Help with SRAM Guide R rear brake going away the longer the ride. LBS no help- Mtbr.com
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  1. #1
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    Help with SRAM Guide R rear brake going away the longer the ride. LBS no help

    Sorry to start another thread on this - the LBS seems to be at a loss.

    I have a brand new Specialized Rhyme...less than 2 months old. The rear brake has never worked correctly. LBS bled the brake and that did nothing. LBS did a warranty replacement of the brake and bled again. Still no progress.

    This is the issue: Brake works perfectly the first time I use it. I like my rear brake to really grab to get the back end loose so I can slid around a corner. As the ride progresses, the brake goes more and more away until I barely have any rear brake. When I do squeeze the rear brake, it makes a slightly squeaky hydraulic sound. Seems like I can adjust the little reach knob out and get a little brake back again, but it goes away just as quickly. I can't imagine the brake cable needs to be shortened when the problem comes and goes, so I'm thinking it's not a stretched out cable.

    As a side note, my husband has the exact same brake setup on his 2016 Santa Cruz Hightower and he has had no issues. I've tried his and they are perfectly "grabbie".

    Does anyone know (from past experience or reading) what might be wrong and how to fix it? I want to make these guys fix my brand new $3k bike. I love the bike otherwise, but this issue has me

    Thanks in advance!

  2. #2
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    Guides have had warranty issues with the lever assembly build tolerance issues. I had mine warranties for that. May want to check into that.

    On my rsc I couldn't get them to have any braking power forb the life of me until I replaces the internal piston on the lever. Pretty simple to do.

    Good luck


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  3. #3
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    Sounds to me like you have a rubbish local bike shop!

    I don't know what the issue is but with the bike in front of them they should be able to find it. Could be several things, although the symptoms are a little odd. SRAM brakes are notoriously problematic and one of their idiosyncrasies is seizing up when they get hot but the fault that causes this should be corrected on newer brakes.

    Contaminated pads or disks or a poor bleed can cause lack of power but the fact that it is consistently ok to begin with then fades does suggest faulty brakes. Bottom line is that you are fully entitled to take the bike to the shop and insist they fix it. I had one bike that had numerous faults and I was back to the shop loads of times. They were great. No arguments, they just cheerfully sorted out every problem on the bike.

    I'll be honest, I wouldn't have SRAM brakes on my bike. I don't know what they heck their malfunction is, it goes way back to the very first hydros made by Avid (now SRAM), but they just keep feckin it up. Maybe this issue has nothing to do with the brakes themselves. It is certainly in line with the piston design fault but as I said, that should be fixed now. I'll be interested to hear what it is.

  4. #4
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    I am experiencing a similar issue with my guide rear brake fading after an hour or so of riding. It never fully goes away, but it gets really mushy and the lever can be pulled almost to the bar. For me, the lever felt ok when I first got the bike, but it was definitely a bit mushy from the start compared to other hydros I've had.

    I got the bike from Competitive Cycles online, so they are sending me a bleed kit. I asked them if it could be any other issue, and they said it sounds like it's probably air bubbles in the system. I'll try a bleed and let you know how it goes.

  5. #5
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    Hope that works for you, kpdemello. Didn't work for me. Your issue sounds very much the same as mine.

    Spoke to the LBS again today. They don't think it would be the piston since they replaced everything with the warranty replacement. I'm leaving the bike with the bike shop early next week for the lead mechanic to ride so that he can feel what's happening and hopefully know what to fix after he rides the bike.

  6. #6
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    Quote Originally Posted by onebratt08 View Post
    I can't imagine the brake cable needs to be shortened when the problem comes and goes, so I'm thinking it's not a stretched out cable.
    Since the Guide Brakes are Hydraulic, I'm a little confused by this statement.

    Brake Fade can be caused by excessive heat. So do you get the bite back after you haven't ridden for awhile? Also, check the spacing between your brake pads and rotor. Is there a gap on both sides without touching the lever? Lift the back end of the bike off the ground and give the rear a spin. Does it spin freely for a long time, or stop within a few seconds? If your LBS didn't use a bleed block while bleeding, then your pads might be too close to the rotor. Which could increase heat buildup.

    I doubt this is the problem, but worth mentioning. Is your LBS using the Shimano bleed method or the SRAM method? Are they making sure to remove the bubbles from the fluid in the syringes before attaching them to the bike?

  7. #7
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    Thanks, OneBratt. Did they replace the caliper, the lever, or both? It would be very strange if they replaced the lever and the caliper and you were still having the same problems. It does sound like maybe they are not bleeding correctly.

  8. #8
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    I think they replaced only the lever.

  9. #9
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    It sounds to me like air in the caliper. These rear brake calipers on newer bikes are mounted so that the bleed port is below part of the caliper, making it difficult to get the air out of there without shifting the caliper's position while bleeding.

  10. #10
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    Did my bleed today and it helped a lot. There was enough air in the system that I am surprised it had worked at all. Took it out for a spin and the rear brake is much more consistent now.

    The lever still doesn't bite as quickly as I'd like. Is that because I didn't pressurize it enough at the end? I did squeeze the lever syringe at the end until it felt fairly stiff, but in removing that syringe and replacing the bleed port screw a fair amount of fluid escaped.

  11. #11
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    Did you remove the air from the fluid before bleeding?

    You can also rotate your lever up so the bleed port is horizontal to the ground to help prevent fluid escaping when removing the syringe.

  12. #12
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    Yes Mike, I definitely did. I followed this guy's instructions pretty closely:

    https://www.youtube.com/watch?v=Oid_MTcW1P4

  13. #13
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    Update: took my pads off to try to move the pistons and accidentally blew one out. Looks like I had up to 3 stuck pistons. Lubricated, put back together, bled and now the back brake feels like the front one.

    Damn, that's annoying on a brand new bike.

  14. #14
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    My Guide R brakes were ready for the bin until I checked the pistons; three out of four in the front caliper were stuck. I got them moving freely and I'm back to one finger braking.
    We have no idea how long the bikes sit on the LBS floor before we buy them. Fork foam rings go dry, brake piston seals go dry…
    Almost = Didn't

  15. #15
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    Quote Originally Posted by slomtbr View Post
    We have no idea how long the bikes sit on the LBS floor before we buy them. Fork foam rings go dry, brake piston seals go dry…
    But they shouldn't. I can leave a bike in the shed over the winter and have no problems with the brakes at all. A friend had Avid brakes, bike was stored on a brick garage built into the house. Fine when he put the bike away, locked solid in the springtime. It's not acceptable. Other manufacturers can get brakes right, why can't SRAM?

  16. #16
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    Yeah it looks to me like the dont lubricate the pistons before shipping or something because mine seemed to be bone dry. Maybe something about the assembly process is flawed.

    I just did 2 hours of dh park riding though and my guide r's were solid. I'm satisfied now.

  17. #17
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    Well here's another update. It appears the little rubber plug that fits in the bleed port of the caliper doesn't like long car rides, as mine apparently fell out during one. Any ideas on obtaining a replacement? Besides tape.

  18. #18
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    I have an update as well. Rode this past weekend and it seems I was able to adjust the lever so that I had more brake and it seemed to hold. It's not an ideal position for me, but I can still reach it. The trail I was on doesn't require as much brake, so tomorrow I will be taking it out on the local trail with several long and fast downhill sections.

    I can't really understand why moving the reach distance from the handle bars around would help the problem. Maybe I'm the problem. Brake still does make a screechy hydraulic sound from time to time - is that normal? I'm not so familiar with new bike technology, especially these hydraulic brakes.

    On the piston thing, I mentioned it to the bike shop and they got angry and said the lever is new (but so was the last one). I'm guessing they didn't look inside the new lever to make sure everything was lubed up. I guess if I still have issues, I will try lubing the pistons as a next step. The bike shop also suggested a larger rotor on the rear wheel. I compared my bike to my husband's and indeed his has a larger rotor (but the same brake set-up otherwise).

  19. #19
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    onebratt I meant the piston in the caliper, not the lever. If you take your brake pad out and look at the caliper, you might be able to tell that one or more pistons are sticking out more than the others. If that is the case, one or more of your pistons in your caliper might be stuck. Apparently that is not an uncommon thing with new SRAM brakes, but the problem is usually easily solved by lubricating them with brake fluid.

    This is definitely something the LBS should be looking at. If the problem isn't in the lever, and it probably isn't since they already replaced that, it is probably in the caliper. I would ask them to check the caliper for stuck pistons, maybe even have them take the pads out and let you inspect the calipers with them to see. If they are getting mad at you, get mad right back and tell them how frustrated you are that you bought a new bike that isn't working right. The back brake should work just as well as the front brake.

    Screechy hydrolic sounds are not normal, and usually only happen when the brake pad is wet or when there is contamination or uneven wear or something like that. If one of your calipers is stuck, and therefore force is not being evenly applied to the brake pad, it can cause screeching.

  20. #20
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    Glad I came across this thread. My rear was giving me issues even after a bleed, and both of my non drive side pistons were stuck! After a little dot lube and bleed, now they are money. Annoying though.Help with SRAM Guide R rear brake going away the longer the ride. LBS no help-img_0428.jpg

  21. #21
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    Thanks kp.

    I rode over the weekend and had the same problems. Spoke with SRAM yesterday and they said they suspect the same thing that you are saying (pistons sticking). They asked me to insert the brake spreader and see what happens. I couldn't really see a visual difference, but I took my bike out for a ride today and things were much better. Maybe not exactly what I like, but my brake was more reactive and didn't go away as the ride went on.

    The other thing they told me to do is keep the lever dialed out pretty far from the handlebars. This is what I've found helps as well. Again, not the ideal position for my small female hands, but I can reach them plenty fine.

    Now the question is, do I take the bike back to the LBS and make them make sure that everything is lubed up properly in the caliper? I'm thinking I will ride it a few more times and see if it gets worse again before doing that (although I realized yesterday that they never gave me the flat pedals that came with my bike and for a new bike with no discount, I think I should be receiving all the parts that came with the bike).

  22. #22
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    Yeah I am still fiddling with mine because I still feel like there is a lot of lever throw before I get a really good bite, but it is consistent and powerful. I'm finding that I have to keep the reach adjust dialed farther out than I would like (I have short stubby fingers). I kind of wish I had the RSC's that have bite point adjust but R's are what came with the bike so all I have is reach adjust.

    Interestingly when I pull the lever and watch the caliper I find that even the slightest lever pull moves the calipers, and the calipers start out pretty darn close to the rotor. That means these things do have incredible modulation, but the penalty for that is much more lever throw before you get a hard grab on the rotor.

  23. #23
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    I'm glad you don't ride like this in our part of town

  24. #24
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    I'm seeing the exact same thing, kp.

    Rode yesterday and rear brake still is improved. I could dial the lever out a bit more, but I think I can work with it in it's current position.

    Thanks again to everyone for the advice!

  25. #25
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    UPDATE: SRAM replaced my rear caliper and it didn't do a thing. I got a second opinion from another bike shop, which I found to have technicians with some pretty extensive training. They told me that there is a specific process they do when they first get a bike with these Guide brakes in (something about rubber banding the lever to the handlebar overnight to set the pistons). We don't think the original bike shop did anything like this. They said they could try it, but that they had never done it on already used brakes, and that the cost would approach just buying new brakes. So I emptied my wallet and put Shimano Deore XT brakes and rotors on the bike. I wish I had gotten a second opinion sooner.

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