Braking bumps, how to prevent & fix.....- Mtbr.com
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  1. #1

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    Braking bumps, how to prevent & fix.....

    Hi guys,

    I'm involved with trail work at a Park in outer Melbourne Australia. We have good relations with the Park managers & have been slowly improving the trails over time. Most of these trails were never planned & built, rather just formed by riders over time. We have made some trail re-alignments but a few problem remain.

    I have 2 questions for the trail building gurus here;

    Are braking bumps & ruts caused by poor trail design & layout or to be expected with heavy MTB traffic?
    The Park gets a lot of MTB traffic & some sections of trail are badly affected by braking bumps.

    How do I fix the bumps?
    I can only re-route the trails so far. It is possible to improve the flow a little into bumped out corners but mostly I have to keep the same alignment. I was thinking if the trail must stay in the same place I need to dig out the bumps, improve drainage & re-lay a harder surface, bringing in rock if possible?

  2. #2
    JmZ
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    It's a pet peeve of mine too. Smoothing down the bumps help out in the short term, but that doesn't even last a season under decent use.

    You've already covered some with putting in some more resistant material (i.e. Rock), but using some of larger rocks might be used to help choke down the trail and slow down the riders.

    Most braking bumps I've seen have come when someone is coming into a corner pretty hot and stands on the brakes. After just a little bit you'll get a pretty good section of braking bumps. If you can slow down the riders earlier, and more gradually, you'll have less braking bumps.

    Good luck,

    JmZ
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  3. #3
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    Braking bumps seem to form in two places, where a turn comes up unexpectedly or where a high-speed section ends in a tight curve. The unexpected turn problem can often be fixed with just a sign warning of the upcoming curve. The turn at the end of a high-speed section requires slowing down the riders before they get to the curve. Using rocks to pinch down the trail or to slalom around can have this effect. Sometimes the obstacles only need to be visual to have the desired effect. A gap cut in a large log across the trail can be as wide as the existing trail tread and still dramatically slow down rider traffic.

  4. #4
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    Ideally you want to design a trail so riders don't have to use their brakes...you can direct the riders slightly uphill before the turn to slow them down or widen the turn so they don't have to brake as much or make the turn into a berm so no braking is needed.

    We've made alot of mistakes regarding this problem and you definitely do not want any sudden turns after a fast section.
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  5. #5
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    Solutions

    Here in Florida we have braking bumps usually, as stated above, after a long fast section with a tight, blind turn or after a steep drop to tight turn.....we usually handle this problem most of the time in two ways.......one is to superelevate the turn to handle the speed as in berm it....and the other is to cut brake lines and cables at the trail head during friendly, distracting chit chat.
    IF YOU CAN READ THIS, YOU'RE NOT RIDING (or building)!

  6. #6
    Cleavage Of The Tetons
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    Rerout trails wherever possible to be under 7% grade, 5 is best.
    Agreed, use the terrain to slow riders naturally...it also provides more 'G-out' opportunities.
    Good luck!
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  7. #7
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    Well placed chicanes can be created without doing a huge reroute. Pick a spot where the riders have to navigate the chicane before they can get going too fast. Another issue can be sight lines just before those turns. If you can clear out some of the brush on the side of the trail to expose the turn, then riders can see it coming and hopefully scrub off some speed more gradually. Or a combination of the above. But to answer your question, I believe it is a result of trail design that allo9wed for long straights followed by sudden sharp turns that require heavey braking. Can you post some pictures to give us a better idea of what the terrain looks like?


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  8. #8
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    All good suggestions and comments. Braking bumps were not an issue before suspension became common.

    Grade reversals before tight corners work for both speed control and drainage (and can make the trail feel swoopier) but are not always possible.

    If the reroutes or chicanes can not be installed, armoring the tread may be the only solution. Rocks and/or porous paving blocks imbedded in the trail like is used on moto trails.
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  9. #9
    Cleavage Of The Tetons
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    Shiggy, I dunno...I remember braking bumps long before suspension on popular trails.
    Personally, I would credit it to the increase in ridership as the sport has become more mainstream as much as the additional speeds attainable by riders equiped with suspension and disc brakes.
    Just my .02!
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  10. #10
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    New question here.

    I had to look up chicane to see that they are roughly sweeper turns to slow vehicles down or allow passing at the end of a straight away in racing.

    There are a couple trails I ride that have pretty bad braking bumps on sections of the trail that aren't really steep. One trail has a series of horseshoe curves back and forth across the fall line with no chicanes or obstacles before the corners. The other trail has this downhill stretch that weaves back and forth in a series of lose "S" turns. Both trails have soil that gets very powdery as it dries out.

    Both trail sections are in places it would be hard to get armoring materials to, so it sounds as if re-alignments that didn't allow folks to pick up so much speed would be the way to go.

    As an aside, I've read that once highway pavement starts to get rough, that very roughness causes trucks to bounce, accelerating the pavement breakup. I wonder if the same is true on bike trails, that is, once you get a bump or hole near a braking spot, it causes the bikes coming through to bounce on their suspension as they brake, further gouging the trailbed...

  11. #11
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    Quote Originally Posted by HarryCallahan
    I had to look up chicane to see that they are roughly sweeper turns to slow vehicles down or allow passing at the end of a straight away in racing.

    There are a couple trails I ride that have pretty bad braking bumps on sections of the trail that aren't really steep. One trail has a series of horseshoe curves back and forth across the fall line with no chicanes or obstacles before the corners. The other trail has this downhill stretch that weaves back and forth in a series of lose "S" turns. Both trails have soil that gets very powdery as it dries out.

    Both trail sections are in places it would be hard to get armoring materials to, so it sounds as if re-alignments that didn't allow folks to pick up so much speed would be the way to go.

    As an aside, I've read that once highway pavement starts to get rough, that very roughness causes trucks to bounce, accelerating the pavement breakup. I wonder if the same is true on bike trails, that is, once you get a bump or hole near a braking spot, it causes the bikes coming through to bounce on their suspension as they brake, further gouging the trailbed...

    You could be right about that.

    Harry, I don't mean to be snoopy but you say you are from Felton. Is that the Felton near Santa Cruz? The conservation corps I work with is starting up a second headquarters in Santa Cruz. I'm finishing up a trail project in a suburb of Phoenix this week and then taking some time off. I hope to go out and visit the new members in Santa Cruz in the near future. I'd love to get a close up look at your trail system, if it is nearby. Maybe even ride it. Maybe we can even find a way for our crews to help you do some of your trail work. Just a thought.


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