That's not a small and light motor. You'll need something with a one-way clutch, so it won't drag on your pedal power or that of your mid drive. When you stack your requirements (front hub, >1kW power, freewheeling), you are left with only the MAC motor as far as I know.

It will add a substantial amount of weight to your bike, and the battery you have probably won't work to provide the power required.

I suggest playing with the Grin Technologies motor simulator to get a sense of what you're up against to achieve your performance goals.

First time using the simulator. I know the bafang g01 is one of the smaller hub motor I've seen mentioned so I setup the sim with it. I did pretty extreme settings with a lot of weight and no human help just for the simulation. If I set it up right it looks like the hub motor would run around 24mph on flats, this would be fine with me. Attached is the screenshot of the simulator.

Cool. That's a close match of top speed to max power. It will run a little faster on a freshly charged battery. Yours needs to be capable of supplying 20 amps.

I thought of the Q128 motor as a candidate for your project. The slow winding might top out lower, though, and the fast one might be underpowered at 20A.

My bike is really heavy, and so am I, so I'd be lucky to get close to 20 mph on the same power.

Are there other hub motors on the lighter side that offer better power to weight ratios? A little heavier is ok if it's a more efficient motor.

The battery may become an issue. I haven't been able to find much info on the shimano battery, I'm sure some proprietary stuff goes on there. I haven't found any info about being able to pull power off the battery in the STePS system. It might well be that tapping into it will trigger some sort of error code and make it shut down. If that's the case I'll probably be looking at a second battery for the hub motor. If there is a way to have the second battery also plug into the charge port on the shimano battery and share power there that would be ok.

If you ride mountain trails, a front hub will be an horrible handling nuisance. And, your small battery will have a very short range powering both motors.

The best solution is to build with a faster, more powerful BB drive, or to trick yours as some had succeeded making it much faster.

The 2nd motor solution must be on the rear in order to make it a good ride.

In all cases, you will need a bigger battery to achieve your goal.

The motors would never be working at the same time. As I described, the hub motor would pretty much be for long flat areas commuting where the stock motor cuts out at 20mph. This is also why the small size / weight of the hub is a consideration. It wouldn't change the stock characteristics of the bike much other than a few pounds on the front wheel.

A few pounds for 25 or so mph is seven or eight pounds. The bike is probably in the 50 pound range now so with a bigger battery you'll be pushing 65.

Its really a bad idea, just stick with your Shimano mid drive motor and maybe upgrade it if you can: buy a bigger battery for it, it will be expensive yes. Can you change the shimano drive in any way, maybe new legit firmware, I really recoil from them proprietary $y$tem$.

Or, just build a 2nd ebike from a bike you already have or a free/cheap bike. But build it with a rear hub, like from Yescomusa or BMSBattery. Then it all comes back to the battery yet again, you will need one.

TristX said:

I have an eMTB with the Shimano Steps system with a 250w Mid Drive Motor (Shimano DU-E8000).

From what I've been able to find researching there is not a way to add a throttle to this system.
It is a proprietary system, its a locked down system, you cant change much of anything, if anything from what I gatehr

The bike is used for short commuting as well as MTB trails.
During commuting a throttle would be nice with the ability to have power assist beyond 20mph.
You wont be able to add a throttle to the system, if it doesnt already have one

I think bike would function as stock for riding until there were long straight paths, then I could throttle up the front hub motor and cruise along.
Why dont you want to cruise along with the Shimano motor?
You will be adding more weight with the motor, you wont be able to tie into the Shimano battery without voiding your warranty and and soldering in some wire and modifying the internals.

*****************>>>>>>>>>>>>>>>>Anything from 25-35 mph would be fine.
Oh I see now, you want to break the law. Good for you :thumb: its still a dumb idea to add a motor to your Shimano mid drive. I do believe there are some hacks out there to bypass the speed limit. But again, I pay no attention to useless proprietary, expensive store bought ebikes.

The battery for this system is as 36v, 14ah (Shimano BT-E8010) in a Shimano case that is semi-integrated into the bike frame.
Proprietary systems means you cant change anything, for legal reasons. Shimano plays it safe.

If possible I would like the Hub Motor to be powered off of the existing battery.
Well, its a proprietary battery. It could be possible, opening up the internals of the battery, hacking and soldering and bypassing. I highly doubt the internals have been documented and posted anywhere on the web. Good luck!


I assume I would have to integrate a controller for the hub motor (unless built into the front hub).
Integrated front hub motor, or rear hub is doable. Again more added weight, a front hub motor would be fine for casual cruising the roads. But you need a battery, lipo from Hobbyking may work well. But again, the overall idea is bad, but I get what you want to do, you want to go fast, beyond the speed limit of the Shimano. You really need to just sell the shimano mid drive bike and build your own bike to go the speeds you want to go. Buy a brand name bicycle, Trek, Giant, whatever suspension flavor you want, buy a BBSHD or Cyclone or Lightning Rods, go 48 or 52V and 40-50A and you can go the speeds you want.

***************>>>>>>>>>My main focus would be a motor as light as possible that still can cruise once the mid drive shuts off at 20mph.
Ya, you want to go faster then the shimano bike. You should have really just built yourself an ebike, or purchased a non proprietary ebike.

Torque for the hub motor isn't much of a factor as I think the mid drive has that covered. Any other ideas or thought I've missed are welcome!

-Bob

Click to expand...

Well beyond that, and your still stuck on the bad idea.
Rear hub motor if you are doing trails.
Front hub motor for city streets, but do use a front fork.
Internal controller, sure why not. 48V will have a 40V cutoff I think. Internal cont should cool down enough, you aint beating on it so.
Battery is the problem, Lipo from Hobbyking. 48V 13S, Multistar in 4S + 4S + 3S all the same Ah, all the same lipo. Then a charger, more cost. Or, Ligo's from Grintech, 36V 2.8Ah https://www.ebikes.ca/shop/electric-bicycle-parts/batteries/36v-ligo-plus-battery.html
means your topspeed will be lower.
Or em3ev smallest battery they got, maybe this one
EM3ev 36V (10S4P) Super Shark Ebike Battery
0 out of 5
From: $275.00 (USD)



Good luck.

As mentioned, a hub motor (especially one that will be dead weight and un-powered in off road mode) will make the bike handle poorly. I don't know, it seems like a complicated way to do things. Two motors that won't even be used together?

You're not going to get a light front hub motor to get you over 20 MPH on 36 volts.

No going to copy everything comment before but I'll make a few points.
I don't intend to break any laws. When I had last looked a class 3 ebike in texas was fine within the parameters I defined. I've reviewed the laws as far as I can tell they are currently and it seems class 1 & 3 have to be pedal assist only, scratch those. Class 2 is pedal or throttle but speed limit of 20mph. Going forward I'll operate on the assumption that I would like the motor to cruise at 20mph on throttle only. I understand that a front hub would be bad to trail riding, I only want the front hub for cruising on flat pavement with very little resistance when the bike is being used for small commutes. I understand during trail use the hub motor setup is basically dead weight. That is ok, if I really want to for trails I can switch to a wheel without the hub. That being said, the front hub motor and wheel would likely see use on multiple bikes which is another reason I'm entertaining this. I'm not out to void my warranty so I won't be "hacking" the shimano system. Thats another reason I was thinking front hub. It will only attach to the suspension fork, which has it's own warranty and is easily replaceable anyway.

In researching motors a bit more I discovered another catch. My front fork has a thru axle. I saw that grin makes an All Axle front hub motor but I couldn't find any others. Is anyone aware of other front hub options that support a thru axle?

It is looking more and more likely that the chance of getting power from the proprietary battery is slim so I'm no adverse to adding on a second 36 volt battery (yes I know, more weight, everything can come off without much trouble if it needs to for trail riding) Does anyone know if there is a way for a second battery to also plug into the charge port of the shimano battery?

I attached another image from the motor sim using Grin v2_Std all axle motor. I put the max weight on there just for argument and 0 human assistance. It seems the sim says the motor basically does what I'm looking for. I'm I missing something where I've input things incorrectly into the sim?

Thanks for all the comments and brainstorming guys.

Is there something special going on in the back where you're not considering rear motor?

Also, not sure, but breaking the fork dropouts off from front motor torque might not be covered under the warranty...



Never mind.. Just reread you have thru axle.

Voltron said:

Is there something special going on in the back where you're not considering rear motor?

Click to expand...

I thought the same for half a minute, but then I remembered that hub motor side covers like to break even when loaded up with pedal power only. I think it would be a bad idea generally to put mid drive power into a hub motor, for that reason.

If you get a rear motor made for cassette it should be fine, esp with just 250 watt. I've seen a couple of motors break with freewheel setup, but they were on rear battery tail-heavy bikes with cheap motors (like an early Pedego)... I haven't seen it be a common failure mode on other motors?

Not all the hubmotor cassette units are very good. The one in my Fusin blew up it's outboard bearing even with just my practically "ghost pedalling" when it was on the test bike and then with no chain and no cluster on it when on the Delta Tripper:
https://endless-sphere.com/forums/viewtopic.php?f=4&t=39877&p=1396593&hilit=fusin+cassette#p1396593
I haven't used the cassette since then with pedal power so dunno if it would still operate correctly even if i replaced the failed bearing rather than leaving it out...if the pawls are as good a quality those could blow up too.

So...YMMV.

If it's "critical" that the middrive be able to function, I would use it thru a regular bike hub, not a motor hub, a number of which have been shown to be problematic even with little to no pedalling.



Regarding the front fork being thru-axle, there are multiple options.

Using the Grin All-axle motor, but it's big and heavy DD motor, vs what you're after.

Making adapters with motor-specific dropouts to bolt/clamp to the fork that put the motor axle just below, in front of, or behind the actual dropouts. This changes the handling of the bike, however.

If the fork has clamps for the crowns, so that the legs are removable or adjustable, then you can simply loosen or remove one of the leg(s) to install the motor into the dropouts, using adapters (you'd have to make) to convert the thru-axle round holes to the doulbe-D of a hubmotor axle. The adapters would have to be torque arms as well, and would be something like those of the Grin all-axle adapters for your specific thru-axle size.

Replace the fork with a non-thru-axle fork, with appropriate torque arms. Pick a fork that has the same travel, and same total length, offset, etc, so that your geometry and steering doesn't change.

Well,I skimmed that other post, and I would say that after doing this to it, and then moving it to a trike where the side loads are racially higher than a two wheeler, along with some loose axle nuts and crashes along the way, just blowing up a bearing seems pretty good! But no broken side cover, right?

You never said whether you have a suspension fork. If you do, that’s a good reason not to use a front hub motor. Even one that’s benign to your fork, like Grin’s All-axle, will cause the suspension to bind when power is applied, and will prematurely wear out the fork bushings.

If you have a rigid thru-axle fork, it’s probably cheaper and more effective to replace the fork and use a regular hubmotor than it is to get an All-axle just to accommodate your fork. It’s an easy swap.

Voltron said:

If you get a rear motor made for cassette it should be fine, esp with just 250 watt. I've seen a couple of motors break with freewheel setup, but they were on rear battery tail-heavy bikes with cheap motors (like an early Pedego)... I haven't seen it be a common failure mode on other motors?

Click to expand...

https://endless-sphere.com/forums/viewtopic.php?t=75580#p1141017
https://endless-sphere.com/forums/viewtopic.php?t=12605#p187643

Plenty of other examples if you look. These were the most relevant ones I found with a quick search.

Voltron said:

Well,I skimmed that other post, and I would say that after doing this to it, and then moving it to a trike where the side loads are racially higher than a two wheeler, along with some loose axle nuts and crashes along the way, just blowing up a bearing seems pretty good! But no broken side cover, right?

Click to expand...

There are no side loads on the bearing that failed, as it was never in use on the trike. It's the outer *cassette mechanism* bearing, not the cover bearing, so it doesn't see any load except when there is force on the cassette cluster from pedalling (or whatever chain drive might be used).

So while the motor itself saw a fair bit of torque loading, and even side-loading, the cassette never had much loading at all, and should never have failed this way.

I can't find them now, but there have been other cases of cassette mechanism (freehub) failure on hubmotors reported here on the forum, though I can't recall how many of them were under loading and how many of them were more like my usage. Either way, it's about the same result--damaged cassette mechanism. :/


So yes, no broken side cover, but since the cassette mechanism is part of the cover, you still have to replace the side cover when you break it, as some of those other reports also couldn't locate a source for just a new freehub (the regular bike hub ones wouldn't fit, IIRC).

Running a frt. hub motor with a mid-drive is not a terrible idea, the OP just needs to lower his expectations.
A small geared hub motor (> 2Kg.) will not greatly effect the handling and can be safely mounted on a alloy suspension fork when installed w/ care.
A low power, small hub motor makes for a much better system up frt. and the power should be kept under 900 Watts. Any more and the tire will start to spin, especially off road.
A "mini" motor on 36 Volts in a 26" whl. will top out around 20 mph in the real world. This is for a "mid" speed range motor (260 rpm rated @ 36 Volts) and a "high" speed range motor should be avoided.
Combined w/ the mid-drive (both on 36 Volts), the two would help ea. other and pick the top speed up to around 22 mph. 48 Volts = 24 to 25 mph. 52 Volts = 25 to 26 mph. This w2ould be the upper limit using said motor systems.
The best way to run a 2WD is w/ two complete independent systems and use a hand throttle to run the frt.
I have found that when using 2 WD, the I would only use the frt. motor about 25% of the time and it's battery could be sized to about a quarter the size of the main batt.

Thanks for all the info everyone.

I was looking at front hub instead of rear for a couple of reason. Rear hub is frame warranty if I had problems, front is simply a fork replacement. Rear wheel is already powered from the mid drive so a front hub creates all wheel drive.

I think the simplest solution is to get a front fork with dropouts for the motor. I had considered this anyway because going back "stock" just means I swap put the fork/wheel combos. I'm a competent bike mechanic so this doesn't bother me any.

So my plan will be a front hub on it's own electronics and that just leaves me back to hub motor choice. What suggestions do y'all have from the lighter motor options? I guess a good place to start would be what is lightest front hub available now? Moving from that are there better options that might be a little heavier, but worth considering because more efficient, reliable etc...

https://www.alibaba.com/product-detail/Greenpedel-36V-250W-lightest-front-wheel_60715270997.html

Is anyone familiar with this motor?

Not specifically, but it might be similar to the smaller of the motors in this thread
https://endless-sphere.com/forums/viewtopic.php?f=2&t=98059

TristX said:

Thanks for all the info everyone.

I was looking at front hub instead of rear for a couple of reason. Rear hub is frame warranty if I had problems, front is simply a fork replacement. Rear wheel is already powered from the mid drive so a front hub creates all wheel drive.

I think the simplest solution is to get a front fork with dropouts for the motor. I had considered this anyway because going back "stock" just means I swap put the fork/wheel combos. I'm a competent bike mechanic so this doesn't bother me any.

So my plan will be a front hub on it's own electronics and that just leaves me back to hub motor choice. What suggestions do y'all have from the lighter motor options? I guess a good place to start would be what is lightest front hub available now? Moving from that are there better options that might be a little heavier, but worth considering because more efficient, reliable etc...

Click to expand...

Hi, I am thinking of doing the same thing. Were you successful? tell me if I should proceed.