Power to Weight Ratio - why it's important in choosing a bike! - Page 3 - Sportbikes.net
Track Time-101 Information and advice about getting on a road course yourself.

User Tag List

Reply
 
LinkBack Thread Tools Display Modes
post #31 of 35 (permalink) Old 03-02-2013, 08:12 AM Thread Starter
Roadracer since '96
 
GSXR RACER MIKE's Avatar
 
Join Date: Jan 2004
Location: Rockford Illinois
Age: 47
Posts: 1,911
Thanks: 3
Thanked 40 Times in 33 Posts
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
 
Power to weight ratio still plays a significant factor with torque engines, especially if that power is able to be delivered to the ground in a usable way (not by excessive tire spin). Power is power, the only difference with your twin is that it's delivered earlier in the acceleration curve than an I-4, but you still benefit from lower weight per horsepower. If your racing against I-4's you have to capitalize on the acceleration twins have during every acceleration before you reach higher speeds, if you can improve that situation by improving the weight per horsepower it will help you to extend the gap between you and your competition every time you accelerate. Improved P/W/R increase the amount of time it takes for I-4's to catch you and reduces or eliminates their chances of even having the opportunity to pass you. If your racing against other twins a lower P/W/R will do the same thing, provide you with more acceleration sooner.

Remember that if you can increase your rate of acceleration by only 1 MPH (with a lower weight per horsepower) it will increase the distance between you and your competition by a bike length apx every 5 seconds (1.466 feet per second). Also remember that lower weight per horsepower can be achieved thru lower combined bike/rider weight and also thru increasing horsepower, BOTH lowering weight AND increasing power can reap great rewards in acceleration and potentially top speed as well.

The only real bad I can think of thru continuing to increase torque numbers on your engine is if it becomes too biased and starts sacrificing top speed, that could be an issue on tracks with longer top speed sections. An example is when I've raced at Road America, I wanted to increase acceleration out of the turns thru more aggressive gearing, but didn't want to sacrifice too much top speed. I kept increasing the aggressiveness of the gearing until I was running out of top end gearing a couple seconds before the end of the fastest section on the track. That resulted in a situation where I was vulnerable to passing for a couple seconds at that point, but increased my acceleration out of all 14 turns around the track - that acceleration greatly out weighed the slight loss in top speed. But... If I had been able to lower the weight per horsepower (instead of changing the gearing) I could have gained the same result without sacrificing the top speed that I did thru more aggressive gearing.

SBN "ON THE TRACK" forum MODERATOR
Questions, concerns, problems? P/M me.


What you just read is my opinion and is based on my experiences and the info I have acquired during my life, it's my interpretation and isn't written in stone. Yes, I post long responses regularly because I like to fully explain my views. Don't like it or agree with what I have to say? Then don't read it or respond to it! Respond like an immature idiot to posts of mine and I will just ignore you. Have a nice day.
GSXR RACER MIKE is offline  
Sponsored Links
Advertisement
 
post #32 of 35 (permalink) Old 04-16-2013, 12:43 AM
World 500 GP Champion
 
TCormier's Avatar
 
Join Date: Jun 2010
Location: Austin, TX
Age: 24
Posts: 6,884
Thanks: 245
Thanked 720 Times in 492 Posts
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Can't believe I haven't seen this before. Very good read! Puts into perspective why I as a heavier rider, on a heavier bike have a hard time running the same lap times as my much lighter friend on his modified SV650!

http://www.hazardousracing.com/
Thanks to Hazardous Racing for helping me get to the track!
TCormier is offline  
post #33 of 35 (permalink) Old 06-30-2013, 06:01 PM
Cheap Bastid
 
OreoGaborio's Avatar
 
Join Date: Jul 2004
Location: Topsfield MA
Age: 37
Posts: 6,366
Thanks: 134
Thanked 319 Times in 187 Posts
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Quote:
Originally Posted by GSXR RACER MIKE View Post
Slides can be caused from so many different things, but the main ones are:
-bad lines thru a turn
-body position on the bike
-tire condition / tire type / tire pressure
-suspension set-up

Power to Weight Ratio is responsible more for tire spin when applying throttle, whether it's while your still leaned over or already vertical.
Not sure how you missed what's easily one of, if not THE biggest cause of a slide: mid-corner steering input.

I see riders with excelent lines, great body position, perfect tires & outstanding suspension get flung off a bike.... 99 times out of 100 it was caused by a mid-corner steering input.

-Pete
LRRS/CCS #82 ECK-Racing, Ironstone Ventures (RiderCoach), Tony's Track Days (Assistant Chief Instructor)

GMD Computrack Boston | Pine Motorparts/PBE Specialists | Phoenix Graphics | Woodcraft | Street & Competition | MTag-Pirelli | OnTrack Media

Last edited by OreoGaborio; 06-30-2013 at 06:05 PM.
OreoGaborio is offline  
 
post #34 of 35 (permalink) Old 07-01-2013, 07:58 AM Thread Starter
Roadracer since '96
 
GSXR RACER MIKE's Avatar
 
Join Date: Jan 2004
Location: Rockford Illinois
Age: 47
Posts: 1,911
Thanks: 3
Thanked 40 Times in 33 Posts
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
 
Quote:
Originally Posted by OreoGaborio View Post
Not sure how you missed what's easily one of, if not THE biggest cause of a slide: mid-corner steering input.

I see riders with excellent lines, great body position, perfect tires & outstanding suspension get flung off a bike.... 99 times out of 100 it was caused by a mid-corner steering input.
In my response I was really trying to stay on the topic of Power to Weight Ratio so I didn't want to stray too far off the topic if I could help it. It can be difficult when writing an informational thread to find a balance between general statements, getting too in depth with off topic info, and constantly giving disclaimers as to every situation.

The situation you described: "excellent lines, great body position, perfect tires & outstanding suspension" is what I would consider somewhat of a 'Unicorn' situation because most Track Day riders, and unfortunately a large percentage of Racers, will rarely or even never be in that situation. That's exactly the reason I gave the following disclaimer at the very start of the thread:
Quote:
Originally Posted by GSXR RACER MIKE View Post
Brand new tires are of course going to spin later than used tires and in turn will be somewhat of an exception to the ranges I list, this advice is going to be aimed more toward tires that have some use on them already since most people don't use new tires for every session they do on the track.
While I do agree that in the situation you described (someone having "excellent lines, great body position, perfect tires & outstanding suspension") steering input is a considerable factor in slides, I also believe that situation still falls under the general category of "bad lines thru a turn" because a mid-corner steering input is ultimately due to a bad line. If you really think about it, even 'avoidance maneuvers' and 'passing attempts' can be grouped in with "bad lines thru a turn".

SBN "ON THE TRACK" forum MODERATOR
Questions, concerns, problems? P/M me.


What you just read is my opinion and is based on my experiences and the info I have acquired during my life, it's my interpretation and isn't written in stone. Yes, I post long responses regularly because I like to fully explain my views. Don't like it or agree with what I have to say? Then don't read it or respond to it! Respond like an immature idiot to posts of mine and I will just ignore you. Have a nice day.
GSXR RACER MIKE is offline  
post #35 of 35 (permalink) Old 07-06-2013, 08:33 AM
Cheap Bastid
 
OreoGaborio's Avatar
 
Join Date: Jul 2004
Location: Topsfield MA
Age: 37
Posts: 6,366
Thanks: 134
Thanked 319 Times in 187 Posts
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Alrighty then.... I strongly disagree with that approach, but okay.

-Pete
LRRS/CCS #82 ECK-Racing, Ironstone Ventures (RiderCoach), Tony's Track Days (Assistant Chief Instructor)

GMD Computrack Boston | Pine Motorparts/PBE Specialists | Phoenix Graphics | Woodcraft | Street & Competition | MTag-Pirelli | OnTrack Media

Last edited by OreoGaborio; 07-06-2013 at 08:47 AM.
OreoGaborio is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Sportbikes.net forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Middle Weight Starter Bike Comparison 92blkSi New Riders 12 08-18-2009 02:07 PM
Michelin Pilot Power & Power 2ct Tire Sale sportbiketrackgear.com Group Buys 0 07-11-2009 12:32 AM
Huge power commander sale Flatout Group Buys 1 12-17-2004 05:11 PM
Low end power . . . an excuse? DreddR6 General Sportbikes 50 08-13-2004 06:32 PM
Arai Tops JD Power List Fred Breaking News 0 08-08-2004 11:18 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome