The Trek Rail is one of the best e-bikes of all time, it’s been consistently great since its 2020 debut, won our e-bike of the year test back in 2021 and now there’s a new version out that comes with Bosch’s latest drive unit, the hottest motor in town. Spoiler alert, Danny’s tested the new Bosch CX motor and it’s excellent, you can read his full review now.

Trek Rail+ Gen 5

But there’s a lot more going on in the new bike than just its power train – Trek’s calling the new bike the Rail+ to tell it apart from the previous four iterations, meaning we’re onto the Gen 5 version now. There’s a bigger, lighter battery to complement the motor, travel has been increased, and Trek’s doubled down on the flip chip idea – there are now two to muck about with. Future classic? We’ll know soon when we get a review on it.

Trek says its Rail+ is for big days in the mountains, with the Slash+ for self shuttling and the EXe for trail riding

Trek Rail+ Gen 5 need to know

• Travel has increased 10mm to 160mm, with the same 160mm fork
• MX wheels are in, full 29in is out (except on size S which is 27.5in all round)
• New Bosch Performance CX motor and 800Wh battery
• More secure battery compartment, with extra security bolt for piece of mind
• Flip chips for geometry and now for the leverage curve too
• Prices start at £6,000 for the Rail+ 8, stop at £12,000
• Four frame sizes from S to XL, with bigger sizing too
• Still comes with a kickstand mount, perfect for trips to the shops

The new Bosch CX motor is smart, powerful and put to good use on the Rail+

New Bosch CX motor

The Rail+ isn’t the only eeb with the new motor, we know of at least five hot new e-bikes with the latest Bosch Performance CX motor, and there are more to come too. The Rail has a long history with Bosch though, with all five versions having uses the German brand’s best motor at the time.

The Fuel Exe is a lightweight eeb, while the new Rail+ packs in all the power and battery it can muster

At present there are three e-bikes on Trek’s books, and rather surprisingly two of them are lightweight or SL eebs. I say surprisingly, because full power e-bikes like the Rail+ outsell lightweight bikes by some way. The Rail+ is very much in the full power camp, the Bosch CX motor kicks out the same power as the old version – 85Nm torque – but the delivery and control of that is night and day better.

There’s also no more rattle in the new CX system, something that bugged us when descending without pedalling. You also get a more intelligent response with adjustable Extended Boost, simply by changing the way you kick the pedals. The motor is also smaller and lighter, with fewer mounting bolts giving more freedom to designers to position suspension elements.

Bosch CX battery options

Batteries are going big in 2025, the DJI-powered Amflow PL Carbon comes with an 800Wh battery, Giant’s already there with its Yamaha system, and more motor makers are going to follow too, watch this space. No surprise the Rail+ comes with an 800Wh option then.

The old Rail was notable for its side-entry battery, which wasn’t always the most secure on the market. For gen 5, Trek has moved the opening for the battery to the underside of the down tube, and it says the new Rib 2.0 is more secure and can be removed with an 6mm Allen key rather than an actual key. Taking a belt and braces approach, there’s also a secondary safety latch and an optional additional tension bolt for ‘extra aggressive terrain’.

The Bosch battery now clips in from underneath, rather than the gen 4 bike’s side entry

Extra battery power means extra weight… except not this time. With new, lighter, denser cells, the 800Wh battery is actually 400g lighter than the old 750Wh battery used in the Rail despite adding 7% extra range – I’m assuming that weight difference includes Trek’s old down tube side plate/cover. Longer rides can be accommodated by adding the Bosch PowerMore 250 range extender. That gives a potential capacity of 1,050Wh – more than enough for most riders.

Rail+ Travel and wheel sizes

The Rail+ is now a 160mm bike front and rear, much closer to the big hitting Slash+ than the lightweight Fuel EXe (170 and 140mm respectively). That’s a trend we’ve seen plenty of recently, the Santa Cruz Bronson and the Santa Cruz Hightower just went up to 150mm travel, Trek’s Slash went big last year to 170mm and it only seems to go one way. It makes sense on the Rail+ here, adding very little weight and potentially making the bike much more capable.

The previous bike had 150mm on the rear but in reality we only measured 140mm on the Trek Rail 9.7 we tested in 2023). So hopefully the new bike lives up to its latest claims. There’s been a big shake up in the wheel sizes, too, with a 27.5in rear wheel now replacing the old 29in hoop to give it an MX set-up. That should inject a bit of extra agility into what was a bike that never wanted for extra stability, as well as giving a bit of extra bum clearance with the additional travel.

More or less sag, the choice is yours. It also lets riders fit a coil shock and add in more progression

Double flip chips

The new Rail+ has two flip chips now, one for the geo and one for the suspension kinematics. As with most Treks, the Mino Link gives 0.5º of head angle / seat angle adjustment and 7mm of BB height tuning. Headline figures are 64º in the slackest setting with a 338mm BB height. Additional head angle adjustment can be made with drop-in headset cups. These give + or -1º from the stock setting and cups are available to buy separately.

A new feature on the gen 5 Rail+ is a leverage chip (introduced on bikes like the Fuel EX and Slash). This gives two progression rates – 19% and 24% – allowing riders to optimise their suspension for coil and air shocks, as well as terrain and riding style. Overall, both positions have a lower leverage rate than the gen 4 Rail.

Sizing… mind the gap

Other important points of note are a steeper seat angle, better dropper post insertion and there are six models available (plus one using the old frame). One model uses an Alpha Platinum Aluminium frame and the rest get the OCLV Mountain Carbon version. Four frame sizes are offered, but there’s a massive gap in reach between the Medium and Large (40mm), so I’m sure some some riders will end up falling through the gap in between these two sizes (S to M is 20mm and L to XL is 25mm). My hunch is that Trek originally wanted to fit a ‘tweener M/L size in here, but it’s a victim of recently announced cut backs at the brand, including a consolidation of SKUs (different model options).

Trek Rail+ gen 5 range and pricing

The 8 gets basic components, but the price is great and it still gets the 800Wh battery

Rail+ 8 £6,000 / €6,499

The entry level bike with the new CX motor is the Rail+ 8, although Trek does have a Rail 5 below this using the old system. The 8 is the only bike in the range with an alloy frame, made from Trek’s Alpha Platinum Aluminium it gets the same Boost 148 back end, 160mm travel Rib 2 battery housing and 800Wh battery. It comes with a RockShox ZEB Select fork with 160mm travel, Super Deluxe Select+ shock, Shimano Deore drivetrain, SRAM DB8 brakes, and Bontrager finishing kit, and Bonty wheels and tyres.

The frames go carbon from here on in, on the Rail+

Rail+ 9.7 £6,500 / €6,999

From here on in the bikes get OCLV Mountain Carbon frames, with the Rib removable 800Wh batteries. Pretty much everything else is the same as the 8, friom the brakes to the RockShox suspension, but the drivetrain goes up to SLX.

The Rail 9.8 is a proper rider’s choice, it gets great suspension (Fox Performance Elite or Zeb Ultimate)

Rail+ 9.8 (GX or XT) £7,750 / €8,499

For me this is the best value bike in the range. It comes in either SRAM GX and Fox, or Shimano XT and RockShox build, and both are really high end in terms of performance. On the Shimano bike you get XT brakes, a mix of e*thirteen and XT drivetrain, RockShox Zeb Ultimate fork and Super Deluxe Ultimate shock. On the SRAM build it’s a GX drivetrain, a Fox Performance Elite 38 fork and Fox Float X shock.

Wirless shifting and dropper post come with the 9.9 X0

Rail+ 9.9 X0 AXS £11,000 / €11,999

It gets posh from here on in, with electronic X0 AXS shifting, SRAM Code Silver brakes, Zeb ultimate Fork, Super Deluxe Ultimate shock, Reverb AXS dropper and Bontrager carbon rims.

The 9.9 XX gets the best of everything, including a XX drivetrain

Rail+ 9.9 XX AXS £12,000 / €12,999

Best of the best, the 9.9 uses SRAM’s 12speed XX AXS drivrtrain, and the rest of the spec is identical to that of the 9.9, which includes the new Bontrager Brevard RSL SE triple compound tyres.