Need some help building a friction drive.
#1
Junior Member
Thread Starter
Join Date: Jul 2019
Posts: 8
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Need some help building a friction drive.
Hey all!
I am new to this forum and ebikes as well. I would like to build a ebike myself.
This is going to be my first build and I have few questions ahead. Hope you guys help me with it.
Here is what I am trying to achieve:
I also read that the speed depends on the diameter of the drive wheel and for a 2.5in drive wheel 2000rpm is required for speed of 25km/hr.
Should I drive the motor shell directly or should I use a coating of sandpaper or rubber? Sandpaper provides best cof but wears out the tires pretty soon... Couldn't get much info on rubber.... is there something that can hit a number between?
Coming to the tires, what kinda tires should I use? flat centre region?
If I want to be able to accelerate the cycle from rest, should I stick to using smaller rollers? I read large rollers have terrible low end power.. How does the diameter of the roller affect the power delivery? speed? torque?
Thanks!
I am new to this forum and ebikes as well. I would like to build a ebike myself.
This is going to be my first build and I have few questions ahead. Hope you guys help me with it.
Here is what I am trying to achieve:
- control engagement and disengagement using the front derailleurs
- Keep the motor power at or below 250W still being able to achieve 25Km/hr without pedal assist.
- Climbs hill with a incline of 15deg
- Be able to use on wet and muddy weathers
I also read that the speed depends on the diameter of the drive wheel and for a 2.5in drive wheel 2000rpm is required for speed of 25km/hr.
Should I drive the motor shell directly or should I use a coating of sandpaper or rubber? Sandpaper provides best cof but wears out the tires pretty soon... Couldn't get much info on rubber.... is there something that can hit a number between?
Coming to the tires, what kinda tires should I use? flat centre region?
If I want to be able to accelerate the cycle from rest, should I stick to using smaller rollers? I read large rollers have terrible low end power.. How does the diameter of the roller affect the power delivery? speed? torque?
Thanks!
#2
Senior Member
Join Date: Jul 2014
Location: socal
Posts: 4,217
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 872 Post(s)
Liked 795 Times
in
603 Posts
Hope you get some help here, but I haven't seen friction-drive discussed except commercial systems. Check "Kepler" on endless sphere; he's the expert on DIY systems.
#3
Senior Member
Join Date: Jun 2014
Location: SF Bay Area
Posts: 3,460
Bikes: Trident Spike 2 recumbent trike w/ e-assist
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1321 Post(s)
Liked 374 Times
in
288 Posts
Yeah, endless sphere has tons of threads on friction drives and how to make 'em. There's one really long one where Kepler goes through his development and all his iterations. Also, he used to sell a sort of mini-kit, if he still does that might work out for you. It was all too complicated for me so I went with a commercial system. Good luck!!!
#5
Senior Member
Join Date: Jul 2010
Location: Michigan
Posts: 4,863
Bikes: too many of all kinds
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 1147 Post(s)
Liked 415 Times
in
335 Posts
I don't know if you are going to post more than one post, but yeah, what they said.
Friction drives are rather noisy and haven't really gotten much "traction" in the ebike world...
Friction drives are rather noisy and haven't really gotten much "traction" in the ebike world...
#7
Senior Member
Join Date: Jun 2014
Location: SF Bay Area
Posts: 3,460
Bikes: Trident Spike 2 recumbent trike w/ e-assist
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1321 Post(s)
Liked 374 Times
in
288 Posts
If you build it right, there's nothing lighter that can supply the same amount of power. My 1Motor pushes 750w and weighs 4.5lbs including
battery. Not everyone wants or needs a big heavy powerful e-bike motor.
I wouldn't have bought a super light 19lb Bike Friday if I had just planned on adding 10 (likely more) pounds to motorize it. I've got a 23.5lb e bike =). So that's why a friction drive! And it works great. They're ideal for light road bikes, too.
battery. Not everyone wants or needs a big heavy powerful e-bike motor.
I wouldn't have bought a super light 19lb Bike Friday if I had just planned on adding 10 (likely more) pounds to motorize it. I've got a 23.5lb e bike =). So that's why a friction drive! And it works great. They're ideal for light road bikes, too.
#8
Junior Member
Thread Starter
Join Date: Jul 2019
Posts: 8
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Yeah, endless sphere has tons of threads on friction drives and how to make 'em. There's one really long one where Kepler goes through his development and all his iterations. Also, he used to sell a sort of mini-kit, if he still does that might work out for you. It was all too complicated for me so I went with a commercial system. Good luck!!!
If you build it right, there's nothing lighter that can supply the same amount of power. My 1Motor pushes 750w and weighs 4.5lbs including
battery. Not everyone wants or needs a big heavy powerful e-bike motor.
I wouldn't have bought a super light 19lb Bike Friday if I had just planned on adding 10 (likely more) pounds to motorize it. I've got a 23.5lb e bike =). So that's why a friction drive! And it works great. They're ideal for light road bikes, too.
battery. Not everyone wants or needs a big heavy powerful e-bike motor.
I wouldn't have bought a super light 19lb Bike Friday if I had just planned on adding 10 (likely more) pounds to motorize it. I've got a 23.5lb e bike =). So that's why a friction drive! And it works great. They're ideal for light road bikes, too.
#9
Senior Member
Join Date: Jul 2014
Location: socal
Posts: 4,217
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 872 Post(s)
Liked 795 Times
in
603 Posts
Two positive considerations for a friction drive AFAICT: light weight and stealth (maybe almost imperceptible with a seat bag battery). Kepler on ES has gone so far as to adapt one for a full suspension off road bike. Hope to try one someday.
#10
Senior Member
Join Date: Jun 2014
Location: SF Bay Area
Posts: 3,460
Bikes: Trident Spike 2 recumbent trike w/ e-assist
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1321 Post(s)
Liked 374 Times
in
288 Posts
Good luck with your mid-drive build. I'm always impressed by folks who can build their own!
#11
Senior Member
Join Date: Jul 2010
Location: Michigan
Posts: 4,863
Bikes: too many of all kinds
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 1147 Post(s)
Liked 415 Times
in
335 Posts
Curious, why Mid drive? You can go lighter and more stealth with a hub, but if you are doing hills, mid drive is the way to go. Just wondering what your decision process is...
#12
Senior Member
Join Date: Jul 2010
Location: Michigan
Posts: 4,863
Bikes: too many of all kinds
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 1147 Post(s)
Liked 415 Times
in
335 Posts
If you build it right, there's nothing lighter that can supply the same amount of power. My 1Motor pushes 750w and weighs 4.5lbs including
battery. Not everyone wants or needs a big heavy powerful e-bike motor.
I wouldn't have bought a super light 19lb Bike Friday if I had just planned on adding 10 (likely more) pounds to motorize it. I've got a 23.5lb e bike =). So that's why a friction drive! And it works great. They're ideal for light road bikes, too.
battery. Not everyone wants or needs a big heavy powerful e-bike motor.
I wouldn't have bought a super light 19lb Bike Friday if I had just planned on adding 10 (likely more) pounds to motorize it. I've got a 23.5lb e bike =). So that's why a friction drive! And it works great. They're ideal for light road bikes, too.
I guess I'm different then you, because I did what you wouldn't do, lol. I put a 2.1kg hub motor on my 19lb bike. If I found an alternative that could save me 1.1kg with similar performance, I would be interested...
#13
Senior Member
Join Date: Jun 2014
Location: SF Bay Area
Posts: 3,460
Bikes: Trident Spike 2 recumbent trike w/ e-assist
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1321 Post(s)
Liked 374 Times
in
288 Posts
Maybe you can teach me something. Got some examples of some well built friction drives? I've done some research on them, but they always seem to disappoint - like 750w just doesn't pull like a 750 watt hub or mid drive. Maybe you know something I don't?
I guess I'm different then you, because I did what you wouldn't do, lol. I put a 2.1kg hub motor on my 19lb bike. If I found an alternative that could save me 1.1kg with similar performance, I would be interested...
I guess I'm different then you, because I did what you wouldn't do, lol. I put a 2.1kg hub motor on my 19lb bike. If I found an alternative that could save me 1.1kg with similar performance, I would be interested...
If you have any other questions I'd be happy to try to answer. For reference, I previously owned a dedicated electric bike with a hub front motor, had it about a year, maybe a little more, when I first returned to riding after a 20 year absence.
#14
Junior Member
Thread Starter
Join Date: Jul 2019
Posts: 8
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
You can read up on what I ended up buying, ymmv. also I'm 135lbs so even with the bike pretty light. I guess it depends on what you're looking for - I am not interested in a fulltime electric bike. I choose to ride leg powered whenever I can and power up for hills and inclines that would hurt my knee, and in nasty ocean headwinds. I've had zero problem climbing 25 degree grades with my drive at a pretty good speed. You can read up on what I have if you want (or not): electricbikereview.com/forum/threads/review-onemotor-the-device-formerly-known-as-shareroller.28504/
If you have any other questions I'd be happy to try to answer. For reference, I previously owned a dedicated electric bike with a hub front motor, had it about a year, maybe a little more, when I first returned to riding after a 20 year absence.
If you have any other questions I'd be happy to try to answer. For reference, I previously owned a dedicated electric bike with a hub front motor, had it about a year, maybe a little more, when I first returned to riding after a 20 year absence.
#15
Senior Member
Join Date: Jul 2010
Location: Michigan
Posts: 4,863
Bikes: too many of all kinds
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 1147 Post(s)
Liked 415 Times
in
335 Posts
Mid drives because there isn't much I can do myself in hub motor except for designing the motor itself.
Sounds like you will enjoy the process. Just let us know if you have any more questions!
#16
Senior Member
Join Date: Jul 2010
Location: Michigan
Posts: 4,863
Bikes: too many of all kinds
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 1147 Post(s)
Liked 415 Times
in
335 Posts
You can read up on what I ended up buying, ymmv. also I'm 135lbs so even with the bike pretty light. I guess it depends on what you're looking for - I am not interested in a fulltime electric bike. I choose to ride leg powered whenever I can and power up for hills and inclines that would hurt my knee, and in nasty ocean headwinds. I've had zero problem climbing 25 degree grades with my drive at a pretty good speed. You can read up on what I have if you want (or not): https://electricbikereview.com/forum...eroller.28504/
If you have any other questions I'd be happy to try to answer. For reference, I previously owned a dedicated electric bike with a hub front motor, had it about a year, maybe a little more, when I first returned to riding after a 20 year absence.
If you have any other questions I'd be happy to try to answer. For reference, I previously owned a dedicated electric bike with a hub front motor, had it about a year, maybe a little more, when I first returned to riding after a 20 year absence.
good to hear they have minimized that RC motor whine. The PAS sounds great. Probably the best Friction Drive example I have seen. Looks like a viable option to a small hub drive, one that works very well for your usage. Good to see bikes that are pedaled like a bike with e-assist (as opposed to converting a bike to an electric mini-bike).
I did a little research on the motor you listed. I agree, for your application, a small 200-350 watt motor can be useful for short ranges on a light bike. I always enjoy seeing light weight builds. Its my passion.
Your build looks like a 250 watt motor that saves 0.5 to 1.1 kg over a small hub motor. It works well on your setup.
I get frustrated with a company like OneMotor specs are a little opaque, and seem to me to be misleading. Maybe I missed something.
https://onemotor.co/indepth/
For instance, the <5lb package has a 130Whr battery, typically 10s1P. That is capable of continuously giving about 4 amps, which puts us at 130 watts continuous. Maybe it can do 8 amps if they are using the best chemistry available. Not exactly a 750 watt motor. It says the top speed is 20mph, which is about 150+ watts on an efficient drop bar bike or 340W on a typical mountain bike. That could be brutal on that little battery – and more practical on their larger battery.
The motor with the small battery would typically be labeled as a 250 watt set up (or whatever the continuous power is), not 750 peak power with a larger battery. With a larger battery, I would guess it as a 350 watt motor as you are not really going to want to pull more than 10 amps continuous on that battery.
Last edited by chas58; 07-10-19 at 09:31 AM.
#17
Senior Member
Join Date: Jun 2014
Location: SF Bay Area
Posts: 3,460
Bikes: Trident Spike 2 recumbent trike w/ e-assist
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1321 Post(s)
Liked 374 Times
in
288 Posts
That is a great write-up. I appreciate it. I love hearing of experiences with a light weight build. You have a great setup there!
good to hear they have minimized that RC motor whine. The PAS sounds great. Probably the best Friction Drive example I have seen. Looks like a viable option to a small hub drive, one that works very well for your usage. Good to see bikes that are pedaled like a bike with e-assist (as opposed to converting a bike to an electric mini-bike).
I did a little research on the motor you listed. I agree, for your application, a small 200-350 watt motor can be useful for short ranges on a light bike. I always enjoy seeing light weight builds. Its my passion.
Your build looks like a 250 watt motor that saves 0.5 to 1.1 kg over a small hub motor. It works well on your setup.
I get frustrated with a company like OneMotor specs are a little opaque, and seem to me to be misleading. Maybe I missed something.
https://onemotor.co/indepth/
For instance, the <5lb package has a 130Whr battery, typically 10s1P. That is capable of continuously giving about 4 amps, which puts us at 130 watts continuous. Maybe it can do 8 amps if they are using the best chemistry available. Not exactly a 750 watt motor. It says the top speed is 20mph, which is about 150+ watts on an efficient drop bar bike or 340W on a typical mountain bike. That could be brutal on that little battery – and more practical on their larger battery.
The motor with the small battery would typically be labeled as a 250 watt set up (or whatever the continuous power is), not 750 peak power with a larger battery. With a larger battery, I would guess it as a 350 watt motor as you are not really going to want to pull more than 10 amps continuous on that battery.
good to hear they have minimized that RC motor whine. The PAS sounds great. Probably the best Friction Drive example I have seen. Looks like a viable option to a small hub drive, one that works very well for your usage. Good to see bikes that are pedaled like a bike with e-assist (as opposed to converting a bike to an electric mini-bike).
I did a little research on the motor you listed. I agree, for your application, a small 200-350 watt motor can be useful for short ranges on a light bike. I always enjoy seeing light weight builds. Its my passion.
Your build looks like a 250 watt motor that saves 0.5 to 1.1 kg over a small hub motor. It works well on your setup.
I get frustrated with a company like OneMotor specs are a little opaque, and seem to me to be misleading. Maybe I missed something.
https://onemotor.co/indepth/
For instance, the <5lb package has a 130Whr battery, typically 10s1P. That is capable of continuously giving about 4 amps, which puts us at 130 watts continuous. Maybe it can do 8 amps if they are using the best chemistry available. Not exactly a 750 watt motor. It says the top speed is 20mph, which is about 150+ watts on an efficient drop bar bike or 340W on a typical mountain bike. That could be brutal on that little battery – and more practical on their larger battery.
The motor with the small battery would typically be labeled as a 250 watt set up (or whatever the continuous power is), not 750 peak power with a larger battery. With a larger battery, I would guess it as a 350 watt motor as you are not really going to want to pull more than 10 amps continuous on that battery.
#18
Senior Member
Join Date: Jul 2010
Location: Michigan
Posts: 4,863
Bikes: too many of all kinds
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 1147 Post(s)
Liked 415 Times
in
335 Posts
you have a great build. That little battery is good for how you use it (not using it full out most of the time).
#19
Senior Member
Join Date: Jun 2014
Location: SF Bay Area
Posts: 3,460
Bikes: Trident Spike 2 recumbent trike w/ e-assist
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1321 Post(s)
Liked 374 Times
in
288 Posts
That is a great write-up. I appreciate it. I love hearing of experiences with a light weight build. You have a great setup there!
good to hear they have minimized that RC motor whine. The PAS sounds great. Probably the best Friction Drive example I have seen. Looks like a viable option to a small hub drive, one that works very well for your usage. Good to see bikes that are pedaled like a bike with e-assist (as opposed to converting a bike to an electric mini-bike).
I did a little research on the motor you listed. I agree, for your application, a small 200-350 watt motor can be useful for short ranges on a light bike. I always enjoy seeing light weight builds. Its my passion.
Your build looks like a 250 watt motor that saves 0.5 to 1.1 kg over a small hub motor. It works well on your setup.
I get frustrated with a company like OneMotor specs are a little opaque, and seem to me to be misleading. Maybe I missed something.
https://onemotor.co/indepth/
For instance, the <5lb package has a 130Whr battery, typically 10s1P. That is capable of continuously giving about 4 amps, which puts us at 130 watts continuous. Maybe it can do 8 amps if they are using the best chemistry available. Not exactly a 750 watt motor. It says the top speed is 20mph, which is about 150+ watts on an efficient drop bar bike or 340W on a typical mountain bike. That could be brutal on that little battery – and more practical on their larger battery.
The motor with the small battery would typically be labeled as a 250 watt set up (or whatever the continuous power is), not 750 peak power with a larger battery. With a larger battery, I would guess it as a 350 watt motor as you are not really going to want to pull more than 10 amps continuous on that battery.
good to hear they have minimized that RC motor whine. The PAS sounds great. Probably the best Friction Drive example I have seen. Looks like a viable option to a small hub drive, one that works very well for your usage. Good to see bikes that are pedaled like a bike with e-assist (as opposed to converting a bike to an electric mini-bike).
I did a little research on the motor you listed. I agree, for your application, a small 200-350 watt motor can be useful for short ranges on a light bike. I always enjoy seeing light weight builds. Its my passion.
Your build looks like a 250 watt motor that saves 0.5 to 1.1 kg over a small hub motor. It works well on your setup.
I get frustrated with a company like OneMotor specs are a little opaque, and seem to me to be misleading. Maybe I missed something.
https://onemotor.co/indepth/
For instance, the <5lb package has a 130Whr battery, typically 10s1P. That is capable of continuously giving about 4 amps, which puts us at 130 watts continuous. Maybe it can do 8 amps if they are using the best chemistry available. Not exactly a 750 watt motor. It says the top speed is 20mph, which is about 150+ watts on an efficient drop bar bike or 340W on a typical mountain bike. That could be brutal on that little battery – and more practical on their larger battery.
The motor with the small battery would typically be labeled as a 250 watt set up (or whatever the continuous power is), not 750 peak power with a larger battery. With a larger battery, I would guess it as a 350 watt motor as you are not really going to want to pull more than 10 amps continuous on that battery.
Our Compact Battery Pack is 12S1P, and built with Sony VTC6 cells, which are capable of 20A continuous discharge. And 20A*43V (under load) = 860W We limit it slightly below that. As far as we know, these are the only cells in the world that can put out 20A for nearly an entire discharge cycle (and 30A for partial) and still have 3.0Ah capacity (other high discharge cells have less capacity), which is why they are multiples more expensive than the average 18650 Ebike cell… in keeping with every component of OneMotor I guess!
Here's a plot in case you’re interested.
#20
Senior Member
Join Date: Jul 2010
Location: Michigan
Posts: 4,863
Bikes: too many of all kinds
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 1147 Post(s)
Liked 415 Times
in
335 Posts
So I emailed 1M about the amp stuff. Not sure I totally understand the answer but thought you might find it interesting:
Our Compact Battery Pack is 12S1P, and built with Sony VTC6 cells, which are capable of 20A continuous discharge. And 20A*43V (under load) = 860W We limit it slightly below that. As far as we know, these are the only cells in the world that can put out 20A for nearly an entire discharge cycle (and 30A for partial) and still have 3.0Ah capacity (other high discharge cells have less capacity), which is why they are multiples more expensive than the average 18650 Ebike cell… in keeping with every component of OneMotor I guess!
Here's a plot in case you’re interested.
Our Compact Battery Pack is 12S1P, and built with Sony VTC6 cells, which are capable of 20A continuous discharge. And 20A*43V (under load) = 860W We limit it slightly below that. As far as we know, these are the only cells in the world that can put out 20A for nearly an entire discharge cycle (and 30A for partial) and still have 3.0Ah capacity (other high discharge cells have less capacity), which is why they are multiples more expensive than the average 18650 Ebike cell… in keeping with every component of OneMotor I guess!
Here's a plot in case you’re interested.
Battery technology is changing fast, and he is using top shelf stuff. that is good to see. Best friction kit I have seen!
(There is a lot of junk out there, and batteries are an easy way to save money and make the price look good - until it craps out a year later).
I usually run at 10 amps (which is 350 watts) and your battery will last about 18 minutes under that load.
(at 20 amps, that specific battery lasts about 8 minutes - don't be doing that!).
Still, this is impressive performance which wasn't available a year or two ago.
Its interesting that he is not running the standard 36 or 48volt system, but actually 43 volts. Never seen that before (although some people like using a 52v battery on a 48v sytem).
Thanks for the info!
(if you want more of those geeky charts - here is his source: https://lygte-info.dk/review/batteri...een)%20UK.html
#21
Senior Member
Join Date: Jun 2014
Location: SF Bay Area
Posts: 3,460
Bikes: Trident Spike 2 recumbent trike w/ e-assist
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1321 Post(s)
Liked 374 Times
in
288 Posts
Wow, that is an impressive battery!
Battery technology is changing fast, and he is using top shelf stuff. that is good to see. Best friction kit I have seen!
(There is a lot of junk out there, and batteries are an easy way to save money and make the price look good - until it craps out a year later).
I usually run at 10 amps (which is 350 watts) and your battery will last about 18 minutes under that load.
(at 20 amps, that specific battery lasts about 8 minutes - don't be doing that!).
Still, this is impressive performance which wasn't available a year or two ago.
Its interesting that he is not running the standard 36 or 48volt system, but actually 43 volts. Never seen that before (although some people like using a 52v battery on a 48v sytem).
Thanks for the info!
(if you want more of those geeky charts - here is his source: https://lygte-info.dk/review/batteri...een)%20UK.html
Battery technology is changing fast, and he is using top shelf stuff. that is good to see. Best friction kit I have seen!
(There is a lot of junk out there, and batteries are an easy way to save money and make the price look good - until it craps out a year later).
I usually run at 10 amps (which is 350 watts) and your battery will last about 18 minutes under that load.
(at 20 amps, that specific battery lasts about 8 minutes - don't be doing that!).
Still, this is impressive performance which wasn't available a year or two ago.
Its interesting that he is not running the standard 36 or 48volt system, but actually 43 volts. Never seen that before (although some people like using a 52v battery on a 48v sytem).
Thanks for the info!
(if you want more of those geeky charts - here is his source: https://lygte-info.dk/review/batteri...een)%20UK.html
#22
Junior Member
Thread Starter
Join Date: Jul 2019
Posts: 8
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
After reading @linberl posts, I am thinking if I should go back to a friction drive build.
#23
Senior Member
Join Date: Jun 2014
Location: SF Bay Area
Posts: 3,460
Bikes: Trident Spike 2 recumbent trike w/ e-assist
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1321 Post(s)
Liked 374 Times
in
288 Posts
I'm hardly an expert, but I think it depends on what you want and how you want to use it. I know mid-drives are great for folks who climbs lots of hills. Hub motors aren't as good on hills but are great on flatter terrain. Both are fine for someone who wants to run the motor all the time on their rides. I've never had a mid-drive but I had a 350w front hub bike at one time, and it suffered on really big hills (Bay Area) and got super hot. Friction drives are, I think, for someone who wants to just have some assist maybe on hills and in winds or to keep up with others on rides, but wants to preserve the human powered nature of their bike...especially if they have a lightweight bike. What do you want? Or are you just looking to build what seems interesting?
#24
Cycleway town
Friction drive on wet/muddy tyres and you're doing maths?! Lol
And the reason we use 54v on a 48v system is because of voltage drop. A half-full 54v battery is around 48v, and it's 42v by the time it needs charging.
Use a 48v battery on a 48v system and it'll cut out at the first steep hill.
And the reason we use 54v on a 48v system is because of voltage drop. A half-full 54v battery is around 48v, and it's 42v by the time it needs charging.
Use a 48v battery on a 48v system and it'll cut out at the first steep hill.
#25
Senior Member
Join Date: Jul 2010
Location: Michigan
Posts: 4,863
Bikes: too many of all kinds
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 1147 Post(s)
Liked 415 Times
in
335 Posts
Of course you can just build a 50+ lb bike that goes 15-20mph without any design effort.
yup, what linberl has is a good alternative too (if you want low torque, fair weather, light weight low powered build). So many Choices!