Things that go Bump on the Road - Pt. 2
from the February, 2006 issue of WheelPeople
This is Part 2 of a two-part series discussing some of the things that can go wrong when you’re just riding along, minding your own businessand what to do about them.
Tire Blowouts: Usually, you can just coast to a stop and fix your tire. However, front-tire blowouts at high speeds can be tricky. The front end of the bike will get very squirrelly. If it happens, get your weight back as far as you can, and gently brake to a stop using the rear brake. If the front tire blows out during a fast, downhill turn, you may need to look for a safe escape route off the side of the road. If that’s not possible, you may need to lay the bike down and slidebetter this than to hit a car or go over a cliff.
Research by Prof. David Gordon Wilson and his students at MIT has shown that a tire that fits tightly around the rim will allow the bicycle to be ridden safely to a stop, while a tire that fits loosely on the rim will tend to flop from side to side, making the bike uncontrollable. Unfortunately, tire and rim sizes are poorly controlled, so finding a tire with a tight fit is a matter of chance. For further details, see http://design.runride.com/news/Tire-rim.pdf.
Common causes of blowouts include improperly inflated tires (usually too little pressure), poorly-seated tires, improperly installed inner tubes (tube is pinched or folded) and punctures by objects that slice the tire (such as shards of bottle glass). If you roll a bike with a tire deflated, the tire and tube tend to creep along the rim, which can twist the valve stem and cause a blowout if not corrected. Often, you can see that the valve stem is tilted. Deflate the tire completely and center the valve stem in the rim hole. Push down on the valve stem before inflating the tire so that its base does not wedge between the tire and rim.
Debris Jammed between Front Tire and Fork: Sometimes, a leaf or twig will become wedged between the front tire and fork. It’s usually harmless and will clear itself quickly. If not, stop well off the road and clear by hand. Never attempt to clear debris while riding. Your fingers could get caught in the spokes and then jam against the forknot only mangling your fingers, but also throwing you over the handlebars. Unfortunately, this happened last season to one of our members (a very experienced rider), and he was seriously hurt.
Larger sticks are another story. Steer clear of these, as they can flip into your spokes and send you flying when they wedge between your spokes and fork.
Chain Drops: Dropping a chain most commonly happens when shifting chainrings, especially when shifting a triple chainring to the smallest ring. To avoid loss of control, it is best to sit down for the difficult shifts. If you’re on the flats or descending, you may be able to coax the chain back on before coasting to a stop, using your front shift lever (not your hands!) while slowly rotating the crank. Don’t, however, rotate the crank if the chain starts to jamyou’ll only make it worse. If on an uphill, unclip quickly as you’ll stop almost instantly. Get well off the road before attempting to fix the chain. If the chain has come off a chainring, avoid getting your hands dirty by using a stick or screwdriver to hold the chain against the bottom of the chainring while rotating the cranks backwards. Then realign the front derailleur if necessary. Similarly, it is usually easiest to replace a chain that has come off in the rear by turning the wheel backwards.
To reduce the chances of dropping a chain, keep your derailleurs properly adjusted, shift gently (especially when shifting to the small chainring), and shift to the small chainring before reaching a steep uphill. Some bikes with triple chainrings are prone to chain drops if the chain is on the largest cog (in the rear) when the rider shifts to the smallest chainring. Shift to the small chainring before shifting to the largest cog to avoid this problem.
Bumping Tires: If your front wheel bumps the rear wheel of a rider you are following, you are very likely to crash. It is sometimes possible to avoid a crash by gripping the handlebar firmly and steering toward the wheel you bumped, to brace yourself against it and regain your balance. Unless riding behind someone you can trust to ride smoothly and point out hazards, keep enough distance to see the pavement surface ahead. Never allow your front tire to overlap (come alongside) the rear tire of a rider you are following. If the rider has to swerve suddenly, you will bump tires.
General Precautions for Group Rides: Keep in mind the safety of others if something goes wrong. Shout a warning (even a scream, if that’s all you can manage) so other riders know that you’re about to slow or that you may lose control. Don’t assume that they can tell. Do not stop suddenly if you can avoid it, especially for unimportant things like dropping your water bottle, missing a turn, or answering your cell phone.
Remembersafety is about choices. What choices will you make?