Gearing Down or Not?
Outstanding HDF Member
Joined: May 2007
Posts: 2,673
Likes: 16
From: Norfolk, VA
Of course increasing RPM's when downshifting does something. It matches the speed of the rear wheel to the speed of the engine/drivetrain. If one downshifts without increasing RPM's of the engine a greater force would be applied to the rear wheel slowing it down quicker as the engine resists the increase in speed. When the rear wheel is slowed like that one runs the risk of losing traction. The purpose is to keep that slowing of the rear wheel gradual, the rpm's go up, shift, let out clutch, the engine speed matches the rear wheel speed, as the rpms go back down the engine breaking occurs without a sudden jolt and a reduced chance of locking up the rear wheel. It is the exact same reason an even application of increased force on the rear brake is much safer then slamming the rear brake on all at once. It becomes more obvious if one is racing a vehicle off road or on a very loose surface. I get some people not doing it because it is not "required", but to say it does nothing is absolutely wrong.
If you do not believe me look up what a slipper clutch does for a race bike, it serves the same purpose. http://en.wikipedia.org/wiki/Slipper_clutch
I drove a truck for a while and I always used the clutch when downshifting and I increased engine speed for the same reason I do on a bike. To avoid losing traction on the real wheels and sliding. It had nothing to do with not using the clutch, nothing at all.
If you do not believe me look up what a slipper clutch does for a race bike, it serves the same purpose. http://en.wikipedia.org/wiki/Slipper_clutch
I drove a truck for a while and I always used the clutch when downshifting and I increased engine speed for the same reason I do on a bike. To avoid losing traction on the real wheels and sliding. It had nothing to do with not using the clutch, nothing at all.
Outstanding HDF Member
Joined: Jul 2010
Posts: 2,979
Likes: 57
From: PA
I believe it's called "rev matching" when you blip the throttle to have a smooth downshift. If I understand correctly, when you do this, the wear on the clutch, as well as the rest of the powertrain, is minimized.
The reason you want to downshift is, as mentioned by others, so you can be in the proper gear for the speed you are travelling. I rarely shift into 1st on a roll, however. I have heard that it's not good for the transmission. I engage 1st once I have stopped.
Rev matching is not hard to learn and the consequences limited. Just don't rev it too much. Give a gentle blip of the throttle as you let the clutch out
The reason you want to downshift is, as mentioned by others, so you can be in the proper gear for the speed you are travelling. I rarely shift into 1st on a roll, however. I have heard that it's not good for the transmission. I engage 1st once I have stopped.
Rev matching is not hard to learn and the consequences limited. Just don't rev it too much. Give a gentle blip of the throttle as you let the clutch out
The only discrepancy I have is that you should ALREADY be in first gear when you stop. OP should take a basic rider's course - you'll learn all about it.
I never engine brake my Harley. I don't want to put the extra strain on it and it's just not necessary. IE: more harm than good.
Seasoned HDF Member
Joined: Mar 2008
Posts: 5,134
Likes: 146
From: texas
also if you rev the throttle while youre are letting out the clutch...having just dropped to a lower gear.....and you happen to rev to much you will most likely find yourself in some trouble.----make sure youre easy on the throttle.Real easy.
also people are talking about two separate topics here really.....are we talking about down shifting to stop quicker? Down shifting so perfect that no one can feel it? These are similar but not quite the same.
also people are talking about two separate topics here really.....are we talking about down shifting to stop quicker? Down shifting so perfect that no one can feel it? These are similar but not quite the same.
Last edited by straydog13; Sep 17, 2011 at 09:30 AM.
Road Captain
Joined: Aug 2008
Posts: 673
Likes: 0
There is no need to blip the throttle on downshifting it does nothing. With that being said i generally use downshifting mainly if i need to decelerate very rapidly. Sometimes especially in town i have no reason to downshift from 3rd to 1st in stop n go traffic. I have dual front calipers on my Roadster but the braking is more powerful then the breaking surface provided by the rubber. If you've ever skidded you will notice only about a 2-3 inch swath of rubber on the ground. Thats not alot for a 600+ lb machine. Engine braking and wheel braking combined is the best but even that is limited at higher speeds.
As Reddogg said, it helps you to maintain vehicle stability not only in coming to a stop but in the many situations which arise on the road. For example downshifting at speed before entering an on ramp. Rev matching makes the transition to a lower speed much smoother and by extension makes you a smoother, safer and better rider.
Try it once and ask your passenger if they noticed a difference.
Better yet, don't rev-match the next time you are driving a manual transmission car and watch your passengers heads jerk forwards and back as you just 'let out the clutch' (and understand you are doing the same thing to your vehicles suspension).
I find there are generally reasons why professional drivers universally employ certain techniques...
Last edited by Red9; Sep 17, 2011 at 09:33 AM.
Cruiser
Joined: Aug 2011
Posts: 128
Likes: 0
From: BC, Canada
the reason big trucks hit he fuel while they are downshifting is because they have such a heavy load that it brings the rpms down real quick...and since they dont use their clutch(rarely) the engine speed much be matched in order to shift....so they rev it up to match truck speed.Its also used to slow down as well.
I myself gear down, but do not blip the engine, I find having clutch and throttle co-ordination makes a smooth transition with no jerking.
Steve
Seasoned HDF Member
Joined: Apr 2009
Posts: 44,902
Likes: 29,882
From: PNW
The only discrepancy I have is that you should ALREADY be in first gear when you stop. OP should take a basic rider's course - you'll learn all about it.
I never engine brake my Harley. I don't want to put the extra strain on it and it's just not necessary. IE: more harm than good.
On engine braking - When you momentarily blip the throttle (for reasons mentioned by many on this thread) it simply gets your engine up to the same speed as the drivelin - key word - momentarily. You immediately let off the throttle and slow the bike using "engine braking". IT is much smoother, better for the bike, and better for maintaining control of your bike. But, you should always use both brakes in conjunction with engine braking. You don't want that back tire to skid.
To the OP - in internetland you will get all kinds of advice. Good and bad. And as another put it - I don't mean to be a dick but......
I'm sorry, to just let the clutch out is bad form. That is not "engine braking", that is wearing the clutch and exhibiting an unfamiliarity with riding and riding dynamics. You may get away with it for a long time, but eventually, on a rainy day, or on pavement irregularities, the bad form you have gotten used to can bite you in the a$$. Attend any driver's or rider's school and the instructors will be all over your sh*t if you do not rev match. Been there.
Best advice you have received in this thread - take a riders course. Learn from real experts - not internet experts. A book I'm re-reading - David Hough's "Profficient MOtorcycling" covers this topic and more. Money well spent imo.
I agree with Thundermug, there's no need to blip the throttle, just let the clutch out. The only reason anyone would blip the throttle is to hear the engine bark.
But, someone else mentioned that they like to be in 1st gear before they come to a stop just in case they need to make a quick get-away. That makes sense, so I'll keep that little nugget in mind .... thanks passea!
Mike
Last edited by mike5380; Sep 17, 2011 at 10:08 AM.
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Club Member
Joined: Dec 2010
Posts: 4,526
Likes: 15,407
From: West of Texas
I don't do the rev matching thing, I simply down shift at the proper time, Just like up shifting. Be one with the bike.
When I come to a stop then I rev the engine a few times to get peoples attention.
When I come to a stop then I rev the engine a few times to get peoples attention.