High performance racing bicycle technology and technique
Components - TRP CX8.4 Brake Review
Tuesday, November 15th, 2016


TRP CX8.4 Brake Review


Paul Horta-Hopkins


A review of the TRP CX8.4 Brake.


Rim brakes? They’re dead aren’t they? Consigned to the dustbin of history by the disc brake. Mention them and you’ll be told to go for discs; they’re more powerful, aren’t affected by mud, have more mud clearance, won’t wear your rims, the list goes on. Well there is an alternative out there. I’ve been testing the TRP CX8.4 brakes this year and have been impressed.


The TRP CX8.4 deliver more control and power over traditional cantilever brakes

The TRP CX8.4 deliver more control and power over traditional cantilever brakes


For some of us cyclo-cross riders changing brakes is not such a clear cut decision. With one or two bikes running rim brakes and a stock of non-disc wheels, changing systems is a major expense. Many riders are unwilling to fork out on a new bike and wheels just to improve their braking. Talk to some ‘cross riders and they’ll also say that super powerful brakes aren’t that much of an advantage in your average ‘cross race. The terrain and course design tend to keep descents short and once the mud gets a grip speeds are so low that it’s not an issue.


I would tend to agree with that opinion, with the exception that over the last few years I’ve been taking my ‘cross bike out on CX Sportive events. On these type of rides I find myself needing something more powerful. Long, steep and bumpy descents would often see me squeezing the levers all the way to the bars in a desperate attempt to get the bike under control. Also on long rides like the CX Century, my hands would so sore from braking that I was in danger of losing control; not a good thing!


I had heard good things from other riders about the TRP CX8.4 brakes, so was pleased to receive a set from Upgrade Bikes to try out. The CX8.4 was designed as a cyclo-cross rim brake and as such works perfectly with drop bar levers. The TT6 aluminium arms are forged and CNC machined into a mini-V design, rather than the classic ‘cross cantilever. Opinion is that the mini-V design delivers more power, but at the cost of reduced mud clearance. Not so much of a problem on summer CX rides, but could be a problem come the mud!


I also ran TRP's DiscConnect Cable and Housing Kit. Compressionless cable housing improves braking

I also ran TRP’s DiscConnect Cable and Housing Kit. Compressionless cable housing improves braking


Straight out of the box and the TRP CX8.4 brakes are a pretty sight. I ‘chose’ raspberry red – Mr Hitchens of Upgrade can be very persuasive – and the metallic colour does stand out. Contrasting machined flats on the front follow the curve of the arms, very nice. All hardware is titanium, which is a nice touch as rusty bolts, while still effective, just look nasty!


If you’ve not used V-brakes before, then the noodle may be new to you. This guides the brake cable and does away with the need for a brake hanger – first designed by Shimano as a way to get around hangers on Mtb suspension forks. The noodle has a handy adjuster on the top that allows you to adjust for cable stretch or pad wear while out on the ride and has proved handy on long rides. It is also useful for swapping between wheels with different widths.


Before you go getting them all dirty, the TRP CX8.4 are a good looking brake.

Before you go getting them all dirty, the TRP CX8.4 are a good looking brake.


The CX8.4s use road sized cartidge brake shoes. This makes changing pads a lot simpler, once you’ve got your position set. Setting up pad position is easy, there’s only one allen key required and the short cartridges are less likely to foul on your forks. Replacing old pads is a simple matter of sliding out the old and inserting a new one. The supplied pads have lasted surprisingly well, considering they have had a lot of use and some long rides. I’ve had them for eight months and they are still going strong.


Set up on the bike was straight forward, with the only fiddly bit being setting the cable length on the front. You have to be careful when cutting the front brake cable. Too long and it will force the noodle down, you want to cut it so the noodle stands straight. It’s not a big issue, just spend a little time checking before you cut the cable. They work best when the pads are set fairly close to the rim, which might be an issue if you buckle a wheel, but I’ve not had that problem, yet.


A quick mention here about cabling. Along with the CX8.4 brakes I also fitted TRP’s DiscConnect Cable and Housing Kit. Designed for mechanical disc brakes, these differ from standard brake cable in the construction of the cable outer. Instead of the standard spiral wound outer, these use straight steel wires to line the outer. These straight wires don’t compress like the spiral ones. That compression in a cable is bad, it’s absorbing power that should be going to the brakes. It’s this loss of power that can make your brakes feel spongy.


The adjuster on top of the 'noodle' allows you to adjust cable tension. A rubber boot sits at the end, keeping the mud at bay

The adjuster on top of the ‘noodle’ allows you to adjust cable tension. A rubber boot sits at the end, keeping the mud at bay


You could use the DiscConnect Cable and Housing Kit on any brakes and expect to see an improvement. The only issue is that the cables are a lot stiffer than standard cables and won’t curve as easily, so you’ might need slightly longer runs. TRP supply a couple of short sections of standard housing to cope with the tight curves on drop bars.


So once the CX8.4s are fitted and cabled up, how do they ride? One word, powerful. Remember the first time you tried hydraulic disc brakes on an Mtb? That’s all I can liken it to. Riding down the road after fitting them, I squeezed the front. Just the normal amount, not any kind of gorilla-like squeeze, just a normal pull. That normal pull almost had me up on the front wheel! To say I was impressed would be an understatement. Riding back and forth on the tarmac I was locking up front and back without any effort. I could see I was going to have to readjust my braking.


Heading out on the rough stuff, I was using a hell of a lot less effort to brake. The only problem was learning to feather that power. The first few rides were a very binary affair; the brakes were either on or off, control took some thought. Heading down bumpy trails, where the wheels were lifting off the ground meant I was landing with a locked up wheel, not good. Now I assume for all you downhill demons, this all comes as second nature, but for a ‘crosser of a certain age, it was a relevation.


Road size cartridge brake pads make changing pads easy

Road size cartridge brake pads make changing pads easy


Well it took a couple of rides, but I’m now able to control these raspberry beasts. They made my ride in the CX Century much more bearable. Whereas in previous editions I was suffering from hand and forearm cramps – from squeezing the brakes so hard on long rutted descents – this year was so much better. Braking was easy, I had more power with less effort and I have relearnt how to brake with the CX8.4 brakes.


Of course the big question for ‘crossers is how do they handle the mud? Well this year they have had a lot of dry and dusty rides. It’s only now towards the end that we’re finally getting some mud. And it’s come just as the trees are shedding their leaves, which makes for a real bike clogging combination. Initial rides – non-racing – along leafy trails suggest that yes, they clog. As to whether it’s quicker than with traditional cantilevers? I’m not so sure.


The TRP CX8.4s are still looking good after almost a year of use

The TRP CX8.4s are still looking good after almost a year of use


On the front most of the build-up is on the rear of the fork, before it hits the brakes. On the rear the crud comes off the wheel and straight onto the brakes. So yes, they do clog quicker here, but if like me you have wishbone seat-stays, then it’s only marginally quicker. In soft runny mud you’ll be fine, but it’s the thick claggy stuff that could be a problem. Or anything with ‘stuff’ in it! Leaves, twigs, barrier tape anything that gives the mud a place to build up.


So, overall what’s my impression of the TRP CX8.4 brakes? They’re great! There you go, nice and simple. Ok, you may find yourself clogging marginally quicker in certain muddy conditions. This can be an issue when racing, but the benefits outweigh this if you’re riding your bike all year. Once you get used to just how much power there is on offer and learn to control it, it’ll change you riding. Excellent bit of kit!


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