Doug's HiRoad Cruzbike

I enjoyed building and riding my first Cruzbike. As a matter of fact, tweaking and testing the Cruzbike concept has become a new hobby for me. I'm really getting into making changes and measuring the results, to the point where it might never really be "finished".

The first bike performed really well. I had some steep goals for the Hardtail bike, and most of them were realized, but some were not.

The original project objectives were: Big skinny wheels front and rear - FWD "hiracer". Weight target 25 lbs. Seating approximating Bacchetta/Volae "superman" position. Better climbing than my R40.

So what did I get, and what did I learn?

Firstly, I definately hit my climbing goal. The bike climbs like a mountain goat, and the ability to add the arms and shoulders into the climbing "powertrain" really makes a difference. Based on the gear combination I use to climb hills on the Cruzbike, versus climbing the same hills on my R40, the Cruzbike appears to be at least 12% better at hill-climbing. I hope to confirm this with a little more quantitative test soon.

Secondly, the "superman" seating position worked well and was (is) very comfortable, but the handlebar arrangement in front of the knees made the bike harder to learn, and reduced my ability to add my arms to the pedal force. They also moved the center of gravity too far back. Once I moved the seat forward and went to a handlebar that had essentially no "tiller", things improved markedly.

Thirdly, I didn't even get close to the weight goal. Because I switched to a Toys R Us steel frame to get out of some initial build problems (the LeTour frame had some adaptation issues), the bike ended up weighing 47 lbs. Makes the climbing results all the more amazing to me. The relatively heavy front suspension fork had springs intended for a somewhat "trimmer" rider, and they stayed bottomed-out when I rode, so they were essentially dead weight.

I ended up with a bike I absolutely loved, but the design has so much more potential, as a tinkerer I just can't leave it at that.

Enter the Cruzbike HiRoad.

Job one: Cut the weight.

Job two: Ditch the front suspension.

Job three: Fit 700c wheels.

Job four: Develop an alternative, light-weight suspension.

I've developed a nasty Ebay habit, and I've been quite interested in the potential of modifying a "Softride" bike frame into a Cruzbike. Softride builds triathalon bikes in aluminum, and they use a carbon-fiber beam to suspend the seat independent of the rest of the bike. The arrangement is quite lightweight, and the frame design offers a lot of latitude in placing a Cruzbike-type seat in a relatively low and forward position. When I found a Softride "Powerwing MTB" frame on Ebay, I bought it.

The frame weighs 4 lbs. (weighed on a certified shipping scale this time; no more bathroom-scale-based weight claims for me!)

Mocked-up with the intended wheels, Cruzbike kit, and hardshell seat, it looks like this:

HiRoadMockup

The first engineering jobs are to mount a rear brake and set-up the front seat mount.

This photo shows the rear brake solution for 700c wheels in the 26" Softride frame. I mounted a Nashbar "Jailbrake" rear caliper in the "bridge" tube between the chainstays by enlarging an existing hole in the bridge. A recessed caliper nut holds it on. This is a "short reach" caliper, and it borders on being too short. A "standard reach" caliper would have more adjustment.

DBHiroadRBrake

Below are photos of the "finished" bike. The steer tube will be shortened 2", and the canti pivots will be replaced by plugs. I'm also replacing the silly silver cable jackets and tightening the cable runs to clean up the look.

DBHiroad2006a

DBHiroad2006b

DBHiroad2006c

More pics and ride test data will be coming soon!

Doug, 30 January 2006

DB54c9

DB20b1

DBdbec

hiroad1

hiroad2