what about buying a scrambler/dirt bike, and adding pedals ?

[knighty]

has anyone here bought an off-road motorbike, stripped it down the frame, then added a motor and pedals to use it as a bike ?

I'm thinking something like this bike...
http://www.ebay.co.uk/itm/Spares-or-Repair-Suzuki-DR200-Djebel-SX-Trail-Enduro-MX-Off-road-/321085888757?pt=UK_Motorcycle_Parts&hash=item4ac235d8f5

strip everything off, stock my cromotor on back (in a motorbike wheel)
adding pedals so it's technically a pedal bike...
bike seat, lights etc...

maybe a few frame mods - nothing major, maybe make it a bit narrower at the top etc...

seams like the best way to get a really strong bike, with loads of frame space for batteries ?

googled but couldn't find anyone else who'd done it, and thought maybe there's a reason I've missed ?

bike would be a bit heavy... but shouldn't be too bad, considering the weight of a cromotor and a load of batteries is quite heavy anyway

(I'm thinking 72v 20ah (or 30ah) right now, but still undecided

 

[SamTexas]

I had the same idea when I wanted a fast ebike with real suspension. My choice was a Honda CRF 100 or 125cc. It was just a thought though. Did not proceed with the plan.

 

[John in CR]

It will end up a lot heavier than you think. Do something like a Motoped. http://motopeds.com/
Here's another take on ultra-light motos http://www.fxbikes.com/

 

[Dauntless]

I've sought a dirtbike, a street bike, anything small enough for minimal weight. Some it's just as well they got away, it'll have to be registered but there were no lights. Don't know about other states, but that's not going to work out in California. Meanwhile, what percentage of motorcycles do you figure are too big and heavy? 90%?

My thought for the pedals is to have crank drive a jackshaft to connect to the main drive chain. There could even be a derailleur inside there. Sure would be nice to find something to try it out on.

 

[dogman dan]

I don't get you thinking at all. If you put a cromotor on any kind of contraption with pedals, it still ain't legal as a bike in california. Unless you gave it less than 1000w anyway.

I also studied cheap china 125 dirtbike frames with such thoughts in mind. The first thought was that it was going to take a lot of mods to make it have pedals, and I don't weld that good. The second thought was that if it ran, I'd just be riding it as is. Later on, having finally purchased a fairly good FS mountain bike, the real reason not to do it became very very clear.

There is simply no way a cheap chinese 125 suspension was going to ride even close to as nice as the good mountain bikes does. And again, if you went for a new honda with really good ride, you'd just want to ride it as is.

All my thinking was aimed at dirt, and street legal was not so big an issue. Legal dirt starts 200' from my driveway.

For street it would be different. A small motorcycle in the 50-125 cc class could be ideal for putting a 5000w hubmotor on it, and getting a licence plate and insurance on it. Build if for about 50 mph, and then go ride in the traffic on 45 mph streets with great confidence. No point in pedals. If wanting to ride 30 mph or less, no point in motorcycle tires and frame.

 

[MadRhino]

Weight of course. The heavier bike I got is sub 80 pounds, and I would like the same power on a lighter build.
A motorcycle frame is not a good place to start when you want to improve power to weight ratio.

Nevertheless I am thinking of the 120 Lbs Gas Gas TXT-e. I wonder if I could ride it in town and the park, after fitting it with bicycle pedals and saddle. Then, we are talking serious torque and suspension here, more than I could realistically build on a DH frame and make it look and handle nicely.

[youtube]JmkGgUlJy-8[/youtube]

 

[knighty]

not sure where California came from... I'm in England so legal limit is 200watts... (even worse)

but I'm not really worried about being legit, as long as it looks a bit like a pedal bike I can bluff/charm my way through any problems I get into...

I've been looking for a good, strong, full suspension mountain bike, with the right shape frame and enough space in it for a decent amount of batteries... and there's not much choice... and pretty much anything that does look ok is crazy expensive

at least if it's cheap it's no big deal when I inevitably destroy it

 

[spinningmagnets]

You can get extra wide BB-cartridges from Sick Bike Parts:
http://www.sickbikeparts.com/catalog/index.php?cPath=23&osCsid=753inh2hovgfaqs6apqi65j8k2

"Sliding bottom bracket shell" from http://problemsolversbike.com/

 

[dogman dan]

Duh. I musta been just reading about california one thread earlier.

This for street or dirt? I did get a definite idea you were thinking street legal, with a cromotor.

I can see how a cromotor could be a bit too heavy, off balancing a "bike", making riding it in dirt less than perfect. But you'd have better balance, at the cost of lots more weight with a motorcycle frame.

I would dearly love to have a good trials motorcycle, and leave it stock. Best motorcycle I ever owned was an old suzuki 250 trials. Handled like shit compared to modern trials bikes, but it sure was cool having the low gears. Used to have a ball climbing bulldoser roads to mines.

 

[sigimem]

I like your idea. I would look after a small dirtbike like a Cr80/85 kx80/ rm 80 ... with big wheels (most are offered with two differen wheel setups)
or replace the wheels with somthing custom made. The ones named 80 instead of 85 are mostly older and more likely have steel frames. You should however consider the fork is really heavy compared to a mountain bike same goes for the hubs und the brakes. Also the Frame could be too wide where you want to mount the pedals a steel often used for the frames is 25crmo4 if you buy a steel frame which is probably the easiest thing to do.