simplified 4 stroke shift kit?? will it work?

B

Board-track Bob

New Member
ok i am a new member and just starting my build with 3 of my friends and we all have decided to do the sick bike parts shifter, i'm using a Micargi Huntington oversized bicycle and going for a 4 stroke engine, my question is i was looking at the gear box that comes with the kit 230761583_o.jpg


and i couldn't help but notice i wonder if you just put in like a 7'' or 8'' piece of keyed 5/8'' shaft from the gear box straight over to the right side by inverting the sick bike parts frame with the 5/8'' bearings and shoot it right over to the right side of the bike.
this would eliminate three chain jumps and also increase the clearance of the rear wheel. i figure it's got to be more effecient and have less chance of chain break to run it from the gear box straight over to the freewheel- but i figure i'll have to do some rigging (as i usually always do!)

what do you guys think, will it work?
board-track bob

.shft.
 
If you are talking a direct drive from the primary reduction to the chain wheel on the oneway, then you will drop one of the reduction steps, not good!
 
wouldn't it be the same as directing it straight back to the wheel without the shifter? maybe i could put a smaller sproket on the end like a 9 tooth instead of an 11 or 17? i dunno, i just thought it would have a cleaner look and not so many chain jumps to worry about... if i lose a reduction would it pop chains from being too torquey?
p.s. thanks for the feedback- my first ever lol who said you can't teach an old dog new tricks!

board-track bob
.shft.
 
Let me see if I understand your plan, I get it on the cross over. Are you building a shifter bike and plan to power it through the pedal crank? If so then the ratios would be WAY to high to power the wheel through the crank. I dont know the reduction on the gear box, but lets say 4:1. If you ran 10t/48-4.8:1 on the right side then the final reduction is 19.2:1 This is really too high. You need a reduction fron the engine to the crank in the area of 30:1, varies with personal preference, and the general use of the bike. The xtra reduction I used was a 10t/17t-1.7:1 now the ratio is 4x1.7x4.8 or 32.6:1. Ought to pull stumps in the lowest gear versus hardly being able to get moving with the other ratio.
 
ocscully said:
If you haven't seen this blog you may find it very interesting I believe he has done what you are trying to accomplish or thinking about doing. nashmoto | blog

ocscully
Click to expand...

Wow!! that site is awesome!! that is exactly what i had planned! but seeing all the trial and error that guy had i may just build the bike EXACTLY the way sick bike parts designed it- at least untill i wind up buying all those crazy presses and machining augers like nashmoto has! man that'd be the life huh? working on the bike and riding all over the countryside?

thank you guys so much for your feedback! i can't wait to get started- still havn't decided between a nuvinci hub and a nexus 3-speed. the nuvinci sounds cool but i think i'd miss the shifting.

i'll post pics as soon as it starts coming together!

board-track bob
 
BTB: I may have done something similar to what you're thinking. I used a staton gearbox and a freewheel and crank from sick bike parts (just their crank, not a shift kit). The gearbox is 18.75:1 reduction. On the output of the gearbox I have a 14t freewheel chained up to a 48t chainring at the crank. This gives me a ~64:1 reduction between engine and crank. I like to pedal between 90-100rpm, so that means when I'm pedaling at my peak, the engine is near its peak as well (~6400rpm). The other chainring is a 36t and is connected to a nuvinci N360 with an 18T cog.

The end result is a bike I can pedal assist at all speeds between stump-pulling and 33mph or so if the wind and hills aren't against me (EH035 engine). I've got about 2000 miles on this setup so far and have had no troubles with the exception of blowing up cheap (ACS) freewheels on the gearbox. Once I switched to a White freewheel, I've had no troubles.

here's a pic of the frame in construction showing the drivetrain arrangement:


Frame With Freewheeling Crank by practicalpedal, on Flickr

And a link to a video of the complete bike showing more of the drivetrain
 
Also, with the nuvinci, you still shift as it's a manually operated transmission. In fact the N360 doesn't like to let you shift up while under power, so you have to let off the gas anyway to shift up, which makes it sort of like regular shifting. However, being able to fine-tune the ratio once you're close is very handy on long grades.

I should also point out that though I have 2000 miles on the bike, only a few hundred with the nuvinci. Before I had a shimano XT hub with an 8-speed cassette on the back. Besides wearing it out after 1500 miles or so, I had no trouble with that either.
 
@wileydavis
just flipped through a few pages of your pics, very nice and great to see an independent innovative approach from the ground up. I see a lot of assembled bikes but yours qualifies as a real build.
 
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