Anatomy of a Race Bicycle
A PistonBikes.com Build
1st Place - April 7th 2012 Grange Race - 2 Stroke Class
1st Place - June 16th 2012 BairdCo Racing Series - 2 Stroke Class
This is our own PistonBikes.com latest race bicycle.
It started as a Micargi Huntington. We chose the Huntington because it was the largest cruiser frame and seemed the most solid bike to build on. We wanted to extend the length of the bike by cutting the seat post and welding a new post further back. This not only puts the rider in a more hunched over position, but strengthened the frame with the brace to hold the post.
The Fork and Bars
The decision to go with a thread less adjustable triple tree fork was to add a disk brake to the front and give use the ability to lower the front end as much as we wanted. Looking for a comfortable bar we stayed with our BMX theme and went with The Shadow Conspiracy Vultus bars held by a Shadow Attack steam.
On this build we were going to go 24" wheels wrapped in Maxxis Hookworm tires. Sealed bearing hubs with a solid 3/8 axel are a tall order, but have used the Surly new disk hub in the past and is still our favorite hub (since writing this they have been discontinued, hopefully a new version will be available soon). Drawing from the world of BMX choosing the Odyssey Hazzard Lite rims for their light weight and triple wall strength was an easy pick. Hubs and rims were drilled out to run 12 gauge spokes.
Great stopping was a must for this build. Using 160mm Avid BB5 mechanical brakes is what makes this bike stop on a dime. Both brakes are controlled by a dual brake lever. We made custom brake and throttle cables using lined cable housing. One obsitical of adding the disk brake to the rear was to make room for the drive gear, disk rotor and caliper.
Using a Surly 135mm rear Hub with disk 6 bolt pattern we bolted up the kingssalesandservice.com 40 tooth sprocket for a 410 chain with a Top Hat for the disk.
The engine was completely torn down, balanced and match ported. This was the first motor to get the designed exclusively for us DDR Stage 2 Head. From our first time at Death race in Tucson we were battling the motor getting over 400 degrees and performing poorly. DDR designed us a higher compression head with massive cooling fins to beat the heat. Bike now does not get over 370 degrees. We used my carb of choice the SHA clone and ran a #74 jet. To spark this beast we used the Jaguar adjustable CDI (formerly the Wolf Pack). Added a boost bottle for throttle response connected to a Manic Mechanic strait intake. Finally to let it breath determined the FMF expansion chamber to be the best choice. Pipe was heavily cut, twisted and modified to fit.
With over 40 hours of welding and assembly ( Thanks Rodney) this build was a labor of love and another attempt to push the little china girl as far as she can go. She walked away from the competition at the April 7th 2012 Grange race, and will update this page with stats as the race season gets underway.