Need some help building a friction drive.
07-11-19, 09:14 AM
#26
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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.
Last edited by linberl; 07-11-19 at 10:45 AM.
07-11-19, 11:09 PM
#27
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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?
When engineering my build of a hub motor, I had to balance the motor windings, noload speed, human input, hill climbing, motor torque, motor speed, motor power. Its purpose built for me, rather unlike anything else, and does 25mph for 25 miles with 25lb weight (+3lb battery, lol).
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!
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!
07-12-19, 07:39 AM
#28
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If you are climbing hills, you may want lower voltage (speed) and higher current (amps). In my case, my commute is flat, so I can over volt my motor and get more speed out of it while keeping the weight down. I could backtrack from the no load speed to a reasonable road speed, but that ebike.ca calculator really takes a lot of the guesswork out. If going outside of the conservative “out of the box” design configuration, I can understand how changing motor winding, Voltage, Current will impact speed, acceleration, climbing, and critically – overheating.
07-12-19, 10:59 PM
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I used off the shelf motors. Its not harder than what you are doing. Typically there are 3-4 varieties of a motor (different motor windings). These are for different voltage levels and different wheel sizes.
If you are climbing hills, you may want lower voltage (speed) and higher current (amps). In my case, my commute is flat, so I can over volt my motor and get more speed out of it while keeping the weight down. I could backtrack from the no load speed to a reasonable road speed, but that ebike.ca calculator really takes a lot of the guesswork out. If going outside of the conservative “out of the box” design configuration, I can understand how changing motor winding, Voltage, Current will impact speed, acceleration, climbing, and critically – overheating.
If you are climbing hills, you may want lower voltage (speed) and higher current (amps). In my case, my commute is flat, so I can over volt my motor and get more speed out of it while keeping the weight down. I could backtrack from the no load speed to a reasonable road speed, but that ebike.ca calculator really takes a lot of the guesswork out. If going outside of the conservative “out of the box” design configuration, I can understand how changing motor winding, Voltage, Current will impact speed, acceleration, climbing, and critically – overheating.
07-14-19, 10:25 AM
#30
Cycleway town
Who said they are riding wet muddy paths? I live where the weather is GOOD, lol. But, in any case, the system I bought has user replaceable belts designed specifically for dry/normal or wet (more grip). Friction drives have come a long way as better materials have developed. And some, like the 1M, even have sophisticated software actuated engagement adjustment. Did you read about how it works, or were you just making a comment based on the old reputation of friction drives?
