GRX-810 levers, RX4+ calipers

What’s the travel / bite point like, with yours? I have plenty of power, no squealing, can lock the back wheel with one finger from the drops, but the lever comes much closer to the bars than I’m used to. Like, right next to the bars so I can’t put max pressure on the levers if my hand is behind them on the drops.

Both lever adjusters, for reach and bite point are set to furthest out (I think) and I’ve bled them following the Hope instructions including the remove-syringe-coax-one-bank-of-pistons-out-repalce-syringe-push-pistons-back-in-and-repeat-for-other-side dance.

I was assuming there must be yet some more bleeding to do to get the more instant bite I’m used to, but then I started to wonder if maybe it’s just how these levers are? Can’t be, though, surely.

I’m pretty certain the calipers are free of air blocks. Maybe something at the lever end though…

I’ve just installed a new set of grx 600 levers and had to bleed them.

They took ages to bleed to get all the air out and make them feel firm.
Mine don’t have the bite point adjuster – but having that on my mtb brakes has not done anything so i’m not concerned.

I had to really move the bike around and push / pull fluid through the system to remove all the tiny air bubbles.

I had similar when I installed on to Ultegra levers on the rear brake. The front was fine. I did the rear first so figured I’d not sucked enough of the air out. I left them a few days and then had another go at the rear and spent more time sucking the fluid and air bubbles back out. That gave me a better lever feel on the rear similar to front. You may just need to have another go at them

Can we swap? That sounds like heaven to me. Mine bite too far out and I’m struggling to wrap a finger tip round the end of the lever blade without coming to a screeching halt.

Can we swap? That sounds like heaven to me. Mine bite too far out and I’m struggling to wrap a finger tip round the end of the lever blade without coming to a screeching halt.

haha we need to, you’ve got the feel I’m after!

I’ve been removing the caliper at the rear to let it dangle, but at the lever end the hose is still wrapped to the bars under the bar tape.

I am wondering if I need to unwrap and let the hose drop straight down to the caliper – perhaps I’m getting bubbles caught in that run of hose around the headtube and bars?

The Shimano GRX lever dealer manual says to bleed with the lever at different orientations (parallel, pointing up and pointing down). I had similar to the OP (though am using Ultegra brakes), following the dealer manual bleed procedure sorted the long lever throw issue for me.

Link to the manual:https://si.shimano.com/en/pdfs/dm/GADBR01/DM-GADBR01-08-ENG.pdf – page 67 onwards

Ah thanks for pointing that out, looseone. I’d been working from that for installation, but had switched to Hope instructions for bleeding, and missed the bit about setting the lever in a variety of positions.

Also notice that it says hoses need to be dangling free, not wrapped to bars, although that’s OK for GRX820.

OK, another bleed attempt coming up…

my first attempt at the back brake lead to this.

didnt even get it off the workstand and went back to bleed with the caliper and the lever at different angles realising there was a trapped bubble somewhere….

Now i have them matching and with a convenient travel range.

Sometimes gently tapping the caliper with something rubbery (so as not to mark it) can encourage bubbles to pop out and up the hose too

My GRX levers and RX4s were amazing… next to no lever throw and consistent as… my Ultegra STIs with RX4s on the other hand are the least consistent I’ve ever had… neither I, nor my buddy (team mechanic) have been able to reliably set them up for months, to the point that I’m replacing the RX4s with Ultegra calipers this weekend. That said, I’d never tried the different lever positions thing in the linked manual having relied on the Hope videos too

I’m just about to put a RX4 on the front of my gravel bike, on RS685s. The caliper has been sitting there for ages for me to do it, these bleed woes aren’t particularly encouraging! I’ve got to fit new bars and tape too, so perhaps I can get the free-moving lever trick done. Part of me is also considering just using a shimano 4-pot mtb caliper, or just sticking with the deore calipers I already have, which have been very good indeed!?

I’ve used RX4 with Ultegra for 18 months & had no issues. Levers have only limited travel & calipers a firm bite, excellent brakes.
I followed this procedure
Hope Shimano Bleed Procedure

So last night I had another go, following the combined Hope and Shimano instructions for the caliper and lever, which makes sense if you think about it for more than 10 seconds, and was rewarded with a lovely stiff-feeling lever.

For the lever, I just put it in as many different positions and orientations as I could and got quite vigorous with the wrist action, which I could see released a few little trains of bubbles. Only small ones but I guess that’s enough.

I am going to do it again tonight, and at the front too, just to be double-sure before I bolt everything back on and wrap the bars again but I’m feeling much more optimistic now.

I used SLX 7100 calipers,(not pre-filled), with GRX-600 dropbar shifters, on my Camino, and had to use the Comma LHM+ mineral oil to bleed them, as no sensibly-priced stocks of Shimano oil anywhere 2 yrs ago.

Bleeding the shifters seemed much fiddlier than mtb levers, and each end took a couple of goes before i got them feeling good, although i always felt that they could have been even better.

I did wonder if this was due to a ‘different’ FHM oil characteristic, as ive always used Shimano, but as it happens, theyve stayed reliably constant for two years now, ive not had to touch them, and braking is still pretty sharp.

Don’t forget you can leave them partly ‘on’ overnight to self bleed. Often when they’re just a bit off, doing this gets them back to rock hard. Not too much pressure mind or you might blow oil past a piston seal.

How’s that done then, boblo? I haven’t heard of that before…

I found that Ultegra di2 levers with RX4 bled easier on the front brake than the back. Got a firm lever that bit fairly early on the travel in the front no problem – the rear I’ve not quite got to match the front on several attempts yet. Although it worked fine.

Sadly the front started to leak oil out of where the hose connector joins the caliper. Can’t quite workout which connector is seeping so I’m going to change all connectors / olives / washers / Barb / shrouds this weekend and start from scratch. Also blow torched the pads and still have to clean the rotor to start again. Annoying as the front brake was awesome – even sat down going fast on the road bike you could pull stoppies from on the hoods.

I’ve also found I’ve got 2 pistons that move in and out easily on the back caliper – but the 2 on the other side are very reluctant to move far so I need to clean and lube those when I get a chance.

How’s that done then, boblo? I haven’t heard of that before…

Just pull the brake on via the lever then hold it on with an elastic band or cable tie and leave overnight. If you’ve a slightly soggy brake, it can bring it back on song without doing a pukka bleed.

Don’t go mad with a death grip as you can end up squeezing oil past the piston seals if you’re a bit too Amazonian. I think I fubared one of my Ultegra calipers this way though it’s hard to be certain as they’ve a reputation for leaky seals anyhoo.

Thanks for that boblo – will keep in mind.

Just to wrap this up – after bleeding both ends again per Hope and Shimano instructions, I have great lever feel and very powerful (and quiet) brakes.

I wouldn’t let this thread put anyone off, it’s just a matter of doing each step carefully and not hoping you can get away with not doing things, especially:

• from the Hope instructions, the steps that involve coaxing out each side of pistons independently of the other, removing and re-attaching the syringe as you go

• from the Shimano instructions, the steps that involve moving the lever to different positions and orientations: I ended up putting them into as many positions as I could imagine, just to be sure

• the ‘flicking’ of the lever: don’t be scared of it, and keep going for longer than you think you should need to

Thanks for the tips on the thread.

Now to get my fork tuned in 🙂