The physics of braking on a motorcycle (manual transmission)

In summary, the question is whether engine braking can have a negative effect on the rate of deceleration when trying to abruptly stop a motorcycle. The fact is that front brakes are most effective in slowing down a motorcycle, but engine braking can also be effective, although not as much as front brakes. In a scenario where the maximum front brakes slow the bike down at a rate of X and the engine braking slows it down at a rate of Y, it is possible that Y may have a negative impact on X and therefore, using only front brakes may stop the bike faster. However, in a theoretical straight line scenario, it is likely that using both front and rear brakes while leaving the engine in gear would be the most effective way to stop the
  • #36
velocity_boy said:
One down and four up, baby.
I prefer the inverted racetrack shift pattern... :smile:
 
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  • #37
berkeman said:
I prefer the inverted racetrack shift pattern... :smile:

I'm too old to readjust I think. All my early motorbikes had that race shift pattern but the gear lever was on the right side. Since the International agreement in the late 60's early 70's I have only had the standard down for down, up for up, on the left bikes. At one stage in the late 60's I had one of each, that was quite interesting, but context made it easier, one bike was a motocross bike and the other a road bike. One bike I had had neutral at the bottom, not recommended!
 
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  • #38
velocity_boy said:
No real motorcyclists would be caught dead on a motor scooter with manual transmission.
As opposed to automatic transmission? Or are you distinguishing between hand-shift transmission vs. foot-shift transmission?

cosmik debris said:
Most motor bikes are not manual they are pedial, if that's a word.
I don't think pedial is a word, but pedal is, and it can be either a noun or a verb.
 
  • #39
Mark44 said:
As opposed to automatic transmission? Or are you distinguishing between hand-shift transmission vs. foot-shift transmission?

I don't think pedial is a word, but pedal is, and it can be either a noun or a verb.
Oops. Sorry. I messed up. Meant to say that no true biker would tide a bike with automatic tranny.
 
  • #40
velocity_boy said:
Oops. Sorry. I messed up. Meant to say that no true biker would tide a bike with automatic tranny.
That's sort of what I thought you meant, although I don't know if there are any that actually shift on their own. The very first bike I rode, Honda 55, back in about 1963, had an automatic clutch (i.e., a centrifugal clutch). There was no clutch lever, but there was a gearshift lever. You just let off the gas when you wanted to shift.

If there are any bikes with transmissions that shift by themselves, they have to be pretty rare.
 
  • #41
Do any of you guys know if engine braking is bad for your engine? Every mechanic I've asked says no. But I cannot help but wonder. Sure it saves over time on brake pads but who cares? Pads are cheap. I just wonder if continual engine braking is tough on valves or rings or seals?

Thanks!
 
  • #42
velocity_boy said:
Do any of you guys know if engine braking is bad for your engine? Every mechanic I've asked says no. But I cannot help but wonder. Sure it saves over time on brake pads but who cares? Pads are cheap. I just wonder if continual engine braking is tough on valves or rings or seals?

Thanks!
IMO, engine braking plus both brakes should be the strategy for smooth riding, including moderate performance riding, and up to racetrack level riding (modulo the back tire off the ground thing I mentioned earlier in the thread).

If you listen to the 2nd Reg Pridmore CLASS video that I posted, you will hear how much Reg uses engine braking as part of his super smooth ( and super fast) riding. He emphasizes smoothness in transitions from throttle to brakes and back to keep the suspension transitions smooth, which keeps your tires in the best contact with the pavement for maximum traction. If you slam on the brakes, you skid them which loses traction and loses you braking power. If you learn to be smooth transitioning into hard braking to let the suspension smoothly (and still quickly) settle, that gives you the best traction for slowing the bike.

I once asked Reg if it was okay to downshift if you were at redline at the end of a straight, since that would over-rev the engine past redline. He answered yes, that since it was not under power going over redline, the brief transition over redline under engine braking was okay. That's an extreme example to answer your question, but maybe it helps some. If you are just using engine braking at normal RPM settings (like 3/4 of redline), it should be pretty gentle on your engine, IMO.
 
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  • #43
berkeman said:
IMO, engine braking plus both brakes should be the strategy for smooth riding, including moderate performance riding, and up to racetrack level riding (modulo the back tire off the ground thing I mentioned earlier in the thread).

If you listen to the 2nd Reg Pridmore CLASS video that I posted, you will hear how much Reg uses engine braking as part of his super smooth ( and super fast) riding. He emphasizes smoothness in transitions from throttle to brakes and back to keep the suspension transitions smooth, which keeps your tires in the best contact with the pavement for maximum traction. If you slam on the brakes, you skid them which loses traction and loses you braking power. If you learn to be smooth transitioning into hard braking to let the suspension smoothly (and still quickly) settle, that gives you the best traction for slowing the bike.

I once asked Reg if it was okay to downshift if you were at redline at the end of a straight, since that would over-rev the engine past redline. He answered yes, that since it was not under power going over redline, the brief transition over redline under engine braking was okay. That's an extreme example to answer your question, but maybe it helps some. If you are just using engine braking at normal RPM settings (like 3/4 of redline), it should be pretty gentle on your engine, IMO.
Thank you! That's all good info to know. I can now practice my smooth deceleration with no worries!

Thanks.

Ride on!
 
  • #44
berkeman said:
IMO, engine braking plus both brakes should be the strategy for smooth riding, including moderate performance riding, and up to racetrack level riding (modulo the back tire off the ground thing I mentioned earlier in the thread).

Yes I agree, it should be part of the strategy and professional riders spend quite a bit of time getting the engine braking to their liking. I prefer low engine braking because with today's ride-by-wire throttles it helps stop the on-off nature of the throttle in turns where you may need to be vey steady.

berkeman said:
I once asked Reg if it was okay to downshift if you were at redline at the end of a straight, since that would over-rev the engine past redline. He answered yes, that since it was not under power going over redline, the brief transition over redline under engine braking was okay. That's an extreme example to answer your question, but maybe it helps some. If you are just using engine braking at normal RPM settings (like 3/4 of redline), it should be pretty gentle on your engine, IMO.

A lot of modern machines have slipper clutches which make this technique even more usable.

Cheers
 
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  • #45
cosmik debris said:
And which side is the gear lever? Most motor bikes are not manual they are pedial, if that's a word.
Yes, pedial is a word, derived from Greek πεδίον (pedion) = metatarsus (literally "foot thing") via truncation of "on" (nonal ending) and appendation of "al" (Latin adjectival ending). It has well-recognized meanings precisely as you intuited -- of or relating to the foot, or of or relating to a foot-operated device, or pedal, and takes the adverbial form "pedially", as in "a pedal is a pedially-operated device". The word "pedial" is more perspicuously an adjective than "pedal" is -- "pedial" does not require special context to be interpreted as an adjective. Although the word "pedal" originated as an adjective (it has adjectival ending "al"), just as some other words commonly used as nouns did, it quickly took on its nonal and verbal usages, while the adjectival usage waned into obscurity. Using "pedial" to distinguish from "manual" regarding motorcycle gearshift lever operation is lexico-structurally elegant.
Mark44 said:
As opposed to automatic transmission? Or are you distinguishing between hand-shift transmission vs. foot-shift transmission?
I read it as the latter.
I don't think pedial is a word, but pedal is, and it can be either a noun or a verb.
The word "pedial" is a rather obscure word, but it's been around for a long time, and it's apt for the usage cosmik debris made of it. You're right that it can be a noun or a verb, along with it being an adjective, having the adverbial form "pedally". I prefer "pedial" and "pedially" for adj. and adv. purposes, because of the strong entrenchment of "pedal" for noun and verb.
 

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