Reverse Trike Noob questions

T

thompjam

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https://photos.app.goo.gl/2KrDrWauNH5ppB8A8

I am just starting to source materials for this reverse trike idea. Any input / tips from the forum would be most welcomed. I am specifically curious about opinions on the appropriate gearing for the drive train and input on the motor choice. This will be fabricated for Burningman, and won't need to go very fast at all, nor up any hills.

I was intending to build it w 5/8 axels. I think I need 2 freewheel adapters and single gears for the front axel so each rider can pedal independently, and a single fixed gear to transfer the power to the rear axel. How many teeth?

The rear axel will need 2 freewheel adapters, one for the motor assist and one for the cassette, and a singe fixed gear on the jack shaft to go to the motorcycle wheel on the swing arm.

I've tried to do my due diligence searching on the forum, and found my way to Stanon-inc, but its a bit unclear to me which adapters / gears to purchase.

I was thinking I would use a 48V moto for the e-assist, and again its a bit intimidating trying to figure out which one to go for.

Thanks for any help, you guys build some cool shit on here!
 
Hi

thompjam said:
This will be fabricated for Burningman, and won't need to go very fast at all, nor up any hills.
Click to expand...
Don't forget the potential mud.

If you look at a old school 15 gears 26" mountain bike, it had a 3 gear front, normally 48/38/28 teeth and a rear freewheel with 14-28 teeth
This gives you a lowest gear with 1 to 1 ratio and the highest gear 3.5 to 1 ratio with 26" wheel. Your rear wheel will probably be smaller than 26"
and if all gearing is done on the rear wheel, you need around 1 or 1.5 to 1 ratio on the lowest gear on a freewheel/cassette with minimum 3 to 1 ratio between lowest and highest gear.

A 5/8" axle is on the smaller side for a e-assist tandem, I would choice 3/4" or even 1" depending on the width between the bearings, but I never tried
your setup, so I might be wrong.

For the motor you can use a universal motor, normally have a output rpm of 1500-3000, or a e-bike hub motor, not used as a hub, with a rpm around 250, you need a ratio of 6 or 12 to 1 on the sprockets for the universal motor.
 
Thanks for the reply, I appreciate your time. Given the weight of this contraption, I figure that it will need to be geared pretty low, or at least have the option of going very low. I was picturing purchasing single chain rings up front like a modem 29er mnt bike ( 30 tooth?) and a fat cassette w perhaps a 50 tooth lowest gear.



If on my design I have the front axel to combine the two riders energy and transfer it to the rear axel, does the fixed gear on the front need to be the same number of teeth? I get a bit lost on the math adding that intermediate step!

Might you have an opinion / link a true and tested universal motor option? Something like this kit?


It would seem that the amount of weight bumping the axel from 5/8 to 1 inch wouldn’t be too much, so thanks for that input.

Thanks again for your help!
 
Hi

If you thinking about a universal motor go for the model with lowest output rpm.

Using a fat cassette on a tandem with a 3kw added motor will probable result in a chain brake. You need to use the same chain size that is in the motor kit T8F, and that chain is not compatible with a bicycle chain or made for gears.

My example above was only to explain which ratio is needed on a bike. To get total ratio on a multi axle system you just multiply the individual ratios.

The simple solution is to have the cassette on the second axle and fixed teeth gear on the rear wheel.

Look at go cart and cyclekart/pit bike parts for the rear setup.

Also take a look at "Ed's 'StreetRunner' Quad Build" at this forum. The motor parts starts around page 18.
 
If you use std 26" MTB gears then going to 20" wheels will reduce that. This then requires you to use very similar or the same gears at the pedals and the jackshaft to maintain that ratio. If you use a much larger pedal cog to the one on the jackshaft of say 32T and 16T then you are doubling the gearing upwards. If anything you'd want a smaller cog at the pedals to the jackshaft.
The no load speed of that motor is 6000rpm. You will want your wheel running massively slower than that so will need a very large rear T8F sprocket. You will also need to find a T8F sprocket that will be mountable to a freewheel as the motor does not have one so you will need one at the wheel unless you intend to run permanently on the motor. Without one you'll be driving the motor when pedalling. That freewheel will likely be designed for a bike and won't like 3000W. You could also consider a one way bearing as found in Tongsheng mid drives but actually making the housing for it isn't a newbie task. An alternative and much easier is to lace whatever rim you want at the back into a hub motor. No extra chain or freewheels. No reason you couldn't lace one into a car rim if you want a very wide one. They tend to cost more than that type of motor but price up everything needed for each drive system as a whole.
 
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