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Shimano Tiagra calipers sticking

by sergius
Mon, Apr 06, 2015 21:16
11

Hi All,

I noticed over my last couple of rides that my rear brake caliper isn't working properly, essentially it seems to have gotten slightly corroded and the spring no longer has the required force to push it back open fully.

The brake works (it separates just enough not to rub) , but the action feels fairly nasty (the first part of pulling the brake lever does nothing, until it reaches the point where the spring stopped). I was limited on time today to do much about it other than trying to apply some lubricant which did nothing - and I'm away on holiday from tomorrow with a Sportive on the Saturday - so I don't want to break something beyond repair without a chance of getting a replacement.

Once I'm back though, has anyone seen this before on the low-end Shimano calipers? The bike has done around 2.5k miles over around 1.5 years so it's fairly new still. The front caliper is just fine - it's only the rear that is effected.

I'm more than happy to have a go at stripping it down, cleaning/greasing and rebuilding the caliper (but not just before a sportive!) - has anyone had any success doing this on a Shimano caliper? It's a £13 part, I'm not sure whether it's entirely worth it - I could get an Ultegra replacement for £30 anyway. I've a new toy with hydraulic disks arriving in a couple of months so this bike is soon to be relegated to my winter steed - so the amount of miles it will do will be drastically curtailed as I'm mostly a fair-weather rider. I don't think it's the cable - all the other cables on the bike move just fine and you can see the caliper is failing to spring apart.

Thanks for any advice,
Cheers,

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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11 comments

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therevokid | 9 years ago
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several levels of shimano over the years have all done this until ... mud guards
got fitted. keeps the salty grime away from the brake (back is the worst affected
for obvious reasons).

yes i know "mudguards make my bike look shit" ... but saves a few bob too 3

Avatar
sergius replied to therevokid | 9 years ago
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therevokid wrote:

several levels of shimano over the years have all done this until ... mud guards
got fitted. keeps the salty grime away from the brake (back is the worst affected
for obvious reasons).

yes i know "mudguards make my bike look shit" ... but saves a few bob too 3

Form over function I'm afraid!

I'd rather replace the calipers every couple of years than fit guards!

Avatar
Stef Marazzi | 9 years ago
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I've got 2010 "thumb shifter" Sora on my Caad 8, and just swapped the Cannondale own brand callipers out for 105 5800 callipers, the braking is awesome now, only £24 each from either wiggle or CRC. Dont spend too much time or money on your old ones, the new 105 brakes are awesome and work amazingly well.

Avatar
ChuckB | 9 years ago
0 likes

This should help ease some of the confusion

http://www.celebrazio.net/bicycling/shimano_compatibility.html

Avatar
sergius | 9 years ago
0 likes

That's a useful link, thanks.

Yeah, it has the bolt to the side of the fixing bolt which is a bit corroded. After the weekends' sportive I'll have a go at dismantling it.

Does anyone know if a 105/Ultegra caliper is compatible with a Tiagra STI?

Avatar
mrmo replied to sergius | 9 years ago
0 likes
sergius wrote:

Does anyone know if a 105/Ultegra caliper is compatible with a Tiagra STI?

From mixing all sorts over the years, you may not get the "best" performance but it will work.

Avatar
mrmo | 9 years ago
0 likes

I can't remember what a tiagra looks like, is there a bolt to the side of the fixing bolt? what happens in the winter particularly is that salt corrodes the bushing on which the arm rotates. Basically what you need to do is dismantle the whole caliper and clean it, doesn't always work. If you see corrosion gentle sandpaper it awy, then grease all the pivots before reassembly.

What I did do on an old set of Campags was loosen the pivot bolt which helped in the short term.

http://www.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/BR...

I know it is ultegra, but it is close enough to guide you if you decide to strip them down. It isn't hard, just watch the spring can be a pain sometimes.

Avatar
sergius | 9 years ago
0 likes

As I said it's not the cables.

The Calipers themselves appear corroded around the nuts. With the cable entirely slackened off it's a two hand job to pull the calipers apart to the full range of their motion.

Avatar
climber | 9 years ago
0 likes

Agreed about the cables. I bought a Genesis with Tiagra kit, the brake 'action' was rubbish ( I should have taken it back to the shop straightaway, didnt cos I was enjoying the ride), the movement was not smooth at all. First thing I did was putting GT85 down the inside of the cables which made things better. Then I changed the outers and inners, problem solved. I worked out it was the cables after disconnecting the brakes and moving the calipers by hand which was smooth. Also while the brake cables disconnected I made sure the lever movement was smooth (which it was).

Avatar
2 Wheeled Idiot | 9 years ago
0 likes

Sounds like it could be a cable issue to me, remove, ran and degrease the rear brake cable and check for corrosion, this should fix it.
If not completely remove the brake caliper. Then remove brake blocks and deep clean the caliper, getting all the inside faces and cycling the calipers through their range of movement. This will reveal lots of well hidden nooks and crannies that attract dirt.

Avatar
sergius | 9 years ago
0 likes

I was just looking on Wiggle, is the stuff around leverage ratios saying that you need to match the caliper to the STI - i.e. ultegra shifter for ultegra brake?

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