Knocking from front fork

high tower

Hi all, just taken delivery of a new road bike. Can anyone come up with suggestions for the following.

When the front brake is applied and the bike is pushed forward there seems to be a clunk/feeling of play somewhere in the front end almost feels like a little bit of play between the stem and front forks.

All bolts are tight. All I had to do was straighten the handle bars and tighten them up but apparently I've screwed that up.

Thanks for any suggestions.

smidsy

Headset play would be my guess.

sungod

^^^this

the preload needs to be set, from park tool's site...

Headset Adjustment - Threadless Type
Threadless headsets work on the same principal as threaded headsets. The bearing races need to press against the bearings. The bolt in the top cap will put pressure on the stem, which presses on washers below the stem, which press on the bearing races, which press against the bearings.

NOTE: The cap and bolt at the top of the stem do not secure the stem onto the steering column. The bolt or bolts on the side of the stem keep the stem from moving once the adjustment is made. The cap is used for bearing adjustment only.

Begin by removing the adjusting bolt in the center of the steering column. Next, remove the top cap. There may be a star-shaped nut or other fittings inside the steering column. The bolt threads into this fitting and pulls on the fork against the headset bearing surfaces, which acts to tighten the adjustment. Note the height of the steering column relative to the stem. It should be about 3mm (1/8") below the level of the stem. The stem needs to press down on the spacers in order to adjust the bearings. If the steering column is level with the top of the stem, another spacer is needed below the stem.



Remove bolt and top cap to inspect steering column. Lubricate adjusting bolt and re-install cap and bolt by hand only. DO NOT TIGHTEN.
Loosen stem bolt(s) that secure stem to the steering column. Lubricate these bolts if they are dry. NOTE: DO NOT LUBRICATE INSIDE STEM OR ON STEERING COLUMN SURFACE.
Wiggle the stem side to side to see that it is loose. If the stem is jammed or rusted frozen to the steering column, no adjustment can be made.
Align stem straight to wheel and gently secure the top bolt. Stop when any resistance is felt.
Tighten stem bolt(s).
Check for play by pulling back and forth on fork. Turn the handlebars in different directions while checking for play. There may be play at this early setting. Use care when grabbing suspension forks, because the legs may have play. Grab upper portion of fork.
To adjust bearings, LOOSEN STEM BOLT(S).
Turn adjusting bolt in center cap only 1/8th turn clockwise.
Secure stem bolts, check for play again.
Repeat adjustments as above until play disappears. Remember to loosen stem bolts before turning adjusting bolt in cap.
Check alignment of stem and tighten stem binder bolts fully.
NOTE: Another test of play is to place the bike on ground and grab the front brake tightly. Press downward on the handlebars and rock the bike forward and back. A knocking sensation may indicate a loose headset. In effect this does the same thing as grabbing and pulling on the fork. However, play in the brake caliper arms may also cause a knocking. Front suspension forks may also have play in the legs, which can cause a knocking.If the adjustment seems very tight, there may be other problems in the headset. Bearing surfaces may be worn out, or the ball bearing retainers may be upside down, or a seal may be improperly aligned. If play always seems present no matter the adjustment, the steering column may be too long for the stem and top cap. Add spacers beneath stem in this case.

Bearing Adjustment and "Feel"
Bearing surfaces are made from hardened steel. The surfaces are cut typically by grinding. Round ball bearings roll on the curved surface of the cup and cone. Even the highest quality bearing surfaces will have slight grinding marks. In the left image below is a high quality cone magnifed two hundred times. Notice the parallel marks from the grinding stone. Also note a slight pit from wear. The right hand image is a bearing magnifed the same amount. It does show some surface marking, but is generally smoother than the cone or cup. Bearing surface smoothness will vary between manufacturers and between models. Some bearing system will simply "feel" smoother because they are smoother. This is why it is difficult to adjust by using a subjective feeling of smoothness. Generally, adjust bearings for the loosest setting that has no knocking or play, regardless of this relative smoothness.

high tower

Thanks Guys. Really comprehensive reply. The bike is at work at the moment but I will check it out tomorrow with your suggestions and post back how I got on.

Thanks for taking the time to reply.

high tower

Thanks again, all fixed in under 5 mins.

Cheers.