Chop Mountain Bike project is complete

June 29, 2010 · 3 comments

The chopped mountain bike project bike is complete. I have named her No Ponder. It is my favorite electric bike so far and she rides like a dream. I get many comments while out and about. It is very unique.

This project was motivated by problems with the existing bike that needed fixed. It was also a learning project for different aspects of bicycle frame building details.

The main problem with the original bike was that it was top heavy and was very unstable. It would start to shimmy around 10mph. Another problem was that the batteries weren’t secure. Every time I parked on the street I would have to remove the batteries and carry a 30 pound bag around.

The fix was to lower the center of gravity by moving the batteries down toward the center and putting them in a box so they would be more secure. This required chopping the frame and extending it to make room for the batteries and building a box for them.

This was a huge learning experience since this was my first major frame building project. I had to learn a lot about frame alignment and fillet brazing as well as how to fabricate a box for the batteries.

Some of the features that are an improvement over the original design are:
• Better weight distribution for a more stable ride
• Battery and controller are secure in their own boxes. The boxes are mounted on the frame.
• Most of the wires are hidden from view so it doesn’t look like a bad science project.
• A handle behind the seat makes moving the bike and lifting the bike up stairs easier.
• The key switch and charging connector are cleanly mounted on the battery box.
• It looks more polished and complete with the components in boxes.

This bike will be a prototype for follow-on projects. There are many features that I’ll carry forward to projects that are designed and built from scratch instead of chopped.

To see photos and videos of this project as it unfolded, read the entries in the Chop Mountain Bike category.

{ 3 comments… read them below or add one }

1 pdxebiker June 29, 2010 at 8:02 pm

Turned out really nice, Dan! I think the handle behind the seat is genius born from experience – I’m constantly looking for the right place to lift up my ebike. Also, since this is similar to an xtracycle, could handlebars be added to that and the rear rack modified to make it into a kid-hauler?

Again, really nice turnout.

2 DanR June 29, 2010 at 10:10 pm

What would you have done differently with this layout?

3 Dan June 30, 2010 at 8:04 am

@pdxebiker – Thanks for the kind words. The handle is definitely handy. The sky’s the limit for possibilities with the rear cargo area. Handlebars, seats, stereo system, wet bar… I’ll explore more of this for future designs. I want to build a custom rack.

@DanR – Since this is a prototype there are several things I would change. The main one is the transition of the top tube through the rear extension is really rough. It needs a smoother line into the rear cargo area. Other changes would be to integrate the controller into the battery box and get it off the side, make the box smaller and lighter, custom rack…

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