Nerding out on Brakes shall we? Not another tech deraliment

Finally got hold of a set of GR4s after years on the Tech 4 V4. As with all things Hope the build quality is a work of art. First impressions:

I bled the ‘old’ way without using the bleed port because I didn’t have the adapter for the funnel yet .Hopes new bleed video gives a few new steps which seem to work good.

Lever is a touch heavier throw than the v4 but much shorter throw before bite due to the new cam design. It’s still very light. 

Extra hook on the lever is really nice, way more secure 

Bigger piston is noticeable in the power increase, not huge on the v4. 

Still a lot of feel at the lever which is my favourite thing about the hopes compared to the mavens or Shimano that have that on/off. Just preference.

Love they share the same pads and some hardware so all my T4 spares are not useless!

This guy always does interesting combos. I dig it

I noticed yesterday that I've managed to kink my rear brake hose on my DHR Evos in 2 places - one at the junction into the head tube (from swapping forks out..) and the other at the entrance to the levers (from my light pushing it in that place).

Never had hoses kink before, could it be that the TRP hoses are softer than anything else (ie Formula and SRAM)? Could I be losing power from the flex?

I'm a little late for this to be news, but I'll post anyway.

After 2.5 years of use I had an issue with the Code RSC brakes. It's going to need a new lever body, I'll replace it and throw them on my spare bike. 

I installed the set of Hayes Dominion A4s that I had been planning to install on the spare bike, but hadn't gotten around to. 

A few quick observations.

The Hayes are easy to get a good bleed on but the process is messy. It's almost the opposite of the bleeding edge system, which is a little more difficult to get a perfect bleed but is very clean. It's a mild pain that Hayes only includes one barb and olive, I originally left my front hose a bit too long and had to wait until more arrived to shorten the hose. Aligning the calipers was easy with the grub screws. 

The brakes feel good, and are quick to get used to. The initial bite is similar to Codes but power ramps up faster more like Shimano.

Can’t answer the question about the hose softness, but wanted to chime in and say it’s unlikely that the kinked lines are causing any power issues. I’ve ridden with some pretty severe kinks with no problems…

Does anyone run smaller rotors in the cold (freezing plus or minus 10-15F) weather to try to keep them working better? Specifically for all-mountain, enduro or whatever we call it these days type of riding. 

I do a lot of enduro fat biking in those temps and run 200/180 rotors. Runs are between 300-500M of elevation drop. Anything smaller wasn't cutting it and anything bigger was too much. On my summer bike and same trails I run 220/200. I also run Sinter green pads so the initial bite is not too dependent on how much heat you have in the system. So to your question, yes downsize. 

No I haven't, thought about it, but just didn't bother, no issues using 203's in freezing temperatures.

I have had this happen on my SRAM setup where the kink was bad enough to cause brake loss. The plastic tube in the brake hose kinked at the sharp head tube routing exit and starting leaking fluid in the housing. Kinda like a pinch flat within the hose. No external fluid loss but enough to cause pressure loss in the system. Some frames like speciazlied have a sharp exit port which I now sand a little bit to make it smoother. Kevlar lined hoses are more resilient because when the same happened to my Intend hose it kept working just fine. YMMV but the general rule of thumb is to replace it.

Funny enough, I trimmed and bled a pal's Elixir for brake issues this weekend (yes, we talked about how updating the brakes would be a good idea). Anyway, the brake with the kinked hose was working-ish. The kink was bad enough to cause a fluid restriction, so the pistons wouldn't return the way they're supposed to. This of course meant a real short lever stroke and pad rubbing.  Nipped the hose down a smidge, new comp bushing and bled and the brake feels fine. Power wasn't an issue, just brake functionality. His was bad enough that I didn't feel 'rounding" the hose back into shape was a valid repair option. If yours isn't terrible, you can give that a go with a set of needle nose pliers. Easy does it, don't go ham fisting the job. I've done it numerous times back in my industry days. When companies were still figuring out how best to run hydro lines there were numerous kinked brake line issues we addressed in the field. Some just needed to be rounded out again and rerouted, but sometimes they were bad enough to cause internal failures. Those were a hoot for everyone involved.

TRP made a running change to the hoses, they added a stiff plastic liner.  I didn’t know about this when installing my Pros and kinked it twice.  Ran it the entire season like that and didn’t have any issues.  Apparently the soft hoses were causing the soft bite point.

when did they make this change?
Quite a few people run the Saint hose still.

Following on from the Shimano/TRP hose question - has anyone used Shimano barb/olives? The only supplier that will deliver to me for TRP barbs and olives wants £20 just for shipping!

Use the TRP barb/olive on the Shimano hose.  Works great, it just a weeee bit snug slipping the olive on the hose, but it works.  

I have early run Pros, so those probably shipped with them from the get go.  I have a set of the DHR Evos with the updated lever adjustment from early 2024 and those still have the old hose.

This is interesting - I received a set of GR’s and they had the bucket adapter in one box.

Cyclocross wrenching background - rather than smaller, we found pads that heat up faster are better. The alloy core rotors manage high temp better but also get up to operating temp faster.

Now have 2 sets of 6 month old T4 V4's that have horrendous amounts of wandering bite point, gets slightly better after a bleed but immediately returns after 200m of descending. No visible leaks and no pad contamination, very odd. At first, I was thinking either the diaphragm or master cylinder piston, but I'm almost wondering if it has something to do with seal rollback on the caliper pistons (ie not retracting fast enough), as it doesn't seem to be ingesting air. Has anyone else had similar problems?

I did have a master cylinder on a V4 that did something this.

It would be fine in the garage and feel spongy on the trail at times, then Ok - very inconsistent.

After a ride I would check things - no leaks, top off fluid at the MC, bleed, and it would help for a bit and then boom - same deal.

Contacted Hope and they recommended swapping out the diaphragm seal as a first troubleshooting step and has been problem free since.

Updating post to add that the diaphragm that was removed didn't have any obvious physical defects - no holes, no chunks missing, etc. I did not run tests to figure out where the diaphragm was leaking.

First day on GR4's today. My dh bike was out of commission, so I was on my ebike instead which in turn requires more braking anyway. All the boys of course were on dh bikes so I was swinging off it to keep up. 

These brakes are absolutely phenomenal, I've used all of the top dog brakes, radic, t4, maven, intend, maximas,I'd rank these at the top of the list. Reasonable dead stroke, firm bite point, wonderful modulation, very good power and easy bleed. 

If you've been put off hopes before because of vague bite point etc, give these a go. Worth a shot 

Oh tough call! I just swapped these directly for T4's, used the same hoses etc. If I had to reroute hoses they'd probably still be in the box 😅

My riding buddy got a set of GR4 and I like them more than my Intends lol

Unfortunately have only had wishy washy customer service so far. They agreed to warranty the master cylinder on the front set that died first, sent me the wrong model after a month (received August 14th), and currently still waiting on a replacement. Contacted them again about the rear, hoping to discuss having a new seal kit or something appropriate sent out other than a new brake, and was told to bring it to the local shop (initial email mentioned that I work in said shop lol). We don't see too much in the way of Hope product, but we've all concluded that it's some sort of seal/diaphragm issue in both sets. Ended up pulling the remaining brake off and threw on an old set of Code RSC's w Cascade Cams and will probably sell the T4's and replace with Mavens eventually.

I just swapped a pair of really unreliable mineral Radics off my bike and but the Evo TR4s on. I’d ordered the GR, but when a pair of TR’s came in to stock I swapped.

I’m super impressed. So much power, very positive bite, minimal dead stroke, bleed was as easy as it gets.

I’ve dropped the rear rotor to 180 from 203mm to see how they cope.

Anyone have some feedback on the TRP RS05 rotors (2.3mm) - specifically related to how true they come out of the box and how true the stay?

I've got 203mm Sharks (that I bought from Europe for ~65/ea before the tariff bullshit) on my ebike and enduro bike, and like them a lot, but certain trails have me thinking about upsizing to a 220.  Hole pattern on the RS05s looks very similar at a much more affordable price point, but in my experience 220mm rotors are much more likely to come warped out of the box and warp during use.

This is identical to my experience with them

Interesting the differences that keep showing between the reliability of mineral vs dot Radics