Custom Bike Frames

Hand built in Portland, Oregon our tough, versatile aluminum frames can be set up with a wide range of drivetrain and cockpit types to form the foundation for a gravel-ready all-road build, a functional and fun internally geared belt drive city bike or even a minimalist yet iconic single-speed. Our modular assembly process gives you infinite flexibility for personalizing your frame with color and component choices and the precision machined surfaces will turn heads wherever you go.


Standard Fit or Short Reach Geometry
Dropouts, Cable Guides, Stops and Bottle Bosses

We’ll work with you to design your frame from digital sketch to custom colors and graphics. Colors are applied before frame assembly, giving you a wide range of personalized expressions.

Each frame is built with unparalleled dimensional accuracy.

Our build process balances machine precision with fine craftsmanship.

Our machined Thru-Axle dropout option is a perfect complement to the high-tolerance requirements of flat mount hydraulic disc brakes.

Every surface of our precision-machined lugs are thoughtfully considered to balance form, function and process.

Our horizontal dropout option is a great solution for single-speeds, internally geared hubs and Gates belt drives. They’re spaced precisely at 132.5mm for enhanced versatility.

All of our frames are hand-built in Portland, Oregon.

The precision-machined CIRCA 5AX-BB bottom bracket is as beautiful as it is practical, with an unyielding attention to detail balanced by the no-hassles functionality English threading.

Have a story you want to tell? Our custom laser graphics and design services can make it happen.

Anodized Finish Options for 2024. CIRCA’s durable, weatherproof anodized finishes are tougher and lighter than paint. Our proprietary construction process gives you the ability to map accent colors to individual elements of the frame with limitless possibilities.


  • Light, tough, smooth-riding 6061 aluminum tubing.
  • Durable, weatherproof anodized finishes stay beautiful with minimal care.
  • Standard or Short Reach geometries.
  • Stock and custom laser graphics packages available.
  • Can be outfitted to be anything from a Gravel-ready AllRoad to a stealthy belt-drive commuter.
  • Plenty of fender clearance for foul-weather riding.
  • Versatile design lets you choose your drivetrain type (internal vs. derailleur vs. single speed) as well as your bar type (drop, flat, etc.)
  • Gates Carbon Belt Drive compatible (when paired with horizontal dropout option). 
  • Sloped top-tube reduces standover height and is comfortable for all genders.

Additional Details:

Seatpost: 31.6mm

Bottom Bracket: 68mm, threaded, standard English

Fork & Headset: Tapered IS41/28.6 IS52/40 

Dropout Options: 12mm Thru Axle or Horizontal

Horizontal Rear Dropout Spacing: 132.5mm (allows wide range of drivetrain options)

Thru Axle Rear Spacing: 142mm

Max Tire Widths: 38c for 700c. 40c for 650b.

Pricing: Starting at $2,300. Please inquire for the specifics of your build.

Geometry: Two Fit Options

Standard and Short-Reach

For sizing and to optimize the fit of your CIRCA, we offer 2 geometry types: Standard and Short-Reach. We think of it as Quick Custom. There’s no extra charge for either option.

Our Standard geometry works for about 90% of riders with typical proportions. The Short-Reach variation pulls in the cockpit a little to accommodate riders with shorter torsos or who may want a more upright position.

Standard Geometry

Best for riders with typical proportions who have no problems fitting stock geometries.

Short Reach Geometry

Riders who have long legs compared to their overall height (and a shorter torso) may prefer the fit of our Short Reach geometries. This fit can also suit riders who want a more upright position.




Contact us to discuss your build and fit requirements. If you’re in Portland, we can arrange a personal design session.



We’ll work together to refine the details of your build, from fit to component selection, colors, finishes and laser etching



Your bike or frame will be built to order in Portland, Oregon and can either be picked up in-person or we’ll ship it to you.

We're here to help!

If you have any questions or are ready to get yourself on a CIRCA, please submit a contact form.