diegob@cca.UUCP (Diego Gonzalez) (11/27/84)
I agree with Mr. McBurnett and the other respondent who pointed to the headset area as a prime target source of front end instability. Since the Mercian frames are imported from England, the frame's diamond (the main part) and the fork were probably shipped separated. Sometimes the headset bearing races are pre-installed in the head tube and on the steering tube. Then your dealer's shop installs the bearings, threaded race, and lock nut. If these are not properly adjusted and tightened at this time, vibration from riding could loosen this assembly to the point that the problems cited might arise. I would suggest that the first approach to the "wobble" problem might be to check the headset for proper adjustment. The steering assembly should rotate smoothly, but there should be no trace of play in the bearings. This check is quite simple to do without tools: 1) Remove the front wheel. 2) Grasp the head tube of the frame in one hand. 3) Grasp the fork near the brake mounting in the other. 4) Try to wiggle the fork in the head tube in a fore-and-aft motion. If there is undesired slack in the assembly, you will feel this as a slightly jerky sensation between the two parts. You may also be able to hear an accompanying noise like a small "tick" or suctiony sound as the bearings move about in the grease packing. I would suggest that if you do find play in the headset bearing, particularly since you indicated that you had ridden some distance with the condition, that you open the bearing (or have the shop do it) and inspect it very carefully. Because this part of a bicycle is subject to impact stress which is magnified by both the amount of play and the load, it is very likely that damage to the races and bearings has occurred. If this is the case, your dealer should accept the responsibility (the "quality of workmanship" clause) and replace the headset unit. As a final note, be aware that the headset is not the only possible cause. If the steps above do not yield any clues, consider the entire front (and even rear) end systematically. Inspect tires for wear and inflation (a loaded bike or car can use more pressure). Examine rims, spokes (both for trueness and tension), hubs (for play), and quick release or axle bolts. Check the stem (fit and tightness in the steering tube) and the bars (same). See that the rack is securely fastened to the brake bolt and fork blades. Should none of these areas indicate any problem, then you may have a (exceedingly rare) mismatch between the head tube angle and the fork rake and trail (offset). Let us net readers know what you find. .