At Bike Connection Summer last week, Pete had a chance to swing a leg over a bike sporting the new, fully integrated SRAM Powertrain.
With the new SRAM Powertrain, you now get a full integrated ebike system with the motor, battery, AXS wireless tech and the T-type transmission.
When we saw the shift ramps on the new T-type SRAM transmission, our first though was it was the precursor to some sort of motor. Just like the UDH hanger was for the T-type transmissions. Smoother shifting under load doesn’t herald in a new species but the addition of somewhere between 85 and 90Nm of additional torque.
In any case, at Bike Connection last week, I met Moritz from SRAM who was on hand to run me through the details of the Powertrain and how it integrates with the T-type transmissions. It’s worth noting at this point that SRAM Powertrain is only available as OE (Original Equipment) kit though and not available aftermarket like the rest of the Eagle and AXS kit is. The brands that partnered with SRAM to develop and release Powertrain are Nukeproof, Transition, Propain and GasGas.
The Powertrain ingredients here are not that many as you might expect. You have the SRAM motor by Brose although with SRAM’s own specific software, either a 630 or 720Wh battery, the AXS Bridge Display which is you on-bike control unit and a 6-magnet speed ring. Those are the bare bones of the Powertrain. T-type AXS tech feeds off the main battery, and is directly connected to the motor by way of Auto Shift and Coast Shift.
Standard AXS pods allow you to control all this, and offer a considerable lack of clutter to the handlebars, especially when combined with an AXS Reverb dropper. Customisation is also available through the AXS app and some tweaks can be done through the control unit on the top tube.
Auto Shift is as straightforward as it sounds. The system shifts for you. Coast Shift shifts as you descend making sure you’re in a suitable gear for whatever’s next. All this is done by way of choosing your mode, seven of which are available within the two power settings, Range or Rally. Each of these modes is cadence-related and you can easily switch between them based on whatever is in front of you.
The motor offers a maximum 90Nm torque with a peak power of 680W. As stock, the motor will put out 85% assist in Rally and 30% in Range. This can be tweaked in the AXS app to offer the full 90Nm and 680W. SRAM claim they’ve achieved category-leading heat related derating too, the phenomenon whereby the motor emits less power as the system heats up.
With Moritz having brought me fully up to speed on the new system, we headed out for a lap of some of Andalo’s classics, with Moritz leading the way to help us make the most of what the kit could offer us. He suggested we leave it in Mid for now and adjust as we saw fit once we’d had a little more time on it.
A short, sharp spin up the road saw the bike do nothing… Moritz had said it would stay in a gear until it really had to shift, and a punchy set of singletrack switchbacks off the tarmac soon made that pretty obvious. Spat out onto the fire road at the top, I immediately grabbed for +2 (range being -3 to +3, Mid being… well, in the middle) to get the gears moving as I spun up. Then I immediately popped it back to Mid to bash along the fire road.
With my only other automatic shifting experience being with the Shimano system, that was my only baseline and I would have one precious day on that, against an afternoon on SRAM’s offering. The need to change between the cadence modes within the two power settings is where the two systems diverge.
Happier with which of the AXS pod buttons did what, after putting the dropper down, or up, a few times by accident, I could better pick the mode for the trail ahead. If I was being lazy, I could switch between Range and Rally to blip me up a section but that’s not really the idea here.
We opted to have a technical climbing challenge to see who could get up a short section of hiker’s path, and again, picking a cadence mode would determine chosen gearing for the short, punchy climb. This is where perhaps the system’s preference to hold a gear slightly longer, rather than shift when the power’s down comes into its own. You can maintain a cadence and keep heading up, rather than having the shift ruin your rhythm at a critical moment.
Elsewhere, I found that I could bypass the shifting by keeping my cadence consistent, this obviously requires more input from the rider and negates the point of auto shifting, but it’s a way of getting around changing your mode if you’re fully committed to using the Auto Shift function. That said, the shifter pods are there, and will do what you tell them to. Override will see the gears run as they would on any other bike, but after a few seconds of no shifting, it will return to automatic shifting. Auto Shift can indeed be turned off completely, if you want to be in full control.
On the downs, I found the Coast Shift to be mostly in a usable gear and didn’t have the dreaded steep down to steep up to contend with. This kind of trail scenario is the arch nemesis of these new auto shifting systems. Shifting is relatively quiet too, as is the motor. The X-Sync shift ramps do work and it certainly makes sense in an ebike context.
While automatic shifting isn’t something I would go for, preferring to shift for myself, the integration is, considering the amount of time spent on it, seamless, and the Auto and Coast shift works well. SRAM’s Powertrain is likely easier to get on and ride, than the Shimano system which requires more initial input to get it right. You will just have to be content with switching between modes and power outputs on the SRAM Powertrain.
Overall I’d struggle to find too much to fault with SRAM Powertrain. Setup was simple and I honed in on how to get it to work for me pretty quickly. How the T-type transmission holds up to the rigours of 90Nm torque is something that would require more than an afternoon of ride time so I can’t speak for reliability. The nice think about the belt-driven motor is the duller whirr compared to the higher pitched whine of other motors. That I can definitely get behind.
