{"id":66713,"date":"2024-07-11T17:00:00","date_gmt":"2024-07-11T15:00:00","guid":{"rendered":"http:\/\/228b8d23-8f7d-47a7-9ae9-a19e73d6084b"},"modified":"2024-07-11T17:25:32","modified_gmt":"2024-07-11T15:25:32","slug":"2025-trek-top-fuel-gen-4-targets-refinement-rather-than-revolution-starting-at-2500","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/cyclingplus\/rss_feed\/2025-trek-top-fuel-gen-4-targets-refinement-rather-than-revolution-starting-at-2500\/","title":{"rendered":"2025 Trek Top Fuel Gen 4 targets refinement rather than revolution \u2013 starting at \u00a32,500"},"content":{"rendered":"

Geometry updates, suspension kinematic tweaks and mixed-wheel compatibility extend Top Fuel\u2019s remit <\/p>

By Alex Evans\n <\/p>

Published: Thursday, 11 July 2024 at 15:00 PM<\/p>

\n\n

Trek has extended the on-trail behaviour of its popular all-rounder the Top Fuel, with subtle geometry and suspension updates for 2025.<\/p>

Also refined \u2013 rather than redesigned \u2013\u00a0are its internal frame storage compartment and door, while shock compatibility is broadened for a wider (120mm to 130mm) travel band.<\/p>

All stock models run 29in wheels<\/a> front and rear,\u00a0except for the small, which uses 27.5in hoops. But Trek\u2019s Mino Link means fans of mixed wheels<\/a> (29in front, 27.5in rear) can give the Top Fuel a more shred-ready setup.<\/p>

Standout geometry figures include a 65.5-degree head tube angle, a 76-degree seat tube angle and size-specific chainstays, from 435mm to 445mm.<\/p>

The seven-bike range spans both alloy and carbon frame<\/a> constructions, with the most affordable Top Fuel 5 costing \u00a32,500 \/ $2,699.99 and the top-end Top Fuel 9.9 XX AXS going for a whopping \u00a310,000 \/ $10,499.99.<\/p>

Better storage and a lighter frame<\/h2>
The frame storage door and aperture have been updated. – Trek<\/figcaption><\/figure>

Trek claims both the alloy and carbon fibre versions of the new Top Fuel Gen 4 have lost 220g compared to their outgoing versions.<\/p>

Claimed full-bike weights start at 15.9kg for the medium Top Fuel 5 and drop more than 2kg to 12.85kg for the medium range-topping 9.9.<\/p>

We tested the previous-generation Top Fuel 8<\/a> as part of 2022\u2019s Bike of the Year and it tipped our scales at 14.8kg (size large, without pedals).<\/p>

The 2025 Top Fuel 8, in a medium, is claimed to weigh 14.58kg, a saving of \u2013\u00a0and there are no prizes for guessing \u2013\u00a0220g!<\/p>

Trek says it has saved weight by redesigning its tubes with \u201csmaller profiles and softer edges\u201d and by reducing stiffness.<\/p>

According to the brand, this reduces mass and \u201cimproves the ride quality of the bike\u201d, making it \u201cmore balanced and forgiving than the Gen 3\u201d.<\/p>

The integrated down tube storage and its access door have also been redesigned.<\/p>

The door now has a tighter seal and a bigger opening, so water is less likely to get in, and sliding stashed items in and out will be easier.<\/p>

Trek also says gear, dropper and brake cables \u2013 which route via the down tube \u2013 are better protected to avoid snagging with the supplied BITS bags.<\/p>

And those bags have also been overhauled.<\/p>

Carbon fibre frames get two bags; a padded tool bag and a second, unpadded bag for tubes, both made from a ripstop material. Alloy frames only get one redesigned BITS bag.<\/p>

Details matter<\/h2>
\"Trek
It’s a downcountry bike with intent. – Trek<\/figcaption><\/figure>

Gear, dropper and brake cables are routed via ports on the side of the down tube \u2013\u00a0instead of through the headset \u2013\u00a0which no longer gets Trek’s signature Knock Block design.<\/p>

The 2025 Top Fuel\u2019s bars can be rotated through 360 degrees, if that\u2019s your bag.<\/p>

Dropper post insertion has also been improved, so longer-travel posts can be fitted.<\/p>

SRAM\u2019s Universal Derailleur Hanger<\/a>\/Full Mount dropout is of course fitted and specced.<\/p>

All frame sizes have a single water bottle mount on the frame’s internal storage door. The size small can fit a 620ml bottle, while the medium and above have space for a 760ml bottle.<\/p>

Upping travel and progression<\/h2>
\"Trek
The Top Fuel’s Mino Link now has four adjustment positions. – Trek<\/figcaption><\/figure>

Thanks to two additional positions on the lower shock mount Mino Link flip chip, the Top Fuel\u2019s suspension kinematics can be tuned.<\/p>

According to Trek, the forward position is 14 per cent progressive, while the rear position is 19 per cent progressive.<\/p>

In the more progressive position, the leverage rate starts higher than the less progressive setting, but at full travel both settings terminate at roughly the same ratio.<\/p>

This means the more progressive position will have a softer, more supple starting stroke compared to the less progressive setting, but both ramp up towards the end of their travel to provide similar bottom-out resistance.<\/p>

The less progressive setting will ramp up more gradually, because the leverage rate doesn’t change as quickly or as much.<\/p>

Anti-squat \u2013\u00a0how much the bike resists pedal bob \u2013\u00a0has been increased slightly compared to the old model, now sitting just above 100 per cent at full travel.<\/p>

The Gen 4\u2019s frame travel remains unchanged at 120mm, but the latest Top Fuel is compatible with a longer-stroke shock. Up the stock 180x50mm shock to a 180x55mm version and travel is increased to 130mm.<\/p>

It\u2019s the same story for the fork. The Stock 130mm fork can be switched to a 140mm model for a more shred-ready frame.<\/p>

The mixed-wheel setup requires a 140mm-travel fork and for the Mino Link to be set in its high position.<\/p>

You can also down-fork the Top Fuel to a 120mm version, potentially making it ready for XC racing<\/a>.<\/p>

Geometry tweaks<\/h2>
\"Trek
You can change the fork and switch to a mullet setup for increased downhill performance. – Trek<\/figcaption><\/figure>

Although the longer, slacker, lower trend<\/a> is still ongoing, the rate of progress has been abated as geometry figures converge on an increasingly unified sweet spot.<\/p>

But this means brands are focusing their efforts on other areas to refine rather than revolutionise handling.<\/p>

The 2025 Top Fuel Gen 4 is a great example of this.<\/p>

Its head angle is either 65 or 65.9 degrees, depending on the Mino Link\u2019s high or low positioning, while the seat tube angle is around 76 degrees for both settings.<\/p>

Reach figures in the five-size line-up (small to extra-large) start at 417mm and rise to 507mm.<\/p>

Fitting a 27.5in rear wheel and 140mm fork slackens the head angle to 64.6 degrees and the seat tube to 75 degrees.<\/p>

<\/colgroup>
\ufeffSize<\/th>Small<\/th>Medium<\/th>Medium-long<\/th>Large<\/th>Extra-large<\/th><\/tr><\/thead>
Reach (mm)<\/td>417<\/td>447<\/td>462<\/td>477<\/td>407<\/td> <\/tr>
Stack (mm)<\/td>570<\/td>603<\/td>607<\/td>612<\/td>630<\/td> <\/tr>
Bottom bracket height low\/high (mm)<\/td>342\/348<\/td>345\/351<\/td>345\/351<\/td>345\/351<\/td>345\/351<\/td> <\/tr>
Seat tube angle low\/high (degrees)<\/td>76\/76.5<\/td>76.9\/77.3<\/td>76.2\/76.6<\/td>75.9\/76.3<\/td>75.2\/75.6<\/td> <\/tr>
Head tube angle low\/high (degrees)<\/td>65.5\/65.9<\/td>65.5\/65.9<\/td>65.5\/65.9<\/td>65.5\/65.9<\/td>65.5\/65.9<\/td> <\/tr>
Wheelbase (mm)<\/td>1151<\/td>1188<\/td>1210<\/td>1227<\/td>1271<\/td> <\/tr>
Chainstay length (mm)<\/td>435<\/td>435<\/td>440<\/td>440<\/td>445<\/td> <\/tr> <\/tbody> <\/table>