I’ve got a Cannondale CAAD12 105 with discs as my training / commuting bike.

Its 105 spec with Shimano BR785/505 Hydraulic callipers.

I replaced both callipers with the same ones this time last year as both were leaking. I’ve not ridden the bike massively since then as now working from home and ride my better bike during the summer.

Over the last month I’ve noticed that the front brake is lacking strength and makes an awful noise. It looks like one piston is moving a lot more freely than the other, so the rotor is getting pushed over to the other pad, rather than both pads squeezing the rotor.

I took the pads out, squeezed the lever to get the pistons out a bit, then worked them back in all the way with some plastic tyre levers, spraying a load of brake cleaner and WD40 in. Then loosened the calliper bolts and re-centred the calliper using a rotor spacer. But no difference, still hardly works and makes an awful noise.

Any thoughts on how to fix?

These brakes have been loads of hassle since I’ve had them, so if the solution is replacing them with something else that is fit and forget, what is it?

Thanks.

I’ve got a pretty similar problem, I’m on my 3rd set of calipers originally 105 ‘s now ultegras, but they all have the same problem, when I was commuting on the bike every day, they were faultless, I never gave them any attention they would get covered in roadgrime and mud and still work great, However then I stoppped commuting and am sometimes only riding the bike once in a few weeks, they squeel and lose power, after a few days of riding them they would be good again. I could ‘fix’ the problem by sanding the disks and pads to clean them up but the problem would be back as soon as the bike is left for a couple of weeks. I’ve got loads of barely used pads where I’ve tried different brands but I think the basic problem is that the calipers leak small amounts of fluid onto the pads/discs over time. I’m seriously considering binning them entirely and either going for Hopes or Clarkes, they don’t have to have endless stopping power, just work consistently, like every other brake I’ve had in the past.

spraying a load of brake cleaner and WD40 in

WD40 is not a great idea for brakes. I would not put it anywhere near my brakes.

You seem to have a sticky piston. I usually remove the pads and clean the caliper with warm water and dish soap, then carefully squeeze the lever to try to get the pistons to extend a bit. Then put a few drops of the appropriate brake fluid (mineral oil based fluid for Shimano brakes) onto the exposed piston and gently push the pistons back into the caliper. (If you have an old worn set of pads, fit these so you can lever a screwdriver between them to avoid damaging the pistons). Then gently squeeze the lever again to work the pistons out again, then push them right back into the caliper and clean it again with dish soap and warm water to get rid of any brake fluid. Then refit good pads loosen the caliper mounting bolts and refit the wheel. Then squeeze the level to apply the brakes and center the caliper, and then tighten the mounting bolts.

However then I stoppped commuting and am sometimes only riding the bike once in a few weeks, they squeel and lose power, after a few days of riding them they would be good again.

Most likely, the rotors are getting dirty just sitting there and you need to get them hot again to burn off the crud.

Most likely, the rotors are getting dirty just sitting there and you need to get them hot again to burn off the crud.

I used to get this with my fatbike if I wasn’t riding it for a few months between winters. The new one gets used more frequently so not a problem.

Probably a micro leak from the caliper given it’s Shimano. They don’t seem to like standing not doing anything for periods of time.

I’ve actually got the same bike as you and have been lucky so far – the calipers look a bit worse for wear from commuting in all weathers – but I haven’t lost any power yet. That said the road bike hasn’t been used much over lockdown as no commuting – just a few longer rides for fitness occasionally. So next time I ride it we’ll see.

I’d buy some Hope RX4 calipers to replace the Shimano ones if they are leaking.

+1 for the Hope RX4 calipers.

Replaced my Shimano RS785 calipers which used to drag and never quite sat quite right. Bolted on the Hopes and now a VERY happy camper. They provide slightly less of an on/off feel compared to the Shimanos and do not drag in the slightest even when drenched in cow muck, mud and water.
Note that this is on my Niner RLT running R7020 road shifters

I fixed my Shimano calliper issues with a pair of Hope RX4’s too. Worked fine since the day I fitted them. also upgraded to the Hope floating discs on my second wheel set…no real performance benefit noticed over the Shimano disks but look very nice!

Thanks for replies.

WD40 is not a great idea for brakes. I would not put it anywhere near my brakes.

You seem to have a sticky piston. I usually remove the pads and clean the caliper with warm water and dish soap, then carefully squeeze the lever to try to get the pistons to extend a bit. Then put a few drops of the appropriate brake fluid (mineral oil based fluid for Shimano brakes) onto the exposed piston and gently push the pistons back into the caliper. (If you have an old worn set of pads, fit these so you can lever a screwdriver between them to avoid damaging the pistons). Then gently squeeze the lever again to work the pistons out again, then push them right back into the caliper and clean it again with dish soap and warm water to get rid of any brake fluid. Then refit good pads loosen the caliper mounting bolts and refit the wheel. Then squeeze the level to apply the brakes and center the caliper, and then tighten the mounting bolts.

Thanks for all of that, I basically went through your procedure but used WD40/brake cleaner instead of soapy water and mineral oil. Both pistons came out and then retracted, but as soon as I was off the drive way they performed in the exact same way.

Sounds like I need to hope for a black friday deal on some RX4’s – post mount front and flat mount rear = £180 RRP.

I had the same and replaced with XT calipers , brilliant . Should have done it a lot sooner .

Yeah they aren’t cheap – but in the long run it’s probably worth it as it doesn’t take many pairs of Shimano to catch up with that price. Plus they look lovely.

Perhaps I should take the XT’s from my MTB and stick Hope’s on that?

I’ve got an Orange Clockwork Evo 29er on order that would really like a set of Orange Hopes!!

I have Shimano road discs on my crap weather bike that generally only get ridden in the winter. The bike is 5 years old and I’m on calipers 7 & 8 I think. It’s pretty shit but at least they’re cheap and easy to replace, I use Deore calipers which are usually about £25 and come with a set of pads.

I have Shimano road discs on my crap weather bike that generally only get ridden in the winter. The bike is 5 years old and I’m on calipers 7 & 8 I think. It’s pretty shit but at least they’re cheap and easy to replace, I use Deore calipers which are usually about £25 and come with a set of pads.

Cant you warranty them with that rate of failure?!

I had the same and replaced with XT calipers , brilliant . Should have done it a lot sooner .

I’ve been running xt calipers on my 105 levers for 5 years and not had any problems. (touch wood)

I remove the wheel and pads and push the calipers out as far as I dare. Then cut down a toothbrush and clean the calipers, I push them back, then spray with disc brake cleaner. Then run pull the brakes and push pistons back several times to make sure it’s worked.

If one side is lazy then I usually hold the other side and push that to free up the other side. Then re bleed the system with the pads all the way in.

Repeat If necessary