Bleeding – Pistons Out or In

I’ve always bled brakes with the pads out and a block wide enough that the pistons are fully retracted. I purchased a set of Hope V4s with vented rotors, so thought I better use a wider block to suit the wider calliper. I’ve 3D printed the official tool from the Hope site and it is the same width as a new set of pads, not included the rotor width, so the pistons are fully out. I’ve yet to try using it; I don’t see why it won’t work, but when the bleed is finished, do you not then end with too much fluid in the system to push the pads back? Does anybody know the advantage to doing it this way?

I always thought the pad spacers were to stop you popping a piston out while bleeding. Once the bleed is finished, the very last thing I do is reset the pistons all the way back into the caliper.

Maybe, if I was using a V4 with single skin rotors, 8 might have the piston protrude enough to compensate for the reduced rotor width.

Hope recommend finishing the bleed by pushing back the pads/pistons to push out any air behind them. its done with the syringe/tube on the caliper with the nipple open

Like the way this lad bleeds us brakes

That method of pushing the pistons back with the pads in feels brave to me as I always worry the hose to the syringe might pop off!

I did a bleed, although the back still feels softer than the front, still super powerful. Pushing the piston back with the cap off was a bit messy (bleeding topless with just an open lever reservoir). I’ll try again on the back using the technique in that video to do a calliper end bleed with the lever held down.

Hope recommend finishing the bleed by pushing back the pads/pistons to push out any air behind them.

Surely just having the pistons fully retracted stops this being a problem in the first place?  I would say Hope don’t know what they’re talking about but they make brakes and I work in IT!

Pushing the pistons back with the reservoir open makes sure that all the air is purged from the reservoir. This is the solution to the wandering bite point problem.

I think this is as much about brake design/foibles as anything else, some are much easier to bleed and less likely to create problems for you, and those you can bleed with the pistons fully pushed back for simplicity and without any worries. Others are not so well designed and more temperamental and for those I reckon it’s better to bleed with pistons out, then as a final step push teh pistons back with the reservoir/top syringe open. It shouldn’t really make a difference but it does.

(I’ve been using the same brakes for a decade so I keep kind of forgetting that not everything is as well made or easy to bleed as they are, it’s such a solved problem that it’s kinda infuriating that they keep managing to unsolve it)

If the pistons are fully out then surely pulling the brake will have the pistons falling out?
If the Hope tool is the size it is then bleed with that as it should work with any Hope disc.

Suspect if the vented discs are thicker then the lever throw will be shorter.