Friday, November 2, 2012

Friday Five: November 2, 2012

Five Myths About Bicycle Maintenance

There are a lot of little maxims, guidelines, and rules-of-thumb out there about taking care of your bike. Some of them are founded in mechanical truth and good to go by (maybe that could be another "Friday Five"...) while others are founded in perception and ought to be ignored or forgotten.

Here are five that fall into the latter category based on my years at the repair stand in 3 major bike shops and now my own operation. Enjoy:
  1. New Chains need re-adjustment after a few rides due to "stretch".
    Chains do stretch. I've covered that before in a few places on the blog. (Here, and here) However, the stretch is slow - or slow-ish depending on the conditions you ride in and your maintenance habits. I have found that occasionally a chain will settle in a little and develop a slight amount of lateral flexibility it may not have had out of the box which may contribute to a change in shifting behavior. This settling may require some slight tweaks to the shift cable tension.

    More likely is this scenario: often when you get a new chain installed at a shop - they probably also recommend new cables. This is a great maintenance move as cables are inexpensive and hold a great deal of influence over your shifting performance. However, new cables do stretch and cable housing and ferrules will compress and settle within the first few rides. This will influence your bike's shifting behavior far more and is likely what you're experiencing and what needs adjustment.
  2. Rotating your tires is a smart way to make them last longer.
    True, but not necessarily the best practice. Here's the details: More of your body weight is usually focused over the rear tire. This coupled with the fact that the rear tire bears all of the motivation duties means that there is a tremendous amount more strain on the rear tire than the front causing it to wear more quickly. Many who have observed this have thought: "I'll just let it wear about half way and then swap the front to the back and vise-versa to even things out." This will help both tires last longer; but it is not a good idea.

    While you are much more likely to get a flat rear tire, have you ever had a flat tire on your front wheel - especially while riding at speed? They are incredibly scary because they are very difficult to control. Your braking and steering are greatly effected due to the tire's sudden ability to squirm around on the rim and along the riding surface (road or trail; whichever the case may be). For this reason, I have long recommended against rotating your tires because it puts the tire with the least amount of rubber - and therefore least puncture resistance - on the front.

    My tire-life-preserving recommendation is this: wear the rear tire out almost to the furthest extent of it's life (but not this far...). Then, remove it; recycle it if possible in your area, and replace it with the lesser worn front tire. Put a new tire on the front and go ride! The results are:

    -You'll have better puncture resistance on the front for safety
    -You'll still get most of the life out of your tires
    -You will buy one tire at a time instead of two.

    Another thought is to replace them in pairs and then keep the lesser-worn front tires around for spares or indoor-trainer tires.
  3. More tire pressure is faster and better.
    Another one I have touched on here before. (In a couple of places, in fact...) This holds true on and off pavement.

    Always obey the range of pressures listed on the side wall of the tire; but there is rarely a reason to use the maximum pressure.
    -Less pressure provides better traction due to a larger contact patch with the riding surface.
    -You'll experience better comfort due to your tire's increased ability to conform to the changing surface
    -You'll also get better cornering from both of those reasons
    -Many argue that it is faster because of all of these qualities plus reduced friction and less vertical undulation on bumpy surfaces.
  4. That wobble on your wheel is nothing to be worried about.
    Couldn't be more wrong. And neither of them will ever get any better by leaving it alone.

    Reason #1: Your rim is out of true (not straight or evenly tensioned). This happens frequently as normal riding conditions stress the wheels and sometimes cause spokes to lose their tension. The rim will move laterally as the tension changes and cause it to look "wobbly" as it rotates.  The easiest place to see this is looking at the gap between your brakepads and rim. With a disc brake equipped bike you may need to hold your finger in a fixed position relative to the rim in order to see if it is true.

    These "wobbly" spots are basically weak spots in the rim because they indicate a spot where the spokes are not tensioned properly to handle the stress of riding. Taking the wheels in to the shop for a truing is a preventive measure that will help them last longer.

    Reason #2: Your hub bearing adjustment may be loose. Also quite common and important; but less frequently noticed as a wobble in the wheel - although if you pick your bike up off the ground and with your other hand wiggle your wheel - you'll feel the wobble.

    Improper bearing adjustment - whether too loose or too tight - will cause your hub bearings to wear prematurely and eventually wear out your hubs; neccessitating replacement. Much like any anomaly with your rims - anything that doesn't feel right with your hubs ought to be addressed as soon as possible. Take your wheels down to the shop.
  5. Ignore that sound and it will go away.
    O.k., I couldn't really come up with a "myth" for #5, but if you're honest with yourself - you've thought this at least once before. I know I have.

    First - there are some noises your bike is supposed to make. The clicking sound your rear wheel makes when you are not pedaling...that is a good sound. (Don't laugh - I've had someone bring a bike in to the shop before because their rear wheel made a clicking sound when they stopped pedaling...I figured I'd just get this out of the way.)

    However, many noises are not good. And they run the gamut really. Squeaks, clicks, ticks, pops, pings, squeals, whines, klunks, thunks, etc., etc. And when they go away under certain conditions - they're not really gone - just sleeping. Especially with the increasing prevalence of carbon fiber in the industry - noises should be taken seriously because they could be catastrophic failure hiding somewhere just waiting to strike.

    A mechanic with a good heart and a persistent work ethic will treat you honestly and work to identify and eliminate a lot of bad noises. Expect to pay them for their time - and this can be time consuming - but it is worth it to know whether the noise was serious or not.

    I've spent hours "noise-sleuthing" to find things as harmless as loose bottle cage rivets and dirty derailleur hanger bolts to things as serious as cracked steerer tubes, cracked seatposts, and improperly molded bottom bracket shells.
So - that was a little longer than my typical Friday Five - but worth while none the less I think.

Have any questions? Any myths that need "busting"? What about a story to share where you discovered the truth behind a cycling "myth". Feel free to post it in the comments. We'd love to hear it!

No comments:

Post a Comment


All content - except where otherwise noted - copyright 2006 - 2013 Matthew Magee. Do not use without permission.

Google Analytics