There are several simple techniques to gather information about how your suspension is working which, when fed back to an expert, make diagnosis and remedy that much quicker.
Try Some of these and when you ask me to "Tweak" your set up I'll be much happier to speak to you !!
Continue Down for "Front End Set Up Procedure"
Front End Set Up Procedure
To measure "Sag", "Droop" "Wheel Movement" etc. apply a cable tie to the chrome section, just tight enough to stop it moving by itself, and it will display the data for you !
NOTE :- To raise the wheel off the floor use a "Headstock" type Paddock Stand as opposed to a "Fork Bottom" or "Wheel Spindle" type to take the weight off the wheels.
All these procedures are the same for "Upside Down" Forks (Just look at the pics Upside Down!)
Here is the Cable Tie Reset to "ZERO", pushed down to the Fork Top with the wheel clear of the floor.
Set the bike on it's wheels (without the rider on) but DON'T bounce it up and down ! Just let it settle under it's own weight. Suspend the bike again and record the distance from the Fork Top to the bottom edge of the Cable Tie .
This is your "Droop" distance
Try this again, suspend the wheel, reset the Cable Tie, set the bike on it's wheels. This time with the riders full weight on the bike - in his riding position but DON'T bounce up and down! (NOTE:- you will need help to steady the bike to get both feet on the 'pegs) Just sit there, then get off. Put the bike up on stands and record the distance moved again.
This is your "Rider Loaded" distance
Now, Reset the cable tie (on the wheels will do for this one) then go out on warm tyres and put in several laps at racing speed, now come in and put the bike up on stands and record the distance the cable tie is from the fork top.
This is your "Wheel Travel" distance.
If you reset the cable tie to zero, with no springs in the forks, and just move the wheel up until the forks bottom out, you will be able to record your
"Maximum Travel" distance.
OK, Say you've done all this, and written it all down. You should have something like:-
60mm of "Maximum Travel" (Springs out, wheel moved up to its stop)
55mm of "Wheel Movement" (Having ridden a couple of hard laps)
so you have 5mm of "Travel Remaining". OK?
Now, you should also have measured something like:-
20mm of "Droop" or "Unladen Sag" (Just the Bike's weight on its wheels)
35mm of "Rider Loaded" (Rider on the bike on it's wheels)
So the difference is 15mm. This is your forks "Sag"
Changing the "Spring Rate" will alter EVERYTHING in ratio.
Increasing the Compression Damping or oil weight will alter the "Wheel Travel" measurement by slowing the forks down during braking or over bumps. This will change the "Feel" as you apply the brakes or tip into a corner.
Rebound Damping will have no effect on these measurements, (unless it is so high that the forks "Pump Down" in which case you are way off ) but will have a large influence on the "Feel" of the bike as you release the brakes into a corner, and determines how the bike "Takes a Set" through a corner.
Raising the Spring "Pre-Load" or reducing the "Air Gap" will raise the overall "Ride Height", by reducing "Droop" and "Sag".
Reducing "Pre-Load" or increasing the "Air Gap" lowers the ride height and increases "Droop" and "Sag"
ONLY "Spring Rate" can truly and accurately control the "Wheel Travel", leaving the Compression Damping to cope with the Handling Requirements.
A Softer Spring will leave you with too little "Travel Remaining" will make it jumpy on the brakes as the forks bottom out.
A Harder Spring will reduce the amount of grip available on the brakes and over bumps.
Only the Correct Spring will offer the right balance between Grip Stability and leave you with enough "Travel Remaining" to cope with unexpected bumps during braking without bottoming out.
Moving the whole fork assembly through the "Yolks" changes the amount of "Rake", and therefore "Trail", which are major chassis parameters. More "Rake" gives stability at the cost of "Turn In". Less "Rake" makes a bike "Flick" quicker but can lead to instability under braking or even on the straights if it's severe enough.
If you thought all that was complicated, lets go and have a look at the
Rear End Set Up Procedure
Or, if you are having trouble with the terminology used,
Confused ? Headache ? Can't seem to figure it all out ?
Suddenly realised there are so many combinations of Front and Rear geometries that it is possible to really mess up your bikes handling?
WE ARE ONLY JUST SCRAPING THE SURFACE !
This is why people like you, need people like us.
Call mailto: HELP@winningperformance.freeserve.co.uk
today and sleep easier.
Next page
technical terms explained
To The Top
|
