• Security incident: ISF was recently accessed by intruders. Please change your password, and change it anywhere else you used it. Read more

electric bicycle?

[X] said:
Sorry Quarky.

You could do it, but it offers no benefits over the existing bicyckle drivetrain.


Have you ever ridden a bike with a generator-headlight?
Try it sometime to get a feel for the resistance of electrical generators.
Granted, the headlights ride on the rim, not the crank, and this amplifies the feeling of resistance somewhat. But it gives an idea.

If people want an easier time pedalling, go to higher-inflation pressures on the tires, or smoother tires.
I run my mountian bikes at 60psi (XC semi-slicktires), and can attain speeds of over 50 kph before my feet can't keep up to the pedals. I can cruise comfortably at 35kph. Road bikes run over 100psi, and with bigger gears, can cruise comfortable at 50kph.
The higher pressure/lower resistance tires roll easier, but if the going gets muddy of sketchy, they provide less traction.
It's a cheaper alternative to re-buiding your bike, if you are looking for ways to make pedalling easier.
It doesn't help with wind or hills, though.
Click to expand...

My mountain bike has a road crank with 2 rings up front, 53 and 34 teeth. With a micro drive cassete in the back I can go anywhere offroad and not reach a point where the pedals can't keep up on the streets.

And I've seen a bike with batteries in the down tube, and an electric motor under the seat. I'll see if I can google one up.
 
Last edited:
I've seen a battery and pedal powered bike. It had a small electric motor, batteries, and the pedals charged the batteries, or ran the motor.

Separate batteries for the lights. I wanted to buy it, but the dude wouldn't sell. He also said they don't make them anymore.

I wonder if that is true.
 
It did not have regenerative braking however. Which would be a real boost when mountain biking.
 
This seems to be the exact kind of thing that you're looking for. Remember that motors and generators are the same thing. So, if it's not too big without the spokes, use one in between the pedals to generate power. Use the other to drive the wheel. You may need some power electronics in between to boost/regulate the voltage.

I can't find the data sheet for it. I assume you have to contact the Wulong company to get one (hopefully they have a good English speaker on staff).
 
Ah, did not know that. I've seen brushless DC generators so it should at least be possible to rig the bike motor as a generator. It might take a little surgery.
 
PingOfPong said:
This seems to be the exact kind of thing that you're looking for. Remember that motors and generators are the same thing. So, if it's not too big without the spokes, use one in between the pedals to generate power. Use the other to drive the wheel. You may need some power electronics in between to boost/regulate the voltage.

I can't find the data sheet for it. I assume you have to contact the Wulong company to get one (hopefully they have a good English speaker on staff).
Click to expand...

good link; thanks
 
PingOfPong said:
Quarky, what do you think of this idea? The rider must pedal at an certain speed or at least a narrow range of speeds. This speed would be optimized for leg pumping comfort. At higher speeds the rider will have to pedal harder to supply the necessary torque. However, no matter how fast the bike moves the rider will still pedal at the same speed.
Click to expand...


90 rpm (pedal speed) is the oft-quoted standard.
Most magazines, pros, and weekend warriors seem to find that to be a magic number.
Me, I'm an oddball. I prefer a higher gear and lower revs. I just find it easier to put down more force a little slower than I do to spin. Although I've heard it's bad for my knees.

As a suggestion to append to this idea: Include gearing to optimize the most common (90rmp) pedal speed, and make it easy to swap out for gearing that suits different preferences. Say every 10 rpm or so.




Delvo said:
There are problems with the chain system. Aside from "exposure to the elements", there's the fact that the chain tends to slip off of the gear it's on when you want it to stay there, and to stay on it when you want it to shift to another. Since this happens mostly or only with the rear gear set, which has 5-7 gears of rather similar size, and rarely or never the front, which has 2 or 3 of more radically different sizes, this could be handled by just reducing the rear gear set to 2 or 3 gears (or even just 1 if the problem is instead related to the different system that's used for transfers between the rear gears). But no bikes like that seem to be built; there seem to always be lots of very similar-sized rear gears if the bike has any gear-shifting at all (and the ones without it are kids' bikes).
Click to expand...


Don't go to department stores for bikes. ;)
Sorry, it was begging to be said. I don't mean to slight you.
Take your bike to a bike shop. Get a mechanic to adjust your derailleurs. It sounds like your rear is a little out of line.

But your suggestion of reducing external gears is sound. Internally-geard hubs are trying valiantly to make a comeback.



Molinaro said:
My mountain bike has a road crank with 2 rings up front, 53 and 34 teeth. With a micro drive cassete in the back I can go anywhere offroad and not reach a point where the pedals can't keep up on the streets.
Click to expand...


Mine has 46 up fron and 12 in the rear. Maybe a bigger gear would help a stomper like me, but I'm selling the bike, so I won't bother.
(I want either something a little more all-mountain oriented, or a cyclocross bike. I don't race, so the XC racer, while fun, is perhaps not the best fit for me. It's a y2k Trek STP 400, if that menas anything to you.)
I'm guessing that, with a road crank, you are a cross-country type of rider. Do you race?








On a note actually related to the OP: I've seen a few electric-pedal bikes out. And they're becoming more popular.
SOme are electirc-assist, which just gives a little extra power if the rider needs it.
But I saw another one recently that the guy bought off e-Bay, and which can do 50 kph.
It looked different, so when he stopped next to my car on the street, I asked him what it was.
But all these run on batteries. None have a generator in the pedals.
 
I was a bike courier who wanted a bike I could work on and go offroad right after work without much hastle. I would just swap the wheels for a pair with some treads instead of slicks. The big ring up front was for work and the little one for the trails.
No organized racing, just riding for work and play. The courier days are behind me but I still ride everywhere I go. My trail riding has lessened of late.
 
You must log in or register to reply here.

Share this page

ISF - Join now!

Every member here is approved by hand. No bots, no spam, just people who care about evidence and honest debate.

Membership is free!

Create your free account

Back
Top Bottom