First thing we noticed about the TRP G-Spec E-MTB Disc Brake is it bedded in way quicker than the old Gwin brake. A few hard stops and it was biting.
As its name suggests, the TRP G-Spec E-MTB disc brake is designed explicitly for e-bikes. Why? Well, typically e-bikes weigh around 8-10kg more than regular trail bikes, so once that juggernaut gets trucking, stopping it can be tricky. Which is why most come fitted with 200 or 203mm rotors front and rear. The bigger rotor offers more power and better heat dissipation, so the brake doesn’t fade when you need it most. Obviously, some manufacturers don’t think this is enough, which is why 220mm rotors have started to appear.
TRP’s idea to make the best mountain bike disc brakes for E-MTBs is to offer a big disc but also a thicker one with its G-Spec E-MTB brake – this has gone up from 1.8 to 2.3mm. Since there’s more metal, it’s a bigger heat sink, and it also shouldn’t warp as easily, which can happen to thinner discs.
I’d like to say TRP has increased the pad/ piston spacing to accommodate the extra thickness but I don’t think it has, or by that much. TRP brakes always had a lot of pad clearance – it’s what I liked about them – but I noticed a little bit of rubbing with the new rotor and getting it centred was a little trickier. Either way, once the pads had bedded in, rubbing wasn’t a problem.
The four-piston Evo caliper is pretty similar in size and shape to the one used for the G-Spec Gwin brake, apart from the surface finish, which is now smooth rather than ribbed. It has lightweight hybrid pistons, contains sintered metallic pads, which are top loading, so can be replaced easily. These are also held in place by a chunky fixing bolt with a 3mm Allen head and kept apart by a stiff spring – small details, but they make a difference.
With its wide blade and square body, the brake lever also shares a lot of the same architecture. There’s no contact adjustment, but it does have a big indexed dial to adjust the reach – no faffing about with a long ball-end Allen key here. And if you don’t like it, it’s only held on with a tiny grub screw.
There are two 2.3mm rotors available for the G-Spec E-MTB – a floating design with a stainless steel braking surface attached to a lightweight aluminium carrier for about £55 (205g) and a regular stainless steel, six-bolt option for about £35 (266g). Both rotors are available in 190, 203 and 220mm sizes.
A couple of little things – the brake doesn’t come as a single unit, so you have to put the lever and caliper together yourself. This means you need a bleed kit, but both parts are filled with fluid and it does allow you to trim the hose to any length required. You don’t get fork/frame adapters either – they cost around £8-10 depending on the size, but I’m OK with this because more modern suspension forks are direct mount and why pay for a part you’re unlikely to use? You do have to pay extra for a SRAM-compatible Matchmaker HD 3.5 Adapter though. That lets you tether the shifter, and possibly a dropper remote, to the underside of the brake lever.
The TRP G-Spec E-MTB disc brake has a touch more modulation too, but still feels quite solid compared to a SRAM or Shimano brake. Some testers described this as wooden, but I got used to the slight on/off feeling pretty quickly. Next to the Magura MT-55 this replaced, it doesn’t have as much progression, but it feels way more solid at the lever, so there’s none of the flex when you’re deep into the stroke, and I reckon it’s harder wearing too.
When you factor in the cost of the rotors, the TRP G-Spec E-MTB is a similar price to a four-piston Shimano XT unit. It doesn’t feel quite as refined, but it’s way more consistent. It’s also easier to bleed, the metal pad seems to last, even in wet weather and it’s powerful. It’s fit and forget; everything you want from an e-bike brake then.