Would like to go really fast!

Hey, i have a regular road bicycle. i think it is 700x25mm. i can cruise at around 20mph on a smooth, flat road. i do not use the top gear. on downhills the most ive ever got was about 45mph and it was dangerous because downhills are always curvy... i didnt have the bike in the top gear so i dont know if i did if i would even be able to pedal it if i wanted to(or the wheel just goes too fast). i feel that on a smooth flat road it would be nice to go 45mph if you're travelling cross country. so i wonder if there are engines that can perform like this??
ive found this site by using google. and so far there seems to be info that >30mph is illegal. i dont care about legality. if a cop stops me and gives me a fine, it's my problem.

also i think that if both electric and chemical engines can go this fast, i would prefer electric because oil smells and all that. but of course it might be a problem to charge an electric engine when going on a long trip as i doubt i can just stop at any restaurant and ask them to charge it?
thanks for any recommendations.

Hi Rider,

I like the way you think! HA...As far as bike choice I'm not sure I've seen anybody with a regular road bike yet....mostly Mountain bikes or cruisers....so it's good to see some variety!

As far as getting that speed....depends on how much you want to spend....

Easy Rider has a uses a really nice engine...I think it is a Morini ....

Lots of people here run the center mount Chinese engines....If you go that route and want speed go with the large displacement models (the so callled
80's (really 66/67 or so CC's) and use a small sprocket in the rear or you can go get Pablo's Shifter....depending on terrain, rider weight, altitude etc....you can get to about 40 or so MPH (My Dax 70 with a 36T sprocket can get to 34.4 MPH at 6400 RPM....NOT sustained because the engine RPMs make it sound like it wants to blow....probably can gear higher (smaller sprocket) for more high speed cruise though...

Hope this helps....Please post pics of your creation!

Andrew

PS - Welcome to the forum!

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45mph is a tall order for the stock 70cc Chinese engines, they just don't have the horsepower.

You may want to consider a scooter. Some of them can go 45 no problem.

Electric is about out of the question for cross country trips because gas stations don't sell battery power.

One option would be to mount a bigger motor like this Lifan 125cc 4-stroke eBay Motors: LIFAN 125CC ENGINE MOTOR HONDA XR50 CRF50 XR 50 1DW/3UP (item 150281871507 end time Aug-18-08 02:25:03 PDT)
on to a homemade pusher cart. It would work by the motor driving the wheel of the cart which would be "towed" by the bike.

Another option is a front mounted engine like this: Briggs and Stratton Bike

As you can see fabrication skills are required most of the higher power options.

45 mph sustained speed on a bicycle is foolish and dangerous. They are not made for that type of use. Buy a motorcycle for that.

The view expressed is the humble "O" of Bikeguy Joe and should not be considered law.

Still, seriously.....

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I was going to say that, but I didn't want to be the barer of bad news.

Hey thank you guys for the replies! I have built nothing. And I wonder if there is some book i could read to learn some of these technical terms about motors? I wonder if it's possible to keep the original wheel and chain? what's a homemade pusher cart? Are electrical batteries charged by an electric plug from a wall? If i go on a crosscountry trip I would still do much of my own cycling but I would use the motor whenever i needed to get somewhere quickly. Like if i wanted to get to some beach 300miles awya, it would be nice to use battery power for 200miles and then get to the beach before dark. I understand that bicycle wheels dont have as much traction as thicker wheels but it doesnt make it unsafe. World class cyclists go for 2miles at 40mph without any problems. Of course if the road is not perfect you will get flat tires whether you go 20mph or 60mph.

i'll put in my 2c,

for the kind of use you describe, buy a for real down hill sport bike. front suspension, rigid rear. many now have hydraulic disk breaks, all have light motorcycle grade forks, rims,hubs and bearings. invest in a sprung seat post.

take your pick of either a frame mount Franco Morini engine (go to the home page and read "EZR's full suspension summer project" for more on that engine )or a Staton rack mount with a GP460 engine.

either of these will give you 45mph sustainable true cruise ability depending on gearing choices.

as you suggest, the consequences are fully yours.

steve

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If it ain't broke, and you mess with it long enough, it will be.