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I have the remaining stock from Simpson, the bike company that was based on Orange County, CA. These are road disc frames in 56cm and 58cm sizes. These were designed in CA and produced in China and Taiwan.

Road disc framesets
Tapered steerer fork (1-1/8" to 1-1/2")
Integrated seat post
Internal cabling (mechanical or electronic), full length housing
160mm post mount front and 140mm post mount rear
Mechanical or hydraulic brakes
Quick-release front and rear (100mm and 135mm)
Black/clear coat finish
BB30 bottom bracket

Frameset package includes:
Full carbon frame
Full carbon, tapered steerer fork
Integrated headset
Fork compression plug
Front/rear derailleur hangers/mounts
Integrated seat post topper (see photo)

I built the first sample (see photo) after cutting the seat tube. This is a strong stiff frame with a nice smooth carbon ride and drivetrain stiffness. Photo shows 25mm tires mounted, and and I also mounted Conti Gatorksin 28s on standard rims with no problem.

$250 per frameset plus shipping via BikeFlights. 56cm and 58cm sizes available, see specs below. Seatpost cutting service available for an additional $20. See photo of seatmast with carbon topper installed after cutting seat tube. There is limited adjustability of the seatpost topper with this design. Either you cut the seat tube again to lower the saddle, or up to 10mm of rise can be gained by using a shim cut from ISP scrap.

Background info:

56cm geometry
Seat tube: 54cm c-t
Effective top tube: 56cm
Headtube length: 155mm
HT angle: 73 degrees
ST angle: 73.5 degrees
Chainstay length: 405mm
BB drop: 70mm
Front center: 595mm
Uncut seat tube: 760mm

58cm geometry
Seat tube: 56cm c-t
Effective top tube: 58cm
Headtube length: 175mm
HT angle: 73.5 degrees
ST angle: 73 degrees
Chainstay length: 407mm
BB drop: 70mm
Front center: 605mm
Uncut seat tube: 780mm
Stack: 579mm
Reach: 403mm