Anyone know anything about disc brakes?

Hadn’t seen this. Super helpful, thank you - I can’t lock the wheels so I think a full brake service is in order first!

Something is up if you can't lock the wheels up. I'm running slick 28s and if I jab the brakes too hard I'm definitely skidding down the road. Your pads and/or rotors are worn, contaminated or maybe shit.

Could also be that the bleed is shit so the brake levers are at the bars before full force is applied?

I can easily lock up the rear (haven't tried the front!) with BB7s and I'm not light, so yeah something isn't right

Something is up if you can't lock the wheels up

On dry tarmac, the limit of the front brake should be a stoppie rather than a skid

Depends on speed, maybe rider weight and their position and road slope?

If I know I'm hitting the anchors hard then I'm moving my bodyweight back. I dunno, I'm having a hard time visualising just jamming on the brakes but I'm pretty sure I'd break traction before I went anywhere near going over the bars.

"Controlled" braking then you'd probably stoppie but that's assuming you were aware of the limits of traction in the first place.

The rotors weren't changed in the service.

In our workshop we usually recommend both to be changed, even if the rotor have minimal wear, it can greatly affect the braking performance.

Different rotor like Magura tend to offer more power due to the difference in steel.

Sound like your brakes is one of those Shimano one that’s pretty hard to get it to feel nice and sharp, a new hydraulic hosing help improve it but there’s only so much we can do

Depends on speed, maybe rider weight and their position and road slope?

Speed is not a factor. Rider weight is a neglible factor since in dominates system weight. Position is technically a factor but for practical solo safety cycles only beach cruisers and Dutch bikes might have sufficiently rear-shifted weight balance to make enough difference, and even then I'm not sure. Slope has an effect, but only going uphill makes skid more likely, and who's hitting the brakes hard going up hill? Very sudden application of the brake can cause a skid in a situation where steady state braking would cause a stoppie, because it brings moment of inertia about the tipping axis much more into the equation, but even then a stoppie is the more likely outcome in most cases.

Essentially, for most classes of solo safety cycle, the tipping limit is about 0.6g deceleration, while the grip limit on dry clean tarmac is about 1.0g, so you need a big geometry shift or very compromised grip to slide the front in a straight line.

Thanks Ed

I almost exclusively crash going around corners or being driven into by arseholes in big metal boxes so I guess my stoppie vs. skiddie experience is limited.

These are a client’s resin pads after a single race. He’s also a tall fella. Ask for Shimano semi-metallic brake pads, or even metallic if you’ve been using semi metallic already.

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Mechanic calling customer “cilent” never get old.

but why not just have the “best” brakes possible - what am I missing!

The tyres aren't big enough to have motorbike brakes, you'll just break traction.

This makes sense, however I only do stoppies when a car cuts on my way and I have no clear way out other than slam brakes and hope for the best.
Most likely scenario it's I'm already in a turn and no amount of braking will save me.

why not just have the “best” brakes possible - what am I missing!

Once the rear brake can lock the wheel and the front brake can lift the back wheel, any "better" brake just means lower lever force and/or easier modulation, not greater deceleration. These things usually cost weight and money, so most cyclists are satisfied with "good enough" brakes

Every day’s a school day.

They're road pads, right? What was the "single race"? Or was it one of those "I started this race with worn pads and they died during it" exaggerations.

I've ridden TCR on a single set of metal pads and now chop and change between metal and resin based on what's in stock. I would normally fit metal for longer stuff, for the durability but I also don't mind swapping pads out during a race nowadays so I tend to just run whatever.

I've worn out a set of pads in about 2hrs before, but they were ceramic, it was in Wales and pissing wet and muddy, and I was riding enduro MTB.
I assume they're road pads, and single race means multiple days and mountain descents - otherwise that's just neglect.

Those brakes need setting up better too, if that's the brake wear coming from them. One pad fucked through the backing plate, the others overhanging the rotor? 👍

Seconded.
Have been using F1s and they’re great. Easy set up, easy adjustment, stop great. Going to try the gt4 version on my next build and have read they are even better performance wise. I think the gt4 use a slightly more available pad type so that is also a consideration for getting bit more choice of pads down the line

Some of us mechanics are also professionals in other fields. 🙄

Should’ve written ‘ride’ rather than race. They were brand new, ridden only on this year’s Tour of Flanders. Thankfully the callipers survived and worked fine for Liege-Bastogne-Liege, with sintered pads.

ToF also killed a set of new Cadex hubs, which took a bit but were warrantied in time for LBL. The new bearings felt fine.

That’s true, we do have a law degrees under our belt too.

Glad to confirm I’m not the only one.

Go new 12s generation 105 or above.
Or my most reliable caliper so far has been tiagra or grx 400 (same thing afaik). Don't burst pistons at anywhere near the rate of older calipers and don't have that insane silver screwdriver pin of death that shimano decided was sensible to fit

All of those white ceramic piston mtb and early flat mount road calipers are susceptible to piston failure. Usually tbh caused by folk putting wheel in and the rotor going behind pads and taking chips out of the ceramic material (or causes a stress fracture point), or pushing pistons back and getting them anything but perfectly straight in with a plastic tool = chips internally. Or very old heat cycled fluid causing piston to just disintegrate internally, either into powder (that travels to lever and kills it) or the piston separates into an inner and outer piece and you can't push it back.

Seen it literally hundreds of times. Just get a newer generation caliper, latest deore is fine, not had any issues with 2019> release date calipers other than usual screwdriver rammed in thr caliper damage.

Tell tale is despite a perfectly clean caliper, after some actual braking effort pada have a circle of fluid on back of them. Or you've got a damp crack between the caliper half's