Shimano Tiagra rear brake caliper: Brakes apply OK, but won't release...

[Mazz]

I changed the rear brake pads on my Allez last night. I thought it was all OK, done it many times before.

When I was riding to work this morning, I applied the rear brakes which worked, but then it was really hard work on the pedals - I dismounted and tried to spin the rear wheel, but the brake pads were jammed against the rim.

In order to free the wheel, I had to manually prise the "jaws" apart and flick that switch thing to increase the gap a bit more (I used the front brake only for the rest of the journey).

Maybe the springs in the caliper need oiling?

It just seems odd that this started happening when I changed the pads.

Thanks

 

[All uphill]

Did you adjust the brake cable length after inserting new pads?

Maybe it's time for new brake cables?

 

[Mazz]

Did you adjust the brake cable length after inserting new pads?

Don't understand the question.
Do you mean did I tighten this up correctly?

 

[Paulus]

Were both blocks hard on the rims, or just one? Are the calipers centred correctly.
As above though, the cables could need cleaning or replacing as there may be corrosion or some fraying inside the outer cable housing.

 

[Paulus]

Don't understand the question.
Do you mean did I tighten this up correctly?
View attachment 729352

When you but new blocks on, because they are wider, the cable has to be slackened off , either at the knurled nut above your arrow, or the clamp below your arrow has to be loosened to allow a little more cable through to allow for the new blocks.

 

[Mazz]

Were both blocks hard on the rims, or just one? Are the calipers centred correctly.
As above though, the cables could need cleaning or replacing as there may be corrosion or some fraying inside the outer cable housing.

One block was more hard on the rim than the other.
As for the caliper, with some finger pressure it will swivel a bit to allow me to even out the gap between the pads/rim.
Does the fact that it will swivel a bit, mean that it needs tightening more? I tightened the hex bolt round the back last night, but the caliper will move when you put manual pressure on it.

 

[PedallingNowhereSlowly]

Rightly or wrongly, I usually tighten calliper brakes so they will move with firm pressure applied to either side of them, so I can easily centre them to make sure the braking force is evenly distributed across both sides of the rim (the rim should not move too to the left or right when the brakes are applied - otherwise you can get uneven rim wear).

I don't know what the torque spec is for the calliper bolt but I can't imagine it's that high anyway. I know some callipers are fixed with a knurled washer to stop them rotating. Also find you can only tighten them up so much anway without rotating the calliper off axis, no matter how much opposing force you apply.

I'd unfasten the cable and make sure it's moving freely - there's no resistance when the brake is applied and it can be pulled back out to it's full extent when you let go of the brake. Then I'd connect it back up, making sure the cable adjustment screw is screwed all the way in, and then backed off a just a couple of turns (means you can slacken up the brakes on the move if a wheel goes slightly out of true).

Then I'd get the calliper centred and then hold it in place before fastening up the calliper bolt to whatever the recommended torque spec is.

 

[T4tomo]

orange to fine tune the overall gap, yellow to centre the gap

go twiddle

 

[Paulus]

I tightened the hex bolt round the back last night, but the caliper will move when you put manual pressure on it.

You may of overtightened the hex bolt so that it is stopping the calipers from moving freely. Back off the nut a small amount, not so much that the assembly wobbles about, and then centre the calipers and see how it goes.

 

[Mazz]

View attachment 729361

orange to fine tune the overall gap, yellow to centre the gap

go twiddle

Twiddle I shall!

 

[13 rider]

Have you attempted to strip and clean the caliper it may just be gunked up and you may have only noticed it since the new pads as the limited spring return is now noticeable . Had a non returning Shimano caliper on my defy good clean and all good , good videos on you tube ,check your tools I think I need a torx key of some size

 

[Mazz]

Have you attempted to strip and clean the caliper it may just be gunked up and you may have only noticed it since the new pads as the limited spring return is now noticeable . Had a non returning Shimano caliper on my defy good clean and all good , good videos on you tube ,check your tools I think I need a torx key of some size

Hi, No I've never cleaned the caliper in all the time I've had it (bought bike second-hand 6 years ago) so it must be well overdue.
Is it easy to separate into its individual parts? Easy to reassemble?

 

[fossyant]

Check you've aligned the pads to the rim correctly, and it's not getting stuck. As for centering a brake, either use the adjuster grub screw or, use a cone spanner on the reverse side of the brake, near the bridge, and slot the spanner in the back and adjust.

As for checking operation. remove wheel, disconnect the cable and see if the calliper moves freely when you squeeze it together. If not, give it a good GT85 (remove the pads first) and give the calliper a good clean.

 

[Dogtrousers]

I'd unfasten the cable and make sure it's moving freely -

This is what I'd do first. If it's sticking then replace the cable. If not, commence random twiddling and fiddling.

 

[Mazz]

This is what I'd do first. If it's sticking then replace the cable. If not, commence random twiddling and fiddling.

Good call - I'll do this first before I even think of dismantling the caliper (there will be springs and screws flying all over the place)!