Introduction: Mountain Bike Scooter
It's a better, faster, funner scooter. Ready for Maker Faire 2010!
Combining the front end of a mountain bike with the back end of a kick scooter makes a high performance scooter that is easy to ride.
The high wheel shape (aka penny farthing) hearkens back to the 1880s when big wheels ruled the roads. They too were pursuing greater comfort and more speed.
Video of synchronized scootering at youtube: www.youtube.com/watch
Dumpster rescued items including: scooter, mountain bike front end, floor boards, spray paint.
Store bought items: 4 nuts and bolts, 2 grips, varnish, 3 feet of 1.5" steel tube
Other unusual bikes located at: www.woodenbikes.com/
Step 1: Layout Using the RAD System (Reality Aided Design)
Reality Aided Design refers to laying the parts out and eyeballing the geometry. (no software needed) Here I'm setting up the basics of a scooter body behind a mountain bike front end. The yardstick represents the steering axis (center of the head-tube). Note the steering axis intersects the ground ahead of the front tire contact point on the road. The tire contact point 'trails" the steering axis. As a side note to bike designers... The bend of the fork blades produces "rake" aka "offset" that consumes part of the trail to shorten or snug-up the trail for a certain head angle and wheel diameter.
Step 2: More Layout
Laying the back bone (aka down-tube) into the picture I see I will have to bend it to get it around the tire and ahead of the foot zone.
Step 3: The Bender
A 12 ton hydraulic press pipe bender easily bends the thin wall tubing. Maybe too easily.
Step 4: Might We Need a Miter?
In order to have a strong joint between two cylindrical tubes we need a mitered joint. That way the end of one tube conforms to the side of other. It gives a lot of length of contact to weld and more widely distributes the forces while riding.
Step 5: Mitering With a Hole Saw
Using a hole saw the same diameter as the head-tube I drilled a hole (in the down-tube) at the connection angle between the down-tube and the head-tube. It was done with the down-tube in a sturdy vice and eye balled to a diagonal line drawn on the tube. Remember to run the drill speed fairly slow (100-200 rpm) for these large diameter holes.
Step 6: Hole Saw Carves a Place for the Head Tube
Might we miter a mighty fine joint to mightily mitigate forces that might manifest from manhandling?
Step 7: Dry Fit
Laying it all out again before the crucial weld, just to admire it.
Step 8: Tack Weld and Then Re-check Alignment
A couple of small weld points hold head-tube to down-tube. The shiny pipe passing through head-tube is for alignment purposes.
Step 9: All Welded Up
Just needs its stem and bars re-installed.
Step 10: With Bars and the Wood Deck Installed
The wood deck is two pieces of 3/4" oak hardwood flooring bolted to the scooter body.
Step 11: Painted and Varnished
Frame was spray painted, Deck was floor stained and varnished. It rides nice!
Lessons learned: next time I will try to curve the down-tube closer to the wheel to try to bring the scooter body further forward. that has the effect of reducing the reach forward, distributing more weight onto the big front wheel and reducing the vehicle length by about 2-3".