The Strummer Unbound CF frameset is designed to deliver maximum performance on smooth roads (tarmac) and gravel. It is made 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 provides more clearance for larger chainrings. The monocoque manufacturing 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 comfort on gravel routes.
Frame-only option, fork not included.
Strummer Unbound CF Frame Specifications
Compatible Seatpost: 27.2 mm Round Shape, Internal-cable Dropper Post Compatible.
Carbon Material: T700.
Maximum Tire Clearance: 700c, Fork Width 45 mm (Front), Frame Width 50 mm (Rear).
Headset Size: Fully Integrated 44/52 Diameter
Bottom Bracket Compatibility: Pressfit 41 mm, Recommended to Use Strummer Press Threaded BB
Cable Routing: All Frame & Fork Cables Routed Internally
Weight: Fork with Internal Cable Routing and 12x100 Front Thru Axle (530 grams), Frame Components & 12x142 Thru Axle (74 grams), Headset 170 grams, Frame Only ST490/ST520 (1040/1090 grams). Total Weight ST490/ST520 (1814/1864 grams).
Note: Due to the handmade manufacturing process of the carbon frame and fork, weight may vary between products.
Strummer Unbound CF Fork Specifications
Weight (Including 6 Bolts & Thru Axle): 530 grams (Internal Cable Routing), 530 grams (External Cable Routing). Weight will be lower after cutting the steerer tube to the required length.
Material: Toray T700 Carbon Fiber
Compatible Tire Size: Maximum 700c (Max Width 45 mm, Road Tires, Tire Tread May Affect Clearance)
Braking System: Disc Brake (Flat Mount)
Compatible Hub Size: 12x100 mm (Thru Axle)
Thru Axle: 125 mm Total Length, P1.5 (11 mm)
Steerer Tube Diameter: 28.6 mm, 39.8 mm at the Tapered Bottom
Additional Mounts: 3 Bolts on Each Side (64 mm Bolt Spacing, Bottle Cage Standard)
Strummer Unbound CF Geometry
| Specifications | 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 |
Height ranges overlap because size selection also depends on inseam, torso and arm length, flexibility, and desired riding position.
Prioritize inseam length and standover clearance. As a guide, leave about 20–30 mm between your crotch and the top tube when standing over the bike.
If your height falls within an overlapping range:
-
Choose a smaller size for a lower position and more agile handling.
-
Choose a larger size for a higher front-end position and a more stable ride.
Stem size, crank length, handlebar width, number of spacers, and saddle position can also affect comfort and riding position.
Examples of Bikes/Frames Compatible with the Strummer Unbound CF Fork (Taper)
Strummer Unbound CF Gravel Carbon Frameset (2024)
Polygon Bend R2 (2024)
B2B Information (for Dealers)
Contents per box: 1 pc
Unbound Fork on 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 it can be installed on your bike, have it inspected at your nearest dealer.
Package Contents
Package contents depend on the option purchased. Check the selected variant and package contents before buying; the frame-only option does not include a fork.
Surly Midnight Special
The compatibility of the Unbound fork with the Surly Midnight Special should be checked first. Match the steerer/headset, axle, brake mount, axle-to-crown, offset, and tire clearance. We recommend having it inspected in person at your nearest dealer before installation.
Unbound Fork for Marin Nicasio 1
A dealer should check whether the Unbound fork is compatible with the Marin Nicasio 1. Make sure the frame supports a tapered steerer, has a compatible headset, a 12×100 mm front hub, flat-mount brakes, and sufficient clearance and compatible fork geometry.
Installing the Unbound fork on another frame
Match the steerer, crown race, steerer length, axle, brake mount, wheel size, tire clearance, and fork geometry to the frame. To ensure the Unbound fork can be installed on another frame, have a dealer inspect it.
Compatible spare parts
| SKU | Product name | Link |
|---|---|---|
| CLAMP-00039 | Strummer Traverse CF2 / Unbound CF Seat Clamp | View product |
Do you have any questions about the product?
If any product information is unclear, please contact Strummer using the Support form. The review field is for sharing your experience using the product.
