building a motorized bicycle, need help deciding on which motor should I buy?

[raindroptree]

Hi. I am new to this forum and looking to buy, build, or have someone build me a motorized bicycle. I need one that 1: goes pretty fast, at least 45mph, and 2: something that doesn't have that much vibration. I know there are the typical 80cc, 2-stroke engines, but it has too much vibration for me and I know there are a lot of motor options out there. I am a small female and sensitive to vibration, my arms will get very itchy when offroading on a bicycle if there is too much vibration and I have to get off the bike. I live in Florida, and I need something that has the least amount of vibration for the top amount to of speed. I thought about getting a 4-stroke engine, but I know they cannot go very fast and I need something that will go a decent speed because I will also be riding this on the road with a driver's license. I would rather not have too much noise because I live in a residential area. I would also like to go offroading on this bike, through trails and other places, though of course I won't be going top speed while offroading, I will probably only use the motor as an assist.

My last questions are 3: if I need to, or could add anything onto the bicycle to reduce the vibration (I know big wheels would help), and 4: if I can add a motor guard so that I don't get burned by the motor while riding(since I live in Florida, long pants are not an option).

 

[bluegoatwoods]

Hmmm.......I'll have to start by raining a bit on your parade.

I'd highly recommend that you give up any notion of going 45 mph on bikes of this sort. The frames and bearings and such were just not designed for it. And making such speeds is just begging for a failure in parts like that. Imagine a bearing shredding at such speeds. I'll bet I don't need to say more. You can picture what would happen.

"Twenty is plenty" I've forgotten who said that. But he's right.

There is one way, though. Buy a complete bike from someone like "Sportsman". They build bikes out of higher quality components. There are a few others. But I'm having trouble remembering names right now. KCVale --a member here-- builds some pretty serious bikes. I don't recall off-hand if he's been building stuff with motorcycle quality hubs, for instance. But whether or not he's done it, I don't doubt that he's capable.

Now...to get a bike of this caliber will cost you about as much as a scooter from Yamaha. Somewhere in that ballpark. It's too bad. But that's just the way it is.

A more serious bike will help with that vibration issue as well.

If you build a bike using low cost engines and bikes from a dept store, or a somewhat better bike from a bike shop, you really ought to plan to ride it not very much faster than you would ride it with no engine. It's a little better than it sounds, though, because you're keeping up the same speed even uphill or in a headwind. So you do go faster, on average, than on a plain old pedal bicycle.

Sorry about that. We'd love to have you with us and you're more than welcome here. But if you really need to do 45 regularly, then you need a motorcycle or something that's pretty darned close.

 

[butterbean]

A predator engine can do 45 if geared properly, and I have personally seen predator bikes doing that speed with a bicycle drum up front and a coaster hub in rear. I don't know if or how much they vibrated. Personally, I do recommend a good strong frame and upgraded hubs. I'm working on a predator build now, but its geared to cruise at 30. However, I'm using an American made frame, hydraulic motorcycle forks, a motorcycle drum up front and a moped hub in rear. Got about $1k worth of parts in this build. And you don't need big wheels to help with vibration, you need wide tires. So many people use the words wheels and tires interchangeably.

 

[butterbean]

BTW, where in Florida? I'm in Gainesville.

 

[Cylon]

Youll be fine just go to Walmart buy a kent glendale and slap on a normal 66cc ebay kit, stock mine goes 38 mph if I hold it wide open for about 30 seconds the avg is about 33 according to my gps. Ive already put over 500 miles on my glendale and Ive had no issues if I were you I would just do what you want to do and dont worry about what other people think but ya 45 mph is a bit fast for these motors tbh I think 35 is pretty quick and I can cover my hole city very quickly. Not to mention it was a 99 dollar bike and the kit I got for 130 so for 230 dollars you can make this in less then 4 hours. Use a old bike tube to lesson the vibration. Some people say you should mount right to the steel but thats not true, like I said Ive had zero issues with mine and if I did its just to damn cheap to really care much about. Very simple to replace. I also recommend good health insurance because things can get sketchy when your in traffic traveling faster then you normally would be.

 

[butterbean]

Youll be fine just go to Walmart buy a kent glendale and slap on a normal 66cc ebay kit engine stock mine goes 38 mph if I hold it wide open for about 30 seconds the avg is about 33 according to my gps. Ive already put over 500 miles on my glendale and Ive had no issues if I were you I would just do what you want to do and dont worry about what other people think but ya 45 mph is a bit fast for these bikes tbh I think 35 is pretty quick and I can cover my hole city very quickly. Not to mention it was a 99 dollar bike and the kit I got for 130 so for 230 dollars you can make this in less then 4 hours. Use a old bike tube to lesson the vibration. Some people say you should mount right to the steel but thats not true like I said Ive had zero issues with mine and if I did its just to damn cheap to really care much about. Very simple to replace. I also recommend good health insurance because things can get sketchy when your in traffic traveling faster then you normally would be.

Do you honestly think any Walmart bike can handle offroading with a motor? Cause I don't. Read your post again and pretend someone else wrote it, then think about how it sounds.

 

[raindroptree]

i am in West Palm beach. If i need a Certain type of bike, i am already prepared for that. I was already expecting to pay around the price of a moped for the bike. I go to gainsville sometimes butterbean. I have some friends that live there. I was also considering puting on an electric motor as well as the gas powered motor, though i dont know if it is necessary or if it would just make things more complicated. I would love it if someone could recommend a good mechanic for this project, i have already decided 100% that this is what i want. I wouldnt mind having someone from gainsville build it for me, then i can pick it up and take it for a test drive. I Need something That is Decent quality, so i came to this forum to ask about parts and different things. thanks for the info about a strong frame and upgraded hubs. Wide tires too

I found this video of some really nice motorized bikes going over 45. https://m.youtube.com/watch?v=G2VGjvF0z_A

 

[butterbean]

Personally, I think adding an electric motor would make things more complicated, not to mention heavier. I gather you don't want too heavy a bike for off-road use. I can build you the bike if you like. I'm not a professional builder, but I've built 4 bikes, two of them custom and I build wheels too. Speed largely depends on gearing. Higher gearing will give you more speed but you may lose some acceleration and hill climbing. But being as you are a small person, I don't think you will have too much of an issue with that. Lower gearing will give you great acceleration and hill climbing, but you won't go as fast. For your needs and desire to go off-roading, I recommend a 49cc four stroke because they are light, which will help when you want to go off-roading. Now, I am assuming you have experience off reading and know what type of tires work best, because I do not. I also recommend a bike with discs front and v-brakes rear, because discs are lighter than drums and will give you stopping power when you need it. That is just my recommendation. If you want me to build it for you, send me a private message and we can go from there.

 

[Cylon]

Do you honestly think any Walmart bike can handle offroading with a motor? Cause I don't. Read your post again and pretend someone else wrote it, then think about how it sounds.

Yeah I just did it all day long today, next time I go out with my fiance I'll take a video and show you that it can. I took a video today of the bike going up a very very steep hill here in Maine it was pretty wet and muddy heading up this hill too it didnt quite make it to the top because it was just too steep but Ill upload that video soon for you just to prove your opinion wrong. Theres some wicked trails Ill try to get shots of tomorrow its just hard because I dont have a gopro

 

[Cylon]

Do you honestly think any Walmart bike can handle offroading with a motor? Cause I don't. Read your post again and pretend someone else wrote it, then think about how it sounds.

Yeah I just did it all day long today, next time I go out with my fiance I'll take a video and show you that it can. I took a video today of the bike going up a very very steep hill here in Maine it was pretty wet and muddy heading up this hill too it didnt quite make it to the top because it was just too steep but Ill upload that video soon for you just to prove your opinion wrong. Theres some wicked trails Ill try to get shots of tomorrow its just hard because I dont have a gopro

Heres the video this bike doesnt have really good off road tires or disk brakes and it still does amazing. I grew up dirt biking so I have some experience off road. Its been an amazing bike and my fiance has a similar bike she uses off road with me and has used it for 3 months to go to work still no failures.