Front End Tips

Dave Barnes — Tue, 08 Jun 2010 15:51:12 GMT

Here are some more tips from Ellis Tull of STS that will help you when working on the front of your bike...

Installing the Front Wheel

Never use a hammer when installing the axle. One of the most common mistakes with suspension is having the forks binding. People will spend hundreds of dollars on their forks and install the front wheel incorrectly, the forks can’t work properly. On most big bike axles a 19 mm hex socket will fit in the end of it. Install the wheel, turn the axle in with the hex socket, hold the axle nut with the appropriate size wrench and tighten the nut to the specified torque. Then tighten the axle pinch bolts to the proper torque and you are done, simple.

Bleeding Air from Forks

When riding, your forks will build up air pressure. It is important to bleed this out through the bleed hole on the top of the fork, as the more air built up in the forks the firmer the forks will feel. Make sure the forks are cool (wait 10 min. after riding), make sure the front wheel is off the ground and before opening the bleed screw clean any dirt that can fall in the bleed hole. When you open the screw you will hear the air escaping, tighten the screw when finished but be careful not to tighten the screw to much as it can strip easily.

Tightening the Steering Head Bearings

Your steering head should have enough drag on it that the front wheel won’t flop over by itself with the front wheel off the ground. Make sure that your top triple clamp bolts are loose, loosen the steering stem lock nut located under the bars on top of the steering stem, tighten the slotted nut under the top clamp to the desired tension, torque the stem nut to the proper torque then tighten the top clamps. The steering head bearings can be used as a poor mans steering damper.

Fork Seal Maintenance

To get better life out of you fork seals, after each ride pull down your fork wipers and clean under them with a brake clean that won’t harm the rubber seal. Pump your forks and you will see dirt run down the fork legs. Keep spraying the brake clean and pumping the forks till the grit stops coming down then slide the wipers back in place. After you wash your bike take the time to wipe your fork tubes clean. If not done there are water spots and grit that will stick to the tubes and prematurely wear the seals on your next ride.

Front Tire Pressure

Check your front tire pressure religiously, buy a good quality gauge, and experiment with different pressures. Check tire pressure before a moto and record it, then after the moto check it again and record it. There will be as much as 2-3 psi more after the moto. Lots of times when your bike is handling poorly it can be traced back to incorrect tire pressure – too little pressure will make the bike push in turns and too much pressure will cause the suspension to feel stiff.

Fork Tube Height

The height that you run your fork tubes in the clamps can dramatically change how your bike handles. Sliding your forks up in the clamps will make your bike more nimble in corners an turn better, by sliding them down in the clamps this changes the attitude of the front end and makes it more stable at speed. One thing to remember is that slight changes in height will make a huge difference on the track. Also remember that if you change the front end make sure not to get the rear out of balance in height. Sometimes a slight change in sag might be needed. On some forks there are lines that are machined into the forks at the top by the cap. You can use these as adjustment guides. I like to use a set of calipers with a depth gauge.

Setting Race Sag - The STS Way

Dave Barnes — Tue, 06 Apr 2010 14:24:36 GMT

This is the first in a series of suspension and bike setup tips from Ellis Tull of STS Suspension. Thanks very much to STS for supporting the NMA and taking the time to educate us on the importance of this these topic.

The most important step in suspension set up is setting your race sag, the first thing to do take your bike for a little ride through the pits just to get all the stiction out of the suspension put your bike on the stand and take a measurement from the rear axle to a marked point on your rear fender, slightly left of vertical, record your measurement (I use mm because you don’t have to work with fractions).

Have the rider with full gear on sit on the bike in their normal riding position, have someone hold the front of the bike take another measurement from the same 2 spots as the first one, record the measurement. The difference should be approximately 100mm (for most bikes, however check your owners manual to verify correct race sag for your bike).

If it less than 100 mm you need to undo the preload lock ring on the shock and turn the shock collar counterclockwise to take some preload off the shock spring, if the second measurement is say 94 mm mark the preload ring with a Sharpie pen then turn the preload ring counterclockwise 2 revolutions (each complete turn on the ring is equal to 3 mm) after you get 100 mm you need tighten the preload lock ring and then check your free sag. This can be done by having your bike on the ground under its own weight and push down on the rear of the bike and let it come up on its own, take a measurement from your axle to the same point on the fender the number you get is your free sag. It should be between 30 and 40 mm.

This measurement tells you if your spring rate is correct or not, if the free sag # is more than 40 mm you need to get a softer spring, and if the # is less than 30 mm the spring is to stiff. This may seem backwards but if your race sag is set at 100 mm and the spring is to stiff you will have had to turn the preload ring close to the top of the usable threads on the shock body to achieve your 100mm number, once you drop the bike to the ground to check the free sag the bike will drop down considerably under its own weight as there is very little preload on the spring thus you free sag # will be quite high. On certain bikes such as KTMs you will need to run 110-115 mm of race sag and with mini bikes the race sag should be 85-95 mm. The most important thing when setting your sag is to take your measurements from the same spots both times. Setting you sag may seem difficult but you are wasting your time trying to do anything without doing this first. Once you get used to this procedure it should take only 5 minutes. I do this pretty much before every ride.

Contact STS at (250) 722-2639 or info@stsracing.ca if you have any questions.

Nanaimo Motocross Association Technical Blog