
FSA Gossamer SB20 Seatpost Black, 31.6mm, 350mm
Replacement option
Velopedia Bicycle Archive
Original specifications: geometry for 4 published sizes.
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At a glance
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2026 archived details
Clues, not proof of model year. Colors vary and components may have been replaced.
| Frame Construction | ABSOLUT Al V4ALLOY 6061, Triple Butted (T4, T6) |
|---|---|
| Frame Material | Aluminum |
| Fork | MARZOCCHI Bomber DJ, 100 mm15 x 100 mm, 37 mm offset |
| Crankset | PROWHEEL, 165 mm, BSA BB, AlloyChainring: PROWHEEL, 28T, Alloy, Black |
|---|---|
| Chain | KMC Z182 links |
| Pedals | No |
| Brakes | SRAM Level T, BlackRotors: TEKTRO TR 160-52, 160 mm, Bolts |
|---|
| Headset | ACROS ZS44/56Sealed bearings with alloy cup |
|---|---|
| Handlebar | BURGTEC RIDE HIGH ALLOY800 mm width, 38 mm Rise |
| Stem | BURGTEC Enduro MK3 4040 mm |
| Saddle | BURGTEC Cloud Boost |
| Seatpost | Ride ALPHA31.6 mm, 250 mm |
| Hubs | Included with wheelset |
|---|---|
| Rims | DT Swiss D190032H, 26" |
| Front Tire | SCHWALBE Billy Bonkers26" x 2.30 |
| Rear Tire | SCHWALBE Billy Bonkers26" x 2.30 |
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Frame measurements by size.
Frame diagram
Select an available measurement to locate it on the frame.
| Measurement | 24 | S | M | L |
|---|---|---|---|---|
| Seat tube | 270 mm | 310 mm | 310 mm | 310 mm |
| Effective top tube | 516 mm | 577 mm | 597 mm | 622 mm |
| Head tube | 115 mm | 120 mm | 120 mm | 120 mm |
| Head-tube angle | 69° | 69° | 69° | 69° |
| Seat-tube angle | 72.5° | 72° | 72° | 72° |
| Chainstay / rear center | 365 mm | 390 mm | 390 mm | 390 mm |
| Wheelbase | 972 mm | 1037 mm | 1057 mm | 1082 mm |
| Bottom-bracket drop | 8 mm | 25 mm | 25 mm | 25 mm |
| Reach | 360 mm | 395 mm | 415 mm | 440 mm |
| Stack | 527 mm | 566 mm | 566 mm | 566 mm |
| Fork length / axle-to-crown | 460 mm | 470 mm | 470 mm | 470 mm |
Dimensions as recorded.
Original gearing is incomplete. Enter your setup to calculate ratios and cadence speeds.
Your changes apply to this calculation. The archived build stays unchanged.
| Measure | Original | Your setup |
|---|---|---|
| Lowest ratio | — | — |
| Highest ratio | — | — |
| Total range | — | — |
| Lowest-gear speed | — | — |
| Highest-gear speed | — | — |
Speeds are estimates. These calculations do not establish component compatibility or available tire clearance.
Parts & serviceability
250 mm

Replacement option
26"
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Archived specifications for reference. Check the fitted parts before ordering.
Checks selected from the archived equipment. Confirm what is fitted today. This is not a complete safety inspection; use the full inspection guide before test riding.
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Archived: Frame: ABSOLUT Al V4ALLOY 6061, Triple Butted (T4, T6) · Fork: MARZOCCHI Bomber DJ, 100 mm15 x 100 mm, 37 mm offset
Archived: Fork: MARZOCCHI Bomber DJ, 100 mm15 x 100 mm, 37 mm offset
Archived: Crankset: PROWHEEL, 165 mm, BSA BB, AlloyChainring: PROWHEEL, 28T, Alloy, Black · Chain: KMC Z182 links
Archived: Brakes: SRAM Level T, BlackRotors: TEKTRO TR 160-52, 160 mm, Bolts
Archived: Rims: DT SWISS D190032H, 26" · Hubs: Included with wheelset · Front tire: SCHWALBE Billy Bonkers26" x 2.30 · Rear tire: SCHWALBE Billy Bonkers26" x 2.30
Archived: Headset: ACROS ZS44/56Sealed bearings with alloy cup · Handlebar: BURGTEC RIDE HIGH ALLOY800 mm width, 38 mm Rise · Stem: BURGTEC Enduro MK3 4040 mm · Seatpost: RIDE ALPHA31.6 mm, 250 mm · Saddle: BURGTEC Cloud Boost · Pedals: No
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Specifications are presented as a reference. Components may vary by market, size, production run, or later manufacturer revisions.