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Discussion Starter · #1 · (Edited)
I have always thought that berms slow you down but I was thinking about it the other day and I had some other thoughts. The reason that we slow down when going up hill is because of the gravitational pull. When we take a berm we are being pulled toward the ground but not back like if we were going up a hill. So why do we slow down? I know that berms slow you down but can someone explain why?
Lets say you rail it and you're at a 90 degree angle would you still lose speed?


does anyone understand what im trying to say?
 

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Glad to Be Alive
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berms make you go faster.....it is a banked turn. if the turn was flat then you would have to slow down to negotiate the turn.....with banking the berm holds you inline so you actually go faster....

a perfect example would be Nascar track Martinsville....there is no banking in the turns so you have to slow down to 40 or 50 and then excellerate in the straitaways.....then there is Talladega where the banking is like 35 degrees....guys were going so fast that they put things on the carbs to slow them down (restrictor plates) mostly guys run around the track with foot on floor the whole time and don't use brakes in corners because the banking holds them in the corner
 

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how did i know SMT would poke in with a nascar analogy? i just misjudged thinking he would post a pic of himself dressed like the rainbow warriors
 

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local trails rider
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Anyway, SMT's explanation - er - explains berms pretty well IMO. Some guys with skills, apparently, manage to exit a berm faster than they enter.
 

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SJensen said:
how did i know SMT would poke in with a nascar analogy? i just misjudged thinking he would post a pic of himself dressed like the rainbow warriors
3 championships in 4 years and barely missing the other one was a great run....would love to see the old gang back.....but chad takes care of jimmy and ray is running his own show.

Go Gordon
 

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l think it sure feels like you speed up in a berm... maybe why l often feel like l want to fly off the top of the ridge if l don't maintain total control.

how's about getting air vs staying on the ground? l have heard in motorcross, 'they' would rather be on the ground BUT there there's an engine to push you faster.
 

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WaveDude said:
Pump berms like you would rollers and bowls. Berms are just horizontal versions of them. Ride a pump track sometime--berms can help you keep or build your speed.
While this is true, one thing that urbody is forgetting is that when you go around a berm, you have to LEAN. I've seen too many riders hit a berm too slow because they were still more or less all the way upright.
I've heard from several riders that first go around a berm that leaning feels uncomfortable.
If that's the case, they need to get over that fear quickly, or they'll never be able to ride them.
Per SMT's NASCAR (in other words...BORING) reference, some of the banked turns on some of those tracks, a person could not even stand straight up on them, and a few of them, you couldn't even climb up. So if you were riding a bike on one of those turns, fast enough to stay on it, you will be more or less 'on your side'.

So yeah, you do pump into a berm like you would a pump track, but you also have to lean away from, and carve into the berm in order to keep your speed.
 

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Pedal Shop said:
how's about getting air vs staying on the ground? l have heard in motorcross, 'they' would rather be on the ground BUT there there's an engine to push you faster.
come on SMT what you say? I think biking would be faster inthe air but then again you wouldn't be rolling own the hill.

(left handed srry)
 

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MTB_prodigy said:
does anyone understand what im trying to say?
ummmmm, maybe, or maybe not....

One thing about berms, especially big, steep ones is that there is a significant elevation difference from the inside line to the outside line. For a downhill berm, or for someone who is railing it, the elevation change probably doesn't matter. But as an intermediate rider who is trying to work up more nerve in the corners, maybe I get what you are saying because sometimes I think about things too much.

If you come into a turn slowly and take a low line, you may still feel fast.

If you come in slow and try to get up on a higher line, you may feel like the bike is stalling out because you are forcing the bike higher in elevation and keeping it there longer. This is fighting gravity.

If you come in faster, the bike will have more momentum to keep it from stalling, you will also be on the berm for less overall time, you will have more centrifugal force holing you on your line, you probably also have some better pumping technique so you can make it work for you.

It is all potential energy and kinetic energy. The more elevation you gain, the more you slow down, but that energy is stored and ready to be released the next time the bike is pointed down. Think about wallrides, it is all about technique and speed. To get on the wall you need the right technique, to take a high line and really ride it, you need to commit with a lot of speed, otherwise you will stall out, lose centrifugal force and you won't stick it.

Or imagine a quarter-pipe. It is just a berm that you ride at directly, you lose speed as you go up, there is a moment where you a basically stopped (no kinetic energy, all potential energy). Then, with the right technique, you will roll back down into the transition, and if you pump it, you will finally roll out the bottom with more speed than on the approach (back to full kinetic energy).

Maybe the kinetic energy changing to potential energy is what you are talking about, maybe not. At any rate, not many people will agree with you that a berm actually slows you down, after all, the whole point of a berm is to carry more speed (and help to transfer potential energy AND pump into even more speed, depending on the berm entrance/exit/gradient, etc, etc...)
 

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Discussion Starter · #16 ·
no one understood what i was trying to say



I knokw berms are faster than taking a flat turn



BUT if you take a berm and you and the bike are at a 90 degree angle why do you slow down if gravity is pulling you down and not back.
 

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SS FR HT
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Its easier to break a frictional force then the force of gravity in this case. The berm keep maintains the angle of the rider and the ground without that to corner your weight would over come your traction or friction on the ground aand you would crash. Or in other words the berm keeps a you and your bike in a perpendicular plain with the ground, this produces a greater amout of surface area thus creating a greater frictional force. Gravity is also a factor but you forward momentom is counter-acting the gravitational force. Gravity is such a small factor in this situation. more surface area is created by the tire as a result of your momentom. The forward momentom might also be lost with bad control of your body over the bike. You have to pump in and out of the berm. So energy is not lost in your body movement.
 

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The whole idea of any banked turn is to transform the lateral gravitational pull into vertical gravitational pull. Since bikes/riders can handle more vertical G's than lateral G's, it would make sense that you could carry/generate more speed using a berm.

I think what you might be experiencing with "Slowing down" is the fact that suspension and dirt friction slow you down, which is true. But if you hit something like a pavement bowl on a BMX bike you would go super fast.
 

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Raptordude said:
The whole idea of any banked turn is to transform the lateral gravitational pull into vertical gravitational pull. Since bikes/riders can handle more vertical G's than lateral G's, it would make sense that you could carry/generate more speed using a berm.
They didn't teach me that at SJSU. :(
 
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