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-   -   Downshift to pass? Could someone explain? (https://cbrforum.com/forum/riding-skills-88/downshift-pass-could-someone-explain-139299/)

Oli 06-15-2012 03:06 PM

Downshift to pass? Could someone explain?
 
Hi All,

I've been getting some solid advice on here, thanks so much! I have another question. I came across a previous thread where a commenter mentioned downshifting to pass another vehicle, or for instances when you need that extra oomph to avoid something. Is this if you're in 6th only? Sorry if this is a dumb question, I had until seeing that assumed the higher the gear, the more power/speed available to you. Could someone explain this? I've tried looking for other threads about it, but can't find anything.

I'm still new and not planning to try this anytime soon, just want to understand it. Thanks!

regener8ed 06-15-2012 04:43 PM

the rpm's suited for cruising are not the same rpm's best suited for acceleration. this applies universally, not just to motorcycles -- ever notice when you floor an automatic car that it downshifts? there's 2 reasons: 1) the power curve for motors gives greater power at the higher end of the rpm band 2) the lower gear's ratio provides a better rpm-to-final-drive ratio for quick acceleration.

Kuroshio 06-15-2012 06:28 PM

Or in Texan English: my f4i pulls harder at 11k rpm than 5k rpm.

So say im cruising at 7k rpm in 6th and need to get outta dodge fast. I have 2 choices:
  • Go wide open throttle and climb to 11k rpm
  • Drop down a gear or 2 and instantly land around 11k rpm

Oli 06-16-2012 10:34 AM

Awesome thanks guys. That does make sense. And I've felt that in my car, but never actually paid attention to the cause of it.

I'm going to try that in a parking lot and see what it feels like! There's a big flea market parking lot near me that's abandoned mid week - it's been great for practicing :)

313racing 06-20-2012 08:58 PM

with an inline 4, i like to always be at least 5K rpms on the street. easier to get out of situations.

jurgs2007 06-30-2012 01:09 AM

look at it this way... if you take off from a stop in first gear, you get up to speed pretty quick.. but if you try to take off in second, or even third, it takes a whole lot longer to get there.

and yes... i do occasionally take off in second or third when ive got a cop on my rear, as my exhaust is a bit loud when i get above 5k. and i also double shift then too.

Oli 06-30-2012 08:09 AM

I've tried taking off from a stop in second gear once by accident because I didn't realize I hadn't downshifted all the way to first. I stalled it of course. I didn't realize you could actually take off in second without stalling it. Maybe I didn't give it enough gas as I let the clutch out?

I haven't had a chance to try the downshifting to get into the powerband yet but I did get a little feel for it by accident the other day. I downshifted as I was coming up to a street to turn off onto and I think I was in fourth. When I shifted to third I felt it surge and the rpms shot up toward the redline. Is that basically it?

jurgs2007 07-01-2012 07:17 AM

well, if you were off the throttle when you felt the surge, and it made you slide forward into your tank, then you just experienced engine braking. downshifting while slowing down is another way to slow your speed faster with less use of the breaks. but you still always want to remember to use your brakes so people see your brake light and know you are stopping.

heres another thing to try.. find a straight stretch with little to no traffic.. get your bike to a steady speed. have your bike at your normal cruising rpms, and then try to take off. note in your head what you felt... next, get back to the same speed you were at before, and then downshift just 1 gear and try to take off again. note the difference you feel that time from the first time. you will feel the bike pull forward harder and accelerate faster. after you try that, you will have pretty much answered your own question.

please keep in mind that if you dont feel comfortable with taking off hard, dont open up your throttle completely right away. take your time, try it a few times giving it a little more throttle each time as you get used to it.

...and if you are inexperienced, when downshifting, always wait until the bike is completely in gear and you are off the clutch lever BEFORE you give it throttle .. or you may end up on the ground with your bike continuing its way down the road on its own, or with your bike on top of you.

grendl 07-01-2012 02:30 PM

Hey. You have been given some good advice. i'll add a little maybe to help better understand. Our inline 4's develop torque at a higher RPM than off idle. The two cylinder - some V4's have their torque right off idle. Ours typically don't you have to move up in RPM to get the full dose. Torque is what pulls weight immediately.This is over simplified, but gives you an idea. So figure you are in 6th cruising around 4k rpm. your max torque may be at around 6k or higher.you want to immediately go faster, ? Downshift and turn it on. Your RPM goes up, putting you in the sweet spot of the torque for your bike, you will immediately accelerate. Assuming you have experience on your bike,try this. find an empty stretch of highway cruise in 6th,twist the throttle now go down one gear and turn it on. Go a step further and start at the same cruising speed in 6th,go down two gears and hang on !! Couple of things, don't redline your bike !! What I mean is dont go down to 2nd be careful in third, just try the two down for the sake of seeing what happens
Now the inverse same stretch of clear highway cruise in 6th go down a gear without twisting the accelerator you will probably slow down. Some bikes are geared close in the 5th and 6th, do 5th first then downshift to 4th you should definitely slow down. Useful in slowing the bike but if you do this with out thinking you or go down too many you can slide you rear tire.Useful in making corners - practice this first. In the curves you match engine speed as you go down the gears this again puts you at a higher engine speed with immediate torque to accelerate out of the curve.I also use the downshift technique to come to a know stop light or sign, staying in the appropriate gear to my speed. I don't get to a stop in 6th. That way if there is an emergency and you need to get out of the way or accelerate around you are in the spot for torque an immediate speed. I STRONGLY SUGGEST YOU PRACTICE THIS ON AN EMPTY - CLEAR STRETCH OF ROAD AT SPEEDS YOU ARE COMFORTABLE WITH ( SLOW). THE NEWER BIKES WILL COME ON RIGHT AWAY WITH UNEXPECTED WHEELIES OR BURST OF SPEED IF YOU ARE NOT CAREFUL !!.Dont punch out of a corner in a low gear until you know what you are doing The modern 600s are no joke - a liter bike needs a cautious and experienced hand at the controls. Practice - develop your skill.There is a lot of good free advice around this subject and a lot more than I can tell you here, but check it out.Do a MSF course (best 100 dollars you'll ever spend). Check out "Twist of the Wrist" on You Tube" for more, and this forum has a ton of experienced riders that can guide you...Have fun be safe...

Kuroshio 07-01-2012 04:12 PM

Be careful practicing downshifts tho. If you don't do it right and decelerate instead of accelerate there's a possibility of locking the rear. As you decelerate, weight shifts forward causing the rear to lose traction. The braking caused by the engine can start the rear to slide.


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