I’m looking for some Hope RX4 calipers to replace my leaking Shimano ones.

Can anyone confirm if the rear flat mount caliper will also fit the front with an adaptor or do I need the front and rear specific calipers?

I have just fitted a pair of RX4 callipers to my Free Ranger and front and rear are totally different shapes,hard to see how an adaptor would work.Brakes themselves are great,better than the Force callipers they replaced.

The front is specific, effectively has the adaptor built as part of the unit.

Thanks guys.

I thought this was the case but the seller seems to think that front and rear are interchangeable.

Front and rear POST are the same, flat mount are different

The rx4 flat mount rear has the +20mm spacer ‘built in’ iirc, so presumably wouldn’t fit properly on the front like a normal flat mount caliper.

Unless you can mount it in the 140 position on the normal front adaptor but have it running 160mm rotors?

Only 160 mm rotors no 140 mm AFAK, so I won’t bother for my roadbike.

Only 160 mm rotors no 140 mm AFAK, so I won’t bother for my roadbike.

160 on the front of my road bike is a big improvement. I’ve left 140 on the back.

I think my road bike has 160mm rotors at both ends. The weight difference in 150mm to 160mm can’t be much surely? Why else would you go for smaller ones (unless they come on a bike and you don’t want to buy new ones)?

One day I’m going to go for these Hope calipers – but the rear caliper I thought was on its way out has stopped squealing horribly having used the bike a bit more recently. So maybe it’s not on it’s way out just yet!

One day I’m going to go for these Hope calipers

I cannot recommend them highly enough – they revolutionised my Arkose.. huge power and good modulation, and the only hint of noise comes after a really wet road session – where they’ve been repeatedly splashed with greasy puddle water – even then its only a chirp when i first use them.

Front and rear POST are the same, flat mount are different

I don’t know that.
FFS! Instead of yet another stupid ‘standard’ being foisted upon us they’ve got two in at once. What is wrong with these people? Just make everything fit!

The weight difference in 140mm to 160mm can’t be much surely? Why else would you go for smaller ones (unless they come on a bike and you don’t want to buy new ones)?

I got a pair of 160mm Avid discs (older designs are very cheap now on eBay) for £10 or so.

However, the nice neat, cheap, Shimano +20mm post-post adaptors dont work with the Hope callipers (the V in the middle isn’t deep enough to accommodate the calliper body) and Hope’s K adaptor moves the calliper position up and back a lot so it looked really ugly.

Also, I think my rear mount needs facing – with the hope mount on I couldn’t centre the calliper on the disc.

The RX4 are a bit of a faff to bleed and while the front is nice and firm the rear lever has much more movement – makes me think I need another go. But surprisingly messy – fluid goes everywhere when you disconnect the syringe.

Why else would you go for smaller ones

Because 140mm on the rear of a road bike is plenty.

@freeagent, what pads are you using?

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simondbarnes
Full Member

Why else would you go for smaller ones

Because 140mm on the rear of a road bike is plenty.

Posted 23 minutes ago

Maybe I’m eating too many pies but there’s a hill near me that my brakes get a bit graunchy on. I don’t know if it’s because I accidentally bought organic brakes pads last time (turns out the brakes had sintered in as standard) or they’re genuinely struggling a bit. That’s 160mm at each end with shimano hydraulic calipers. Think rs785 with finned pads or something like that.

I had 160 rear, changed frames to one with 140 so thought I’d give it a go. It’s still fine, plenty of power and slightly lighter so it works for me.

New frame is only FM on the front and frankly it’s just fiddlier than post mount. Adjusting the caliper always seems to take ages longer than the rear. I do confess to liking the neatness of the swap between 140 and 160 though

My partner has RX4 PM shimano calipers.

A work colleague has RX4 Sram FM calipers.

For some reason they dont take the same pads. The shinano PM used by Mrs B take the Hope E4 pads…..no idea what the sram take but they are smaller!

@freeagent, what pads are you using?

The Callipers came with two sets of pads – one marked ‘Road’ and one ‘Gravel’

I’m using the Road pads, but i think they’re pretty much at the end of their life so will swap the Gravel pads in shortly.

The flat mount RX4 only goes down to 160 mm, you generally want 140 mm rear on a roadbike as it saves a smidgen of weight and aero drag, plus it reduces the risk of locking up the rear (less power can be more) (AAAND it looks better..)

Does anyone want to buy a hope Post mount K adaptor!

The flat mount RX4 only goes down to 160 mm, you generally want 140 mm rear on a roadbike as it saves a smidgen of weight and aero drag, plus it reduces the risk of locking up the rear (less power can be more) (AAAND it looks better..)

As someone who isn’t racing I feel the benefits of 140mm over 160mm isn’t really there. I’d rather have a more powerful brake / better resistance to heat build up. As for looks – I very much doubt worth a quick look I’d notice 20mm difference in disc size. Can’t say I lock up the rear much either – but then I do a lot of mtb with Sram Code brakes and 200/180mm rotors so used to modulating brakes.

My frame is only warrantied for a 140 rear. It’s flat mount. I’d have gone down the hope route at least 2 years ago if they made them. The actually do make a 140mm flat mount caliper for XC, but it’s for dot oil. X2 flat mount I think. Nowt that’ll work with my Shimano brifters.

However, noticed Magura are making a flat mount 140mm caliper which could be compatible as it’s for mineral oil. Expensive experiment possibly.

Can anyone confirm if the rear flat mount caliper will also fit the front with an adaptor or do I need the front and rear specific calipers?

Yeah you need specific front and rear.

I’ve just fitted rx4s on my bike and having a nightmare with “lazy” pistons, where one side comes out more than the other, meaning the rotor gets pushed. I tried lubricating the pistons and pushing them in and out a bit so I’ll see how that goes at the weekend.

you generally want 140 mm rear on a roadbike as it saves a smidgen of weight and aero drag, plus it reduces the risk of locking up the rear (less power can be more) (AAAND it looks better..)

I generally don’t. I’ve always used 160f and rear on my road bikes, I think they look better but also, I have spare rotors all the same size if I ever need to switch about. I’ve never had a problem with accidentally locking up the rear due to too much power available, you can modulate the brakes easily, they’re not on/off switches.

I’ve never had a problem with accidentally locking up the rear due to too much power available, you can modulate the brakes easily, they’re not on/off switches.

This.

I’m using the Road pads, but i think they’re pretty much at the end of their life so will swap the Gravel pads in shortly.

Does anyone know what the difference is with the blue pads? I’m pretty sure the red are the standard organic compound but wondered what the difference with the blue was supposed to be

They’re sintered, aren’t they?

They don’t look it and e4 sintered are normally a gold plate.

Does anyone know what the difference is with the blue pads?

They’re organic, but different to the red organic

you can modulate the brakes easily, they’re not on/off switches.

I meant during emergency breaking. If you live somewhere hilly 160 rear could make sense, but I live somewhere flat so they don’t, but it’s not a huge difference either way and mostly comes down to aesthetic preference.

I had issues with my RX4 calipers.
Bleeding is straightforward if you you follow the Hope guide on the website.
Got very firm braking which is great on the fast downhills when on the drops you can feather the levers and get maximum control.
The issues I found the pads sat too close.
Constant noise and rubbing.
Clear one minute then constant drag.
I think I was getting the odd sticking piston which is a nightmare on a 4 pot!
Changed to a Shimano Ultegra with no issues.
Firm braking with no rubbing great!
Have always been a Hope fan and use their MTB brakes with no problems.
These just didn’t work out for me!
Max.

Yeah the pads do sit really close. I’ve managed to get the alignment just right, wheels were spinning freely. I went for a ride yesterday morning and they performed well. But when I got back noticed one pad slightly touching the rotor front and rear. Maybe the rotor is not perfectly centered?

Possibly.
I must admit my rear rotor Was a little wobbly.
But the Shimano caliper clears it and works perfectly.
The rotors have to be perfectly true to clear the Hope calipers.
Even then with heat there is likely to be some run out at some time.
Max.

Has anyone tried any of the disc space alignment things – Birzman make a set of 3 ?

I fitted a front post mount RX4 a couple of weeks back to my CAAD12 to replace a leaky shimano.

Was annoyed to find the adapter didnt fit as mentioned above. Nothing on Hope’s website suggest this is a problem and the £17 hope adapter isnt available everywhere.

So I got my file out and filed down the shimano one I had. There is still some material left, but not a great deal and it did get a bit bendy towards the end when it was thin and hot. I dont think its structural?!

Found it easy to bleed, the caliper came with everything needed including a syringe and the nipple. Its a bit of a messy design when you detach the bleed nipple and have to put the grub screw back in.

I’ve got a much firmer brake lever now, which is great, but doesnt help having the bite point so high with my little hands when on the drops.

Might have to do the rear now, but will wait until the rear starts leaking to I can get a refund on warranty to put towards to the cost (as I did with the front).

Having worked in a bike shop for a few years and built and maintained many disc-braked bikes, I can safely say the RX4s were by far the most difficult brakes I’ve ever had to set up (Followed the Hope setup video carefully, lubricated the pistons etc, etc). In the end, many hours of trial and error tiny adjustments was the only way to get them to spin freely.

Now they are set up though they are fantastic, big improvement over Ultegra (which conversely were incredibly easy to set up!)

Is there a cheap alternative to the hope split olive and barbs?

I’ve just bought a set of rx4’s with shimano levers and need to fit longer hoses.

The hope olive and barbs seem pricey for a pair, the barb is clearly quite different from shimano barbs.

Can anyone link me to buying a set?!

I know if I’m careful I can probably re-use the ones current fitted but would like to have some spare incase it doesnt go to plan.

Cheaper than what? Google brings them up for as little as £2.80.

The olives aren’t very specific – google showed some for 1.50.

how much cheaper are you hoping to get?

I’ve reused both in the past without issues but its a bit of a faff. I’d at least screw the olive and then you usually lever the barb out with a small screwdriver. Easy to stab yourself doing it which is why I just keep some in stock now.

Cheap than what?
Cheaper than the ones you mention.

I can buy a set of 10 shimano olive and barbs on amazon for about a fiver.

I’m looking for a similar priced alternative to the expensive hope ones.
Theres hope split olives with the hope insert on Ali express for about £1.50 but they don’t deliver to UK currently.

Was hoping someone could link me to something similar rather than suggest the first links on Google!

No. I don’t believe anyone makes cheap non-OEM copies of a Hope specific part.