Top Fuel 9.8 GX AXS Gen 4
Trek
Trail
Top Fuel 9.8 GX AXS Gen 4 is a carbon trail mountain bike (2025), from Trek, part of the Top Fuel family. This bike is aimed at riders who want a more active, performance-leaning off-road feel, with a setup that gives you a sporty, active riding position, and is well suited to natural trails and mixed off-road terrain. Its profile is strongest in areas like strong climbing friendliness for sustained uphill riding, a balanced ride feel between comfort and directness, and balanced, versatile speed for everyday riding. Relative to category specialists, the trade-off is a value score that depends more on priorities than pure price efficiency. Compare this bike on MatchBikes.com to similar trail models.
Rating

Score Summary
Performance
Built for speed and efficiency
Fit
Dialed-in Fit & Comfort
Value
Specifications
General
Frame
Drivetrain
Wheels
Brakes
Cockpit
Seat
Geometry
| Measurement | SM High | SM Low | MD High | MD Low | MD/LG High | MD/LG Low | LG High | LG Low | XL High | XL Low |
|---|---|---|---|---|---|---|---|---|---|---|
| Stack Reach Ratio | 1.341 mm | 1.367 mm | 1.325 mm | 1.349 mm | 1.293 mm | 1.314 mm | 1.261 mm | 1.283 mm | 1.223 mm | 1.243 mm |
| Bottom Bracket Height | 345 mm | 339 mm | 348 mm | 342 mm | 348 mm | 342 mm | 348 mm | 342 mm | 348 mm | 342 mm |
| Front Center | 716 mm | 716 mm | 755 mm | 755 mm | 772 mm | 772 mm | 789 mm | 789 mm | 827 mm | 828 mm |
| Rake | 41 mm | 43 mm | 42 mm | 43 mm | 42 mm | 43 mm | 42 mm | 43 mm | 42 mm | 43 mm |
| Trail | 111 mm | 115 mm | 121 mm | 125 mm | 121 mm | 125 mm | 121 mm | 125 mm | 121 mm | 125 mm |
| Stack | 566 mm | 570 mm | 599 mm | 603 mm | 604 mm | 607 mm | 608 mm | 612 mm | 626 mm | 630 mm |
| Reach | 422 mm | 417 mm | 452 mm | 447 mm | 467 mm | 462 mm | 482 mm | 477 mm | 512 mm | 507 mm |
| Top Tube Length | 558 mm | 559 mm | 587 mm | 588 mm | 611 mm | 612 mm | 630 mm | 631 mm | 672 mm | 673 mm |
| Seat Tube Angle | 76.5 ° | 76 ° | 77.3 ° | 76.9 ° | 76.6 ° | 76.2 ° | 76.3 ° | 75.9 ° | 75.6 ° | 75.2 ° |
| Seat Tube Length | 360 mm | 360 mm | 410 mm | 410 mm | 420 mm | 420 mm | 435 mm | 435 mm | 470 mm | 470 mm |
| Head Tube Angle | 65.9 ° | 65.5 ° | 65.9 ° | 65.5 ° | 65.9 ° | 65.5 ° | 65.9 ° | 65.5 ° | 65.9 ° | 65.5 ° |
| Head Tube Length | 105 mm | 105 mm | 105 mm | 105 mm | 110 mm | 110 mm | 115 mm | 115 mm | 135 mm | 135 mm |
| Chainstay Length | 434 mm | 435 mm | 434 mm | 435 mm | 439 mm | 440 mm | 439 mm | 440 mm | 444 mm | 445 mm |
| Wheelbase | 1150 mm | 1151 mm | 1188 mm | 1188 mm | 1210 mm | 1210 mm | 1227 mm | 1227 mm | 1270 mm | 1271 mm |
| Bottom Bracket Drop | 10 mm | 16 mm | 26 mm | 32 mm | 26 mm | 32 mm | 26 mm | 32 mm | 26 mm | 32 mm |
| Standover Height | 705 mm | 700 | 755 mm | 750 mm | 757 mm | 752 mm | 758 mm | 753 mm | 763 mm | 758 mm |
| Wheels | 27" | 27" | 29" | 29" | 29" | 29" | 29" | 29" | 29" | 29" |
| Rider Min Height | 155 cm | 155 cm | 164 cm | 164 cm | 173 cm | 173 cm | 177 cm | 177 cm | 187 cm | 187 cm |
| Rider Max Height | 166 cm | 166 cm | 176 cm | 176 cm | 180 cm | 180 cm | 189 cm | 189 cm | 195 cm | 195 cm |




























































