New Build

[linkinlime34]

I have given up on my current MB for speed, and I'm gonna start a new bike, and I'm looking to make this thing FAST! I would like some suggestions on the bicycle to buy, engine, and mods to do to it. I have a need for speed, and I love building these things, so any suggestions would be appreciated.

 

[SimpleSimon]

If you need speed (what young man doesn't?), I'd suggest you buy an older actual motorcycle and rebuild it for your "mechanicking" fix. Something designed and built for those stresses, unlike a bicycle designed for lower speeds and stresses.

 

[kerf]

You don't mention which style (rack or frame mount) you like. Fast isn't a problem at all, pretty much depends on the depth of your pockets but fast is rather ambiguous. Thirty mph is a lot different than 50, also a lot less dangerous. A little more info would help.

 

[linkinlime34]

What i have now is a frame mounted engine 2 stroke. I am most familiar with those styles of engines. I can spend around $700 total on this next build. I would like to be able to hit 45 mph with it.

 

[Al.Fisherman]

Tell your parents that they just might want to increase both your health and life insurance. Bicycles are not designed for speed.

 

[Porkchop]

In my home state of South Carolina, motorized bicycles can not be capable of going over 30 miles per hour period. S. Carolina seems to be fairly lenient about motorized bicycle laws, but I’d bet a top speed law applies in pretty much all 50 states. 45 mph on the average bike is a funeral waiting to happen. If you plan on riding your motored bike on public property, check your local laws.

 

[kerf]

Ok, hitting 45 isn't too bad, long as you don't intend to run that fast. IMO, 30 is a fast cruise speed, 25 is even better. Mine will exceed 40 but I don't run it that fast because bicycles aren't designed to do that. If you want to run 45 or even better, follow Simon's recommendation.

To answer your question and I take no responsibility for your well being, a rack mount with one of the larger 4 strokes would work fine. You could look into a frame mounted 4 stroke with a SBP shifter, don't know if they've brought it to market yet.