The Strummer Unbound CF Frameset is designed to deliver maximum performance on smooth roads (tarmac) and gravel. It is manufactured with Toray T700 and designed with a shape that provides extra strength.
The asymmetrical chainstay design increases stiffness on the drive side, improves stability on the non-drive side, and increases clearance for larger chainrings. The monocoque frame production process for the front and rear sections makes this frame more precise and stiff.
The top tube is designed with a vibration dampening zone that absorbs vibrations, providing a comfortable feel when riding gravel routes.
Frame Only variant; fork not included.
Strummer Unbound CF Frame Specifications
Compatible Seatpost: 27.2 mm round shape; an internally routed dropper post can be used.
Carbon Material: T700.
Maximum Tire Clearance: 700c, Fork Width 45 mm (Front), Frame Width 50 mm (Rear).
Headset Size: Fully integrated 44/52 mm diameter
Bottom Bracket Compatibility: Pressfit 41 mm; recommended to use the threaded Strummer Press BB
Cable Routing: All frame and fork cable routing is internal
Weight: Fork with internal cable routing and 12x100 front thru axle (530 grams), frame components and 12x142 thru axle (74 grams), headset 170 grams, Frame Only ST490/ST520 (1040/1090 grams). Total Weight ST490/ST520 (1814/1864 grams).
Note: Because the Carbon Frame and Fork are handmade, weight may vary between individual products.
Strummer Unbound CF Fork Specifications
Weight (including 6 bolts & thru axle): 530 grams (internal cable routing), 530 grams (external cable routing). The weight will be lower after cutting the steerer tube to the required length.
Material: Toray T700 carbon fiber
Compatible Tire Size: Maximum 700c (Maximum width 45 mm, road-type tires; tire tread can affect clearance)
Braking System: Disc Brake (Flat Mount)
Compatible Hub Size: 12x100 mm (Thru Axle)
Thru Axle: Total length 125 mm, P1.5 (11 mm)
Steerer Tube Diameter: 28.6 mm, 39.8 mm at the lower tapered section
Additional Mounts: 3 bolts on each side (64 mm bolt spacing, standard bottle cage)
Strummer Unbound CF Geometry
| Specification | 490 | 520 | 550 |
|---|---|---|---|
| Seatpost Insertion Length | 180 mm | 220 mm | 250 mm |
| Reach | 374,1 mm | 377,5 mm | 386 mm |
| Effective Top Tube Length | 535 mm | 550 mm | 575 mm |
| Stack | 542,6 mm | 563,4 mm | 598,6 mm |
| Wheelbase | 1.008,9 mm | 1.014,5 mm | 1.029,6 mm |
| Chainstay Length | 430 mm | 430 mm | 430 mm |
| Front Center | 593,8 mm | 599,4 mm | 614,5 mm |
| Bottom Bracket Drop | 70 mm | 70 mm | 70 mm |
| Bottom Bracket Height | 285 mm | 285 mm | 285 mm |
| Seat Tube Angle | 73,5° | 73° | 72,5° |
| Head Tube Angle | 71° | 71,5° | 72° |
| Seat Tube Length | 490 mm | 520 mm | 550 mm |
| Head Tube Length | 120 mm | 140 mm | 175 mm |
| Standover Height with 700 × 50c | 776,4 mm | 793,4 mm | 833,4 mm |
| Standover Height with 650B × 2,1 inches | 766,4 mm | 783,4 mm | 823,4 mm |
| Fork Rake / Offset | 50 mm | 50 mm | 50 mm |
| Axle-to-Crown | 399 mm | 399 mm | 399 mm |
| Trail | 69,3 mm | 66,1 mm | 62,7 mm |
Size Selection Guide
| Size | Recommended Rider Height | Estimated Minimum Inseam |
|---|---|---|
| 490 / Small | 165–174 cm | Approximately 79 cm |
| 520 / Medium | 172–180 cm | Approximately 81 cm |
| 550 / Large | 180–186 cm | Approximately 85 cm |
The height ranges overlap because size selection is also influenced by inseam, torso and arm length, body flexibility, and the desired riding position.
Prioritize inseam length and standover clearance. As a guide, leave approximately 20–30 mm between your crotch and the top tube when standing over the bike.
If your height falls within an overlapping range:
-
Choose the smaller size for a lower position and more agile handling.
-
Choose the larger size for a higher front-end position and more stable riding characteristics.
Stem size, crank length, handlebar width, number of spacers, and saddle position can also affect comfort and riding position.
Example Bikes/Frames Compatible with the Strummer Unbound CF (Taper) Fork
Strummer Unbound CF Gravel Carbon Frameset (2024)
Polygon Bend R2 (2024)
B2B Information (for Dealers)
Contents per box: 1 piece
Unbound Fork on the Java Wahoo 2026
The Unbound Fork can be used if the bike supports a tapered fork. Match the headset/crown race, 12×100 mm front thru-axle hub, flat-mount brakes, and fork geometry. To ensure installation on your bike, have it inspected at your nearest dealer.
Package Contents
Package contents depend on the option purchased. Check the variant and package contents before buying; the frame-only option does not include the fork.
Surly Midnight Special
Compatibility between the Unbound Fork and the Surly Midnight Special must be checked first. Match the steerer/headset, axle, brake mount, axle-to-crown, offset, and tire clearance. We recommend having it inspected at your nearest dealer before installation.
Unbound Fork for the Marin Nicasio 1
Compatibility of the Unbound Fork with the Marin Nicasio 1 must be checked by a dealer. Ensure that the frame supports a tapered steerer, the headset is compatible, the front hub is 12×100 mm, the brakes are flat mount, and the fork clearance and geometry are suitable.
Installing the Unbound Fork on Another Frame
Match the steerer, crown race, steerer length, axle, brake mount, wheel size, tire clearance, and fork geometry with the frame. To ensure installation of the Unbound Fork on another frame, request a dealer inspection.
