'lightest.bike' 1.7kg 1000w mid drive
- Thread starter Grantmac
- Start date
Doesn't need to change much, you just need to find a way to tip it inwards more to clear another 1-2T. I'm looking at your pictures and seeing room to make it contact the frame.
Does it pull that kind of power when climbing? if so, we effectively have the same power give or take 100-200w, so thermal talk is relevant to both of us.
Does it pull that kind of power when climbing? if so, we effectively have the same power give or take 100-200w, so thermal talk is relevant to both of us.
BBSHD is estimated to have a net efficiency of 80%, it has more rotating weight, an additional gear reduction, larger gears made of lower quality metals probably, therefore more friction, etc etc..
.. now you have substantially more heat and need more metal to shed that heat to.. and that's how we get about the same power @ 3x the weight of this drive.
Makes the BBSHD look like a relic doesn't.
ps - edit - ebikes.ca motor simulator has a simulation of the BBSHD which puts it at 81-82% efficient from 25-30mph.
Motor Simulator - Tools
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Here's something funny..
I was watching some ebike show in Australia from a week or two ago, everyone was showing off their little 250w legal mid drives..
The smallest one was maybe 10% smaller than the 1000w lightest... most of them were a bit bigger.
So.. designed around 2020 and still ahead of the competition 4 years later in power density and probably efficiency too.
I'm impressed!
I was watching some ebike show in Australia from a week or two ago, everyone was showing off their little 250w legal mid drives..
The smallest one was maybe 10% smaller than the 1000w lightest... most of them were a bit bigger.
So.. designed around 2020 and still ahead of the competition 4 years later in power density and probably efficiency too.
I'm impressed!
rhauff
100 mW
Exactly. My point was that because a larger motor pinion would make the motor spin slower, it would make the top speed higher for offroad use. Also the larger motor pinion would slightly raise the chain and give more clearance for a larger chainring. Maybe it would only be suited to 1000W and/or high torque version.
..this kind of looks like my ~123mm bottom bracket.. IE the smallest size available.. i think this could work only with the next 1-2 steps up of BB width.
Your bottom bracket is pretty uncommon on bikes.. it's possible you could modify a cheap one both physically and electrically.. these things can be found that are thinner than a penny..
Your bottom bracket is pretty uncommon on bikes.. it's possible you could modify a cheap one both physically and electrically.. these things can be found that are thinner than a penny..
Here's a thought.
Many people with long term mid drive experience don't like sprockets below 14T because they wear too fast.
But we really need these tiny gears to hit the top speed of the motor and a big chainring..
How about using an IGH to achieve the correct gearing and keep that short mount..
IGH will typically have a 19T or 21T sprocket..
This is good because it will raise your chainline and make it so you can fit a bigger sprocket and reduce that pedaling RPM.
Just read this article: Mid Drive Kits, Dump the Derailleur and get an IGH?
Quick summary.. for the power level of the BBSHD they would recommend a 3 speed.. which sounds funny.. but people with BBSHDs end up using 2-3 gears anyway.. and we have that kind of power..
On my kit with a 48T front, 14T rear, and a 33% increase/decrease possible in the gearing, it'd work out like:
Gear 1 - 16mph
Gear 2 - 23.8 mph
Gear 3 - 31.6 mph
If i swap to a 50T front chainring then my top speed is 33.7mph which may be beyond the continuous limit of the motor.. so there's a lot of headroom to move the gearing now
Some people seem to have success with 8 speed IGH and high power drives. The Shimano Alfine 8 would be next on the list of IGH to consider, but is 3x the cost of a 3 speed IGH.
Many people with long term mid drive experience don't like sprockets below 14T because they wear too fast.
But we really need these tiny gears to hit the top speed of the motor and a big chainring..
How about using an IGH to achieve the correct gearing and keep that short mount..
IGH will typically have a 19T or 21T sprocket..
This is good because it will raise your chainline and make it so you can fit a bigger sprocket and reduce that pedaling RPM.
Just read this article: Mid Drive Kits, Dump the Derailleur and get an IGH?
Quick summary.. for the power level of the BBSHD they would recommend a 3 speed.. which sounds funny.. but people with BBSHDs end up using 2-3 gears anyway.. and we have that kind of power..
On my kit with a 48T front, 14T rear, and a 33% increase/decrease possible in the gearing, it'd work out like:
Gear 1 - 16mph
Gear 2 - 23.8 mph
Gear 3 - 31.6 mph
If i swap to a 50T front chainring then my top speed is 33.7mph which may be beyond the continuous limit of the motor.. so there's a lot of headroom to move the gearing now
Some people seem to have success with 8 speed IGH and high power drives. The Shimano Alfine 8 would be next on the list of IGH to consider, but is 3x the cost of a 3 speed IGH.
Pilot Engineer
10 W
- Joined
- Dec 11, 2013
- Messages
- 76
I wish we could do that. The fact is that on the drive side we have already the freewheel which takes some space. Adding a PAS in there would impact on the Q factor. On the other side that's not happening.
Pilot Engineer
10 W
- Joined
- Dec 11, 2013
- Messages
- 76
Here's a thought.
Many people with long term mid drive experience don't like sprockets below 14T because they wear too fast.
But we really need these tiny gears to hit the top speed of the motor and a big chainring..
How about using an IGH to achieve the correct gearing and keep that short mount..
IGH will typically have a 19T or 21T sprocket..
This is good because it will raise your chainline and make it so you can fit a bigger sprocket and reduce that pedaling RPM.
Just read this article: Mid Drive Kits, Dump the Derailleur and get an IGH?
Quick summary.. for the power level of the BBSHD they would recommend a 3 speed.. which sounds funny.. but people with BBSHDs end up using 2-3 gears anyway.. and we have that kind of power..
On my kit with a 48T front, 14T rear, and a 33% increase/decrease possible in the gearing, it'd work out like:
Gear 1 - 16mph
Gear 2 - 23.8 mph
Gear 3 - 31.6 mph
If i swap to a 50T front chainring then my top speed is 33.7mph which may be beyond the continuous limit of the motor.. so there's a lot of headroom to move the gearing now
Some people seem to have success with 8 speed IGH and high power drives. The Shimano Alfine 8 would be next on the list of IGH to consider, but is 3x the cost of a 3 speed IGH.
Sounds fair. Just one suggestion on that. Since the torque sensor is working releasing and freeing some chain length, it's important to put a chain tensioner along with the IGH, in such a way that the chain length variations of the torque sensor are compensated by the tensioner.
Pilot Engineer
10 W
- Joined
- Dec 11, 2013
- Messages
- 76
We can do that. I sent you an email. If you want we talk about it, and other topics, on Whatsapp!
rivers
1 W
Guys,
None of this talk addresses the noise problem.
None of this talk addresses the noise problem.
rivers
1 W
Thanks, I did see the post.
It would have been good for Bikee to warn buyers in advance that 300 miles of break-in would be needed to make the motor noise less obtrusive. Wouldn't it be better for Bikee to factory run the motors under load prior to shipping for a time and speed equivalent to 300 miles?
raylo32
100 kW
I was expecting better speed. Photon in unrestricted mode will pull up to ~38 mph on throttle or so on my 26" bike with 42/12 gears and 52v battery. That 12 might be 11t but I don't think so. Of course you can't do this for long or it would overheat. And also, of course, that is just throttle because at this speed you can't really do much if anything with the pedals.
raylo32
100 kW
No, not unloaded. Bike with me (200 pounds) on the road, without headwind. It will do it in unrestricted mode. Remember, the Photon in unrestricted will have a higher peak power. But it is temperature limited and will throttle back pretty fast if you try this when the motor is already pretty warm. I don't do this often because I am a pedaler and like the torque assist. But it is good for beating traffic sometimes and other specific situations.
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