My new e-bike - Grin Tech hub motor first impressions

[rgthom]

Thanks to this forum, I put together a mid-drive conversion of an old mountain bike and it has been my main commuter and cargo hauling car replacement for several years now. Doing the mid drive means it is a full time e-bike, you cannot just pop off the motor and the bike is no fun to ride without the boost. Here it is hauling groceries:



I wanted to try boosting our urban tandem, but this time do it as an easy to convert front hub motor. I went with a setup from Grin Technologies in Canada. They specialize in hub motors, with a lot of options and a completely user programmable system. The Grin website and YouTube channel have tutorials to help the noobs. The Grin system uses their BaseRunner motor controller, which fits into a standard Hailong battery mount and is programmable for almost any available motor. Coupled with their Cycle Analyst display/control unit you can set any parameter of interest.

Per advice from Grin tech support I went with a small gear driven motor, the Shengyi SX1. It is a little bigger and can handle more power than the smaller Bafang G311, but at 6.5 lb is still very light. The motor was laced up into a 700C wheel with a Dyad rim. I already had a 48 V, 17.5 Ah Hailong battery from the mid drive.

The motor axle has 10 mm flats to fit into the bike's dropouts, for some reason this is usually too big and Grin recommends filing the dropouts. I did not want to do that and confirmed with them that it was OK to file down the motor flats.

[LeeG]

It’ll be interesting to see how the Dyad holds up. Btw I got a Tongsen midrive for my Surly LHT but haven’t installed it yet. So far the ClemSmith has held up w the bbshd on it. I rode it over a trail that I used to set at level 7 and decided to go with 3 and it was fine. That motor is a beast. Still considering a Gus Boots frame.

[Joe (SoCal)]

The roses are a nice touch

[Ted Hoppe]

Subscribed!

[rgthom]

Since the wheel can go in any other 700c bike I decided to try it first in my fancy custom steel randonneur, just to see what it would do.

The axle flats in steel dropouts are supposed to be enough for moderate power use, but Grin recommends using a torque arm. At $20 it is cheap insurance against spinning out the dropouts. Here the wheel is installed in the rando fork, using a rack mount braze-on as the torque arm anchor. My ever present assistant watching on.

[rgthom]

Grin does provide a lot of information. Between the manuals for each part, the website, YouTube videos and the depths of Endless Sphere you can usually find the answer. The problem for a noob is where to look for the simple things. I did not order a complete kit, that would have come with everything fit up and all programming done, so I had a few bumps in the learning curve. First was that Grin does not use the same battery connector as my Hailong battery, so I had to solder my existing connector over to the BaseRunner battery wires. The BaseRunner had a plastic knob which seemed to push in like a switch but I could not find it in the manual. Turns out it is just a plastic plug to protect the programming port . There are extra cables from both BaseRunner and Cycle Analyst, including PAS connectors on each of these. Tech support finally got me straightened out on all the issues, they were very helpful.

[rgthom]

With the BaseRunner installed inside the battery mount, I needed a place to locate the battery. Downtube is the usual place, and Grin makes a downtube mount adapter, but I wanted to keep the rando bike e-stealthy and chose to put it on the rear rack where I can hide the battery under a rack bag. This took a little fiddling to make some aluminum and wooden mounting pieces, otherwise no problem:

[rgthom]

The Grin system is adaptable to a lot of motors and to interface with other makers systems. The Cycle Analyst acts basically as a smart throttle, in that it takes various inputs, calculates desired motor power, then puts out a "throttle" signal to drive the motor through whichever motor controller is being used. It supports basic throttle, a "cruise control" throttle mode, basic pedal assist (PAS), and several torque sensing systems.

I wanted just PAS. As a cyclist, I just want the motor to turn on when I start to pedal. Grin sells several PAS sensor setups that mount somewhere near the bottom bracket. Their integrated magnet/sensor unit was not going to fit on either the tandem or the rando bike, so I got a model with separate magnet disk and sensor. The magnet disk is made to fit onto a square taper crank, which I have, but mine does not have enough exposed shaft. I opened up the center of the plastic magnet ring to fit over my cranks, and am holding it with a cable tie:



This moved the magnet ring farther out than normal, so now I needed to make a little bracket to hold the sensor:

[rgthom]

For my simple system, cabling is straightforward. There is a motor drive cable from the battery mount/BaseRunner to the hub motor, a control cable from battery mount to Cycle Analyst, and cables from Cycle Analyst to the PAS sensor and to a handlebar thumb switch unit. Both the Cycle Analyst and the thumb switch have hinged mounting clamps, so no need to remove anything just clamp onto almost any handlebar.

[StevenBauer]

Looks great. How's the ride?
What kind of suspension does this bike have?

[StevenBauer]

Oh, and what size battery and what is your expected range?

[LeeG]

Looks great. How's the ride?
What kind of suspension does this bike have?

#5 shows one part of the suspension, the other being knees and elbows.

[rgthom]

As Lee says, this is my rando road bike. Suspension is in the flex forks and a B67 sprung saddle. Here it is with the Grin system installed:

[Jim Bow]

Did you lace up the wheel yourself, or a bikeshop.

[Canoeyawl]

Great photo!



I want one of these

FD4127A4-5F76-45A9-9FE0-FBD997D75C6E.jpg

[rgthom]

Did you lace up the wheel yourself, or a bikeshop.

Bike shop. I used to build a few wheels but that is a skill worth paying for. It is hard enough to calculate and order the right length spokes.

[rgthom]

Oh, and what size battery and what is your expected range?

The battery is the 48 V, 17.5 Ah taken from the mid drive bike. I can swap it around as I am not going to be riding both. On the mid drive I do my 35 mile commute at power levels mostly 250 and 400 W, occasionally 600 W on the hills. On a calm day I get to work with ~30% power remaining, on a 20 kt headwind summer day it gets close to empty. I have not done the commute yet on the rando bike, but plan to try it.

[phiil]

Very nice conversion. I put a Bafang mid-drive on my mountain bike a few years ago. Crude and powerful. I’ve since graduated to high end bikes like reise and muller and Tern, but the kit is what made me a convert. I no longer own any Internal Combustion Engines.

[amish rob]

Bike shop. I used to build a few wheels but that is a skill worth paying for. It is hard enough to calculate and order the right length spokes.

There are several inline spoke length calculators that are wonderful. FWIW. Building custom wheels is the one bike related job I can still be coerced into doing; aside from race prep.
There are still a few cats whose bikes I prep for big races. Fun stuff, though I admit to despising carbon frames with internally routed hydraulic brake lines (actually, I don’t like ANY internal routing) and electronic derailleurs.

Be wary of turning at speed with power on. Not that I imagine you’ll be doing any circuitous maneuvering, but a driven front wheel can have some effects on the handling of a two wheeler.

It looks super clean, and I bet it’ll be fun to ride. I’ll bet that wheel will feel “stiff” with that high flange, short spokes, and two cross.

I look forward to a full report.

[rgthom]

Programming the system was easy. The Baserunner motor controller is programmed through a USB cable from a Grin dashboard. The cable has a custom plug on the controller end, so a Grin cable has to be purchased for $14. You just download the configuration for the motor being programmed and load it. The configurations are available for most motors out there, but for a special case there is a motor autodetect function. Anything can also be tweaked from the dashboard. I just loaded the stock configuration.

More parameters can then be set in the Cycle Analyst through a series of setup modes. This sets wheel size and number of pulses per rev to calibrate the speedometer, battery chemistry and voltage, battery low V safety cutoff, throttle input and output, speed and power limits (to meet local regulations), PAS and torque sensor settings, temperature sensor type and power reduction curve for thermal protection. There is also regen, brake cutoff, and other features I am not using.

[rgthom]

I look forward to a full report.

Getting to that! Had to set the stage of where I am at the moment .

First to note is that the hub motor has a clutch and is freewheeling. Riding the bike no battery with the motor wheel vs the normal wheel I can tell the difference but it is not much. I could ride home from work unpowered, something it would be very hard to do on the mid drive.

An issue for a front hub motor is less traction up front as Rob notes. I have been able to lose traction at 500 W up a steep hill when edging onto the gravel at the side of the road, but so far wet road has not been a problem. I ride more at 200 to 300 W, human type power levels, so the front hub with me pedaling on the back is like AWD.

Compared to mid drive the hub motor does not use the gears to better match motor torque to the bike speed. Now I have tried both it is less noticeable than I expected. There is still a lot of useful torque at 300 W while climbing at 6 - 8 mph.

I would not use a front hub on a mountain bike, but so far on this road bike the simplicity and ease of swapping to another bike wins big.

On the mid drive converted mountain bike I typically ride flat windless at 20 to 22 mph using my 250 W setting. On this new bike set to 300 W I was hitting the 28 mph motor cutoff limit frequently on a 20 mile ride. This is probably due to better bike and lower riding position, but the hub motor is clearly very efficient used at typical road speeds.

My plan for when this string of atmospheric rivers is over is to do my commute on the new bike. I have it well characterized on the mid drive, so it will be interesting to see if I can do it any faster or use less charge.

[rgthom]

Notes on motor power: Grin makes a point that rating motor power is meaningless. Motors will take as much power as the controller puts into them, the limit is when the motor heats up to the level of damage. They say this little SX1 is nominally a 250 to 500 W motor, but that many people get away using much higher levels at least for limited time. I set the thermal protection to what they call very safe levels - begin rolloff at 90 C and finally no power if it reaches 130 C. On my 20 mile test ride I used 300 W mostly but pushed to 500 W for a while to see how hot it got. With outside temperature around 20 C the hottest the motor reached was 47 C, only 27 C rise. Even on a 30 C day I do not think with my riding I would ever see it reach the lower limit at 60 C over ambient.

[Bob (oh, THAT Bob)]

I like the torque mount. Frame axle slots are just not designed for that, very short bearing area and moment arm.

I like that the spokes have a cross pattern; I've seen a lot of large e-hubs that didn't cross spokes, just a mild splay angle, also don't like, although that may be more necessary on a 20" wheel and smaller due to crossed spokes having a poor angle at the rim/nipple interface.

Your front and rear racks look like Nitto and chrome moly steel, yes?

I bike for exercise. If I need electric, I want it without compromise to gearing. Front hub drive does that, I've considered, but mid drive is more efficient. Though on a 20" wheel, sufficient motor torque is less of a problem. 1x11 systems make mid drives more possible (I think a primary motivation for their invention), but on a 20" wheel folder, a big pie-plate low gear means that long derailleur cage may drag on the ground. I've read about the Pinion mid-transmission, 18 speeds with no duplicates, fabulous but super expensive, available on $5000 bikes, but I don't know if it is compatible with a mid-drive electric.

[rgthom]

I like the torque mount. Frame axle slots are just not designed for that, very short bearing area and moment arm.

I like that the spokes have a cross pattern; I've seen a lot of large e-hubs that didn't cross spokes, just a mild splay angle, also don't like, although that may be more necessary on a 20" wheel and smaller due to crossed spokes having a poor angle at the rim/nipple interface.

Your front and rear racks look like Nitto and chrome moly steel, yes?

I bike for exercise. If I need electric, I want it without compromise to gearing. Front hub drive does that, I've considered, but mid drive is more efficient. Though on a 20" wheel, sufficient motor torque is less of a problem. 1x11 systems make mid drives more possible (I think a primary motivation for their invention), but on a 20" wheel folder, a big pie-plate low gear means that long derailleur cage may drag on the ground. I've read about the Pinion mid-transmission, 18 speeds with no duplicates, fabulous but super expensive, available on $5000 bikes, but I don't know if it is compatible with a mid-drive electric.

Peter White built the wheel, he knows what he is doing, but next time I will ask Rob ;-)
The front rack is by the framebuilder, John Fitzgerald. The rear is one Nitto makes for Rivendell. Both are stainless.
I read that mid drive is more efficient too, but this bike is going faster on similar power than my mid drive. I want too see how it compares on my commute.
Mid drive is always 1X, I think, you get rid of the whole crank and front gears. Mine is 1X9, I like the range but with the motor power small gear steps are just not useful. Could use only 5 cassettes if such a thing was still made.
The alternate gearing compatible with mid drive that I know about is the e-Rohloff. They teamed with Bosch to integrate shifting with the Bosch motor, only available to OEMs so far.

[LeeG]

Yeah I’d say Peter White is on the ball. I’m looking more and more at IGHs that can take the BBSHD torque and there aren’t many. The good stuff is made in Germany and of course it’s not cheap. There are some new manufacturers besides Rohloff I’m hoping to see show up . Kindernay and 3x3 look promising. I don’t have much hope for Shimano.

I could get by fine with a 300% gear range and six gears. Going 20mph honestly takes more attention than I feel like giving on dirt roads.

[Jfitzger]

It’ll be interesting to see how the Dyad holds up.

I built a wheel set with Dyads ten years ago and they've been bullet proof. I have over 12,000 miles on them and they're just about due for replacement because the braking surface is starting to get thin. I built them 3x, 32 spoke front and 36 rear with DT Swiss 2.0/1.8 spokes.

I've used them hard for touring, cyclocross and all season commuting.

The Grin system looks interesting. I tow my 8' pram six miles to the lake with my bike. It's normally fine but if it's really windy or I've had a hard day it can be a bit of a chore. I wonder if I could do the assist on the dinghy wheel instead of the bike.

Thanks for posting. It's inspiring a future project.

[LeeG]

I built a wheel set with Dyads ten years ago and they've been bullet proof. I have over 12,000 miles on them and they're just about due for replacement because the braking surface is starting to get thin. I built them 3x, 32 spoke front and 36 rear with DT Swiss 2.0/1.8 spokes.

I've used them hard for touring, cyclocross and all season commuting.

The Grin system looks interesting. I tow my 8' pram six miles to the lake with my bike. It's normally fine but if it's really windy or I've had a hard day it can be a bit of a chore. I wonder if I could do the assist on the dinghy wheel instead of the bike.

Thanks for posting. It's inspiring a future project.

They’re very strong for their weight. I built up some 26” wheels for a mtn bike a long time ago and bent the rim flange when bottoming out on a
bump and attempting to bend the flange back it seemed thinner than Mavics and Ringle of a similar size. So the rim wasn’t really out of round but the braking surface wasn’t good anymore. The nipple holes run straight out instead of angled but there’s a lot of metal there so who knows. Their Atlas rim would be my preference for a tough rim for rim brakes.

[rgthom]

The Grin system looks interesting. I tow my 8' pram six miles to the lake with my bike. It's normally fine but if it's really windy or I've had a hard day it can be a bit of a chore. I wonder if I could do the assist on the dinghy wheel instead of the bike.

Thanks for posting. It's inspiring a future project.

If you peruse the Grin website there are a lot of motor types and wheels. Some can work single sided, there's even a powered wheelbarrow wheel. I've been intrigued by what they show, now having tried out the system I feel confident they have something pretty cool. There's a version of the Cycle Analyst that can manage solar inputs and charging, and Justin has been working on that solar electric boat motor for a while and now seems to be ready with a product. The motor simulator and trip analyzer tools are fun to play with also.
https://ebikes.ca/

[LeeG]

If you peruse the Grin website there are a lot of motor types and wheels. Some can work single sided, there's even a powered wheelbarrow wheel. I've been intrigued by what they show, now having tried out the system I feel confident they have something pretty cool. There's a version of the Cycle Analyst that can manage solar inputs and charging, and Justin has been working on that solar electric boat motor for a while and now seems to be ready with a product. The motor simulator and trip analyzer tools are fun to play with also.
https://ebikes.ca/

A powered wheelbarrow wheel! That’s what I want.

[StevenBauer]

A powered wheelbarrow wheel! That’s what I want.

Makita makes a powered wheelbarrow, too.

https://www.makitatools.com/products/details/XUC01X1

[LeeG]

Makita makes a powered wheelbarrow, too.

https://www.makitatools.com/products/details/XUC01X1

ok now get two wheels on either side of a 30”x 48” platform that sits a few inches above axle height w stake sockets on the side no dumping bucket. And with dead man brakes. About the size of a utv bed but narrow lengthwise.

[David G]

Fascinating system. I've got a friend who wants to convert his bike so he can ride from his new place along the creek into downtown to teach his meteorology classes. I keep telling him I know zip about the new systems, but I'll mention this one to him.

Fun to see that OP foto with Burley trailer. I was their first GM, and that was when we brought the original Burley trailer to market. Alan Scholz was the engineering boffin who had the inspiration, and from what I can see in the bike shops, Burley may just still be the best bike trailer.

[rgthom]

Stealthed out for commuting with a cheap rack bag to hide the battery. Some of the bike paths on my way to work are allowed for 20 mph Class 1 e-bikes. The speed limit is 15 for any bike and that is all I do on the paths, but on the road fast is useful so I set the limit to 28 mph Class 3. No one has ever stopped me on my other bike, but stealthier seems safer.

[Bob (oh, THAT Bob)]

re various above:

Serious trailers:
https://www.bikesatwork.com/

Rohloff hubs: Superb quality and design, but...
- expensive to buy
- expensive to maintain (if ridden in rain a lot, annual teardown and lube with marine bearing grease)
- expensive to fix
- magnet for thieves, they know what they are looking at; Saw poster on phone/electrical pole offering reward for stolen bike, no questions asked, "not worth much except to me"; I can see from photo, Rivendell frame or some other custom that I recognized, can't recall, and Rohloff rear. Uh-huh. They knew what they were stealing. You can't carry a big enough chain that thieves cannot cut through these days. If I can't bring bike in with me, I don't bike there. Low-grade thieves will steal even relatively cheap bikes these days except perhaps big-box-store cheap, and then even the homeless will steal those, many of the rental bikes here have had the locator disabled and the bike rattlecan painted.

Old Shimano Deore 8 and 9 speed is bombproof reliable and reasonable replacement parts cost on Amazon. Heck I have a cheap copy of hyperglide 8 and it's reliable. Decent chains are $10 new on sale. Ability to seal out water on the hubs and freehub body, that's where a bit more money is better, but again, I don't think you can do better than Deore or equivalent quality on that.

[rgthom]

Wow, those trailers look sturdy. 300 lb capacity, and a sheet plywood rack to boot. They are pricey, but when you compare to a $10k R&M bakfeits not so bad.

I get a case of Rohloff lust every so often, but as you say fear of theft puts me off. I take the mid drive shopping and lock it for an hour, but half expect to find the $500 battery sawed off the frame sometime. I would only use the Fitz to commute to the office.

For a bombproof drivetrain in current production at low price I like the Microshift Advent 9 speed. When the stock alloy cassette on the mid drive wore out fast, I replaced with the Advent and it seems impervious to the extra power with 11-46 all chro-mo cogs. Around $100 for cassette, mech, and trigger shifter.