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Gearing To Create Flow Around A Track

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Gentlemen,

I have a question that pertains to gearing and flow around a track. I have gone to different race schools and read many articles on gearing. One thing that I have not heard about is flow yet many guys that go fast talk about flow around a track. I was asking the question about gearing yesterday. I called two guys that I consider to be at the upper tier of riding. I'm sure both could line up on an AMA starting grid.

I asked both of them about there gearing for my home track (Barber). Both stated that they run the track hardly ever getting out of fourth gear.

Most articles I have read and at least one school I have attended talk about being in the top three gears when on the track. Being as close to red line in the gears that give one the closest ratios. At some point on the longest straight on the track one should be close to red line in sixth gear. The taller gears make it easier to shift and easier to predict exit speed by where one is shifting at exit of turns.

One of the guys asked me what sprockets I was running and I told him 15 tooth front 45 rear. He said that Barber has a flow and rhythm that I wouldn't get into by using a 15 tooth sprocket on the front. I am having trying to understand what the difference is in the logic of one method vs the apparent speed of the guys I talked to on the track and their gearing.

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I don't understand it much, because I ride stock everything on my bike. I do know it makes a huge difference. Firebird has 3 tracks. One is small (1.1 miles) and technical. You can take some off the front, and you lose top end (which you would never use in the first place), but acceleration picks up. 600 riders who have changed their gearing absolutely take off on me on my 636. I start to pick up at the end of the straight, but they've put so much distance between us it doesn't compare. I hit 4th for about 2 seconds before I drop back down to corner, but the one's who change their gearing are in 4th much longer.

I was talking with a friend Sunday at the track, and he told me that he loves running Main (2.25 miles and HUGE straight) on West settings, because of the turns. It's an out and back type track. The straight gets you to the end, and then it's a huge left/right/left followed by tighter turns of the same all the way back, until you're back on the straight. Chuck said he tops out quickly on the straight, but has a good old time on the way back. He uses different gearing for racing.

I do have a few questions of my own. Would one have to remap their power commander every time they change gearing? What does adding teeth to the rear do?

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Gentlemen,

I have a question that pertains to gearing and flow around a track. I have gone to different race schools and read many articles on gearing. One thing that I have not heard about is flow yet many guys that go fast talk about flow around a track. I was asking the question about gearing yesterday. I called two guys that I consider to be at the upper tier of riding. I'm sure both could line up on an AMA starting grid.

I asked both of them about there gearing for my home track (Barber). Both stated that they run the track hardly ever getting out of fourth gear.

Most articles I have read and at least one school I have attended talk about being in the top three gears when on the track. Being as close to red line in the gears that give one the closest ratios. At some point on the longest straight on the track one should be close to red line in sixth gear. The taller gears make it easier to shift and easier to predict exit speed by where one is shifting at exit of turns.

One of the guys asked me what sprockets I was running and I told him 15 tooth front 45 rear. He said that Barber has a flow and rhythm that I wouldn't get into by using a 15 tooth sprocket on the front. I am having trying to understand what the difference is in the logic of one method vs the apparent speed of the guys I talked to on the track and their gearing.

fossilfuel;

A very knowledgable friend of mine offered me this chart for understanding gearing. It is based upon a Ducati 748 set up with sprockets that I have but you can deduct the logic and apply it to your bike; the ratios listed are derived from dividing # of rear teeth by the # of front teeth.

14F/39R = 2.7857 (lowest top speed, quickest acceleration)

14F/38R = 2.7143

14F/37R = 2.6428

15F/39R = 2.600

14F/36R = 2.5714

15F/38R = 2.533

15F/37R = 2.4667

15F/36R = 2.400 (highest top speed, slowest acceleration)

There is an entire section on breaking down a track to determine where to use which ratios but this is a good jumping off point for your question. Maybe Stuman or others who race can add some perspective.

 

Kevin

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One thing that comes to mind, though loosely related to your post is that it is commonly thought that one must rev an engine to the rev limiter to get max performance out of the engine and this is not so.

 

Sportrider magazine did an article a few years back about shift points and found that sometimes the ideal shift points are not in the red zone. When you change your gear ratios you are changing this as well. Perhaps these top guys have considered the loss of flow based on the change that is introduced from the gearing change.

 

Take a look at this article Keith wrote about the character of Willow

http://forums.superbikeschool.com/index.php?showtopic=110

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Kevin,

I understand calculating ratios but I guess I am confused about what information is out there from different sources. If I was smart enough to understand this problem I would'nt be stairing at a B.A. in Liberal Arts diploma right now.

What is perplexing is this. Say Nicki Hayden runs around the track never getting out of fourth gear running stock sprockets, lets say 16/42 = 2.625 but the transmission gear ratios for fourth gear on his bike is 1.381:1. I on the other hand am running the same track with a 15/46 = 3.06 arrangement topping out in 6th gear transmission ratio of 1.160:1. Wouldn't I have a lower gear ratio but at maximum rpm and be shifting in a tighter pattern between 4th, 5th, and 6th vs his shifting between 2nd, 3rd and 4th?

What this all boils down to in my mind is keeping the engine in the power band, a smooth transition from shift to turn, maintaining stability in the close tall gear ratios and not missing shifts. Wouldn't it be better to be shifting in to 4th in a curve than 2nd? Just curious....And no I haven't read Keiths article yet but I will.

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Kevin,

I understand calculating ratios but I guess I am confused about what information is out there from different sources. If I was smart enough to understand this problem I would'nt be stairing at a B.A. in Liberal Arts diploma right now.

What is perplexing is this. Say Nicki Hayden runs around the track never getting out of fourth gear running stock sprockets, lets say 16/42 = 2.625 but the transmission gear ratios for fourth gear on his bike is 1.381:1. I on the other hand am running the same track with a 15/46 = 3.06 arrangement topping out in 6th gear transmission ratio of 1.160:1. Wouldn't I have a lower gear ratio but at maximum rpm and be shifting in a tighter pattern between 4th, 5th, and 6th vs his shifting between 2nd, 3rd and 4th?

What this all boils down to in my mind is keeping the engine in the power band, a smooth transition from shift to turn, maintaining stability in the close tall gear ratios and not missing shifts. Wouldn't it be better to be shifting in to 4th in a curve than 2nd? Just curious....And no I haven't read Keiths article yet but I will.

With conventional bikes, you don't want to change gears midcorner. A quickshifter will allow you to do that. With that said, let's assume that you don't have one. You want to time the shifts when the bike is straight up/down. Perhaps having more gears wouldn't be helpful because it would force you outside the best operating range when in the corners. Just a thought and 2 shillings.

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Kevin,

I understand calculating ratios but I guess I am confused about what information is out there from different sources. If I was smart enough to understand this problem I would'nt be stairing at a B.A. in Liberal Arts diploma right now.

What is perplexing is this. Say Nicki Hayden runs around the track never getting out of fourth gear running stock sprockets, lets say 16/42 = 2.625 but the transmission gear ratios for fourth gear on his bike is 1.381:1. I on the other hand am running the same track with a 15/46 = 3.06 arrangement topping out in 6th gear transmission ratio of 1.160:1. Wouldn't I have a lower gear ratio but at maximum rpm and be shifting in a tighter pattern between 4th, 5th, and 6th vs his shifting between 2nd, 3rd and 4th?

What this all boils down to in my mind is keeping the engine in the power band, a smooth transition from shift to turn, maintaining stability in the close tall gear ratios and not missing shifts. Wouldn't it be better to be shifting in to 4th in a curve than 2nd? Just curious....And no I haven't read Keiths article yet but I will.

fossilfuel;

It's tough when you use an anology that includes Nicki because most of us ride or race in circumstances that don't allow internal mods to the transmission box ergo my sending you an external gearing matrix. That said, there is a combination that will allow you to maximize the time you are in the Gixer's power band at Barber...

If we are talking about downshifting, I can't tell you that it is better to be shifting to 4th rather than 2nd because I find that I do shift more into 2nd than 4th; I know I have more experience making that change plus if I am going down to 4th for a corner entry, then I am freakin' flying. I can only think of a handful of corners where I actually do that (T11 at Mosport, T6 at Mid-Ohio, T1 at VIR). If I am upshifting, I can't think of too many places (actually any) where I would corner in first gear but I do everything I can to avoid shifting while cornering.

 

Kevin

 

Kevin

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I have a tendancy to use sarcasm sometime so please forget about the Nicky Hayden analogy! I do not or will I ever shift mid corner.......I have been to many Keith Code schools and wouldn't want my coaches to think I wasn't paying attention so if you are a coach and reading this, don't panic. I'm not suggesting anything stupid. I am actually talking about the shift before the turn.

What I have noticed is that I have been running out of gear close to the end of the straight ( two of these at Barber between 4 and 5 and 6 and 7) with no time for the needed next shift so instead of trying to gear from a 3.0 to something higher and make another shift nearer the middle of the straight I should go down to a 2.9 to stretch out the gear for the end of the straight? I'm going next weekend and was thinking about changing my current set up.

Somethings are easy to understand and somethings raise more questions for me like primary and final drive gearing. I feel like Forrest Gump.

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I have a tendancy to use sarcasm sometime so please forget about the Nicky Hayden analogy! I do not or will I ever shift mid corner.......I have been to many Keith Code schools and wouldn't want my coaches to think I wasn't paying attention so if you are a coach and reading this, don't panic. I'm not suggesting anything stupid. I am actually talking about the shift before the turn.

What I have noticed is that I have been running out of gear close to the end of the straight ( two of these at Barber between 4 and 5 and 6 and 7) with no time for the needed next shift so instead of trying to gear from a 3.0 to something higher and make another shift nearer the middle of the straight I should go down to a 2.9 to stretch out the gear for the end of the straight? I'm going next weekend and was thinking about changing my current set up.

Somethings are easy to understand and somethings raise more questions for me like primary and final drive gearing. I feel like Forrest Gump.

What about short shifting? Select a higher gear into the corner and use that bikes' impressive torque to carry you through; your drive out will be pretty seamless if you hit it correctly. I learned this from one of the Penguin instructors at Loudon when I was struggling through the bowl there...it required an upshift at mid corner and he told me to avoid the last downshift and just drive it out and he was absolutely right. It works like a charm ...but I would be a bit more delicate with a liter bike's throttle.

 

Kevin

 

Kevin

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The measure I always use is lap time. How to set the gearing up to get around the track the fastest. Things I don't want, 1. To need to shift coming out of a corner leaned over 2. Not to be in the power when standing the bike up at the end of a corner 3. Not to be on the rev-limiter anywhere on the track.

 

I raced at Streets of Willow and Big Willow with the same gearing on my ZX9 and my 636? I didn't run into any of the situations above.

 

The 9 was five teeth lower than stock, the 636 was three, and more recently Lonnie's 600 was five teeth lower than stock.

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Thanks Guys! Great information. I appreciate all the feedback. This just gives me more of an excuse to sign up for more track days so I can experiment with set up.

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Thanks Guys! Great information. I appreciate all the feedback. This just gives me more of an excuse to sign up for more track days so I can experiment with set up.

 

One thing (you might already do it) but Will and I shift w/out the clutch, up or down. This makes shifting pretty easy, and can do it better, quicker, with less attention than for some others.

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I do have a few questions of my own. Would one have to remap their power commander every time they change gearing? What does adding teeth to the rear do?

 

I spoke to the dynojet guy about this when I was getting my power commander set up on the dyno and he said I would not have to change the map if I changed the gearing, my bike (CBR600RR) redlines at 15500 rpm but makes max power at 13700, I have the printouts that show me this, so I aim to upshift at 13700 (max power) never getting close to redlining my bike! I am assured that if I did change my gearing it would have no effect on the engine mapping, max power would still be at 13700!

Adding teeth to the rear has the same effect as removing teeth from the front on a lesser scale, basically more acceleration less top end speed!

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Hey Cobie,

I am using the clutchless upshift so this is not a problem. You taught me this as well as blipping the throttle. Thanks. I am going to research the gearing more and in the mean time go faster!!!

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I found a web sight that has a gearing calculator for CBR1000RR 04-07. One puts in the sproket sizes and wheel diameter and it spits out a chart with speed and rpm range for each gear. This was what I was looking for.

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I found a web sight that has a gearing calculator for CBR1000RR 04-07. One puts in the sproket sizes and wheel diameter and it spits out a chart with speed and rpm range for each gear. This was what I was looking for.

 

One other thing that I've seen over and over is riders sacrificing good gearing for the "idea" that they should never overrev the bike. While it is not good to overrev your motor on a routine basis if you have a small section of a track where you are on the rev limiter for a second or two it isn't the end of the world and won't affect your times anything that you could measure. On the other hand if you gear the bike so it is never on the revlimiter and it messes up your drives or adds shifts that are difficult to do, then you've gone backwards and created more problems than you are solving.

 

When the bike is on the limiter for just one second it can seem like an eternity, you have to be really objective about how long it really is on the limiter and if the gearing is good everywhere else, it saves you some gear changes, you can get good drives, you aren't overrevving in mid corner, let it scream a bit.

 

Keith

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Keith,

Thanks for the post. You are so right. I do not mind being at the rev limiter in some situations. The one thing that drives me in this endeavor is to be smooth but with maximum power. I am trying to be efficient with the use of gearing and power to maximize speed in places that can make a difference, where throttle control comes in to play. My goal this year is to cut two seconds off my current fastest lap time.

On the track and in many other sports youth masks mistakes. I am at the age where the margin of error is much smaller. I have to be better prepared.

An example of my perspective on this subject might be the drive out of a corner. The gearing calculator I found would prove this to be true. Say the bikes were the same, a CBR1000RR, there is a 60 mph turn and one has stock sprockets 16/42 this is 6000 rpm in second gear. if ones sprockets have been changed to 15/46 the rpm is 7000 in second gear. If the rear sprocket is increased to 48 the rpm at 60 mph is 8000 rpm. From apex to corner exit the 8000 rpm setting should be the fastest? I'm in the power baby! I don't care that the bike will not go 180 mph if the fastest straight is 140 mph. But one corner does not make a track. This is just an example.

I would think that evaluating the track, corner speed, and picking the right gearing would be a big advantage. I am no expert and for the accomplished racer this may be a mute point but for me this means making up time in a safe controlled manner.

This thread has really helped. Thanks to all of you for posting.

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Fossilfuel, (et al),

 

One minor point in gearing, and I'm trying to recall exactly where it is, but KC has in the books some info on what happens when the bike goes from upright to turned in, and how that also raises the RPMs--do you guys recall where this was, pretty sure T-2?

 

CF

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Fossilfuel, (et al),

 

One minor point in gearing, and I'm trying to recall exactly where it is, but KC has in the books some info on what happens when the bike goes from upright to turned in, and how that also raises the RPMs--do you guys recall where this was, pretty sure T-2?

 

CF

I'm sure it's in T2 (don't have mine with me at work to find Chapter/ Verse), but I thought I read that it causes the RPM to go down a bit.

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Fossilfuel, (et al),

 

One minor point in gearing, and I'm trying to recall exactly where it is, but KC has in the books some info on what happens when the bike goes from upright to turned in, and how that also raises the RPMs--do you guys recall where this was, pretty sure T-2?

 

CF

I'm sure it's in T2 (don't have mine with me at work to find Chapter/ Verse), but I thought I read that it causes the RPM to go down a bit.

 

When the bike goes from upright to turned in--RPM doesn't go down. Anyone find it yet?

 

CF

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Fossilfuel, (et al),

 

One minor point in gearing, and I'm trying to recall exactly where it is, but KC has in the books some info on what happens when the bike goes from upright to turned in, and how that also raises the RPMs--do you guys recall where this was, pretty sure T-2?

 

CF

I'm sure it's in T2 (don't have mine with me at work to find Chapter/ Verse), but I thought I read that it causes the RPM to go down a bit.

 

When the bike goes from upright to turned in--RPM doesn't go down. Anyone find it yet?

 

CF

The rpm should go up because one should be on the throttle.

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Fossilfuel, (et al),

 

One minor point in gearing, and I'm trying to recall exactly where it is, but KC has in the books some info on what happens when the bike goes from upright to turned in, and how that also raises the RPMs--do you guys recall where this was, pretty sure T-2?

 

CF

I'm sure it's in T2 (don't have mine with me at work to find Chapter/ Verse), but I thought I read that it causes the RPM to go down a bit.

 

When the bike goes from upright to turned in--RPM doesn't go down. Anyone find it yet?

 

CF

See Paragraph 3, PG 21 of T2.

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Fossilfuel, (et al),

 

One minor point in gearing, and I'm trying to recall exactly where it is, but KC has in the books some info on what happens when the bike goes from upright to turned in, and how that also raises the RPMs--do you guys recall where this was, pretty sure T-2?

 

CF

I'm sure it's in T2 (don't have mine with me at work to find Chapter/ Verse), but I thought I read that it causes the RPM to go down a bit.

 

When the bike goes from upright to turned in--RPM doesn't go down. Anyone find it yet?

 

CF

See Paragraph 3, PG 21 of T2.

 

Hey we are in a recession for God's sake! I can't afford a trip to Laguna Seca and the book. Can you paraphrase?

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Fossilfuel, (et al),

 

One minor point in gearing, and I'm trying to recall exactly where it is, but KC has in the books some info on what happens when the bike goes from upright to turned in, and how that also raises the RPMs--do you guys recall where this was, pretty sure T-2?

 

CF

I'm sure it's in T2 (don't have mine with me at work to find Chapter/ Verse), but I thought I read that it causes the RPM to go down a bit.

 

When the bike goes from upright to turned in--RPM doesn't go down. Anyone find it yet?

 

CF

See Paragraph 3, PG 21 of T2.

 

Hey we are in a recession for God's sake! I can't afford a trip to Laguna Seca and the book. Can you paraphrase?

I'm at work and thought long and hard about bringing my T2 with me. I figured I spend too much time on the forum at work anyway (shhhhh, don't tell).

 

psst- I'd recommend NOT telling on yourself around here about not having T2, you might get flamed. Hint- Occasionally, some poor sap won't appreciate the value of what he has and will sell a NEW one on eBay. I got mine this way, and am now awaiting shipping on T1 and Soft Science :rolleyes: .

 

Can someone help FOSSIL with some words from pg 21?

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I'm at work and thought long and hard about bringing my T2 with me. I figured I spend too much time on the forum at work anyway (shhhhh, don't tell).

 

psst- I'd recommend NOT telling on yourself around here about not having T2, you might get flamed. Hint- Occasionally, some poor sap won't appreciate the value of what he has and will sell a NEW one on eBay. I got mine this way, and am now awaiting shipping on T1 and Soft Science :rolleyes: .

 

Can someone help FOSSIL with some words from pg 21?

 

Oh hell no, this is way more fun!

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