Rear Brake issue Levo 2019 COMP

[Maastricht]

Hi all,

Short question, I ride a Levo 2019 COMP manufactured by Specialized at 21st of July 2018.

I live in The Netherlands where we normally ride on hilly terrain (not mountains) this summer I have been riding near Garda Lake and Livigno Italy. During intense downhill rides I had at least 4 times zero braking power in my rear brake which is a SRAM Guide RE, 4-piston caliper, hydraulic disc, 200mm.

After cooling the brakes with water pressure came back and I could continue my ride. After that ride I visited a local Specialized dealer and bought new sintered brake pads. I replaced them before I went to Livigno.

By the way Livigno is one of the most beautiful bike areas I have ever been. I rode the Tutti Frutti track (10 times with the cable car up the mountain) twice on one day: Real bucket list experience!

Coming back on the brake topic, also there braking power was a few times zero and unpredictable when it could happen. I understood afterwards most likely the reason will be related to "vapor lock" where water in the braking fluid near the caliper starts to cook, due to the gas in the brake line the brake fluid is not able anymore to push the pistons onto the brake pads. I am only wondering if the brake fluid of a bike which is manufactured about a year ago could already have this issue. I found it pretty dangerous to be honest especially because it's very unpredictable.

Any thoughts or advises of other forum members?

 

[khorn]

It does indeed sounds like water contamination in your brake fluid. Every time I change pads I also change fluid in the system. I have long ago ditched the RE’s as I found them inferior and unpredictable.

Karsten

 

[KenX]

Used to happen to me on my DH bike to begin with, definitely caused by dragging the rear brake on long descents. Pour water on the rear caliper and the brake came back, tried new fluid, same result. Started getting more confidence in the front end and using the front brake more and the problem went away........

 

[Lockey8]

If you have exceeded the boiling point of the fluid it will need changing, new fluid 100%

 

[Mikerb]

Definitely change the fluid but maybe also think abkut your braking technique. If you drag the rear brake on long descents you will build up a lot of heat. Use both brakes together and cadence brake. I set my front brake lever travel closer to the bar than the rear which helps to apply the back brake slightly before the front when using both brakes.

 

[Maastricht]

Thanks for your thoughts and advise!

I guess it's a combination of braking technique (after first ride when it happened more frequently) I tried my last ride to brake much more on the front. Despite my efforts it still happened but less frequently in the last ride. I guess a ride of 3000 meters downwards in one go, needs a lot of braking and causes heat in the system. Only surprised that braking fluid is loosing it's original boiling point that quickly. Again bike is manufactured in July last year and I bought it in November so expected everything to be fine. Also wasn't aware about the phenomenon before so when I suddenly lost all rear braking power I was very surprised.

I will ask my LBS to change the fluid next time. Funny, also the shop mechanic never heared about this and was highly surprised one could have zero braking power due to this issue. I believe we live in a too flat country...

 

[Webike]

Interesting article in Pink-Bike regarding resin pads:

When running these pads with smaller rotors, they will "manage" the heat better, meaning your oil is less likely to boil, which would cause a loss of power.

Brake Pads - A break down of what you need to know - Pinkbike