Hope RX4 Caliper

[MichaelB]

Bugger. Those Top Gear episodes with tghe English cars was a cracker.

Back to the calipers - what is your next step ? Persist or go to Saint/Zee or even Magura MT5/MT7 instead ?

[TobinHatesYou]

Bugger. Those Top Gear episodes with tghe English cars was a cracker.

Back to the calipers - what is your next step ? Persist or go to Saint/Zee or even Magura MT5/MT7 instead ?

Persist for now, I'm not just going to accept the fact that I have two defective Hope calipers. Also my setup is SRAM eTap HRD and as far as I know my only options are going back to the SRAM calipers or RX4s.

[MichaelB]

Persist for now, I'm not just going to accept the fact that I have two defective Hope calipers. Also my setup is SRAM eTap HRD and as far as I know my only options are going back to the SRAM calipers or RX4s.

Ahh. Good luck and keep us informed.

[Klaster_1]

@TobinHatesYou how the grub screw leak looks like when caliper's installed on frame? Will the brake fluid just sip through it and drip down the machined channels?

[robo]

FWIW I'm very impressed with the Hope RX4 calipers, having switched to them from Shimano 785s which leaked.

I did find the bleeding process took some time to become fully familiar with, and it took me a couple of bleeds per caliper to get things set up correctly.

@TobinHatesYou - I found the step in the bleeding process where you pull-back on the bleed syringe to extract air from behind the pistons to be essential to ensure all retracted and operated freely?

[TobinHatesYou]

FWIW I'm very impressed with the Hope RX4 calipers, having switched to them from Shimano 785s which leaked.

I did find the bleeding process took some time to become fully familiar with, and it took me a couple of bleeds per caliper to get things set up correctly.

@TobinHatesYou - I found the step in the bleeding process where you pull-back on the bleed syringe to extract air from behind the pistons to be essential to ensure all retracted and operated freely?

I followed the instructions exactly like the video, including tying down the lever and shaking the bubbles out of the caliper by pushing and slightly tugging on the the syringe plunger to agitate the air. After that, I slowly released the caliper while depressing the plunger. I then removed the syringe at the caliper and replaced the bleed screw. Then I flicked the lever while pressurizing it to get all the bubbles out.

The bleed process is exceedingly simple and I'm used to the SRAM method anyway. This is not a case of user error, it is a quality control issue.

@TobinHatesYou how the grub screw leak looks like when caliper's installed on frame? Will the brake fluid just sip through it and drip down the machined channels?

I unbolt the rear caliper from the frame before bleeding it so the bleed port is at the highest point relative to the caliper body. The DOT 5.1 fluid just dribbles out slowly along the raised portions of the body, pooling in some of the machined cavities, and then dripping off the lowest point. This only happens with the second rear caliper that I bought at retail. Neither the first caliper, not its replacement (I suspect they sent me the same body with new pistons) leaked at all.

[dvq]

I'm switching away from the RX4 and back to SRAM Red, rear caliper had stuck pistons, tried to free them up, didn't work so great. Twice the pistons just means twice as many stuck pistons.

[Broady]

Hmm, I know a couple with the RX4 and they all love them, Hope are generally pretty bombproof so a shame to see these bad reports. I'm still probably going to upgrade to them at some point.

[sebrenaud]

Alright so I have had quite a saga with RX4s and I haven't even gotten to ride them yet.

About a month ago I ordered front and rear SRAM compatible RX4s from my LBS through QBP. They arrived, I installed them. The outboard small piston on the rear was completely stuck. I could immobilize the three other pistons and force the stuck piston to advance, but not without making grinding noises every time. Pushing the piston back in was even harder. I managed to do it a couple times. I tried using brake lube to free up the movement. Nothing worked. I had a shop mechanic look at it, he ended up cracking the piston (which is ceramic.)

I sent it back to Hope's USA office to get it looked at and replaced. I knew this was going to take some time to get back to me, so I ended up just buying another rear caliper to use in the meantime.

Well that second caliper I purchased had a leaky bleed port. It would seal with my bleed kit syringe, but not with the included grub screw. I contacted Hope USA again and they threw a grub screw in with my warranty replacement caliper, which I got today. My first step was to test the leaky caliper with the new bleed port screw (and after q-tipping the port.) Nope, still leaks. So I mounted the warranty replacement and that bled fine. However after trying to set my pad distance, the same freaking small outboard piston was exhibiting the same behavior. Completely stuck, moves only when the other 3 pistons are held in place...makes grinding noises when it advances.

You know the Top Gear joke about English craftmanship? Apparently it pertains to Hope bicycle components too. Needless to say I'm pissed.

Interesting feedback, could you tell us why you’ve switched from sram red calipers to rx4 ?

[Broady]

I've got a set of 9170 levers on the way and was looking to get some RX4s ordered too. I know the 9170 use BH90 hoses, can anyone confirm that these are fine with the RX4s?

[Klaster_1]

I know the 9170 use BH90 hoses, can anyone confirm that these are fine with the RX4s?

Yes, they are fine, I run BH90 and RX4. The Hope barbs were a little tight to push into hose, but nothing a hair dryer can't fix.

[Broady]

I know the 9170 use BH90 hoses, can anyone confirm that these are fine with the RX4s?

Yes, they are fine, I run BH90 and RX4. The Hope barbs were a little tight to push into hose, but nothing a hair dryer can't fix.

Brilliant, thanks.

[Klaster_1]

Here's the brake pad bolt from one of my RX4's:

Hope RX4 pads bolt

A week ago I ordered a pair of Ti replacements from Titaniumplanet, "Weight (mesured): 2,80g /2 parts". Nothing suspicious and a small weight saving, right? Wrong, turns out stock bolts are already Ti, I took a magnet to one this morning :facepalm:

[CallumRD1]

Remember that stainless steel is also not ferromagnetic...

[Klaster_1]

Remember that stainless steel is also not ferromagnetic...

I didn't know about that! But you are correct, I tried a spoon and it doesn't stick to magnet. Maybe there are more steel parts on my bike I didn't know about