hi,
I've got shimano GRX 400 levers on my gravel bike with hope RX4 Calipers.
The front lever, with very little pull, will put you over the bars.
The rear lever needs pulled hard against the bar to get the rear wheel locking up even on grass.
Is this level of imbalance normal? Not ridden the bike for a while. Therear was always a little softer. Can't remember it being this bad. The brakes have been bled by local bike mechanic.
I have 105 with Hope callipers.
Both the levers feel the same and have always been progressive and felt great.
I think there may be something wrong with your brakes.
They have always been imbalanced and had issues with leaking etc. Local mechanic diagnosed and replaced a mashed copper washer.
This is how they came back. Same feel as before. But no longer leaking and contaminating pads.
I had this with Hope RX4 - and now with an Ultegra replacement caliper on the rear. The front brake is easy to get a good bleed on it with the short cable run - the rear is much much harder.
The RX4 caliper in particular gets air trapped behind the pistons and you have to really work at it to get it out. It’s made harder by internal routing so you can’t move the caliper about much to dislodge the air.
With the RX4 there’s a really messy process of pumping the pistons out then pushing them back and locking off / unlocking the bleed screw (having to unscrew the syringe every time). I found it insanely messy and annoying.
You also need to go this process with the brake at different angles - which is difficult with the funnel thing. You need to effectively loosen and twist your handlebar to allow this without spilling mineral oil everywhere.
I’d send it back to the bike mechanic and ask him to do a better job.
At a guess, the brakes have been bled but the pads haven't been reset, so the pistons on the front are closer to the rotor so require less pull. The rear had the pistons pushed all the way back (and may require new pads due to wearing down or just a proper good bleed), so there is more lever pull.
You could remove the rear wheel and progress the pistons slightly - and then rebleed the rear brake without resetting the pistons - that should mean the lever throw is shortened, but will cause rubbing when you replace worn pads with fresh ones.
You could reset the pistons on both brakes and do a full bleed on both brakes and hopefully that will give a more consistent feel to both levers.
If there is air behind the pistons, connect a syringe with a bit of fluid in it to the caliper and draw the syringe back...it should pull the air out - keep syringe higher than the caliper and as you slowly release the plunger, fluid rather than air will be sucked back into the system.
Recently built my bike up with GRX 820 levers and RX4+ calipers and lever feel is completely balanced.
Uneven feeling can be a bad bleed or a misaligned caliper. I've always used Putoline rather than Shimano oil and never had wandering bite point or bleed issues.
Hope are renowned for being sensitive to caliper alignment. Squeezing the lever and tightening bolts doesn't work. Centre the caliper accurately then balance the pistons. Useful videos on YouTube.
Thanks good people.
I'll have a bash at bleeding the rear myself. See if I can get it any better.
I remember them being a pain when I first installed them. Few years ago tho. Thought the pro would have been a good shout ?
They sound like they need bleeding.
Undid the caliper letting it drop below the stay. Got a much better bleed. Problem Solved.
Much better balance between the levers and far more effective rear brake.
Many thanks