Poor braking..

turbo1191

hi folks..i have a couple of bikes with Tiagra 4700 and Tektro dual pivot brakes on them. stopping power is pretty poor and brake never seems to return properly. I replaced the cable outer, inner and new cable and also replaced pads with Ultegra.. The braking is still not great, i even tried a new Tektro unit thinking this may be the problem but still it seemed (sticky) when returning.. Anyone got any idea's? :?

imposter2.0

Poor return is probably due to the cable run. Difficult to diagnose that without seeing a pic of it..

Andymaxy

Old springs most likely. The spring may not be strong enough. Try cleaning the whole brake and cover the spring with some grease.

The cheap Tektro brakes are usually not stiff enough, on my training bike if I pull on the brake I can see the caliper flexing, the definitely mean a loss of power. Maybe get some 105 calipers.

imposter2.0

Not sure what 'covering the spring in grease' will achieve - apart from making a mess. The springs are unlikely to be the issue and a change of calipers will simply be a waste of money. Ironically, I just fixed a 5800 caliper which was not returning properly, by shortening the cable run. There is far more potential for friction within the cable run than anywhere else - and if the caliper is not returning fully, then that seems the obvious place to look.

turbo1191

I had thought that the only other thing it could be was cable run. I used the older cables as template's for the newer ones.. I just can't recall if the braking was that poor before.

slowbike

If you think it's cable run - disconnect the cable, hold onto it with your fingers - apply the brakes - then see what friction there is as you try and pull the cable back ...

as a rule of thumb - the tighter the bend or longer the run, the more friction there will be. Obviously, the cable will need to go through a bend and be long enough to reach the brake - so it's a careful balance to make it a smooth enough bend without making it too long. Remember though - it's easy to trim a cable or outer ... not so easy to put more on ...

fenix

My tektros were pretty good. Never had a problem with them.

Andymaxy

Imposter wrote:

Not sure what 'covering the spring in grease' will achieve - apart from making a mess. The springs are unlikely to be the issue and a change of calipers will simply be a waste of money. Ironically, I just fixed a 5800 caliper which was not returning properly, by shortening the cable run. There is far more potential for friction within the cable run than anywhere else - and if the caliper is not returning fully, then that seems the obvious place to look.

If grease doesn't serve a purpose, shimano wouldn't cover their new caliper's spring in a layer of grease.
Some cheap tektro calipers flex a lot, if you pull in the brake and you see flex, you know it's not the most efficient brake. I switched from a random tektro caliper to 105 and it worked so well.

imposter2.0

Andymaxy wrote:

If grease doesn't serve a purpose, shimano wouldn't cover their new caliper's spring in a layer of grease.

Indeed. It's there as a surface protectant, while it's in the box. It serves no mechanical purpose.

captain_tiara

Disconnect cable - do brakes spring back ok?

Y>cable issue N>brake caliper issue, as per Slowbike above.

I have found that if the cable outer is too "firm" , especially on that last elbow into the caliper, the spring wont spring freely. Took me ages to work out the cause of intermittent brake rub once.

david7m

If you've fitted new outters, have you crushed it when cutting and it binding on the inner? If so, easiest way to fix is fold away the offending piece back with long nose pliers, small screwdriver etc.
Dont use a grinder as the heat melts the inner coating on the outter
Dave
(too many inner and outter references )

kingdav

I had poor return on some older tiagra calipers and considered replacing them, but they'd just seized up a bit. Taking them to bits, cleaning the bits and lubricating the parts that move made them all nice again. It's reasonably easy to tell if that's the problem by undoing the cable clamp and check the action with no cable resistance

I finish cut wound brake housing ends with a file, takes a few moment, but you can get a nice flat end to ensure the outers have fixed length and it also removes any burrs which might compromise free movement of the cable. My cable cutters always seem to leave a sharp 'tongue' on the wound metal part.

svetty

In the original post the OP says that stopping power is poor. Assuming the rims are OK and given that he has swapped to decent pads the likely remedy is new calipers. 4700s would do fine although the new R7000s should be better when they are available in a week or two.

figbat

I wonder what stopping power is being expected? I have some Tektro calipers on my Synapse and they pull me up no problem at all from the hoods. Perhaps pad alignment needs sorting out?

keef66

Rim brakes ain't complicated things. Even cheap Tektro calipers can provide perfectly good braking if they have decent cables and the calipers are properly adjusted and lubricated, and the rims and brake blocks clean.

If my old 4500's started to lose effectiveness I would take off the blocks and sand them clean and flat, and clean up the rims with a bit of emery cloth. That alone would make a huge difference.

And then I had the chance to snap up some nearly new 5800 calipers. Mainly for vanity because the colour better matched the bike, but paired with my older 5600 levers they are astoundingly good. How much is down to the metal cartridge holders vs all-in-one moulded blocks, or the stiffer calipers, or better mechanical advantage I don't know, but I nearly went over the bars when I first tried them.

Anyhoo, the fact you say that 2 different calipers don't return properly suggests a cable issue with yours, so I'd try to sort that out first.

Bumo_b

Halfords/Cycle Republic sell Miche calipers for £25 quid at the moment. Great for the money and good stopping power if set up correctly.

turbo1191

Thanks for all the replie's. I trimmed some length of the cable outer's and it seems to have solved the problem.. as many had suggested it was a process of elimination, but as i'd used the originals as a template i thought it would have been right..