New Fangled Hope Disc Brakes…

[FZRIP]

By the way, congrats on an excellent buy!

Thanks.
I did get “the look” when I got it home…

 

[Cloverleaf]

Thank you for your help.
I notice that there’s a tiny little bit of interference of the rotors and pads, is this something to be expected? Or something that can be addressed with the procedures you mentioned?

Sorry, I forgot you're completely new to discs on all fronts. Basically, there are a few things which can cause rubbing; a warped or bent disc, and a misaligned caliper. Well, there is a third and that's sticky pistons causing a pad to be permanently in contact with the disc. In sloppy grit you're always going to find a little noise as the clearances are so tight but that sort of thing clears up with a few applications. You can easily check the warping issue by seeing if the rotor is moving about much left and right between the pads. Minor (<0.5mm) is annoying but not a problem. Anything more and it can cause pad knock back where it's pushing the pads back into the caliper so that when you squeeze the lever it comes in further. You can get around this by pumping the lever a few times but it's annoying (actually, if you pump the rear lever quite a few times in quick succession does the bite point change?). To cure this you can use your hands carefully (make sure they're clean or wipe the disc down with solvent cleaner) and massage the disc left and right to get it straight. If there's a visible kink then special tools can help, or it's new disc time (I wouldn't worry about that too much, Hope discs are very resilient).

For aligning the calipers, align them to the straight and non-wobbly disc, and not the pads. That way the caliper and pistons are square to the disc which means that the pads will always at least start wearing evenly. 2 Pot calipers are generally pretty good for this but offset piston sizes on 4 pots always lead to one end of the pad wearing more quickly than the other. You have IS mounts there which means shims are required to get alignment perfect. Some don't like this compared to the slotted 74mm post mounts that modern bikes use it but I prefer it as you always know what's required to get it back square if you've had a caliper off the bike. I used to use 0.5mm and 1mm shims to get it in the ballpark and then some 0.2mm shims for final adjustment. It sounds faffy, and the first time it is, but it'll be bang on forever more as long as you remember what your setup was! You can then use a small, thin screwdriver between the pad and piston on each side to move the pads/pistons one way or the other to get them sitting even too. Again, you can't bugger this up - if you go too far one way, just do a little on the opposite side to bring it back. Don't go mental with the force here, gentle is enough if the pistons are moving freely.

Also, pad recommendations I think Hope still sell pads for them in which case go for sintered if you ride in the wet a lot as they last longer - I suspect that being an old Explosif you aren't pushing it down steep descents so you won't hit the downside of sintered in that they transfer heat to the fluid more quickly. Many different manufacturers of pads these days but Hope stuff is good (mostly made by Galfer). I suspect that these days the limitation may be who still makes pads, but Hope are pretty good with supporting their old stuff and they're not an obscure brake. If Galfer do pads then black are a general all purpose which will be slightly more powerful than gold (sintered) but slightly less long lasting.

 

[bikeworkshop]

Don't forget pads and discs must be kept scrupulously clean, particularly of anything oily.
Spraying oil nearby is a frequent cause of poor braking and ruined pads.
It's worth having some bicycle disc brake cleaner
(car stuff is no good it's got perfumes in it - i mean we all know what car mechanics are like)
The solvent comes in handy for other jobs.

Be super careful of levering on the pads or pistons, you can contaminate or damage the pad material, and you can jam the piston with uneven, off-centre force.
We get in loads of brakes where the owner has jammed one piston

 

[clubby]

How can I check the pad wear? Is there a known pad thickness or something?
Any recommendations for new pads?

I’ve had brand new sets of pads with slightly different thicknesses of pad material, so there is no exact measurement.
If you have a Halfords or LBS then go have a browse and look at any set of new pads. It will give you an idea of how much a new pad should have. Compare that to what you have. Easiest way to do this is with wheel out. This will also show up any uneven wear. Never run a pad all the way down though as it may well break up and fall off the backing mid descent. That moment was certainly a lesson to check my pads more often.

Cloverleaf is probably right about the performance of the fluid but you are never likely to need the amount you have to buy. I always use a fresh small bottle of DOT 5.1 and do a few bikes at the same time. More expensive per ml but I wouldn’t be using brake fluid that’s been sat open for years. More readily available as well if you just need a top up in a hurry.

Best bit about Hope is that they are very easy to bleed. No fancy syringes needed. Only thing you may not have is a small length of rubber tubing to go from bleed nipple to a disposal container. I use a jam jar with a hole punched in the lid.

 

[bikeworkshop]

Clear silicone hose should be available from hardware stores - its easier to check for bubbles as the fluid emerges from the bleed nipple.

Dot fluid can damage certain rubbers.

Try to always use a ring spanner on the bleed nipple - an open C spanner can easily round the corners


These brakes are from the golden era when component designers wanted the parts to be User-Serviceable.

Those days are gone

 

[Cloverleaf]

Clear silicone hose should be available from hardware stores - its easier to check for bubbles as the fluid emerges from the bleed nipple.

Dot fluid can damage certain rubbers.

Try to always use a ring spanner on the bleed nipple - an open C spanner can easily round the corners


These brakes are from the golden era when component designers wanted the parts to be User-Serviceable.

Those days are gone

To be fair, even Hope were still slightly off centre when it came to that behaviour. Still are for that matter! I mean they don't have stock of the super old stuff but you can still get bits going back at least fifteen years, although I think I got the last Tech 2 pivot bolt a few years ago! Then again, that's a standard, off the shelf part that's easy to replace with a bolt and nut if you need it. Seals are all still available for them and that lever design goes back to 2009.

100% on the ring spanner, or proper flare wrenches, although with them you need to be very careful with nipping them up given they're designed for steel into steel on automotive stuff.

Fair point on the brake fluid shelf life @clubby. One thing I've done in the past is decant brake fluid into a proper clip top glass bottle so that it remains good for longer - much better for having in the van when you might just want a top up etc. Somehow I always get through a reasonable amount of fluid between the bikes and cars (the Impreza gets its fluid changed every 6 months when being used hard) so never have it sitting on the shelf long enough these days for it to be a concern. That's probably not the case for most on here. That's the other advantage of a 'super' dot 4 as they're called; not only are they less hygroscopic than 5.1, but their wet boiling point is significantly higher. For bike brake systems there shouldn't really be any ingress as it's a closed system (even an 'open' modern mtb system is still closed to the atmosphere), unlike some car reservoirs, but I've always found super dot 4's to feel better for longer than 5.1, especially if you're using them hard and getting them proper hot. I think 500ml of RBF600 is £12 or so which is only a few quid more than a 100/250ml bottle, and about on a par with what most bike shops sell brake fluid at, so to me the cost element isn't really one I consider.

 

[FZRIP]

Thanks for all the help.
I’ll have a go at the brakes over the next week or two and let you know how I get on.