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Braking And Turn Entry Question


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I have been watching the twist 2 video a lot and everytime I watch it I catch something I didn't before.

 

A question I had was when your braking and setting up for your turn entry speed it says to be hard on the brakes and trail off. Does this mean get your hard braking done at your braking point and then using the rear brake to finish setting your speed before the turn entry?

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I don't go near my rear brake on track, in fact I don't go near it ever. What it means is that you build up quickly (i.e. a few tenths of a second, not snatching full power immediately) to your maximum braking force, then trail off the pressure on the lever as you get down to your entry speed, not the other way round which would be to start off with a little pressure and then build it up as you panic and realise you're not going to shed enough speed in time.

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The book explains that in more detail.

 

No rear brake.

 

The idea is to perform the gross reduction of speed first and then fine tune your entry speed.

 

Let's say, you have three seconds to reduce from 80 mph to 50 mph, which you know is your best entry speed.

Use the first second to go from 80 to 62 (reduction of 18 mph in one second) and the other two seconds to go from 62 to 50 mph (reduction of 6 mph in each second).

 

 

 

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Steve is cloest, IMHO.

 

If you go immediately from 0% to 100% braking force, tou are more likely to overload the front suspension and lock up the front wheel. Hence, you should make a moderated transition from no brakes to full brakes (consider slamming the brakes just as the front wheel goes over the top of a hill - a classic way of locking up the front wheel).

 

There are at least two reasons for making a calculated release of the brake: First, in order to allow the front suspension to do its work, and secondly to fine-tune the entry speed (going from max braking to zero braking usually tricks you into braking too much).

 

Hope this helps,

 

Kai

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I don't go near my rear brake on track, in fact I don't go near it ever. What it means is that you build up quickly (i.e. a few tenths of a second, not snatching full power immediately) to your maximum braking force, then trail off the pressure on the lever as you get down to your entry speed, not the other way round which would be to start off with a little pressure and then build it up as you panic and realise you're not going to shed enough speed in time.

 

 

 

Oh ok this makes sense, yea I could see a SR kicking in if you didn't trail off before the turn entry. Also my next question is braking technique, I use the two finger method but it's hard for me to get the timing down on clutch in- downshift- clutch out- twist throttle- brake- let off throttle and repeat. I hope the way I explained that makes sense. Also it would help if I had different levers to help with this but at this point I think it's more timing and understanding rather then blaming it on my stock lever being too far out.

 

This video shows what I am talking about from 3:13 to 3:17

 

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I do it whilst I'm braking, maintaining a constant pressure on the brake lever and twisting my hand down, sort of using my palm to twist the throttle for the blip. Takes practice, but is useful especially on track.

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I do it whilst I'm braking, maintaining a constant pressure on the brake lever and twisting my hand down, sort of using my palm to twist the throttle for the blip. Takes practice, but is useful especially on track.

 

 

 

Ah ok that helps me a lot, I was trying it the other way around. I was trying to blip the throttle and catch the brake lever.....thanks for the help! I will try that next time.

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I do it whilst I'm braking, maintaining a constant pressure on the brake lever and twisting my hand down, sort of using my palm to twist the throttle for the blip. Takes practice, but is useful especially on track.

 

 

 

Ah ok that helps me a lot, I was trying it the other way around. I was trying to blip the throttle and catch the brake lever.....thanks for the help! I will try that next time.

 

Do you have the timing down on the blip and downshift by itself, without trying to brake? If not, start there, so you can do it on a gradient without too many things going on at once.

 

Also, have you tried clutchless downshifting? If you already are able to blip and match RPMs, it's jsut a small step to downshift without the clutch. Would it be simpler to coordinate the downshifting and braking if you could eliminate the having to coordinate both hands and time the clutch on-off, and instead just worry about the brake and throttle blip?

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No I can't say that I have, I thought upshifting without using the clutch was fine but downshifting without the clutch was really bad for it? Or as long as you blip the throttle it wont be as bad?

 

As long as you blip the throttle to match RPMs it's totally fine. Do a search on this forum for clutchless downshifting and you can find threads where we've discussed this in some detail, and you can find some comments from Will who is the mechanic for the school and knows these bikes inside and out.

 

I do not use the clutch at all for upshifting or downshifting, and as far as I know all of the coaches use clutchless shifting all the time. I find that is faster and consumes a lot less attention.

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I do not use the clutch at all for upshifting or downshifting, and as far as I know all of the coaches use clutchless shifting all the time. I find that is faster and consumes a lot less attention.

For clutchless upshifting, I agree. But for clutchless downshifting, I have found that my R1 requires the engine to be at very low RPMs to make it work well (ie: getting the RPMs to match to avoid grinding the gears) - and that requires more time and attention than just using the clutch.

 

From my personal experience, I'd get the normal clutch operation and clutchless upshifting working well before trying the clutchless downshifting.

 

I seem to recall that Rainman said he only used clutchless downshifting when going slow too.

 

Kai

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Until you get the hang of blipping the throttle when changing down using the clutch, I wouldn't start yet on clutchless downchanges (which I personally don't like anyway). get it right and you can be pretty quick anyway to be honest. Check your throttle cable slack, too much and you have to exaggerate the blip to get the engine to pick up appreciably. It really is only a small, quick bit of gas that's needed.

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FYI braking and downshifting can be done as an off track drill at the school, getting a coach to help with the timing helps enormously. It can be coached with or without the clutch - but usually the best result is acheived clutchless, the shift tends to be quicker. However, when not using the clutch if the blip is not enough or the timing is off, it won't shift. It definitely takes some practice. It does seem easier to get the clutchless downshifts on some bikes than others, and it's a lot easier at low RPMs, since you don't have to blip it as much or as quickly.

 

On my bikes I've noticed that the EASIEST way to get a clutchless downshift (and mayeb a good way to try it the first time) is to be on the gas (at a low or moderate RPM), then click the shift lever the INSTANT you let off the gas. Works great on the street, but on the track that's often impractical because when going really fast you need to slow down BEFORE shifting (RPM is too high to downshift), so you let off the throttle, slow down some, then have to have a blip to match RPMs to get your shift.

 

Will recently built a neat training tool that has a gauge to monitor brake pressure during a blip, so you can measure yourself to see how steady you can keep the brake on during the blip!

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Same time; I try to think of my foot being connected to my hand so I move them both together.

 

Do you know WHY we need to blip the throttle to get a clutchless downshift? Anybody want to tackle that explanation, for the benefit of any readers that are unsure?

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The only guess I have is so you still have control over the bike and downshifting without blipping the throttle could jerk you forward transferring weight where it shouldn't go......kinda like going from half throttle to just completely letting off.

 

Only thing I can think of!

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Probably not the clearest explanation but:

 

When you are slowing down (and off throttle) the engine is braking and helping with the reduction of speed. In the gearbox there are two cogs meshed together, 1 connected to the engine and 1 connected to the road (via chain, sprockets etc). Since the "road cog" and "engine cog" are trying to move at different speeds they are pressed tightly together and thus make it difficult to change gear. When you blip the throttle you raise the engine revs and during this process the "engine cog" goes from trying to move slower than the "road cog" to trying to move faster than it. There is obviously a crossover point where the "road cog" and "engine cog" are trying to rotate at the same speed. During this precise, brief moment there is no load holding the two cogs tightly together and you can change gear with ease. Since you've also matched the engine speed to the road speed you won't lock up the rear wheel.

 

The opposite is true when changing up without the clutch - you briefly close the throttle instead of blipping it. This is because the speeds mentioned above are reversed in so much as the "engine cog" is initially trying to go faster than the "road cog" so we close the throttle to slow it down and remove the load binding the two cogs tightly together. If we left the throttle closed we'd end up in an engine braking situation so we open it back up again to match engine and road speed. All this happens extremely quickly.

 

If you press the gear pedal very lightly whilst blipping/closing the throttle you'll feel the next higher/lower gear engage at the precise crossover point where the load on the cogs is removed. Make the blip too slow or too large and you'll end up with a very jerky gear change.

 

I hope that makes sense - really easy to understand and really hard to explain! I purposefully avoided terms like "output shaft" etc.. in an a attempt to make the explanation nice and clear (as mud biggrin.gif ).

 

 

Dae.

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The only guess I have is so you still have control over the bike and downshifting without blipping the throttle could jerk you forward transferring weight where it shouldn't go......kinda like going from half throttle to just completely letting off.

 

Only thing I can think of!

 

Blipping the throttle is used to match the engine RPM from one gear to another. Due to the difference in gear ratios, when you shift from a higher gear to a lower gear, the engine RPMs have to be higher to maintain the rear wheel speed. Let's say you try to downshift (at a reasonably high RPM), using the clutch, WITHOUT doing a throttle blip -if you let the clutch out very quickly the engine speed in the new gear will not match the speed the rear wheel is traveling so you can get the rear tire chattering, chirping, or sliding as it is abruptly slowed down, and this also puts a heavy load on the tranmission, in the direction it is NOT designed to handle (slowing versus accelerating - you should use the BRAKES to slow the bike, not the transmission!). If you let the clutch out slowly the rear wheel will still slow down but not as quickly and you can eliminate the rear tire chatter; but it is still wear and tear on both clutch and transmission as they have to absorb the forces involved in matching engine RPMs to the new gear.

 

Most street riders tend to do a very slow downshift, holding in the clutch a relatively long time, so that makes the problem worse, as they are off the throttle and the engine RPM drops EVEN MORE while they have the clutch held in and the throttle off.

 

If you blip the throttle the correct amount to match the RPM you can smoothly downshift; so smoothly, in fact, that it will easily change gears without using the clutch at all, because you are taking the load off the transmission and it can click happily into the new gear. It is also easy to get a clutchless downshift if you accelerate, then let off the throttle and click the shift lever at the same time you let off (before the engine RPM drops and the bike starts slowing down) - that unloads the tranny and makes for an easy shift.

 

Per your post above, if you blip the throttle too MUCH, you can make the bike jerk forward a bit.

 

In my experience with my own bikes, for clutchless downshifts if you don't get the blip right, the bike simply won't downshift; but using a little bit of clutch (partially held in) and getting the blip wrong can result in grinding of gears.

 

Here is an article from Keith (in this forum, under Articles) about braking and downshifting:

http://forums.superbikeschool.com/index.php?showtopic=258

 

And here are some past threads about clutchless downshifting:

http://forums.superbikeschool.com/index.php?showtopic=2115

 

http://forums.superbikeschool.com/index.php?showtopic=3097

 

http://forums.superbikeschool.com/index.php?showtopic=2522

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That makes sense to me, so what speed/gear range would be good to practice this in that would offer some forgiveness to get used to the timing and the feel of it before risking locking up the rear wheel at say 50mph-60mph?

 

Thanks for the explanation!

 

I had good success at LOW RPM (maybe 30-40mph?) going from 4th to 3rd, acclerating a little in 4th then letting off the throttle and clicking the shift lever at the SAME INSTANT I let off the gas (no blip). At low RPM you are VERY unlikely to lock up your rear wheel, in fact in my experience if you are using clutchless downshifts is is VERY hard to lock up the rear ever because if there is that much load on the tranny it won't shift at all - personally I have never had the rear wheel ever lock up on a clutchless downshift.

 

After you are comfortable getting the shift with just throttle-off action, then go to a little higher RPM, let off the gas and let the RPMs fall a little, then do a small blip and downshift. I think you'll be surprised how smooth and easy it is, once you get the feel of it.

 

Once you get the timing figured out you can try it faster and at higher RPMs.

 

If you blip too MUCH you can get a forward surge, too LITTLE or bad timing and it usually just won't change gears.

 

If the timing is right the lever should click easily into gear - so DON'T put extra pressure on it to try to force it.

 

It's easiest at higher gears and lower RPMs. It's by far the hardest to do in first gear, most riders I know that use clutchless downshifts WILL use the clutch to go down to first gear.

 

Of course you would want to do this in a safe area (like a track or parking lot) since you will be thinking about your shifting instead of traffic!

 

Keep in mind you can get coached on this at the school, it is available as an off-track drill.

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That makes sense to me, so what speed/gear range would be good to practice this in that would offer some forgiveness to get used to the timing and the feel of it before risking locking up the rear wheel at say 50mph-60mph?

 

Thanks for the explanation!

 

I had good success at LOW RPM (maybe 30-40mph?) going from 4th to 3rd, acclerating a little in 4th then letting off the throttle and clicking the shift lever at the SAME INSTANT I let off the gas (no blip). At low RPM you are VERY unlikely to lock up your rear wheel, in fact in my experience if you are using clutchless downshifts is is VERY hard to lock up the rear ever because if there is that much load on the tranny it won't shift at all - personally I have never had the rear wheel ever lock up on a clutchless downshift.

 

After you are comfortable getting the shift with just throttle-off action, then go to a little higher RPM, let off the gas and let the RPMs fall a little, then do a small blip and downshift. I think you'll be surprised how smooth and easy it is, once you get the feel of it.

 

Once you get the timing figured out you can try it faster and at higher RPMs.

 

If you blip too MUCH you can get a forward surge, too LITTLE or bad timing and it usually just won't change gears.

 

If the timing is right the lever should click easily into gear - so DON'T put extra pressure on it to try to force it.

 

It's easiest at higher gears and lower RPMs. It's by far the hardest to do in first gear, most riders I know that use clutchless downshifts WILL use the clutch to go down to first gear.

 

Of course you would want to do this in a safe area (like a track or parking lot) since you will be thinking about your shifting instead of traffic!

 

Keep in mind you can get coached on this at the school, it is available as an off-track drill.

 

 

 

 

Cool thanks for the advice!

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Hotfoot,

 

I believe that your explanation works for bikes that have some mechanism to help the shifting of gears without using the clutch, like most modern sport bikes have.

 

For simpler bikes, clutch-less downshift can't work for the same reasons explained above.

Without a regular clutch, there is a solid transmission from crankshaft to rear wheel, any blip of the throttle will increase torque of the engine, and rpms' of the connected gears and wheel alike.

 

By clutching-in plus blip (old fashion way), the gear to be engaged (engine side) is accelerated to match the spinning speed of the wheel side gear.

 

I may be wrong, but clutch-less downshifting can't be accomplished for any old standard motorcycle.

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Sure you can. If the speed for the actual speed is 8913 rpm as you're slowing, bringing the rpm to 8913 rpm will freewheel the gears and it can be released without effort. The trick is to, in the split second when the gears are released and on their way into the next, lower gears, to bring the rpm to the exact amount required, which may be 10477 rpm. Also, in actual life you do not have to be quite as accurate since a bit of force will persuade the gears to move even with less than 100% perfect matching of rpm.

 

My biggest gripe against clutchless downshifts is that when, not if, you get it wrong for whatever reason, the whole drivetrain takes a hell of a beating, a beating that will be greatly lessened with the use of the clutch.

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