TOP FUEL 8 GEN 4 IS A NIMBLE ALLOY TRAIL BIKE THAT STRIKES A BALANCE BETWEEN QUICK CLIMBING EFFICIENCY AND DESCENDING CONFIDENCE. IT PACKS IN A VERSATILE 130MM FRONT AND 120MM REAR TRAVEL FOR RIPPING OVER ROCKS AND ROOTS WITHOUT SACRIFICING POWER ON ASCENTS. IT'S BUILT FROM LIGHTWEIGHT ALPHA PLATINUM ALUMINUM THAT HELPS SAVE YOUR BUDGET FOR BIKE TRIPS, BUT PACKS IN UPGRADES WHERE THEY MATTER, LIKE A 12-SPEED SHIMANO XT AND SLX DRIVETRAIN, AND A FOX RHYTHM 34 FORK.
OVERVIEW
It's right for you if...
You want an alloy full suspension that's ready to rip. You like to ride everything from cross-country hot laps to all-mountain adventures, and you need a bike that's light, versatile, and confident. You've got an appreciation for the durability of aluminum, but want upgrades where they matter, like your drivetrain and suspension.
The tech you get
An Alpha Platinum Aluminum frame equipped with a 4-way Mino Link lower shock mount for tweaking geometry and suspension leverage rate. A 130mm FOX Rhythm 34 fork with Float EVOL air spring and GRIP damper, plus 120mm of rear travel from a FOX Performance Float shock with a 3-position damper. It's topped off with a Shimano XT/SLX 12-speed groupset, hydraulic disc brakes, a Bontrager Line dropper post, and Tubeless Ready Bontrager Line Comp 30 wheels.
The final word
Top Fuel 8 Gen 4 is ready to cut loose from all-day climbs to rooty descents. It balances capability and efficiency, with just enough travel to keep the ride smooth without eating up your pedaling power. It gives you the perfect blend of affordability, with a rugged alloy frame, and upgrades where they matter, like the Shimano XT/SLX drivetrain.
SPECS
| Frameset | |
| Frame |
Alpha Platinum Aluminum, internal storage, tapered head tube, internal guided routing, downtube guard, alloy rocker link, 4-way Mino Link, ABP, Boost148, 120mm travel
|
| Fork |
Fox Rhythm 34, Float EVOL air spring, GRIP damper, tapered steerer, 44mm offset, Boost110, 15mm Kabolt axle, 130mm travel
|
| Shock | Fox Performance Float DPS, 2-position damper, 185mm x 50mm |
| Max compatible fork travel | 140mm |
| Wheels | |
|
*Wheel front
|
Size: S Bontrager Line Comp 30, Tubeless Ready, 6-bolt, Boost110, 15mm thru axle, 27.5'' |
|
Size: M, ML, L, XL Bontrager Line Comp 30, Tubeless Ready, 6-bolt, Boost110, 15mm thru axle, 29'' |
|
|
*Wheel rear
|
Size: S
Bontrager Line Comp 30, High Strength 6000 Series Aluminum rim, Tubeless Ready, Rapid Drive 108, 6-bolt, Shimano MicroSpline freehub, Boost148, 12mm thru axle, 27.5'' |
|
Size: M, ML, L, XL
Bontrager Line Comp 30, High Strength 6000 Series Aluminum rim, Tubeless Ready, Rapid Drive 108, 6-bolt, Shimano MicroSpline freehub, Boost148, 12mm thru axle, 29'' |
|
| Skewer rear | Bontrager Switch thru axle, removable lever |
|
*Tire
|
Size: S Bontrager Gunnison Pro XR, Tubeless Ready, wire bead, 60 tpi, 27.5x2.40'' |
| Size: M, ML, L, XL Bontrager Gunnison Pro XR, Tubeless Ready, dual compound, aramid bead, 60 tpi, 29x2.40'' |
|
| Tire part | Bontrager TLR sealant, 6oz |
| Max tire size | Frame: 29x2.50", Fork: See manufacturer |
| Drivetrain | |
| Shifter | Shimano XT M8100, 12 speed |
| Rear derailleur | Shimano XT M8100, long cage |
| Crank | Shimano Deore M6120, 30T ring, 55mm chainline, 170mm length |
| Bottom bracket | Shimano BB-MT501 BSA |
| Cassette | Shimano SLX M7100, 10-51T, 12 speed |
| Chain | Shimano SLX M7100, 12 speed |
| Max chainring size | 1x: 34T, min 30T |
| Components | |
| Saddle | Bontrager Verse P3, chromoly rails |
|
*Seatpost
|
Size: S Bontrager Line Dropper, 100mm travel, MaxFlow, internal routing, 34.9mm, 310mm length |
| Size: M, ML, L, XL Bontrager Line Dropper, 170mm travel, MaxFlow, internal routing, 34.9mm, 450mm length |
|
| Handlebar | Bontrager Line, alloy, 35mm, 27.5mm rise, 780mm width |
| Grips | Bontrager XR Trail Comp, nylon lock-on |
| Stem | Bontrager Elite, 35mm, 0 degree, 45mm length |
| Brake | Shimano 4-piston hydraulic disc, M6100 lever, M6120 caliper |
| Brake rotor | Shimano RT66, 6-bolt, 180mm |
| Rotor size | Max brake rotor sizes - Frame: 200mm, min 180mm, Fork: see fork manufacturer |
| Accessories | |
| Bag | Bontrager BITS Internal Frame Storage Bag |
| Weight | |
| Weight | M - 14.58 kg / 32.15 lbs (with TLR sealant, no tubes) |
| Weight limit |
This bike has a maximum total weight limit (combined weight of bicycle, rider, and cargo) of 300 pounds (136 kg).
|
SIZING GUIDE AND GEOMETRY
| Frame size letter | S | S | M | M | ML | ML | L | L | XL | XL |
| Geometry position | High | Low | High | Low | High | Low | High | Low | High | Low |
| Wheel size | 27.5" | 27.5" | 29" | 29" | 29" | 29" | 29" | 29" | 29" | 29" |
| A — Seat tube | 36 | 36 | 41 | 41 | 42 | 42 | 43.5 | 43.5 | 47 | 47 |
| B — Seat tube angle | 69.5° | 69.0° | 70.5° | 70.0° | 70.5° | 70.0° | 70.5° | 70.0° | 70.5° | 70.0° |
| Effective seat tube angle | 76.5° | 76.0° | 77.3° | 76.9° | 76.6° | 76.2° | 76.3° | 75.9° | 75.6° | 75.2° |
| C — Head tube length | 10.5 | 10.5 | 10.5 | 10.5 | 11 | 11 | 11.5 | 11.5 | 13.5 | 13.5 |
| D — Head angle | 65.9° | 65.5° | 65.9° | 65.5° | 65.9° | 65.5° | 65.9° | 65.5° | 65.9° | 65.5° |
| E — Effective top tube | 55.8 | 55.9 | 58.7 | 58.8 | 61.1 | 61.2 | 63 | 63.1 | 67.2 | 67.3 |
| G — Bottom bracket drop | 1 | 1.6 | 2.6 | 3.2 | 2.6 | 3.2 | 2.6 | 3.2 | 2.6 | 3.2 |
| H — Chainstay length | 43.4 | 43.5 | 43.4 | 43.5 | 43.9 | 44 | 43.9 | 44 | 44.4 | 44.5 |
| I — Offset | 4.3 | 4.3 | 4.3 | 4.3 | 4.3 | 4.3 | 4.3 | 4.3 | 4.3 | 4.3 |
| J — Trail | 11.1 | 11.5 | 12.1 | 12.5 | 12.1 | 12.5 | 12.1 | 12.5 | 12.1 | 12.5 |
| K — Wheelbase | 115 | 115.1 | 118.8 | 118.8 | 121 | 121 | 122.7 | 122.7 | 127 | 127.1 |
| L — Standover | 70.5 | 70 | 75.5 | 75 | 75.5 | 75 | 76 | 75.5 | 76.5 | 76 |
| M — Frame reach | 42.2 | 41.7 | 45.2 | 44.7 | 46.7 | 46.2 | 48.2 | 47.7 | 51.2 | 50.7 |
| N — Frame stack | 56.6 | 57 | 59.9 | 60.3 | 60.4 | 60.7 | 60.8 | 61.2 | 62.6 | 63 |
All measurements provided in cm unless otherwise noted.