Hi rev/low gear vs. low rev/high gear

[SteveM]

This is something I've wondered about, but I'm just too lazy to look it up.

I know you will know.

At any given speed, we can ride at higher revs in a lower gear or at lower revs in a higher gear.

My questions is how do these choices affect the handling of the motorcycle?

Other than great noise and presumably worse gas mileage, what are the pros/cons of higher revs/lower gear for both street and track?

Is there any gyroscope effect when the motor is spinning faster?

[Harley Davidson]

This is something I've wondered about, but I'm just too lazy to look it up.

Too lazy to google 'precession' or 'rigidity in space'?

Look those up and think about what is rotating on your motorcycle and how things change under different operating conditions.

[CBR929RE]

simple non technical answer is yes higher revs will make the bike handle better. they don't have to be sky high but somewhere in the meat of the powerband. regular everyday casual street riding you're better off staying lower to save the gas and not piss people off if you have an aftermarket exhaust.

[SteveM]

Too lazy to google 'precession' or 'rigidity in space'?

Look those up and think about what is rotating on your motorcycle and how things change under different operating conditions.

Thanks for the helpful reply.

[SteveM]

simple non technical answer is yes higher revs will make the bike handle better. they don't have to be sky high but somewhere in the meat of the powerband. regular everyday casual street riding you're better off staying lower to save the gas and not piss people off if you have an aftermarket exhaust.

There's no doubt that the engine is happier in the meat of the powerband. I'm wondering about the effect on suspension, stability, turn in, etc.

[OreoGaborio]

I'm not sure what the heck it is you're expecting to get with this thread, but engine RPM has absolutely zero effect on suspension.

However it does slightly affect your ability to quickly change direction due to the things that Harley mentioned that you so hastily dismissed.

[ZX-12R]

In a typical transverse mounting arrangement of sportbike engines, the gyroscopic forces of the engine tend to resist the bike wanting lean (rigidity in space). The faster the engine, the stronger the force. The wheels on a bike do the same but on a much more noticable scale. The higher the velocity of the bike, the harder it is to lean it over and stand it back up.

This is why the MotoCzysz C1 had a longitudinally mounted engine with 2 counter-rotating crankshafts.

[Paul_E_D]

Also, Pete, the revs DO affect the suspension quite a bit. Higher revs and associated acceleration hold the chain taut. This adds quite a bit of anti-squat to the rear of the bike, whether it's cornering, negotiating bumps, or landing from a SX style jump.

Just cruising around town? No, not much difference. High performance riding? Yes, more revs have a lot of positive effects.

[ZX-12R]

Higher revs and associated acceleration hold the chain taut.

But revs alone doesn't equal a taught chain since you can have high revs but no acceleration. It's an awkward concept for non-squids as your typical rider wont be putting around at 35mph @ 8K rpm since they look and sound like a weirdo.

[OreoGaborio]

Also, Pete, the revs DO affect the suspension quite a bit. Higher revs and associated acceleration hold the chain taut. This adds quite a bit of anti-squat to the rear of the bike, whether it's cornering, negotiating bumps, or landing from a SX style jump.

Just cruising around town? No, not much difference. High performance riding? Yes, more revs have a lot of positive effects.

But that's not associated with RPM's or what gear you're in though, is it?
I thought that had more to do with whether or not you were on the throttle.

EDIT: Yeah, what Bill said. You can be up by the rev limiter but still be off the throttle and have slack in the chain.

[gadget]

I would also imagine that this effect varies a great deal on the motorcycle and the type of engine it has.

I would have to say it is impossible to answer the OPs question unless you knew exactly which motorcycle is being talked about.

For example, a V-Twin with a chain drive and a Boxer with a shaft drive are going to have completely different characteristics.

[Garandman]

I would also imagine that this effect varies a great deal on the motorcycle and the type of engine it has.//.

bingo.

The V-Strom DL650 and SV650 have the same engine mechanically. but the V-Strom has been tuned with a little less peak power and more torque at lower rpms. And the SV650 itself has a relatively flat torque curve compared to inline fours of the same displacement.

Old BMW boxers had much heavier flywheels and you could feel a torque effect when you revved the engine while stationary. But since the engine cannot spool up that fast under load, the effect while actually riding was nil.

[Harley Davidson]

Thanks for the helpful reply.

You're welcome? Shall I take the mope as a sarcastic thanks?

Seriously, you can read about this sort of thing and for the most part you don't need to be a math pro or engineer to understand the concepts. I gave you a couple good key words to start a search. Add motorcycle as a key word and you can get even more.

If you're really too lazy to put in any effort on your own part after someone gives you good clues, why should you expect the community to do the work for you?

[SteveM]

I'm not that lazy, I read about 10 minutes on precession after getting your reply before I had to leave this morning.

But I am looking for opinions about the practical aspect and whether it makes a difference one can feel either on the street or on the track.

As this thread has already demonstrated, there is not unanimity of opinion.

Three things I've learned so far:

First, engine configuration matters. I have a VFR, V4, I believe transverse as opposed to an ST1300 which is V4 but longitudinal. (Please correct me if I have this wrong)

Second, drive type matters. I have a chain.

Third, if I'm understanding this correctly, higher revs (after considering 1 and 2 above) may make it harder to turn in as the "gyroscope" (my loose term) causes the bike to resist lean. Would this also mean that once leaned, the bike is more stable in a turn at higher revs than at lower revs, speed being equal?

[Paul_E_D]

You may be looking at this in the wrong way. High revs help you go faster! They put the bike in the meat of the power, and when your riding skills are there to use it in corners, then yes, it will help you bike in some ways. Until you are trying to go faster, then revs are irrelevant. The effects on the bike will be minor if your riding around slow, but a gear lower.

[SteveM]

Paul,

Thanks.

The effect is minimal at normal public street speeds, but becomes more noticeable as things pick up.

Clear as a bell.

I'm thinking not about NESR group rides 10 years ago (I'm sure you were group leading at least 1 I was on) and remembering that as things wicked up in the corners, I found it easier to maintain speed in the corners when I approach in a lower gear at higher revs.

[NobodySpecific]

I'm thinking not about NESR group rides 10 years ago (I'm sure you were group leading at least 1 I was on) and remembering that as things wicked up in the corners, I found it easier to maintain speed in the corners when I approach in a lower gear at higher revs.

Going around a corner requires acceleration, acceleration is "easier" when the bike is in the meat of the powerband. I suspect that you would have no change in feel in different gears from the bike, but mentally it's a lot harder to turn the throttle a lot in the corner (on the street, while trying to maintain a margin of safety). Higher gear = less throttle turn to maintain speed through the corner?

[OreoGaborio]

You're overthinking it.

It's just as easy for me to go around a corner at half pace as it is is at full pace.
It's not how MUCH power you put down to the ground, only that you tighten up the top of the chain by opening the throttle... how much or how little isn't all that important.

The sole reason for downshifting is to be in the proper gear for corner EXIT. I subscribe to the philosophy that it's best to be in the HIGHEST gear possible (and lowest RPM's) entering a corner, that still allows good acceleration OUT of the corner. That's not because of bike stability or handling or anything like that, it's because being in too LOW of a gear means more shifting and twitchier off/on throttle response.

[SteveM]

good point.

There's no question that being on the throttle a bit helps stability in turns, that comes straight from MSF BRC all the way to the track.

Everything is better when the top of the chain is working.

[Harley Davidson]

I subscribe to the philosophy that it's best to be in the HIGHEST gear possible (and lowest RPM's) entering a corner, that still allows good acceleration OUT of the corner. That's not because of bike stability or handling or anything like that, it's because being in too LOW of a gear means more shifting and twitchier off/on throttle response.

I agree with Pete here. At NHMS for example, with my stock gearing there are places I should be in first gear to get good acceleration, but I simply don't have the comfort level with my skills to do it. Fact is, I only need third on the front straight, so I leave it in second for most of the track and don't have to shift much. When I first started on the track, I pretty much left it in third all the way around. When I felt up to going faster, I needed to use second in places. Now I'll need to regear my bike or stop being scared of first gear on the track if I want to get better drives out of the slower corners. Nevertheless, it is really obvious, regardless of gear, that the bike feels better when there is at least a slight bit of power going to the rear wheel, and this is especially noticeable to me in the bumpy corners like 2, 3, and 10.

[butcher bergs]

What are you riding that has such a tall 1st gear?

[Harley Davidson]

This is why the MotoCzysz C1 had a longitudinally mounted engine with 2 counter-rotating crankshafts.

Very cool. Does all the rotating mass balance out?. I would think if it didn't the bike would tend to yaw one way or anoher if you did a wheelie ( or braked hard, for that matter).

[Harley Davidson]

What are you riding that has such a tall 1st gear?

08 cbr1000rr

Keep in mind I am basically a beginner as far as the track goes, with less than 10 track days of experience.

The problem isn't that first gear is too tall, it's that second is too tall and I'm a little scared of first on the track.

Second gear redline is around 120mph, and I only hit 110 or so between t2 and t3, so third gear is really only needed on the front straight. Plenty of drive out of all the turns except T3 and T12 when in second. This is where I feel slow in a relative sense. For me, turn 3 is no more than 40 mph, less after crashing once in T3, so that's less than 4,000 rpm and while it has a good midrange, 4,000 rpm it's kind of weak. It starts driving harder in the 6 to 7k range.

I know my bike isn't really geared for NHMS, but I ride it on the street too, so I am hesitant to change the ratios. I probably just need to suck it up and get it into first gear in those turns....

[butcher bergs]

With that bike there may well be some new surprises if you end up clicking into 1st....and I don't mean good surprises. I personally would not consider 1st gear in any scenario unless I was starting from a standstill or very close to it. Too much can go wrong.

[Harley Davidson]

With that bike there may well be some new surprises if you end up clicking into 1st....and I don't mean good surprises. I personally would not consider 1st gear in any scenario unless I was starting from a standstill or very close to it. Too much can go wrong.

Yeah, it has more power than I can really use in first, and the
last thing I want to do is take a high side ride, I really wish I had a gear in between first and second. Maybe doing the sprockets would be worthwhile......