Bernie Mikkelsen

building frames since 1974

inventor of the "Pro Sizer"

sizing bicycle, and the "Pro Fit" sizer


Area Served


Northern California

Located at the Grand Marina in Alameda

Ten miles East of San Francisco as the crow flies

I have been building the "new" sloping top tube frame geomrtry for well over a decade
I built my own tandem frame jig from a turn of the century S.F.Chronicle cast iron type setting table

What Makes Me Different

We make bicycle frames using steel only

  We blend Reynolds, Columbus, True Temper,

Dedacciai, and Tange tubing to tune the ride

I created several types of sizers

for duplicating any size, or geometry bicycle frame for riding tests

Unlike other sizing devices

mine has a front wheel so that it can actually be ridden outside

Stationary sizing devices provide no handling feedback

Why guess?

Test ride along the bay with a view of San Francisco

All you need is a few test rides

with some readjustments

to find your best position on the bicycle

There is nothing else like it

Steel bicyle frames

Any configuration

Any size

Custom geometry every time

Why compromise?

Custom paint and powdercoating



Tandem (Road or Mountain)


Time Trial


Single Speed


Custom Forks

TIG welded, Fillet Brazed, or Classic Lugged

Frame Repairs

Braze Ons

(dimensional reproductions of any existing frame)

Build Kits Available With Frames


An e mail from a customer:



        A couple saturdays a ago, I did 107 miles and 5,000 vertical with my brother on an organized

ride in Fresno. 

   Thanks to the frame rebuild you did to my bike, I was much more comfortable.

   Thanks also for the referal to your friend at Pleasant Hill Cyclery (Eric).

   They were able to order a  seatpost with 1" setback on it, which enables me to flatten out a bit

more over the bike.

  I am finally at a point where I am perfectly comfortable on the bike - like wearing comfortable but

supportive athletic shoes.

   Keep up the good work!

      Dan Bergmann

Dan's Bicycle