Meet the BMC Trailfox AMP. As the name suggests, it’s based on the much lauded Trailfox enduro bike, with added electrical assistance.
Like the original Trailfox, it has 150mm travel at each end via BMC’s short-link APS suspension design. The Trailfox AMP’s extra oomph is provided by a Shimano Steps E-8000 motor, along with a 504 Wh battery pack that slots into the down tube of the carbon front / alloy rear frame.
It rolls on 650b+ tyres and is offered in three spec levels. The cheapest model will retail for a not-exactly-cheap €6,999, but that’s small change compared to the flagship model — and we’d suggest sitting down for this — which retails for €11,999.
Yep, that’s right. It’s a lot. In Switzerland, you could almost buy a watch for that.
Now, if you haven’t fallen off your chair and are still reading, let’s get down to some of the tech details.
BMC was keen to point out that it increased the width of the linkages by 60 percent and increased the bearing diameter by 27 percent compared to the original Trailfox in a bid to increase rear-end stiffness.
Meanwhile, the down tube features what BMC is calling its “Twin Hollow-core tube Design”. Basically, the down tube is U-shaped in cross-section in order to allow the battery pack to slot in and out.
This compromises the stiffness of the tube, but BMC says it has got around this by adding a pair of hollow D-shaped tubes either side of the battery pack to boost the stiffness to weight ratio.
The AMP’s geometry is remarkably similar to the original Trailfox. It’s got a relatively short rear-centre for an e-bike at 445mm. As far as I can tell, that’s the shortest of any full-sus e-bike. I’ll come back to whether or not that’s actually a good thing later.
The bottom bracket, while slightly higher than the original Trailfox, remains reassuringly low at 338mm. I checked both of these measurements with a tape measure and BMC wasn’t fibbing.
The head angle and seat angle are both fairly conservative at 66 degrees and at 74 degrees respectively. BMC only offers three sizes: Small, Medium and Large.
Sizing it up
Now, at 6’3” tall, I would normally ride an XL frame, and even then prefer bikes on the longer side. So my size-large test bike was not ideal. Still, the Large is roomier than many, with a claimed reach of 469mm.
Along with a 50mm stem, 780mm bar, this made for a comfy cockpit that would suit someone around or just under the six-foot mark.
I immediately put the bars to their maximum height on the steerer. This makes it easier to pick up the front end, which is a blessing on an e-bike. I had no problem holding manuals after making this change, and even bunny hopping is possible, if hard work, and despite a weight figure that’s north of 22kg.
A question of balance
Those 445mm chainstays may be short for an e-bike, but combined with the big battery pack up front, they’re long enough to keep the weight nicely balanced front-to-rear. This means the bike turns really nicely, with plenty of front-end traction and a surprisingly agile feel.
I’m a big advocate of long chainstays on long bikes, but other e-bikes, such as Focus’ Jam2 and Giant's Full-E, have a long back-end, combined with a short front-centre. This results in awkward handling on steep descents and tight corners. The BMC feels far more balanced front to rear and as a result, it corners more predictably and confidently than any other e-bike I’ve ridden.
The relatively short back-end did make me wonder if keeping the front end down on steep climbs would become an issue as this can be a real problem with e-bikes. I asked if BMC had considered steepening the seat angle to compensate for the wheelie-effect and BMC said it simply didn’t feel the need.
As for me, when climbing fairly steep, prolonged gradients, the extra power and smoother delivery of the motor meant this was simply not as much of an issue as I expected, especially after I shunted my saddle fully forwards on its rails.
However, on the kind of really steep pinch climbs where an e-bike excels, I feel it would benefit from being steeper still to eliminate the need to sit on the saddle’s nose.
Power play
The Shimano Steps motor continued to impress on the BMC. Its smooth, predictable power delivery makes low-traction climbs far more manageable than the slightly delayed yet sudden torque of competitor motors from Bosch, Brose and Yamaha.
The power delivery is predictable and subtle enough for me to hold a wheelie with the assistance on. This is not something I can say about the Yamaha/Giant motor on the Giant Full-E.
The Steps has less grunt at low revs, but benefits from spinning at a slightly higher cadence than normal to get the maximum power out of it. The Shimano motor is like a revvy two-stroke engine: it’s not got much low-end grunt, but the power keeps coming at higher cadences.
Shimano’s Di2 gearing makes shifting under load a little easier, but I’m not convinced it’s completely necessary even with an e-bike. The default setting for the shifter sees the outboard paddle shift down and the inboard one shift up. Pretty much everyone at the press camp found this counter-intuitive. It’s relatively simple to swap this round though using Shimano’s Di2 app.
The Saint brakes were very welcome, though. I usually find its lever feel grabby and inconsistent, but the sheer power and ability to shrug off heat was a gift when riding this 22kg vehicle down an Alp.
Suspension setup
As we discovered when we strapped lead weights to bikes — check out this video for more on that experiment — adding sprung mass (weight that is held up by the suspension) to a bike makes the ride far smoother and the suspension feel far more sensitive. This means that e-bikes – which inevitably have loads of sprung weight – track the ground superbly well.
The Trailfox Amp is no exception. The suspension needed to be set up harder than usual (I ran 110psi in the Fox 36 fork and around 25 percent sag in the shock), yet it soaks up bumps and keeps traction remarkably well. The way it deals with bumps is uncanny at first.
This makes the Cane Creek shock seem rather an odd choice; the suspension feels so good right off the bat, there’s little need to fiddle with the four-way adjustability the shock offers. In fact, out of 12 journalists at the press camp, I think I was the only one to get an Allen key out on the trail to adjust settings.
The lockout lever is also pretty unnecessary when you have electrical assistance. A far simpler shock with a fairly firm stock tune – such as the Fox DPS fitted to the cheaper models – would probably be a better choice, as a simple tool-free rebound dial is all that’s necessary, and this makes it easier for the end user to set the bike up correctly.
While I felt little need to adjust the shock’s damping settings, it did need more volume spacers to match the progression of the fork. Most of the damping adjustments I made were an attempt to compensate for this imbalance.
The top-end model I rode comes with carbon fibre wheels – which are a little unnecessary on an e-bike - and they also have an internal width of only 30mm. My tyres were squirming a lot in the corners, despite running 22psi front / 24psi rear, and I suspect wider rims would help with this a little. Thankfully, cheaper models use 35mm internal alloy rims.
Tyre trouble
The tyres are another questionable spec choice. The Maxxis Rekon+ 2.8” rear tyre comes up very narrow for a ‘plus’ tyre, hence the high pressures used. It’s also puncture-prone and is a little lacking in grip.
Unlike normal bikes, e-bikes arguably have more need of traction on the rear than the front, due to the massive power going through the rear wheel. I’d rather see something grippier, wider and tougher out back.
While the expensive spec on the top-level bike is almost silly, the cheaper models appear to have a far more sensible parts package. I only got to ride the top model, but I’d conjecture the simpler dampers, mechanical gears and alloy rims on these models wouldn’t adversely affect the ride. That’s a good thing too, as the ride of the top bike is pretty impressive.
I'd prefer it if it was a little longer and slacker, but thanks to a geometry that’s well-balanced, along with the suspension-flattering benefits of an e-bike, the ride is smooth, agile and confidence inspiring. It’s not perfect, and the top model is outrageously expensive, but this could just be one of the best riding e-bikes currently on the market.
