TIP OF THE MONTH

PRE-RIDE INSPECTION

1. Check to be sure that the quickrelease levers or axle nuts (the ones that secure the hub  axle to the dropouts) are tight.

2. Check the brake pads for excessive or uneven wear.

3. Grab and twist the brake pads and brake arms to make sure the bolts are tight.

4. Squeeze the brake levers. This should bring the pads flat against the rims (or slightly toed-in) without hitting the tires. Make certain that you cannot squeeze the levers all of the way to the handlebars.

5. Spin the wheels. Check for wobbles while sighting on the rims, not the tires. (If a tire wobbles excessively on a straight rim, it may not be fully seated in the rim; check it all of the way around on both sides.) Make sure that the rims do not rub on the brake pads.

6. Check the tire pressure. On most mountain bike tires, the proper pressure is between 35 and 60 pounds per square inch (psi). Look to see that there are no foreign objects sticking in the tire, If there are, you may have to pull the tube out and repair or replace it. For some, it may be worth your time to look at the selection of tire sealants at your local bike shop. This goop is placed inside the tube and fills at least the smaller holes you may get.

7. Check the tires for excessive wear, cracking or gashes.

8. Be certain that the handlebar and stem are tight and that the stem is lined up with the front tire.

9. Check that the gears shift smoothly and the chain does not skip or shift by itself. Ensure that indexed (or "click") shifting moves the chain one cog, starting with the first click. Make sure that the chain does not overshift the smallest or biggest rear cog or the smallest or biggest front chainring.

10. Check the chain for rust, dirt, stiff links or noticeable signs of wear. It should be clean and lubricated. (Be cautious about overdoing it, though. Over-lubricated, gooey chains pick up a lot of dirt, particularly in dry climates.) The chain should be replaced on a mountain bike about every 500 to 1000 miles of off-road riding or every 2000 miles of paved riding.

11. Apply the front brake and push the bike forward and back. The headset should be tight and make no "clunking" noises or allow the fork any fore-aft play.

Finally, you need to get into the habit of regularly checking your suspension fork for wear and tear.


FORK INSPECTION

For the most part, forks are pretty durable, but they do break sometimes. A fork failure can ruin your day, since the means of control of the bike is eliminated. Such loss of control usually involves the rapid transfer of your body directly onto the ground resulting in substantial pain and serious injury.

When you inspect a fork, remove the front wheel, clean the mud off, and look under the crown and between the fork legs.

Carefully examine all of the outside areas. Look for any areas where the paint or finish looks cracked or stretched. Look for bent parts, from little ripples in fork legs to skewed cantilever posts and bent dropouts.

Put your wheel back in, and watch to see if the fork legs twist when you tighten the hub into the dropouts. Check to make sure that a true wheel centers under the fork crown. If it doesn't, turn the wheel around and put it back in the fork. That way you can confirm whether the misalignment is in the fork or the wheel If the wheel lines up off to one side when it is in one way and off the same amount to the other side when it is in the other way, the wheel is off, and the fork is straight. If the wheel is skewed off to the same side in the fork matter which direction you play the wheel, the fork is misalign

Hold the stem up next to the steering tube to make sure that when your stem is inserted to depth you have been using it, bottom of the stem is always more than an inch below the bottom of the steering tube threads. If you expand your stem in the threaded region, you are asking for trouble; the threads cut the steering tube wall thickness down by about 50 percent, and each thread offers a sharp breakage plane along which the tub can cleave.


ON TELESCOPING SUSPENSION FORKS

Check that any clamp bolts are tight (ideally, you would do this with a torque wrench to check that they are tightened to the torque recommended by the fork manufacturer). If you have titanium clamp bolts on your fork crown and you do lots of fast and rough downhill riding, consider replacing them annually; the heads of titanium fork crown bolts have been known to snap off. Check for oil leaks, either from around the top of the outer leg or around the bolt at the bottom of the outer leg. Check for torn, cracked or missing seals around the top of the outer leg.

On linkage forks, there are a lot of bolts, pins and pivots that need to be checked regularly. Make sure that all bolts are tight and all pins have their circlips or other retaining devices in place so they do not fall out. Check for cracks and bends around the pivot points.

If you have any doubts about anything on your fork, take it to the expert at your bike shop. When it comes to forks, err on the side of caution. Replacing a damaged fork is expensive, but it is probably a lot cheaper than not replacing it.

FRAME INSPECTION

You can avoid potentially dangerous, or at least ride-shortening frame failures by inspecting your frame frequently. If you find damage, and you are not sure how dangerous the bike is to ride, take it to a bike shop for advice.

1. Clean your frame every few rides, so that you can spot problems early.

2. Inspect all tubes for cracks, bends, buckles, dents, and paint stretching or cracking, especially near the joints where stress is at its highest. If in doubt, take it to an expert for advice.

3. Inspect the rear dropouts and the welds around the brake bosses and cable hanger for cracks. Check to be sure the dropouts, brake bosses and cable hangers are not bent. Some dropouts and brake bosses bolt on (or, in some cases, even glue on) and are replaceable. Otherwise, badly bent or broken dropouts, brake bossers and cable hangers need to be replaced; a framebuilder in your area may be able to do it.

4. Look for deeply rusted areas on steel frames. Remove the seatpost every few months and invert the bike to see if water pours out of seat tube. Look and feel for deep rusted areas inside. We recommend shooting rust-preventive sprays for bicycle frames, WD-40 or oil inside your tubes periodically. Remember to grease both the seatpost and inside of the seat tube when you reinsert the seatpost.

5. On suspension frames, disconnect the shock. Move the swingarm up and down, and flex it laterally, feeling for play or binding in the pivots. Check the shock for leaking oil, cracks, a bent shaft or other damage.

6. Check that a true and properly dished wheel sits straight in the frame, centered between the chainstays and seatstays, and lined up in the same plane as the front triangle. Tightening the hub skewer should not result in chainstay or seatstay bowing or twisting.

 

Monthly Bike Tips by Lennard Zinn and the Technical editors of Velonews and are available in "Mountain Bike Owner's Manuel", VeloPress books - 800/234-8356,  www.velocatalogue.com