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This is a concept bike that I'm trying out. 650c wheels and disc brakes on a fixed gear drive. Designed more for slow speed manuverability and safety than full speed road handling.





  • Down Tube - 1.250 - True Temper HOXPLAT06, 680mm, .7/.4/.7, 89/51/392/38/110
  • Top Tube - 1.000 - Nova CRTT 858, 600mm, .8/.5/.8, 60/51/381/38/90
  • Seat Tube - NOVA CMST 460, External Butt Seat Tube, 28.6/30.0 X 460
  • Chain Stay, Drive - Dedacciai COM12.5 Road 24mm Chainstay (CXCS_OVST_410), 16/30 OVAL, Straight, [1]
  • Chain Stay, Non-drive - Dedacciai COM12.5 Road 24mm Chainstay (CXCS_OVST_410), 16/30 OVAL, Straight, [2]
  • Seat Stays - Dedacciai AMSS_16ST .7, 16mm to 10.5mm, 560mm, 0.7mm wall
  • Bottom Bracket - Phil Wood 1/2 pitch EBB
  • Dropouts - PVD Designed IF Dropouts
  • Braze-ons - Pacenti Hydro
  • Headtube - PVD Design

PVD 650c Disc Fork

  • 340 axel to crown
  • 35mm offset
  • Paragon thin disc tab, cut and mounted for 140mm rotor
  • True Temper Versus MSRDLT 28.6mm, 1.65/1.14 Steerer
  • True Temper Platnum HOXPLAT-CS4 27.6x20, .76/.56 Oval Blades
  • 1.000"x0.035" struts @ 45 degrees
  • Special Alpha Q Star Nut
  • Generic 9mm Dropouts w/ Safety tabs
  • PVD crown race seat

PVD 'Rise' Stem

  • 140mm @ 49 Degree
  • 1.250x0.035 tube, custom bent
  • 1.125 Steerer Clamp
  • 1.250 Split Handlebar Clamp

650c 16 spoke wheels

This is an experiment. 16 spokes on a 32 hole hub/rim. The spokes were going to be configured in a paired configuration, but after some discussions with one of the most notorious wheelbuilders in the country, the dicision was made not to. Gravy said that without a special drilling on both the rim and hub the rim would snake. Not good. A skip spoke pattern, he assured me, would stay true. I may still be too heavy for the wheels, but at least the wheel can make it onto the bike.

As any wheelbuilder knows, the goal of a cross spoke pattern is to have the spkes at maximum tangency to the hub flanges. This reduces the wind up the wheel suffers under the induced torque from driving and braking. For most hubs and rims, a 4 cross pattern is the closest to this limit that can be acheived. Sizing the spokes for 32 4-cross is the same as 16 2-cross, so that gives an idea how the wheel will come together. I will be using butted 2mm spokes and the new DT hex nipples to handle the increased tension in the system.


I want to keep my rear cog between 16 and 18 while starting with 200-225 inches of developement. That means I'm going to have to use chainrings in the 42 to 53 inch range. I'm really not sure about my gearing since I did all of my past fixed gear riding in Boston. I think that I was running 47/16 on 700x25c. That's 244 inches. San Fracisco/Marin is a very different animal that will require a very different gear.

I'll first try 45x16 for 215 inches of development.


Crank and Chainline

The 135mm Surley Fixed/Disc hub has a chainline of 52mm. This is very close to the chainline of the outer ring on a double crank. That is about 49mm. If I add a 2mm spacer to both sides of the BB, that should work fine. The outer ring on a triple crankset would come out just about perfect, but then the pedals would be out 4mm farther.


Urban... hummm.

Parts Spec