Turns up the trail-riding buzz
BMC Speedfox AMP Two need to know
- Shimano STEPS E-8000 Motor and E-8020 battery pack deliver smooth pedal assistance
- BMC’s APS suspension boasts 130mm travel via a Fox Float DPS Performance series shock.
- Travel is matched up front with a 130mm RockShox Revelation RC suspension fork
It’s easy to make the connection between AMP and electric current; after all there’s a 13amp fuse in the plug that connects the battery pack on the Speedfox AMP to the mains when you run out of juice.
For BMC though, AMP is actually short for amplification, probably the most apt term to date for describe the experience on any pedal-assist mountain bike. Climb higher, ride faster… you get the picture.
With BMC’s APS twin-link suspension design delivering 130mm travel, the Speedfox AMP has a lot in common with the regular Speedfox. Both have 29in wheels and both are out and out trail bikes. The key differences being the compact Shimano STEPS 8000 motor and integrated battery pack.
If the oversized down tube housing the battery looks familiar, that’s probably because you’ve seen it before; the Speedfox AMP sharing the same carbon front end with BMC’s first e-mtb, the Trailfox AMP.
By using a shorter stroke shock with the same eye-to-eye length as the 150mm travel Trailfox AMP, BMC is able to reduce travel to 130mm. It then produces a dedicated rear end to correct the geometry for the bigger 29in wheels. The Speedfox AMP One, Two and Three all get alloy rear triangles, but the Limited version get as carbon rear end that’s 700g lighter than the carbon Trailfox swingarm.
BMC claims that the Speedfox AMP has the same anti-squat characteristics as the Trailfox AMP, but all things being equal this isn’t actually possible. When I pulled them up on this at the launch at Bike Connection in Italy, BMC was already one step ahead. Because the Speedfox AMP has 29in wheels and the Trailfox AMP is rolling on smaller 27.5 Plus wheels, you’re always going to use a lower gear on the 29er, which changes the chain angle and corrects the discrepancy. Very cleaver.
Even though all four models in the Speedfox AMP range come with 29in wheels, the frames and forks are 100 pre cent compatible with 27.5 Plus wheels. With the super muddy conditions we experienced in Italy however, the 29er wheels with 2.35in Maxxis Forecaster tyres helped slice though the clag to find traction, where Plus size tyre would be floating on the surface. The bigger wheels and thinner tyres also meant the frame and fork clogged less, keeping the wheels tuning more easily and putting less drain on the battery. It wasn’t all rosy though, as the harder 3C MaxxSpeed rubber pinged off rooks and roots so you’d swap from maximum traction to zero traction in the blink of an eye.
To get a feel for the BMC I did repeated laps to of the same climb with different descents, and while I was super impressed with overall handing of the Speedfox AMP Two I noticed that as the battery level indicator went down I couldn’t climb as fast, even though I was in the same power mode and trying every bit as hard.
Initially I though it was something in the software, a built in failsafe designed to prolong battery life. I’ve experienced it on Bosch and Brose equipped e-bikes too, but with a bit of digging I discovered it’s just an inherent characteristic of batteries, they become less efficient at delivering power as they drain. Pretty much like the rider on a normal bike then!
I really liked the combination of the mechanical XT gears with the Shimano STEPS motor, but once again I struggled to get my head around Shimano’s Fire Bolt shifter for toggling through the power modes – often reducing the assistance right before a punchy climb. So if there were one thing I’d change on the BMC Speedfox AMP Two straightaway, I’d swap the Thunder Bolt shifter for the basic switch unit that offers all of the came functionality in a more compact design that’s easier to use.