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Bontrager Speed Limit rear brake problem.

Tuesday, July 29, 2014 by  
Filed under Daily Blog

July
29
2014

Since late last August I’ve put 15,000 kilometers on my 2013 Trek Madone 5.9, and I absolutely love this bike. I’ve also done all my own mechanical work on the Madone, and I find that it’s almost as fun to work on as it is to ride.

So, after nearly a year of ownership, 15,000 kilometers in its saddle and dozens of hours in my work stand for routine maintenance, I think I have a pretty good feel for my Madone’s strength and weaknesses. Her strengths are many, and her weaknesses are few. The 2013 Madone, simply put, is a phenomenal bike.

My only complaint with the Madone involves the rear brakes. The 2013 Madone 5.9 uses Bontrager Speed Limit integrated brakes, which are mounted under the chainstay. Trek’s decision to mount the rear brakes under the chainstay near the bottom bracket is supposed to provide some aero benefits, and there’s no question that having the rear brake under the bike provides a nice, clean aesthetic. Unfortunately I don’t feel these two marginal benefits outweigh the downsides.

The rear brake, thanks to its mounting location, is constantly exposed to water, mud, grime and everything else the road has on it. Because of this, the rear brakes require frequent cleaning and servicing. Too bad the brakes are such a pain to work on…

The bolts used for these brakes are prone to rusting, and their heads will round if you’re not extremely careful.

The pad centering screws are located behind the crankset, and while one of the screws can (somewhat) be reached at an angle through the crank arms, the cranks must be pulled for unfettered access to the screws.

The stock brake pads and pad holders are absolute garbage. I replaced the pads and pad holders with the excellent SwissStop FlashPro Elite Black Prince brake pads and holders very early on.

But the real problem–the one that has been driving me absolutely insane for quite some time–is that the rear caliper doesn’t full open after a brake squeeze. It’s almost like it is sticking.

Here’s the brake immediately after adjusting (click to enlarge, note the caption):

After adjusting and centering the Bontrager Speed Limit rear brake. Plenty of clearance, everything looks good. Note that the brakes are properly centered, the angle of the photo is why the right pad doesn't show clearance.

After adjusting and centering the Bontrager Speed Limit rear brake. Plenty of clearance, everything looks good. Note that the brakes are properly centered, the angle of the photo is why the right pad doesn’t show clearance.

 

Here’s the brake after one squeeze of the lever (click to enlarge, note the caption):

Bontrager Speed Limit rear brake after pulling the brake lever one time. Notice that the calipers have not fully opened, and the clearance between the brake pad and the rim is extremely tight. The brakes are still properly centered (the angle of the photo is why the right pad doesn't show clearance. )

Bontrager Speed Limit rear brake after pulling the brake lever one time. Notice that the calipers have not fully opened, and the clearance between the brake pad and the rim is extremely tight. The brakes are still properly centered (the angle of the photo is why the right pad doesn’t show clearance. )

 

When I grab the brake arms and apply just a little extra pressure, they open the rest of the way. The brakes simply will not automatically open the entire way after a lever pull. I’ve spent countless hours trying to solve this problem, and nothing is working. I’m not sure if I have a defective brake or what. Note that the front brake has never been a problem, and is very easy to adjust and service.

Also, know the following: I have the dealer service manual and dealer installation manual, I’ve replaced the brake cable and the cable housing, the housing is cut to the proper length, the cable and brake lever are silky smooth and operating normally, the brake arms have been thoroughly cleaned and greased (many times) and the brakes are properly centered.

I would simply replace the brake with Shimano Dura-Ace if I could, but they have clearance issues with the Stages power meter. So I’m stuck with the Speed Limit brakes.

Any thoughts or ideas?

John Stone Fitness Comments

4 Responses to “Bontrager Speed Limit rear brake problem.”
  1. Interesting. I know from the past that you’re very thorough, so I bet you’ve already walked through most of what I have to suggest. But here’s a shot:

    * First things first, locating the rear brake under the bike is a bad decision. Mountain bikes made this mistake years ago, and it will be just as ugly for road bikes. Imaging the people riding with salt on the roads? Fuggedaboutit!

    * I think the cable routing on your bike looks approximately like the image at http://bit.ly/1nXYefh.

    * You say that you’ve completely removed, cleaned, lubed, and reassembled the brake. No drag there, eh?

    * If you disconnect the cable and squeeze the brake by hand, can you replicate the “hang up?” If so, the problem’s in the brake itself. If not, look elsewhere. I’m tempted to think that the cause of the issue is split between the brake itself and the housing.

    * Pull the brake lever all the way with the cable disengaged at the other end. Now gently pull on the cable to see if it returns freely or if the cable has resistance. Front brakes tend to work “better” than rears because of shorter cables and less housing. Trek’s recent design change invites water to run down into the housing where both the cable and the housing will corrode and pick up gunk.

    * If you haven’t done it already, pull the brake cable out through the front of the brake hood — but not all the way ’cause it’s a pain to get back in. Any kinks in the cable? Rust? Take a few fingerfuls of light grease and work it into the exposed cable. Give any exposed housings a few squirts of light Park oil and let it run down inside. Slide the cable back down, work it back and forth a few times, and that may make the difference.

    * If you can shorten the bottom piece of housing and make a cleaner line for the cable, now’s the time. Less housing means less drag. (Doing this up top sucks because then you’ll want to do the other one to match.) Use an awl to make sure that the ferrule and housing holes are clean and open. Cutting brake cable can lead

    * In some cases the interface between the end of the cable and the brake itself can shift slightly so that the hole in the housing ferrule now causes the cable to rub slightly on the cable stop. You may even be able to see where the cable has been rubbing. Shortening the cable and the other steps may address this automatically.

    * I am not familiar with the brake itself. I found a manual using that Google Innernet thing, but it doesn’t look like there’s any way to adjust the spring tension in the brake arch or that there are any Allen adjustments for fine tuning the pads. Is this right?

    Any changes?

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    • Hey Neil, thanks so much for posting such a detailed reply. That’s some extremely solid information there.

      As you surmised, I have tried most of the things you’ve suggested above. Also, you’re correct that there is no spring tension adjustment on these brakes. There is a 2mm hex adjustment, but it’s used to center the pads.

      There was also some excellent information posted to Facebook in response to this article. Two of the guys I know personally: one owns Pure Cycles, a local bike shop, and the other is the head mechanic at Brick City Bicycles.

      So here’s where I am now. As I was tinkering in my shop, I pulled a little plastic piece that is, presumably, designed to keep crud from getting up into the cable housing. When I did that I noticed that the calipers sprung open a few mm. It’s still not perfect, but it’s much, much better. At this point it definitely seems to be a friction issue. I think the prudent thing to do is replace all the cables and housings. At the suggestion of Thomas from Brick City, I’m going to go with Gore and see if that helps.

      Here’s a picture of the bit I’m talking about. Also, thanks again for your awesome post. I’m sure that the information you provided will wind up helping countless people who find this article from searches!

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  2. Glad you found it and addressed the issue. Gore parts may do the trick. In the ideal world they would have a setting to change spring tension for the brake or the levers, but it would cost more.

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    • Yeah, I was very surprised that there was no way to adjust the spring tension.

      The problem is definitely still there, but at least I got thing to where my brake is not dragging now…

      If the new cable doesn’t do the trick, I’ll be taking the bike to the shop for warranty work. It could be the caliper is simply defective.

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