Grin All Axle front hub motor

[JRA]

I was in Vancouver today to visit my son and pick up this: (Link Removed - No Longer Exists)

I have been following Grins development of the through axle motor and it is the result of their thought process due to extensive testing of all motors and represents the solutions that they have come up with in one neat package which they explain in the link.

I know that front hub motors are not that popular but I am enjoying great success with the one I put together at the end of August. I have put about 800 miles on it averaging 25 miles per trip or so on just about every surface and dry/wet weather condition you can imagine on a drop handlebar bike with 45c tires. Basically it is a 1000w system, legal in the OR where I live, with a 48v Dolphin battery I sourced from EM3ev. The 9c motor, controller, CAv3 and thumb throttle I got from Grin.

The problem with any hub motor in the front or the rear is the torque it produces makes it want to climb out of the dropouts and so a torque arm is necessary (you can see the one on this bike in the lower left pic below the dropout). Even with a carbon fiber fork I have not had any issues with rotational forces causing any problems, even maxing out the watts climbing very steep terrain which puts the most stress on it. The solid axle like the one on this bike, which are a PITA to deal with because they mostly are 10mm and most bikes these days have 9mm drop outs. My solution was to file the flats on the axles instead of the dropouts on the ones I have done but it is fussy work. Then the disc brake mount surface is not in the right relation to the caliper so more filing.....Not the road to popularity when most are more apt to just walk in to a store and out with a complete working bike. Even though they might not understand how it works .

Thru axle forks are readily available these days and the fact that this motor will work with all axle standards and have a stout and reliable torque arm setup alleviates the fussiness and all I will have to do is lace it up, put a tire on it and put it on my fork. Unfortunately neither my gravé bike as shown or my mtb have thru axle forks and the cost of one is more than the motor so I opted with the standard skewer inserts for now. But when I can source the right fork I will be switching probably but the cleaner torque arm setup is what means the most. There was an older gentleman at Grin when I was there that was picking up a 20" wheel with this motor who said he had ruined a few forks previously but admitted that it was his own fault due to lack of any torque arms.

Another plus is that they speced it as a 32h which makes it compatible with modern rims. All other hub motors must use 36h rims which are becoming more and more scarce and are practically non-existent in tubeless type rims. Tubeless technology is at a good point and worth having on your bike. It has less chance of pinch flatting and you can run lower psi which is a very good thing for traction and comfort and doesn't affect rolling resistance. I have been running in the low 30psi range with the above bike the entire time and it
really makes a difference in how the bike handles overall, even though it is a heavyish bike.

I will try and update this thread as developments occur.

 

[JRA]

This project hasn't been front burner but progress is being made. Ended up getting a CL deal on this bike to use it on

Got the wheel laced up and so now almost all the parts are together.

Next step is assembly which I'll try to fit in over the upcoming holidays. Pretty cold and snowy here and I have my other bike to ride in the meantime.

 

[George S.]

Grin seems to have enough of a following to get away with this kind of developmental product. Gee, I have to submit my plans and qualify to buy one. It's an interesting way to market things. The price is quite high.

The other side of the coin, in a sense, is the very cheap Bafang hub motors which show up a lot in low end assembled ebikes.

The DIY world is fractured in bizarre ways. The low end motors show up mostly on Ebay and Amazon, but they probably work. People will not learn much about torque arms from these vendors, most of the time. No one really offers a cost effective DIY version of the Bafang hubs, at least not conspicuously so. The Mac motor remains a curiosity with minimal support and a supply chain that adds immensely to the price. The Golden Motors are powerful but they lack much refinement and they just seem to be in a kind of limbo with two indifferent suppliers.

The innovators are people putting out ebikes around $1500 that are decently built with decent motors and some company backing, like warranty support. I was looking at the leading supplier of DIY mid-drives and it remains a premium DIY product. Even a BBS02 with some accessories and upgrades is an expensive product, and it is not without problems. The vendors are all going for higher margins, in the DIY market. Grin has always been what I would call 'super high margin'. Some companies can get away with it, for sure.

On the other side you have Chinese vendors who are selling Chinese products. Everyone is selling Chinese products, anyway. When they work out the supply chain issues, which means warehouses in the US, then their cost structures may take hold and there may be a lot of low end products that are OK. They have to get to where they have a reputation to protect.

 

[JRA]

I didn't have to put forth any plan or pass a test to get this, just be in the right place at the right time which was the result of my being aware of its existence and recognizing the potential it can have for my riding needs.

Grin is not what I would consider super high margin at all, especially when you can now get "close out" models of manufactures bikes for thousands off. My wheel cost is less than what many will spend on a wheel without a motor in the biking world and I consider that to be a bargain. They are not cheap but are involved with the evolution of electric assist which is time consuming and has a significant cost factor but after awhile will trickle down to that sector of the market.

The overall cost of this project, including the bike, all in is under 2 grand. For the performance it provides and the features like the built in torque arm, 32h drilling which greatly expands rim options in todays market, ability to use quick release axles in all standards, lighter weight (4 lbs. lighter than my current one and on par with geared hub motors), use of Statorade, which they brought to light, helps keep the motor running cool and regen capability to use as an assist for braking are all of value to me but perhaps not to others which is fine. Their Cycle Analyst ties it all together and gives me the info I need while riding to eliminate range anxiety and the ability to change parameters easily.

Innovation to me is pushing the envelope of currently accepted technology and producing products that address this. Grin is not the only company out there that doing this but for me their analytical approach and attention to detail is worth every penny over just getting a kit or complete bike from people that are just interested in selling existing product as cheaply as possible without much support to make a buck.

Their website alone, while not full of flash and promise of huge power and mileage, contains a wealth of information that others fail to even acknowledge exists and the big companies keep behind closed doors. They test everything and document the results for all to see and use for comparison. I just used their spoke calculator for this build and it was right on the money and all I had to do basically was insert my ERD. It is this attention to detail and their willingness to share freely their findings that to me is the value.

But because their philosophy and components works for me it doesn't mean it has to work for everyone. The DIY path is not nearly as easy as walking in to a shop and throwing down on a floor model ready to ride. The fact that there are options for both far above and beyond what there was even 2 years ago bodes well for the future of e bikes and that is a good thing.

 

[George S.]

If people want the most sophisticated ebike I think it will be AI type shifting, nothing manual, super smooth. But mid drive all the way. That's down the road. This Grin motor will be hard to explain.

You are can make a nice hub for $200, enough power, not much need to shift. Maybe basic ebikes should go with solid rubber tires. It's sort of tubeless...

 

[JRA]

Not really sure what your point is George? Is it this?

As a life long cyclist that has a very defined sense of how I want my cranks to turn I am the very antithesis of your "sophisticated AI nothing manual" ideology. I am once again going to say that what works for me does not necessarily work for others but this motor is easier to explain perhaps to a true cyclist in that it can fit in with modern standards and allow for them to be able to switch between manual and e bikes seamlessly. The people that I have put on my bike sure to seem to get it just fine.

Sure there are cheaper hubs and the fitting problems that go with them as I mentioned earlier. Glad they are there to fill that end of the market place but they are not going to fit everyone's needs either.

Have you ever ridden on solid rubber tires? You will really need a suspension seatpost if you go there. Pneumatic tires are still the industry standard for a reason and tubeless technology is just as logical of step forward as it was for auto's and trucks.

 

[George S.]

Well, the whole idea of the AI would be to learn what you want, and nothing more. The assist has to do something. I would use AI to train the assist. How you change gears is optional but I could see super smooth cv, that sort of thing, with a MD. Automatic, but what you want.

An advanced ebike has to be a mid drive to adjust the drive train. If you are going to stay at the 750 watt Cal standard, you are better off with gears that can give speed and climb.

Isn't Statorade an admission the motor has to run hot, and therefore inefficiently? The MD can find a gear to stay cool.

I guess this is about reducing size & weight in a DD. Big DD hubs dissipate heat. So Grin has a liquid cooling option. We'll see how it works.

As mid drives progress at the higher end, I don't know if premium hubs survive. There is the Stromer. Some say they push 1200 watts through them, to get the performance. Basic hubs are terrific. I have a 20# GM Pie. Fantastic all around hub, but heavy. For now I'll take that weight or use a good geared motor. Steel frame, and rear mount. It's not a cyclists bike, it's a terrific ebike.

 

[JRA]

I'm glad that you have found what works best for you George. I am still not getting your AI line of logic but I am kind of an analog type for the most part.

I see Statorade as nothing more than why gas engines use a coolant system. Any motor creates friction and if there is an effective way to help dissipate it why not use it? It is not a shot in the dark, Grin has done extensive testing that proves that it works but nothing is perfect.

Moving forward with the original intent of the thread I finally got the wheel built up



(not sure why the pic won't post right but use your imagination to get it there)

and the necessary clamp made for the torque arm



My goal for the clamp was tool less ability to remove and replace the wheel and this setup achieves that. Also in the interest of not every fork leg profile is the same I tried to come up with a method that would be adaptable to any profile/diameter. Using .032 brass strip from the local hardware store bends easily enough to conform and when doubled up and fastened is plenty strong for the task. I need to source a better shoulder bolt however than what was available in their bins so I need to get to a supply house that may have one.

 

[JRA]

Got it from rolling chassis to ridable today after work.


The 50t chainring on the stock cranks was over the edge of the battery so I put my other Schlumpf on. It is only a Speed Drive but has plenty of gear range for my purposes.

1000w (legal in OR where I live)
52v
572wh battery

Lighter than my other bike but now I am going to have to find a set of scales to weigh them both. This one was much easier to get up the stairs for sure.

Need to do some cabling up in the cockpit but for the most part ready to ride around on. The short ride I took around a couple of blocks was very encouraging. I am really getting used to riding drop bars after years of straight ones and liking it.

 

[Trail Cruiser]

One thousand watt direct drive is a pretty fast bike. Having a PAS will make your ride more enjoyable and increases the range of your battery. With that speed capability, the rider needs to be protected from road impacts (magnified due to higher speeds). You got to have some kind of suspension seat post (such as body float) and stem cushioning (stafast or shockstop) or even a suspension fork.

 

[JRA]

Not sure why you assume that I go "that fast"? Sometimes under the right conditions I let it rip sure but mainly I average around 15-20mph at 10-15 wh/mi. I do use the extra wattage sometimes climbing really steep terrain or getting through tough spots and am glad it is there. As to PAS, I have tried them all pretty much, just numbs the experience for me and I prefer to set my own cadence/pedal resistance. I don't feel that I sacrifice battery range as my wh/mi average is good because I pedal all the time in an appropriate gear.

I have a little under 1000 miles on a similar bike and there is not once in a very varied amount of terrain that I have ridden that I have felt the need for any suspension other than my ability to run pretty low psi in my tires has afforded.

I'm pretty mature about my decisions while riding, as I am whenever I am on the road driving any vehicle. Not everyone is a hooligan that has something other than an EU spec bike.

 

[JRA]

Got the temp cable made and the throttle cable shortened at the E bike store here in Portland by Wake. He is the longest running e bike shop in the area and really knows his stuff. His staff is very helpful also. Highly recommended.

Got a better feel for the bike on the way over and for riding in the city this is all the bike anyone would ever need I feel. On the way home I stopped by a friends conventional shop and weighed the bike with the battery in place.

Battery is fully charged now and the bike is ready for its first chance to fully use it up in the morning.

There are tools in the bag just in case!

 

[JRA]

The test ride was a success albeit a bit chilly to start out. Rolling up to 23 or so mph got my face stinging real fast and made me think about a face shield and why motorcycles traditionally have them. After my blood got pumping it wasn't bad but the fog was sticking to my Oakleys so they became a hindrance. The excellent post on here about riding in the winter addresses those issues however and I'll make adjustments to my gear.

My rides encompass a variety of terrain and surfaces. Mainly I ride paved road until I get to gravel until I get to unimproved and down to mellow single track. I cruise the road and gravel but slow down a lot and poke around on the latter. Yesterday I got in to several dead ends trying to link together two routes but had fun and saw some unusual things like a possum I almost ran over on a faint double track and a deer that bounded by after I had stopped to see if I could figure out if there was a trail in front of me or not. Also some algae on a pond that was a color I hadn't seen before. Good times.

My exploring drags down my average speed but that only shows up on my CA and doesn't interfere with my overall experience. I don't have as high a gear ratio yet on this bike as the other and pedaling above 27 mph is a furious affair. There was no wind and flat road spinning like mad resulted in the top speed. Not somewhere I go often but fun to do for a spurt. Happy enough with my wh/mi consumption rate with the motor @52v 25amp and it is on par and probably a bit below what my other bike with the 48v 25amp 9c motor does. The biggest thing I notice is that this motor is silent, as in completely, no noise.

The two wheel drive feature plays well for me here where it is wet and muddy. Within reason it will go through soft terrain in a very sure manner like a hot knife through butter.

Have a great Holiday!

 

[JRA]

Today's trial plan was to stick to the pavé. The roads around me are two lane country roads with little to no shoulder but are popular with cyclists from downtown. I have discovered that cruising in the 23-24 mph range nets me the best combination of speed and distance. Not so fast that you can't look around and see the sights and not pushing too much wind decreasing distance. I don't do this often because strictly riding on pavé is boring to me but it was a reasonably nice day and hardly any traffic due to the holiday so I went for it.

As you can see by the numbers my wh/mi consumption goes up, I pedal in an appropriate gear ratio at all times 60-80 rpms btw, but for strictly a speed run this is pretty much the same as my 9c bike

Silver bike on same route

The big difference is in ride quality and handling. The silver bike is more nimble and feels lighter. I haven't gotten a wider tubeless rim on the rear to be able to run lower psi and have been riding them both @40psi which is a harsh ride on the black bike but feels good on the silver one.

Going to put on some bars with a longer reach and get a shorter stem as the compact bars on there don't feel right to me. I like a little more bar length behind the brake hoods and longer reach will get me there. The setup is 1" longer on the silver bike due to a longer top tube which is why I am getting a shorter stem to keep it more or less the same. Also considering going to wider fenders. I adjusted the ones that came on the bike that are good for up to 38c, and I have 40c on the bike, so that they don't even rattle but in the woods I was getting some stuff up in there that I had to stop and clear out a few times which hasn't been the case with the next size wider fenders on the black bike.

The biggest reason I made the switch to the new motor was convenience in changing the front wheel in a tool less fashion and to get a lighter weight overall bike with comparable performance and range. I would have to say at this point that I achieved my goals. And now that I have two of them I can get someone else to ride with! If you live in the PDX and want to go for a spin let me know.

 

[JRA]

Got V 1.0 to the scale today

 

[Trail Cruiser]

As you go above 20 mph the additional power requirement per mph increase is exponential but your numbers are within the ball park of an efficient direct drive motor. Speed above 20 mph is also where the DD motor shines (in both efficiency and durability).

 

[JRA]

Flat 2 lane country road with a slight headwind efficiency test. Most of my rides are not in consistent terrain so wh vary but on the way to where I was headed the other day I set my cc and pedaled in the appropriate gear.



And I get good low end performance all with a dd motor which some seem to believe is not possible

 

[Trail Cruiser]

" And I get good low end performance all with a dd motor which some seem to believe is not possible "

With my DD hub on that kind of hill with the low speed , I just put the assist level to 2 or even 1 (out of 4) and pedal more. I would sacrifice some speed rather than cook my motor.

It is a different story with my mid drive on that hill since I can freely spin the motor in lower gears. So I can confidently use all the wattage without concerns of burning the motor. I guess that is where the thrill and fun factor comes from in a mid drive.

Here is a similar comparison.

 

[Trail Cruiser]

pedaled in the appropriate gear.

Appropriate gear could mean different things. Mountain bikers and trail riders consider appropriate gearing at cadence 50-80. Most road cyclist consider appropriate gearing at cadence 80-100 and even higher ( 110's ) when accelerating.

I am a road cyclist wannabe so I maintain a minimum of 80 rpm.

 

[JRA]

"I am a road cyclist wannabe so I maintain a minimum of 80 rpm."

So one would assume that you stay in a gear appropriate to accommodate that while adding wattage enough to help the forward momentum of the bicycle. There is no set standard for cadence that I know of that will work for everyone. I'm glad you found yours.

At some point I hope to get together with a comparable mid drive here and reach my own conclusions. I have a hard time believing the weights they say those bikes in the video are. My silver bike is lighter due to all factors pertaining to it as a bicycle than their base units due to sus fork, heavier wheels and tires etc. and the e system is not over bloated. If they showed them hanging from a scale it would be more believable.