Stuff I’ve Learned: Buying a Rolling Chassis

One of the common questions you see is about what to start with for a donor chassis on a conversion project.  Having bought a couple, I’ve had a bit of experience with good, and not so good choices.

You can find bikes on Ebay or Craigslist by searching “frame” or “rolling chassis”.  I usually look under the motorcycle category, but I found the bike above in the free section.  There are a couple of things you have to watch out for when you consider a donor.

First, clear ownership.  Most of the laws of most of the states have something in place to deal with stolen bikes being parted out.  The one traceable part is the frame, since that has the serial number and VIN.  Even for off-road bikes, in some states, you need a clean title or bill of sale to get an off-road permit regardless of what the seller will tell you.  My personal opinion is that it’s well worth the extra dollars to get a bike with a legal title, that I know will be registerable in my state, than to try to save a buck and risk never having a legal bike.

Second- mechanical condition.  The bike you see above seemed good, but in fact, it needed all new brakes, hydraulics, bearings and even suspension to make it run…  forget about safe.  I’m starting my project out with a complete rebuild of a bike- really, making it into two projects.  If you get a bike that is in pretty good shape, with basically operational systems, you’re saving yourself a crap-ton of work.

Also, and in particular with a trail bike, keep in mind the bike has likely seen a few crashes or laydowns.  Check for frame dents, twisted forks, scrapes on bar-ends, dents in tanks.  See that the forks move smoothly.  Check contact points for telltales of crashes- control levers, mirrors (or lack of), directionals and footpegs are all things that get scraped, ground or broken off in a laydown.  Not to say a bike that has been crashed won’t be OK, but it definitely needs close scrutiny.

Third, is the bike style itself.  This may seem obvious, but get a bike that is close to the bike you want to end up with.  I wanted a street bike, cafe-racer streetfighter type of bike.  This trail bike, free or not, was a waste of time- it wasn’t the bike I wanted to end up with, by the time I made it into the street bike I was envisioning it would be 5 years from now, and a total hack job.  Keep in mind how much space the batteries you want to run take up- as well as the motor.  On a small frame, you’re going to be limited in how much weight and volume you can carry.  A hub motor gives you some more room in the frame, too- the motor is in the wheel itself.  A big frame with lots of room is going to be heavy…  especially when you load it with batteries.  All stuff to keep in mind when you’re fleshing out the kind of build you want to do…  but decide on the build and buy the frame to match, rather than letting the frame dictate the build.

One point on frame materials- an aluminum frame is going to take a bit more to have welded properly.  The fabrication part of aluminum is a lot less challenging than steel since it’s softer and easier to cut, but you’re going to have to pay more to get it welded, or pay more for a welding rig (as well as put a lot more practice in when trying to learn) than steel.  The weight difference is probably not enough to justify one way or another- it’s more about the overall frame design than the materials.  (i.e.: give me a good vintage ’70s tube steel frame any day of the week…  🙂 )

Finally, don’t forget about reselling parts- but don’t count on it either.  Here’s the problem.  If you find a cheap bike, chances are it has a blown motor or something.  Blown motors are hard to sell, you have to rip them down to parts.  That takes time.  If you have a good motor, you’re going to pay more but you’re also can get more for the motor.  At first I figured I’d resell the bits I didn’t need- ultimately it wasn’t worth the time.  

You may luck out, but ultimately you get what you pay for.  With a conversion like this, you’ll find that the parts you get- the motor, controller, batteries and chargers- are pretty interchangeable. If you want to grab what you can for a chassis and slap parts in to make it go- that’s one approach.  But if you have a clear idea in mind, I’d suggest holding out for the frame that you really want and biting the bullet.  You’ll have a good condition, pretty, safe and legal build after all your hard work.



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