Results 1 to 13 of 13
  1. #1
    RoadBikeReview Member
    Reputation:
    Join Date
    Mar 2018
    Posts
    3

    Road Bike Rear Brake Spongy and Rough

    My road bikes rear brake is spongy, rough, and hard to pull. I have a Diamondback Podium 4 carbon bike with internal cable routing and the brake has been crap from the first day I bought it. It has Shimano 105 shifter/brake levers.


    I thought that maybe the cable housing was too long or getting hung up in the body so I replaced both the front and rear brake housings and cables with Shimano brand cables and housings. The front brake improved but the rear brake is still terrible and I can't for the life of me figure it out. On top of that now the rear derailleur is extremely hard to push up to the next gear with the lever which boggles me since I didn't touch either of the derailleurs cables or housings.



    Does anyone have any idea what might be the problem? I know it's not the brake pads or the wheels.

  2. #2
    RoadBikeReview Member
    Reputation:
    Join Date
    Dec 2006
    Posts
    3,867
    I'd try, just for test purposes, to run full housing from the lever to the rear brake OUTSIDE of the top tube. Test it in the stand and see if it feels better. That will tell you something.

    Before you run the test, remove the cabling and squeeze the lever to see if there's any resistance with no cable connected. Then squeeze the brake caliper by hand to see if it's binding.

    Are you sure you're using BRAKE housing for the brake and not derailleur housing? After you cut the brake housing, you should file the end of the spiral wound housing so that it's nice and flat, with no burrs. A bench grinder is a godsend for this task, although I use a regular file and a little patience.

    Once you solve the brake issue, we'll try to address the change in derailleur performance.

  3. #3
    RoadBikeReview Member
    Reputation:
    Join Date
    Mar 2018
    Posts
    3
    Yes I purchased a Shimano brand brake cable and housing set.

    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    I had clean cuts and ground the ends smooth using my angle grinder. I will check the lever for smoothness under no cable load. I do have a feeling it may be something in the top tube. The bike has an internal sleeve in the carbon fiber top tube so I didn't have to do any cable fishing. I have had the thought that maybe they screwed up this internal tub when they cast the carbon frame but am not sure.

  4. #4
    RoadBikeReview Member
    Reputation:
    Join Date
    Mar 2018
    Posts
    3
    Also the shifting was fine before hand. The only thing I did was remove bar tape and tape holding the cable down to the bar. Then replaced the tapes. How would that cause the new extreme difficulty in pushing the level up a gear?

  5. #5
    RoadBikeReview Member
    Reputation:
    Join Date
    Dec 2006
    Posts
    3,867
    I don't have an answer to the shifting problem-yet. That's why I want to solve the braking issue first-I'm stalling for time!

  6. #6
    Los Barriles, BCS, Mexico
    Reputation: DaveT's Avatar
    Join Date
    Feb 2004
    Posts
    1,422
    Quote Originally Posted by Stockfoot13 View Post
    Also the shifting was fine before hand. The only thing I did was remove bar tape and tape holding the cable down to the bar. Then replaced the tapes. How would that cause the new extreme difficulty in pushing the level up a gear?
    A possibility is that you may have wrapped the bar tape too tightly, which could distort the shift cable housing and cause your issue.
    Trying to cram the rest of my life into the rest of my life!

  7. #7
    RoadBikeReview Member
    Reputation: velodog's Avatar
    Join Date
    Sep 2007
    Posts
    7,053
    When you retaped the bars could you have altered the shift cables in such a way as to cause it to bind?
    Too old to ride plastic

  8. #8
    'brifter' is a lame word.
    Reputation: cxwrench's Avatar
    Join Date
    Nov 2004
    Posts
    13,170
    Quote Originally Posted by DaveT View Post
    A possibility is that you may have wrapped the bar tape too tightly, which could distort the shift cable housing and cause your issue.
    You're kidding, right?
    I work for some bike racers
    I've got some bikes, some guns,
    and a bunch of skateboards

  9. #9
    Los Barriles, BCS, Mexico
    Reputation: DaveT's Avatar
    Join Date
    Feb 2004
    Posts
    1,422
    Quote Originally Posted by cxwrench View Post
    You're kidding, right?
    Nope. I made the assumption perhaps in error, that the OPs bike might be fairly new and have the shift cables under the bar tape. Years ago I installed the then new 6700 shifters and very tightly wrapped my bars. The bike had terrible, sluggish shifting until I untaped the bars and miraculously it shifted perfectly. I changed out the housing that was underneath the tape and less vigorously retaped and itís been perfect ever since.
    Trying to cram the rest of my life into the rest of my life!

  10. #10
    RoadBikeReview Member
    Reputation: velodog's Avatar
    Join Date
    Sep 2007
    Posts
    7,053
    Try pinching the calipers together so the brake cable is slack and them apply the brake lever. If still sluggish I would think cable or lever issue but if smooth operating I would assume caliper issue.
    Too old to ride plastic

  11. #11
    'brifter' is a lame word.
    Reputation: cxwrench's Avatar
    Join Date
    Nov 2004
    Posts
    13,170
    Quote Originally Posted by DaveT View Post
    Nope. I made the assumption perhaps in error, that the OPs bike might be fairly new and have the shift cables under the bar tape. Years ago I installed the then new 6700 shifters and very tightly wrapped my bars. The bike had terrible, sluggish shifting until I untaped the bars and miraculously it shifted perfectly. I changed out the housing that was underneath the tape and less vigorously retaped and itís been perfect ever since.
    Sorry, but there's no way that more tightly wrapped bar tape will have any affect on shifting. There has to be something else that caused that. I wrap shift and brake housing as tightly as I can w/ electrical tape then wrap the bar tap very tightly so it won't slip. Never had a problem related to that and I'm talking thousands of examples. No way you can 'smash' housing w/ tape.
    I work for some bike racers
    I've got some bikes, some guns,
    and a bunch of skateboards

  12. #12
    RoadBikeReview Member
    Reputation: velodog's Avatar
    Join Date
    Sep 2007
    Posts
    7,053
    Quote Originally Posted by DaveT View Post
    Nope. I made the assumption perhaps in error, that the OPs bike might be fairly new and have the shift cables under the bar tape. Years ago I installed the then new 6700 shifters and very tightly wrapped my bars. The bike had terrible, sluggish shifting until I untaped the bars and miraculously it shifted perfectly. I changed out the housing that was underneath the tape and less vigorously retaped and itís been perfect ever since.
    I would guess that the housing shifting when you tightly taped the bars is what caused the cable drag.
    Too old to ride plastic

  13. #13
    RoadBikeReview Member
    Reputation: Lombard's Avatar
    Join Date
    May 2014
    Posts
    7,451
    Quote Originally Posted by velodog View Post
    I would guess that the housing shifting when you tightly taped the bars is what caused the cable drag.
    Or an inadvertent kink in the cable/housing somewhere.
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

    ďStatistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.Ē -- Aaron Levenstein



Similar Threads

  1. Stiff frame = rough ride...how rough are we talking
    By rs_herhuth in forum General Cycling Discussion
    Replies: 15
    Last Post: 03-29-2012, 05:43 PM
  2. Cane Creek 200TT levers feel spongy
    By f3rg in forum Components, Wrenching
    Replies: 5
    Last Post: 10-15-2009, 03:22 PM
  3. Are Northern Marin/Sonoma road too rough for road bikes?
    By max_n in forum Northern California
    Replies: 5
    Last Post: 07-25-2009, 07:59 PM
  4. Sheldon Brown/Spongy Brakes
    By S2H in forum Components, Wrenching
    Replies: 13
    Last Post: 07-21-2006, 05:49 AM
  5. spongy shifting
    By greyghost in forum Components, Wrenching
    Replies: 1
    Last Post: 12-07-2004, 09:41 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

THE SITE

ABOUT ROADBIKEREVIEW

VISIT US AT

roadbikereview.com and the ConsumerReview Network are business units of Invenda Corporation

(C) Copyright 1996-2018. All Rights Reserved.