The brake hierarchy is really split up into two groups, with SRAM and Shimano seeing the lion's share of spec across the board and the leftovers fought over by four or five less common names. TRP is - or maybe was - a minor player, even among that second group, but their signing of Aaron Gwin went a long way towards changing that.
Essentially the high-performance arm of Tektro, TRP had their Quadiem SL's on Gwin's bike at the beginning of last year's World Cup season, but it wasn't long until he showed up with a set of brakes tailor-made to his liking. TRP says that those four-piston brakes are exactly what you see reviewed here: the $199.99 USD (sans rotor) G-Spec Quadiem.
G-Spec Quadiem Details
• Intended use: all-mountain / downhill
• Mineral oil system
• Four-piston caliper
• Ceramic/steel pistons
• CNC two-piece caliper
• Tool-free indexed reach adjust
• Polished, anodized finish
• Weight: 317-grams (front, w/o rotor and hardware)
• MSRP: $199.99 USD (without rotor)
When I first took the G-Spec brake out of the box, I briefly thought that someone at TRP had accidentally sent me some sort of motorbike setup. Shimano and SRAM's four-piston calipers look downright shapely compared to the comparatively massive TRP block that sees cooling fins machined into its roof. Inside, it's home to a set of ceramic and steel hybrid pistons that are said to shave 30-grams over the steel pistons that were used on the standard Quadiem, although both models now employ these ceramic and steel hybrid pucks.
Up top, you'll find an equally solid looking master cylinder and lever blade, as well as a hinged clamp that's tightened down by a 4mm hex bolt. That small black dial behind the lever is there for you to adjust how far away it sits from the handlebar, and it's indexed to keep it from backing in or out during use. Unlike high-end offerings from some other brands, there is no second dial to tweak the G-Spec's bite point, with TRP going with a simpler setup instead.
The lever itself is relatively tall and has a pronounced hook to it and, apparently, Gwin wanted a dimpled, textured surface for a bit of extra traction for his digits. That means that we also a get dimpled, textured surface; Gwin is the 'G' in G-Spec, after all. All of the above is finished up with a hand polishing and anodizing to give it a shiny enough look that it might attract a few crows while you're out on your ride. Here's a hot tip for you: it's that finish that's actually the only difference between the $199.99 USD G-Spec brake and the less flashy, $149 USD standard Quadiem SL
Like some other brakes on the market, the G-Spec's ship with a set of semi-metallic pads ($19.99 USD on TRP's website) installed, something that I always find a bit odd given that four-piston stoppers should equal all the bite and all the power. TRP also offers metallic pads ($24.99 USD on TRP's website), but you'll need to buy them separately from the brake itself, and it's no secret that Shimano's four-piston pads are the exact same shape and fit perfectly. Mineral oil pushes those pads down onto the rotor, so you won't melt the paint off your bike or contribute to killing a bunch of dolphins as you might with DOT fluid.
Rotors range in price from $29.99 USD to $59.99 USD, so factor that into the G-Spec's $199.99 USD, and they're available in all the sizes, as well as both six-bolt and Centerlock mounting. TRP also sells a load of small parts on their website, so if you're handy and prefer to fix things yourself, you can probably order what you need instead of taking the brake to a shop.
The G-Specs have seen approximately a zillion miles of use, including the BC Bikes Race, shuttle laps, and even some time in the Whistler Bike Park on a short-travel rig, and I've come away from that with two notable talking points. First, they've been impressively consistent during that time; second, they offer a remarkable amount of feel and modulation, especially for a four-piston brake intended for downhill use.
TRP sells the G-Spec with semi-metallic pads, so while that's rarely my preference of stopping material, that's how I ran them for the first few months. In this stock setup, there's less initial bite and overall power than I expected, but it's still more than reasonable enough when it comes time to drop anchor. A bleed and line shortening later and they felt the same, which was certainly less outright stopping force than a four-piston Code or Saint offering but, more importantly, with so much modulation that it was like the neurons in my brain were acting on the G-Spec's ceramic and hybrid steel pistons rather than my two pointer fingers.
They were that good, and remarkably impressive when traction was a guessing game. But, considering that these are four-piston brakes made for downhill use, power wasn't as high as I expected, so in went a set of TRP's metallic pads.
As you'd assume, the change in pad material bumped the brake's outright power up to where it belongs, which will be enough for pretty much anyone, but the more interesting bit is that the full-metallic friction material didn't do much to dampen the modulation. If I had to pick one word to describe the G-Spec brake, it'd have to be 'control,' with the shiny silver brake offering a huge amount of it, especially compared to Shimano's four-piston offerings.
With full metallic pads, which is how most riders will run them, their initial bite feels gentle, yet it's not because the friction and power aren't there. It's a bit like that initial lever pressure is just the pads whispering to the rotor, ''Hey, let's just take a chill pill and avoid a needless lock-up, alright?'' And that's exactly what happens, too, unless you want to lay down a big skid for shits and giggles, of course. The great modulation is a real boon in those low traction settings, which pretty much sums up my entire summer riding season that saw about as much moisture as my stomach sees vegetables.
Locking your wheel (or wheels) up is always good fun, but the quickest way to ride a trail is often just on that fine edge between breaking traction and not braking enough, which is where the G-Specs shine brighter than any other brake I've used.
So, there's more feel to this brake than watching 'Marley & Me' by yourself on a Saturday night, but outright stopping power doesn't seem quite as high as a four-piston setup from SRAM, and especially Shimano's Saint system. I'm not a huge guy, so I've never felt the need for 200mm rotors, even on a downhill rig while on long, steep trails, but I'd want to bump up to the largest size rotors if I was using the G-Spec brakes in that type of setting on a regular basis. They're not short on power, mind you, and they easily trump any two-piston system, but they just never had that massive, train stopping type of authority that a Code or Saint anchor does.
TRP vs Everyone
Well, not literally everyone, but let's talk more about how the high-end TRP stoppers compare against the likes of SRAM, Shimano, and a few others.
Modulation: I've long believed that Magura and SRAM own this one and that Shimano's brakes have a lot in common with a light switch when it comes to power delivery. The G-Spec Quadiem's could take the crown, however, especially when it comes to four-piston control. TRP's brakes have a gentle initial bite, both with semi-metallic and metallic pads, and power that ramps up from there in a controllable way without ever feeling like someone's jammed a golf club through your spokes. This type of thing is especially important when the ground is wet or exceptionally dry and slippery, and those are the type of settings where it's clear the G-Spec Quadiems win this one.
Consistency: I've gone through two sets of the stock semi-metallic pads and one set of metallic pads since I bolted the G-Spec Quadiems to my bike, and not a single reliability concern has come up. Lever feel will change slightly when the pads become excessively worn (I'll have to talk to my mechanic about why he's so lazy...), but there has been zero pumping up when descents are long, and all eight pistons are still moving freely and evenly. The one bleed that I did perform was really only to see how difficult the job was (it wasn't), and in a time when brake reliability has gotten worse rather than better, it's interesting to see a name that a lot of riders would consider as a "budget brand" turn out to be very dependable.
Ergonomics / Design: With no bite point adjustment, a feature that I'm a big fan of, the G-Specs can't ever win this one, at least in my mind. So while I didn't have an issue where the TRP brakes engage, I would have definitely tinkered with it if I had the option to do so. On the flip side, the missing adjustment probably does make for a more reliable design. Also, the robust master cylinder perch and huge lever blade aren't really my cup of tea - they look bulky and like they belong dirt bike - but the shape of the lever does feel good. The long blade also means that there's plenty of real estate for your other controls to be wherever you need them.