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Dealing with mid-corner bumps

Discussion in 'New Riders and Riding Tips' at netrider.net.au started by raven, Oct 27, 2008.

  1. This has been discussed on a past thread, but I thought I would bring it back, just to riase the awareness level a bit, at the suggestion of a fellow Netrider.
    Here's the orginal thread with some good info in it for newer riders, on how to deal with such things.

    https://netrider.net.au/forums/viewtopic.php?t=42422&highlight=bumps+corner+mid

    And having re-read that thread, it's full of really good advice.



    But it does depend on the bumps, and the rider needs to know how his bike reacts to those different kinds of bumps. Whether his/her front-end "chatters" over rough surfaces and "pushes" wide, or if it "lol's" around on the suspension and tries to "steer" wide.

    Either way...a rider will nearly always run wide. :)...But one version is from a suspension/tyre combination issue...the other is a suspension/rider combination issue.
    To erradicate THIS second one, you must be loose on the bars. It's the only way. If you're arms are in any way tight at the time you hit a bump, then as the bars come up to you, your leading arm will resist, and THIS will cause the bike to turn a little.

    The first version is harder to avoid since it is inherent to the way your suspension and tyres work. Just get to know your bike and how it reacts to different surfaces, and then ride your bike to it's strengths and weaknesses...Learn something from the way your bike "feels" underneath you at all times while riding.

    Going light in the seat and supporting your weight with your legs also helps a great deal, as Flux has alluded to in the past.

    Open for discussion...

    John.
     
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  2. i generally try to read the road, and pick my lines and speed accordingly.
    im quite used to noticing the slight contours of the road, from riding the pushbike everywhere.

    generally i dont have any issues with bumpy bits, i think it has pushed me wider at times, but not going at 100%, and just keep on taking the corner, the bike will ride it out.

    only once can i recall a major issue with a bump i didnt see. up just on the reefton side of cumberland junction, through the nice Esses up top after the ascent but before arriving at the junction, i was going hammer and tongs and loving it, really in my zone. then wham, at full lean, apexing on a lefty, the front slides out for a split second. absolutely no cotrol over it and no time to do anything, gladly it regripped moments later.

    i almost ran wide finishing the corner, i think SR's had kicked in a bit. on the brakes, do a u-ee, and go to check out wtf it was. turns out to be a slight indent about the area of two dinnerplates, looks like some old roadworks had sunk down a bit. it didnt cast any shadow along the contours, and i can barely see it whenever i ride through there now, i just know its there though.

    i think the front must have became slightly airborne/lost alot of upforce from the road, and thus began to slide out over the dint in the road. amazingly it grabbed back on once it reached the other side of the dint, and regained traction.

    but yeah, im a big believer of loose on the bars, and it will sort itself out generally. just pick an appropriate line and speed to begin with and tighten the sphincter not the arms if it gets interesting :grin:
     
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  3. good on ya for keeping loose, Robin..I think "yumps" like you found are the worst, if you have tight arms mate. :)
    John.
     
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  4. You've read my mind John, I was thinking about mid-corner bumps after last Thursday's mystery ride.

    We were out Bulla way, through narrower-than-usual roads with messy corregated bits on the edge, and I was taking things slower to stay in the middle of lane because my first reaction was the bike wasn't going to grip if it hit the bumps and I'd either low-side the bike or run too wide and onto the dirt. I guess my faith in the grip of the tyres and the suspension's ability to absorb the bumps isn't 100% there yet.

    I'm not stranger to momentarily losing traction (like going over an expansion joint in the wet with a bit of lean) where the bike just grips again and gets on with it, but the concept of hitting a bump and possibly losing contact on the front end makes me nervous when on the bike. But the forks should just absorb it right??

    Can anybody share some light on my noob ignorance? Did anybody else have similar experience in their early riding days?
     
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  5. I've ridden dirt bikes on bitumen before...plenty of bumps, and more than once i've been leaned over, gotten both wheels off the ground while leaned, landed and managed to hold it, at about 60kph.

    I imagine it depends hugely on what type of bike you have, what profile tyres you have, and how you react in the air.
     
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  7. ok off topic here sorry :p
    but check out the other video from that guy.
    bloke drops the clutch during a race start, and does some amazing dancing/dodging with the bike :shock: :shock:

    http://vids.myspace.com/index.cfm?fuseaction=vids.individual&videoid=499004

    back on topic, Dannyboy what i mentioned was a dip in the road, not a bump. kinda like a pothole, just its still bitumen and not roughed up, simply sunken down. as i was at a big lean angle, i dont think the forks could rebound adequately in the time there was due to the angle, and such traction was lost on the front end momentarily.

    its possible with a bump not a dip too, if they cant rebound quickly enough after the bump, the opposing upward force from the road is not enough to maintain proper traction. i can only assume this will sort itself out rather quickly, depending on the level of the bump/speed/forks etc. or it might have you come down.

    who knows. just ride safely, pick an appropriate speed and riding style for the road conditions, if you know the road this obviously helps immensely.

    what tyres do you have on the VTR?
     
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  8. I too had a similar experience. But I hit a rock while having the Hornet cranked over at a fair angle. The front slid out a bit

    I ran a little ride on the exit of the turn, but managed it to save it. I think being loose on the handlebar saved me from crashing.
     
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  9. Believe its all in the suspension.

    On the sports bike bumps have the ability to be fatal.

    I also ride a tourer and find the same streach of road with bumps is soaked up by the much softer front end.

    I'll stick to hard lean angles on a track where the surface is a known quantity
     
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  10. All suspension/tyre combinations suit certain conditions better than others, and each "package" has it's weaknesses and strengths...all effected by the rider and prevailing conditions. There is no perfect combination that covers all circumstances.

    The plan is to get to know your bike well enough so that you can better judge how it will perform in a given corner, with a certain type of bump mechanics.

    ie...For road riding...hitting a bump (a ridge higher that the prevailing surface of the road) is a test of your rebound. If it is slow then the tyre will have a tendency to skip a little bit as it is slower to get the tyre back down onto the surface. That millisecondwhen it has broken contact, and if you are in a corner, the fornt end will move across a little...hit a series of them, such as ripples, and if the ripples are bad enough to break front end contact, your front-end will chatter and move a little or alot.
    You can dial-in your suspension to a point by adjusting the dampening effect of the forks. You'll never get it perfect but you can make it better, assuming your suspension is up to snuff in the first place.

    The real problem is when trying to improve the front-end for one type of bump, it can often make it worse for others...so we are forced to find a middle ground that will do a reasonable job of all circumstances. THAT'S what the mfrs do, and is their idea of an alround good compromize of what they envision that style of bike will encounter...then we can make minor setup adjustments to suit our styles, but all in all, it can never be great for all situations, due to all the variables.

    Keeping the weight off the bars, allows the suspension to work unencumbered by our inputs and additional weight, allowing it to perform as best it can...so that's proably rule #1.

    John.
     
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  11. I've found what works for me is if there's a big dip/bump coming up mid corner I'll move in closer to the inside of the corner (tighter line) so that the bike exits where it normally would have without the bump.
     
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  12. Can happen if you hit a huge puddle going around a corner, aquaplane the bike, not fall over and recover with the front wheel slightly askew... Been there, done that, don't recommend it. I did manage somehow to stay on the bike and not crash the entire time though :shock:
     
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