What would you ask MNZ for?

[cs363]

Twister you are at it again, not content to take your shame gracefully you continue to act like a sad little man.
Frankly I care no longer if I get nailed for this....of course motards are going to pitch and squat because theres lots more travel to account for it you moron. You need to seek help for your permanent chip on your shoulder, big time.
For the record I dont mind Motards and if its a way of getting more people to cross over from MX then its all good. They have an interesting set of dynamics going on, especially compensating for trail figures that are not ideal for road race, and pro squat going on in the rear if they are lowered lots.

I don't mind Motards but I don't think they should be racing as road race bikes, I'd love to see more (some?) proper Motard tracks set up - the one they have at X Games is absolutely awesome!

I'm not sure what the problem is between GSVR and you, as most of your arguments seem very sound - is there more to this than meets the eye? Everything you suggest is black it seems he comes out and says it absolutely, categorically white...
He's not some failed suspension tuner that you've put out of business or something is he? Maybe the previous Ohlins importer perhaps??
C'mon....spill....

[Robert Taylor]

2008 Aprilia 550 SXV Rake angle: 25.2° Trail: 104 mm.
SV650 Rake 24.8 degrees Trail 100mm
GSX600 Katana Rake 24 degrees Trail 96mm
K9GSXR1000 Rake 23.8 Trail 98.3mm
2008 KTM Superduke R Rake 22.7 Trail 94mm
2007 KTM 660 SMC Rake 27.0 Trail 99mm

Whats that about trail figures? Whats a good set of rake and trail figures for a 600 racebike? I know how to measure it but its not something I've seen people measuring at the track!

You would have learnt those figures had you been invited to the Peter Goddard seminars we ran. But a) I didnt think youd be prepared to pay for such a seminar because I very much get the vibe that EVERYTHING should be cheap, and b ) I didnt wish to see the pain on Peters face.
As it was we had a great bunch of peole at all the seminars, I even invited the CEO of MNZ who although a polar opposite was very cordial.
Someone else might like to elaborate on those figures.

[cowpoos]

Someone else might like to elaborate on those figures.

I'll make it a lil easy...but use copy paste

Rake and trail are terms often used when discussing sportbike handling. Manufacturers sometimes highly tout these numbers in their brochures, and we often refer to them in testing. Trail especially affects how a bike feels, and can determine its stability, steering quickness, and in general, a large portion of the bike's handling characteristics.

Rake is the angle of the steering head with respect to a vertical axis. Trail is the horizontal distance from the front axle to where a line drawn through the steering axis meets the ground.

Trail can be calculated from triple-clamp offset (0), tire radius (R) and rake (ø). Changing any of these three variables will alter trail, but each also has other-and sometimes unfavorable-effects.


Rake is defined as the angle of the steering head with respect to a line drawn perpendicular to the ground . A smaller angle, or less rake, is sometimes referred to as being steeper, and production sportbikes are currently in the neighborhood of 23 degrees of rake.

Trail is the horizontal measurement from the front axle to the point at which a line drawn through the steering head intersects the ground . Current sportbikes have 90-95mm of trail.

While the two dimensions are interrelated, trail is the number that mostly changes the steering feel of a motorcycle. Trail gives a motorcycle stability because of the self-centering effect caused by the front wheel being behind (or trailing) the steering axis. Too little trail, and this self-centering effect is decreased to the point of instability. Too much trail, and the effect is so great that steering becomes heavy. There is a lot more to trail than this (and for more detail, you can refer to the resources listed here), but these are the basics for the purposes of this discussion.

At first glance, most sportbikes appear to have a set rake and trail that cannot be changed, but that is not necessarily the case. Given a motorcycle's basic dimensions, we can calculate trail as follows

(equation 1)
Trail=RSinø-0/cosø
R=tire radius
0=triple-clamp offset
ø=rake


Raising or lowering the front end of your motorcycle puts more or less weight on the front end. However, the handling change due solely to the change in weight bias is negligible.

As an example, a bike with a front tire having a circumference of 1890mm, a 23-degree rake and 27mm of offset will have 98.5mm of trail. Note that in the range of variables we are dealing with, using a tire with a smaller radius, increasing offset or decreasing rake can decrease trail. On most stock sportbikes, you cannot change two of the three variables (tire diameter and offset) without resorting to modifications, but the third variable, rake, we can change slightly by raising or lowering the fork tubes in the triple clamps.

An expert-level roadracer can notice a change in the order of 1mm in trail, and working equation 1 backward, we can calculate the change in rake required as just less than 0.2 degrees. Using an approximation based on the arc length from the rear axle to the steering head, we can further calculate that a fork-height change of just 4mm is enough to effect this angle change.


You can measure rake angle by using an inclinometer, available at hardware stores.





Many riders refer to fork height or rear-ride height change as "putting more (or less) weight on the front end," but we can calculate the change in weight bias brought about by this 4mm change.

A typical sportbike and rider combination weighing 600 pounds has approximately a 50/50 weight bias, with its center of gravity (CG) at a height 1_2 of its 1400mm wheelbase (figure 3). Front-end weight is calculated as:

Wf=Wt(L-x)/L
Wf=front-end weight
Wt=total weight
x=distance from front axle to CG
L=wheelbase

Offset is the perpendicular distance from the steering axis to a line drawn between the two fork tube centers.

In this case, the bike's weight is evenly distributed, with 300 pounds on each wheel. Raising the fork tubes in the triple clamp and changing rake by 0.2 degrees will move the CG forward by approximately 3.5mm (you can use trigonometry to calculate this), resulting in a front-end weight of 301.5 pounds. This is practically insignificant compared to the change in trail resulting from the adjustment-you would have far more of an effect on weight bias by simply moving your body a little bit forward.

Raising or lowering the front end of your bike changes much more than just rake and trail, however. It also changes the angle of the swingarm, which can play a big part in handling, especially on more powerful bikes. We will cover more rear-end geometry in a later issue, but you should know that adjustments in trail are by far the most apparent change a rider will feel when raising/lowering the bike's front end.

Adjustable triple clamps allow you to vary offset in increments. This is the preferred method for changing trail, as it affects other handling variables the least.

Tire diameter is one of the other variables affecting geometry, and we can calculate the change in trail resulting in a switch between two brands of tires. In our last tire test ("DOT Race Tire Test," Feb. '03), the tallest front tire was the Michelin Pilot Race 2, at 1910mm in circumference. The smallest tire was the Metzeler Racetec/Pirelli Supercorsa, at 1878mm. We always measure tire circumference and change ride heights to make the overall chassis attitude (and rake) the same , and in this case, the fork tube height would need to be changed by 5mm just to level the chassis.

Even taking that into account, however, the change in trail due only to the change in tire size is 2mm. Add in the different tire's profile (that changes trail at various lean angles), and you can see why adjusting only to keep the bike's attitude the same when changing tire brands is sometimes not enough.

The last way we can adjust trail is by changing the triple-clamp offset, and you will see that racebikes often have this adjustment. In this case, a 1mm change makes approximately the same change in trail (but opposite-more offset gives less trail, and vice versa) with very little effect on ride height and rake angle.

Resources

Motorcycle Handling and Chassis Design: The Art and Science
Tony Foale
www.tonyfoale.com

The Racing Motorcycle: A Technical Guide For Constructors
John Bradley
www.eurospares.com

[FROSTY:Me]

No, you are right they are not for everyone.
But almost anyone can actually ride one and ride one fast.
You know, in every country in the world that has any current currency in roadracing, the premier class for youth and racer development is 125GP .

What does a mid pack 125 cost to buy and what does it cost to run for a season?
Please dont take this as negative guys I don't know and I DO want to know. (er actually mr 13 wants to know)

[GSVR]

What does a mid pack 125 cost to buy and what does it cost to run for a season?
Please dont take this as negative guys I don't know and I DO want to know. (er actually mr 13 wants to know)

Did you see the bikes GP Honda where going to import. Brand spanking 125GP bikes. I talked to a a 125 rider about this and he told me that you can get really good bikes second hand from Austrailia that come with heaps of performance parts. Apparenlty its very competitive over there and people are upgradeing often so the secondhand maket is a buyers market.

Can anyone here confirm this?

[Billy]

Did you see the bikes GP Honda where going to import. Brand spanking 125GP bikes. I talked to a a 125 rider about this and he told me that you can get really good bikes second hand from Austrailia that come with heaps of performance parts. Apparenlty its very competitive over there and people are upgradeing often so the secondhand maket is a buyers market.

Can anyone here confirm this?

I can confirm GP Honda were not importing these bikes,they were available to anybody through Blue Wing and were part of a cancelled order.To the best of my knowlege they were sold through another dealer

[Billy]

What does a mid pack 125 cost to buy and what does it cost to run for a season?
Please dont take this as negative guys I don't know and I DO want to know. (er actually mr 13 wants to know)

Er trying to run before walking can only end 1 way Frosty.Im sure thats not the advice Peter Jones would have given you

[FROSTY:Me]

Er trying to run before walking can only end 1 way Frosty.Im sure thats not the advice Peter Jones would have given you

No billy me ol chinwa. no way I wanna do that -slowly gently catchee monkey me
Kinda thinking it would be fun in a couple of years if the old fulla (me) and the young fulla (him) were racing in the same class. Im still 72kg so i might fit a 125 and be able to roundee round slowly on it.

[Kevin G]

What does a mid pack 125 cost to buy and what does it cost to run for a season?
Please dont take this as negative guys I don't know and I DO want to know. (er actually mr 13 wants to know)

A good bike might cost $8,000 ish and for that you would have a bike pretty much capable of winning in the right hands.
For a learning year you can use 2nd hand tyres and probably allow $ 500 a round and your done. This is the budget end of the class but a bike capable of winning. Like anything you can spend whatever you like,depends on the depth of the pockets. The budget this year to win the championship was $1100 per round excluding travel and accomodation etc.
With this we have good used parts (pistons) and tyres to burn up in the off season.
If you want to talk about it call me on 021379030.
Kevin Goddard

[FROSTY:Me]

Thanks Kevin. --couple of years away yet mate
but compared to anything else but an old 400 F3 bike is bloody cheap racing. AND unlike anything cept buckets you could probably put the bike on the back of a family sedan saving travel expenses

[oyster]

Best advice to young Mr 13. Tell mum and dad to book a heap of cheap fares to the South Island for Streetstock. Motorcycling Canterbury will support him with a bike, $15 membership, $15 entries training, tons of tracktime (some events 7 times on the track), school holiday coaching etc etc etc.....
Heaps (about 30) of his PEERS to race, have fun with and learn from.
And a true junior championship, the Sportzfotoz Cup.
If he needs support to show this is good economic sense compared to the NI scene, talk to young Alex from Ngatea who did just this last year. As a family, they have no regrets.
Once Streetstock is mastered, then and only then consider a 125GP My boy was 13 when he got on a 125, but he had 38 logbook entries, all roadracing!!! And once he got underway on a 125, he went quite well, but we realised he only had the BARE MINIMUM skill/experience to do justice to the outstanding capabilites of a true GP bike. These cost a lot to run, and it doesn't make sense to use an expensive platform like this to just learn how to ride a bike. As I've described, this money is better spent travelling and maximising racing time/experience

[FROSTY:Me]

OYSTER--Have I told you how much I HATE you
You couldnt hide that post couldya ??
now I got a 13 year old hassling me
But that aside could ya please e mail me the dates concerned so mr 13 can look for flights n stuff.
By the way I need your address to send that parcel to.
Head n barrel n powervalve etc.