Rear Braking Problem?

[Deleted member 89023]

Hi all, I've noticed my rear brake lever has recently become "spongy" and isn't as effective at stopping the bike. It has moved closer to the handlebars and despite adjusting the lever, there is still little resistance. The obvious answer would be worn pads, but changing them hasn't solved the problem. The brakes work when up on the stand, but not when under weight and there doesn't seem to be a hydraulic leak. The bike is a Trek Xcaliber MTB 2019. Any advice would be greatly appreciated. Many Thanks.

 

[Jody]

First would be a fluid change and re-bleed if spongy.

Did you clean the disc and scotch the surface when replacing the pads?

 

[Deleted member 89023]

First would be a fluid change and re-bleed if spongy.

Did you clean the disc and scotch the surface when replacing the pads?

I have cleaned the cleaned the disc many times. I forgot to add that the rear brake also squeals when the lever is pulled. Scotch?

 

[Ming the Merciless]

Spongy is a symptom of air in the hoses. Bleed the brakes and will be good again.

 

[Deleted member 89023]

Spongy is a symptom of air in the hoses. Bleed the brakes and will be good again.

Straightfoward job?

 

[Ming the Merciless]

Straightfoward job?

You’ll need a bleed kit , and suitable brake fluid, but if you’re reasonably mechanically sympathetic it’s a quick job, perhaps 15-30 mins. I replaced a calliper and bled my front brake just last week.

Do you know the make of brakes you have ?

 

[Deleted member 89023]

You’ll need a bleed kit , and suitable brake fluid, but if you’re reasonably mechanically sympathetic it’s a quick job, perhaps 15-30 mins. I replaced a calliper and bled my front brake just last week.

Do you know the make of brakes you have ?

Shimano Deore.

 

[Ming the Merciless]

Shimano Deore.

In which case you want mineral oil. You don’t need much per bleed, no more than 50 mL. But it works out cheaper long run if you buy the bigger containers. Then you want to get a bleed kit. I have an epic bleed kit but others are available. They come with instructions or you can watch a you tube video.

 

[Ming the Merciless]

A bleed kit

• Two syringes
• Flexible plastic tubing
• One syringe mounts into holder to keep it vertical when screwed into lever bleed port
• Calliper piston spacers (yellow blocks)
• 7mm spanner to undo bleed port on calliper

 

[Ming the Merciless]

A 1ltr container of mineral oil

 

[Deleted member 89023]

A 1ltr container of mineral oil

View attachment 675507

Thank you. I will give it a go.

 

[Deleted member 89023]

Success! I did it! It took me a while (over an hour) and I probably used a little more mineral oil than needed, but my bike now stops on a sixpence. Thanks @Ming the Merciless & @Jody.

 

[Jody]

Scotch?

Probably a local term but to rough the surface up using a scotch pad or abrasive.


Anyway, glad you've sorted it

 

[Ming the Merciless]

Success! I did it! It took me a while (over an hour) and I probably used a little more mineral oil than needed, but my bike now stops on a sixpence. Thanks @Ming the Merciless & @Jody.

Well done. You get quicker with practice. Just bleed them when you notice it getting spongy again. Note this is not the same as more lever travel but still firm, which is usually a sign the pads are reaching their limit before replacement.