Brakes are feeling spongy

[Deleted member 20519]

I'm having a little trouble with my brakes recently where they feel spongy when I press them. I thought that it might be because the cables were getting frayed so I replaced the cables, lubricated the housing and adjusted the brake pads so they were an even distance away from my rims - no luck.

I quite like knowing that I could brake to the point of flying over the handlebars, now when I pull my brakes in so that they're touching the handlebars, it stops me but not nearly as quickly as it did when my bike was new.

Yes, I've tried new brake pads with no joy.

Any thoughts on how to fix this? I'm stumped!

 

[Deleted member 20519]

I should also mention that these are dual pivot brakes and STI shifters.

 

[Broadside]

I reckon you've got two options:

1) strip the calipers down for a thorough clean of the pivots and regrease, this involves complete removal and fully dismantling the caliper including all the nuts/bolts that hold the assembly together.

2) upgrade the calipers to something new as it might be the calipers themselves that have a bit of flex in them which is causing the sponginess

I did option 1 on my bike and it returned the brakes to feeling like new.

 

[RecordAceFromNew]

I'm having a little trouble with my brakes recently where they feel spongy when I press them. I thought that it might be because the cables were getting frayed so I replaced the cables, lubricated the housing and adjusted the brake pads so they were an even distance away from my rims - no luck.

I quite like knowing that I could brake to the point of flying over the handlebars, now when I pull my brakes in so that they're touching the handlebars, it stops me but not nearly as quickly as it did when my bike was new.

Yes, I've tried new brake pads with no joy.

Any thoughts on how to fix this? I'm stumped!

My theory as to why a brake system that had been working fine can feel spongy is that the pads are still not biting hard on the rim even when the lever hits the handlebar, so what is left stopping bike and rider is just the springiness of the housing.

While other causes are possible, the two main likely culprits are: a) excessive pad to rim clearance, and b) cable housing issue including poor ferrule-housing interface. In comparison inner cables don't stretch nor do decent forged calipers/levers have play or deflect by any appreciable amount.

For example Shimano recommends 3mm to 4mm pad to rim clearance in total for both sides, i.e. 1.5mm to 2mm at each side of the rim, which is hard to achieve unless your wheels are fairly true, with e.g. under 1mm wobble/buckle. What is your clearance set at?

When you said you replaced the cable did you check and replace the housing? The housing needs to be of reasonable quality and in a good state, the ends are cut straight well finished and not frayed, and that they fit snugly inside correctly sized ferrules.

Hope it helps.

 

[Biker Joe]

Contaminated wheel rims is my bet. Oil or grease maybe? Give the rims a good clean and see.

 

[accountantpete]

I'd go with BJ (nice initials!) and start by cleaning the rim and pads with a scouring pad and some fairy liquid. Then rub dry with a paper towel or two.

 

[RecordAceFromNew]

Contaminated wheel rims is my bet. Oil or grease maybe? Give the rims a good clean and see.

I'd go with BJ (nice initials!) and start by cleaning the rim and pads with a scouring pad and some fairy liquid. Then rub dry with a paper towel or two.

This ignores the fundamental problem of the OP's brake system setup. The OP said: " when I pull my brakes in so that they're touching the handlebars, it stops me but ..." - levers shouldn't be able to touch the handlebars. When the OP's lever touches the handlebars, his stopping power is no longer controlled by him.

 

[Biker Joe]

This ignores the fundamental problem of the OP's brake system setup. The OP said: " when I pull my brakes in so that they're touching the handlebars, it stops me but ..." - levers shouldn't be able to touch the handlebars. When the OP's lever touches the handlebars, his stopping power is no longer controlled by him.

Agree.

 

[Deleted member 20519]

I reckon you've got two options:

1) strip the calipers down for a thorough clean of the pivots and regrease, this involves complete removal and fully dismantling the caliper including all the nuts/bolts that hold the assembly together.

2) upgrade the calipers to something new as it might be the calipers themselves that have a bit of flex in them which is causing the sponginess

I did option 1 on my bike and it returned the brakes to feeling like new.

My friend was in a car accident a few days ago and his bike is trashed, he's offered me his set of Shimano 105 brakes for £30? Good deal?

 

[Deleted member 20519]

I'd go with BJ (nice initials!) and start by cleaning the rim and pads with a scouring pad and some fairy liquid. Then rub dry with a paper towel or two.

I'm actually getting new wheels tomorrow so I'll see what braking is like tomorrow, the rims will be nice and clean.

 

[HovR]

This ignores the fundamental problem of the OP's brake system setup. The OP said: " when I pull my brakes in so that they're touching the handlebars, it stops me but ..." - levers shouldn't be able to touch the handlebars. When the OP's lever touches the handlebars, his stopping power is no longer controlled by him.

+1 to this. If you can pull the brake levers to the bars then there's your pads are too far from the rims. Increase the tension in the cable with either the barrel adjuster or releasing the cable anchor screw and pulling the cable taught whilst you hold the brake calipers against the rims.

I've also found, especially with V-Brakes, that brakes can begin to feel spongy when the brake pads are getting worn. Replacing them may also help.

 

[Deleted member 20519]

+1 to this. If you can pull the brake levers to the bars then there's your pads are too far from the rims. Increase the tension in the cable with either the barrel adjuster or releasing the cable anchor screw and pulling the cable taught whilst you hold the brake calipers against the rims.

I've also found, especially with V-Brakes, that brakes can begin to feel spongy when the brake pads are getting worn. Replacing them may also help.

My pads are about 3mm away from my rims so definitely not far at all, my wheels are also true.

 

[HovR]

My pads are about 3mm away from my rims so definitely not far at all, my wheels are also true.

Wouldn't harm to try to bring them closer, as RAFN said above 1.5 to 2mm per side is the recommended distance, although 3mm isn't too far. Are you using shims in your levers to bring them closer to the bars? It might also be worth checking that all sections of outer cable are securely seated in their cable stops and ferrules.

Otherwise some pictures might help.

 

[Deleted member 20519]

Wouldn't harm to try to bring them closer, as RAFN said above 1.5 to 2mm per side is the recommended distance, although 3mm isn't too far. Are you using shims in your levers to bring them closer to the bars? It might also be worth checking that all sections of outer cable are securely seated in their cable stops and ferrules.

Otherwise some pictures might help.

I'll try bringing the pads closer & no I'm not using any shims in my brakes. What do you want me to take pictures of?

 

[HovR]

I'll try bringing the pads closer & no I'm not using any shims in my brakes. What do you want me to take pictures of?

Pictures of the caliper in an open and closed position may be of some use. In the past I've seen incorrect pad placement on the rim caused by wear give the brakes a spongy feel, although if you've just fitted new pads this may not be the case.