I've been waiting for something that's a generational leap over the Leafbike 35mm in power to weight ratio for over a decade and i was very happy to see this on grin's site today:
Introducing Max45 Single Speed. All that Power on Even More Platforms
I'm alarmed by such a wide dropout width. So i decided to measure my late 2020 era bike and i found the dropouts are already 137.5mm wide uncompressed. So, the chainstays each bend inwards by 1.25mm already when the wheel is clamped on.
With this motor, each chainstay moves outwards by 1.5mm instead.
Seeing that, this doesn't seem like an unreasonable amount of additional bending.
Power wise, you are looking at 2500w continuous in a 29 inch wheel at high voltage.
Hill climbing wise, if we downgear it a little with a 27.5" rear wheel, and run 52v, we see that it can do a 7.5% grade continuously for 24 miles without overheating.
That's stout for a DD, and statorade could be used to improve this further.
The smaller the wheel, the higher the continuous grade it can climb. In a 20", it can climb a 12% grade continuously, which is nuts.
Efficiency on the flats is outstanding at both ~40mph and during acceleration compared to a narrower motor.
The motor comes out to 6.2kg or 13.7lbs.
The main concern i have is that i like to pedal. That makes the 16T freewheel a huge negative.
It looks like a 14T freewheel could be used, which means you need a 64T chainring to pedal up to the top speed of 33mph in the above 52v / 27.5" scenario; this is doable.
On a 29er, you'd be able to pedal a bit beyond 35mph with the above setup.
Losing multiple gears is another negative. One thing you could do on a multi speed bike is to keep the rear deraileur and use a 3 speed derailleur up front.
This way you have a top speed gear, a climbing gear, and a much smaller gear for pedaling if the battery goes out.
With such high power on tap, 3 gears is enough ( shifting is basically optional ).
I don't know if it comes with a beefed up torque arm interface or not. If it doesn't, you probably want to keep battery amps constrained, as i have in these grin simulations.
At least one poster here destroyed the original torque arm interface on ~7.7kw peak: Salsa Blackborow with Grin Max45
This motor has a lot of torque per amp, so constrained amps isn't too bad. 3kw peak is my best guess on a sane limit for the original interface, if that's what this motor ships with.
If you get a flat, you'll find the motor much easier to get on/off the bike due to the way this kind of motor interfaces to the frame. This also makes the bike much easier to chuck into a small passenger car. I liked this very much about my 27mm all axle.
The price is currently ~$900 USD. About the cost of a high power mid power drive.
If you are in the USA, the motor is CUSMA compliant, so you shouldn't be paying a tariff on it.
As for me, i think i'll pick one up. My area is quite hilly and with powerful mid drives, i dislike the weird Q factors and lack of regen.
What's your thoughts on it?
Introducing Max45 Single Speed. All that Power on Even More Platforms
I'm alarmed by such a wide dropout width. So i decided to measure my late 2020 era bike and i found the dropouts are already 137.5mm wide uncompressed. So, the chainstays each bend inwards by 1.25mm already when the wheel is clamped on.
With this motor, each chainstay moves outwards by 1.5mm instead.
Seeing that, this doesn't seem like an unreasonable amount of additional bending.
Power wise, you are looking at 2500w continuous in a 29 inch wheel at high voltage.
Hill climbing wise, if we downgear it a little with a 27.5" rear wheel, and run 52v, we see that it can do a 7.5% grade continuously for 24 miles without overheating.
That's stout for a DD, and statorade could be used to improve this further.
The smaller the wheel, the higher the continuous grade it can climb. In a 20", it can climb a 12% grade continuously, which is nuts.
Efficiency on the flats is outstanding at both ~40mph and during acceleration compared to a narrower motor.
The motor comes out to 6.2kg or 13.7lbs.
The main concern i have is that i like to pedal. That makes the 16T freewheel a huge negative.
It looks like a 14T freewheel could be used, which means you need a 64T chainring to pedal up to the top speed of 33mph in the above 52v / 27.5" scenario; this is doable.
On a 29er, you'd be able to pedal a bit beyond 35mph with the above setup.
Losing multiple gears is another negative. One thing you could do on a multi speed bike is to keep the rear deraileur and use a 3 speed derailleur up front.
This way you have a top speed gear, a climbing gear, and a much smaller gear for pedaling if the battery goes out.
With such high power on tap, 3 gears is enough ( shifting is basically optional ).
I don't know if it comes with a beefed up torque arm interface or not. If it doesn't, you probably want to keep battery amps constrained, as i have in these grin simulations.
At least one poster here destroyed the original torque arm interface on ~7.7kw peak: Salsa Blackborow with Grin Max45
This motor has a lot of torque per amp, so constrained amps isn't too bad. 3kw peak is my best guess on a sane limit for the original interface, if that's what this motor ships with.
If you get a flat, you'll find the motor much easier to get on/off the bike due to the way this kind of motor interfaces to the frame. This also makes the bike much easier to chuck into a small passenger car. I liked this very much about my 27mm all axle.
The price is currently ~$900 USD. About the cost of a high power mid power drive.
If you are in the USA, the motor is CUSMA compliant, so you shouldn't be paying a tariff on it.
As for me, i think i'll pick one up. My area is quite hilly and with powerful mid drives, i dislike the weird Q factors and lack of regen.
What's your thoughts on it?
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