Alternative disc calipers on GRX levers

Just out of interest, has anyone tried using a different make of disc caliper on Shimano GRX levers?

I can see that I can buy some Hope ones for nearly double the price of GRX ones but is there any other alternatives?

Im pretty sure someone will be along to tell you to use mtb calipers. However i dont think mtb do flatmount.

Mrs B has some Hope rx4 and loves them

Just noticed that the RX4’s are 4-pot, I’ve never used anything but 2-pot in the past. I’m interested in these especially as I can get them in (controversial) purple. 👍 The price is a bit high for me but maybe I just need to save up 😣

I’ve got Ultegra post mount on my GRX810, works fine.

I have RX4s, they are awesome.

I’ve been using RX4 calipers on my two ebikes and they’ve been great. Almost 2 years in and no issues, bled once a year.

has anyone tried using a different make of disc caliper on Shimano GRX levers?

I’ve got Ultegra post mount

Who makes Ultegra?

Shimano make Ultegra

Alternative disc calipers on GRX levers

😜

If they are Di2 levers hopes won’t work just a heads up.

Why’s that then @wookster?

I honestly don’t know mate. I’m guessing it could be to do with the “servo wave” set up on the levers but I might be talking rubbish!! But GRX RX815 Di2 GRX RX817 Di2 are listed as not currently compatible.

I also have Hope RX4 callipers with GRX levers (non Di2) and think they are excellent. Stopping power is good but the big win for me was the ease of set-up and much less grinding noise as they seem to have a bit more clearance between pads & discs.

They look ace too!

XTR trail should work, and they come in flat mount, I think

@wookster – I’ve been using RX4s and 815 Di2 levers for 10 months on one bike and 8 months on another with no issues in a combined 8000km.

I know that Hope say it doesn’t work, and I even emailed them asking why (no response) but they do.

It looks like SLX have a flatmount option too – https://bike.shimano.com/en-EU/product/component/slx-m7100/BR-M7110.html – if you’re after a less pricey option.

@didnthurt – why are you looking for different callipers?

Most folk go Hope when/because Shimano develop microleaks and start howling like a banshee in all conditions and lose any ability to stop.

The grx di2 levers have a different pivot point in the lever to make braking from the hoods better, maybe this changes the braking in such a way that hope aren’t happy with it.

What Daffy said about leaky Shimano calipers.I might have an issue with my GRX400 calipers (GRX600 levers fyi).

Shame that magura don’t make a flatmount caliper as my magura mt5’s on my mountain bike have been great.

@Daffy Ah now that’s good to know mate! Nice one!

Just noticed that the Hope RX4 rear caliper is only compatible with a 160mm rotor, I have a 140mm rotor. Does this mean I’d need to get a new rotor as well?