mid drive and front gears

[yyayin]

are there mid drive systems that keeps the front gears?
on the way back from office i like to turn off the motor (for sport) and then i need the front gears.

 

[spinningmagnets]

It wouldn't be difficult to do that yourself, but every chainring you add to the stack puts even more sideways twisting force onto the freewheel bearing. White Industries has said they "may" come out with an ENO freewheel with two bearings, but I don't believe they have done that just yet.

One option might be to add a 3-speed IGH (like the Sturmey or Nexus) that is made for trikes (two cogs, one on a freewheel, and one on the hub shell), and locate it halfway between the BB and the rear wheel, using it as a jackshaft.

Also, there were quite a few threads a while back on the SRAM Dual-Drive, its a copy of the Sachs 3X7. Its a 3-speed internally geared hub with an additional common external 7-speed, making a compact 21-speed rear wheel.

http://endless-sphere.com/forums/viewtopic.php?f=28&t=15216

 

[yyayin]

been searching and found the cyclone 3 chain wheel kit, does it allow to keep and use the original front gears? (even if without motor assistance).
http://www.cyclone-tw.com/3chkit.htm

 

[d8veh]

The Cyclone three-chainwheel has one for the motor chain and two for the chain to the back wheel, so you get 2 speed on the front.

 

[yyayin]

thanks for the explanation, that's encouraging!
one more thing which i really want to know - when i pedal with no electricity, will i feel the motor drag?
my plan is to go one way on elec. and back just by pedaling, for the sport.

 

[maxplanck]

For my build, I got a left hand spider and used the motor to drive the bike through the cranks and original bike drivetrain (yep... my motor has a 21 gear transmission ). I was also able to incorporate a freewheel on the jackshaft to decouple the motor when I am under pedal power alone. If you do want to pedal, the bike acts exactly as it did before modification, though a bit heavier.

Of course, this method does limit your top speed to what your bike's gearing and your cadence will allow. Also, even though you may not be putting much power into the system, you're always pedaling. Those are just minor issues in my opinion, far from deal breakers.

 

[pdf]

For my build, I got a left hand spider and used the motor to drive the bike through the cranks and original bike drivetrain (yep... my motor has a 21 gear transmission ). I was also able to incorporate a freewheel on the jackshaft to decouple the motor when I am under pedal power alone. If you do want to pedal, the bike acts exactly as it did before modification, though a bit heavier.

Of course, this method does limit your top speed to what your bike's gearing and your cadence will allow. Also, even though you may not be putting much power into the system, you're always pedaling. Those are just minor issues in my opinion, far from deal breakers.

The Stokemonkey Xtracycle conversion works this way. This is probably not the right conversion for the OP unless he/she wants to convert to a longbike. I've got a bit over 5k miles on my Stokemonkey converted hybrid and I have never had a problem related to driving the left hand crank. There is no freewheel between the motor and the cranks and so when the motor goes round, so do the pedals. This bike is truly an electric-human hybrid. Your feet have to go round but how much effort you put into it is up to you. I think it works great. Some people don't like having the pedals linked to the motor but in my opinion, as long as you get the gear ratios right, it works well.

 

[Warren]

pdf is right. If you are a bicyclist, Stokemonkey style works great. If you gear the motor to the cranks correctly, with 2-3 front rings, you can run 4-40 mph at normal pedaling cadence. No worry about smacking your foot on madly spinning pedals. If a foot slips off, the cranks actually slow down, not magically speed up, because the motor is now doing all the work. Way easier than a fixed gear bike, if you have ever ridden one of those.

6084 miles so far, no freewheeling cranks for me