I have a pair of BR-R517 Shimano mechanical disc brakes and they don’t work. These were the replacement for the BR-R515 which had a safety recall that also didn’t work. There’s not nearly enough bite to actually stop you.

Anyone else have this issue? I’ve cleaned them, replaced pads and in every ride after an hour or so they are completely unsafe.

Every set of mechanical brakes I’ve used required the cable shortening, either through the barrel adjusters or just nipping the brake up with it almost on all the time.

The alternative, and much better solution, is pick up a set of Deore hydros from Merlin etc.

+1 to the cable shortening.

You need no slack in the cable, so the pad isn’t even fully retracted. Then you can choose to fly over the bars or pull lovely long skids any time you like.

This is on my CX75 calipers with 105STIs. I really must send them back for the recall and get some CX77s, but I’d just put new pads in when the recall was announced, and they’ve lasted rather well.

Bed the pads in well.
Get them hotter than hot.

You’re doing something wrong.

I have a set of BRR517’s also that I received as replacements for the 515’s on my Cotic X. I’m using mine with 700×33 Raze’s and 160mm RT66’s front and back.

They’re Awesome – way more stop than required but you do need to make sure the cable is the right length and you’ve adjusted both adjusters.

The big silver adjuster on the inside sets the non moving pad. The little black allen on the outside that doesn’t look like much sets the moving pad. If you’re in any doubt what’s going on with adjustments drop the wheel and upend the bike and site through the calliper while tweaking. As it’s not hydraulic you will not accidentally eject a piston and spend all night swearing as a result. Ignoring the moving adjuster and dialling the non moving adjuster gets a very similar result to the described.

Caveat: They’re for road levers which have a different pull ratio to regular V brake levers. If you aren’t using them on drop bar levers I’m not sure how well they’d work – badly, I think.

midlife: you don’t need to return the pads with teh callipers. drop the pads, return the brakes and have spare pads…

Cheers all, I have the cable length so that there is virtually zero slack, pads are very close to rotors but still after they’ve heated up on a descent there is no chance of a decent bite.

Tempted to ditch these for some Avid bb7s but I’ll give them some more tinkering (again!) especially if they are being referred to as ‘awesome’.

Running them with 105 levers and the standard pads they cam with which are definitely well bedded in.

My computer wont let me paste but wozza is speaking the voice of the absolutely clueless

There is a nack to setting them up , i suggest trying your local shop to set them up to show you what they are really capible of, youll likely have the same issue with the bb7s as shimano and bb7s dont have much between them these days ( it used to be the case bb7s were much better but even my deore cables are similar to my bb7s and bb5s these days .)

If you do go to bb7 make sure you get the bb7 r – for road levers . I had mtns set up on my versa brifters and they worked fine , but you had to adjust them weekly as the pads wore down and the lever just couldnt compensate. Where as with the road pull you get longer between adjustments due to the, being match properly to the pull ratio

Maybe check on the Sram website, their downloadable instructions for the BB7s will give you a great heads up.

I *think* from what you’ve been saying above, that when your pads actually hit the disc, the angle between the top of cable arm and the cable will be more than 90 degrees. For good performance, the cable and the cable arm should be at 90 degrees to each other when the pads hit the disc.

If you’re using the cable pull adjuster or the barrel adjuster on the levers, you will lose this position.

Also, like any cable brake, if your cables have a lot of friction (old, dirty or kinked cable outers) the brakes will feel terrible. I just ran basic Shimano outer for the full length with my BB7s, filled it with some waxy dry lube, and had no problems.

Just a thought, but it’s not the tyres that are limiting is it?

I’ve yet to find a situation that defeats my 517’s apart from when I had them badly set up when I first got them.

What are you running for discs? Apart from icetechs (believe the cooling on them is more to stop heat feedback into piston on hydraulics, not sure they’d be any advantage on mechanicals) they ought to be much of a muchness assuming you have pad coverage but you never know.

If it’s heat that’s defeating them then maybe you need a different compound? The default pads are Organic I believe.

Or, if they’ve got to hot, maybe you’ve accidentally glazed them?

I was given a Shimano front mechanical to see what I thought of it. I fitted it and dragged the bike up Ben Nevis to test it. It soon bedded in and the power was fantastic.

Bed it in,set it up again and report back.

I have a set of tektro mechanicals on a spare bike which are surprisingly good, now. I did find however, that the pads got contaminated / glazed badly during bedding in though, so I gave them a good sand plus cleaned the disks. Until I had done that and they were re-bedded in properly they were about as effective as cantis on a £50 childs bike.

The cable has to be tight as already pointed out, otherwise they do the same as early v-brakes used to which didn’t have the pads set 2mm or less off the rim.