Hey Everyone! Nice place you have here...

I'm not new to machinery, but I am a total no0b when it comes to the World of Motorized Bicycles. I bought a single two-stroke kit from an acquaintance at work; he said he and a friend had purchased ten of them...

Now you guys have prolly seen and heard the same stories from countless others, and I haven't browsed your site for other Schwinn builds, so, please bear with me.

It appears as if I'll have to modify just about everything to get this kit solidly and reliably mounted on this particular bicycle... the first thing is that the engine position will require custom mount spacers and longer mounting studs. The bike's seat and downtube dias. are smaller than the kit's existing mount bracket shapes too.

It was suggested that I check the kit's drive chain length before I nailed the final motor position... that's when I opened another can O' worms with the rear sprocket mounting issues.

I have access to a friend and his machine tools, so we bored the sprocket center to fit the Shimano single-speed coaster-brake hub only to find that the Shimano brake arm will not clear the sprocket's bolt circle.

Is there another brake arm with a different shape I can use tht will fit the axle's flats dimension?

The bolt circle is also slightly smaller that the hub's spoke flange o.d. We can either drill a new, larger bolt circle, or I can slightly groove the hub flange if I can use a different brake arm or even a differeent hub, but then I may need to make a ring spacer to replace the eighth-inch or so removed from the sprocket's centerbore. Then I've misplaced the nine-hole rubber donuts that sandwich between the sprocket and three-piece plate.

ETC.

This is what I'm up against so far. Hahaha...

Looking forward to hearing from someone; thanks for being here!


-Chris in Los Angeles

Wow! What kinda hub you got that you have to re-arrange the bolt hole pattern? I have seen where I had to enlarge the HOLE to go around a three speed hub, but never had to move the bolt pattern.


So....having said that, I'll say this- You can bend the brake arm into a "zigzag" and it will clear the bolts....done it three times now. Also, yes, you can "slot" the holes to clear your hub....just don't bend the brake arm until you've got the sprocket mounted.

While you're at it, if you enlarge the hole to fit the hub, you'll be doing yourself a favor in that these sprockets are a little hard to get perfectly centered. By boring the hole to just fit over the hub, you won't be having that hassle.

So, your difficulties are actually an asset.

Bean Oil, Even after bending the brake arm, I still had to use a grinder and shave a little off the bolt heads of the sprocket mounting bolts to get the brake arm to clear. Some flat headed bolt's might work better.

Ya know, I never tried carrige bolts....maybe they'd work?

GENTLEMEN!

Thank you very much for your prompt replies...

Haven't yet been back to the bike today, but I've been pondering as well as looking online... I've seen a very similar sprocket in what appears to be an identical kit; the sprocket's bolt circle holes are slotted... seems as though the various possible hub flange o.d.'s have reared their head.

Thanks again for the imput. My friend and I were considering countersinking the bolt holes slightly and using an oval or panhead fastener. Joe's idea of carriage bolts isn't bad, but I've never seen a carriage bolt small enough for this app, plus the fact that their strength "rating" (grade 5, 8, etc...)has always eluded me.

Whichever method I use to achieve a proper fit with the sprocket I have I will post pics of when I get a chance.

Again, thanks.

Maybe this will help-
Grade 5 is "standard hardware", which should be just fine, it's all I ever use and
Grade 8 are technicly stronger, but MUCH more brittle.
We NEVR use Grade 8 hardware in aircraft applications since they tend to snap like pretzels when subjected to a shear load when not used correctly.

Counter sinking the sprocket holes and using a panhead or maybe even a hex head (allen) screw should do you good.

Counter sinking the sprocket holes and using a panhead or maybe even a hex head (allen) screw should do you good.
Brilliant, sir!

Two months later, here's a link to an 800 X 600-sized pic of the countersunk and drilled sprocket:

http://i34.photobucket.com/albums/d127/Z63R/Bicycle_motor002a.jpg

I've since moved the brake arm back to the chainstay and I've been riding this thing for about three weeks almost every afternoon! Weeeee!!!1one...





Thanks for all your help. ~

Post edited by: Bean Oil, at: 2008/01/09 20:36

Hey, good to see you again....where 'ya been?

Nice clean installation.

Super Duper looking sprocket application!

yes, this is exactly what i will do for my install!!!! that looks exponentially better than any others i've seen. were you able to clearance the sprocket to keep the dust seal for your bearings also?