Originally Posted by
NYMXer
A few cramps when I got home but after a beet salad w apple cider vinegar, they stopped. The odd thing here is that I never cramp up during a ride. Sometimes after a ride and rarely ever night time cramps, unless I have a beer. That seems to bring on night time cramps for me, and night time bathroom trips too, lol.
I missed a couple of things initially. "...Unless I have a beer" may be the key. Like caffeine, alcohol is a diuretic. Added to the potassium, you could end up with electrolyte levels that are too high. That can cause cramps as if they are too low.
I really don't think the "soda" was the problem as much as what was in it. A 7-Up or other soda without caffiene might not have caused the problem.
Originally Posted by
NYMXer
Last thing, on a steep climb, we had a fast decent and for the first time ever, my front tire shimmied violently (about 45 mph). The bike is a Specialized Roubaix and nothing was loose (headset, wheel, etc) but I barely saved myself from a near wreck. That was not a good feeling but I did squeeze the top tube with my knees and shift my weight back and that helped a lot.
Yup. A "
death wobble". It happens on lots of bikes for a variety of reasons. 45 mph is a bit higher than most people experience on a bicycle.
Wikipedia's page on bicycle dynamics has this to say about it:
Wobble,
shimmy,
tank-slapper,
speed wobble, and
death wobble are all words and phrases used to describe a rapid (4–10 Hz) oscillation of primarily just the front end (front wheel, fork, and handlebars). Also involved is the yawing of the rear frame which may contribute to the wobble when too flexible.
[74] This instability occurs mostly at high speed and is similar to that experienced by shopping cart wheels, airplane landing gear, and automobile front wheels.
[9][11] While wobble or shimmy can be easily remedied by adjusting speed, position, or grip on the handlebar, it can be fatal if left uncontrolled.
[75]
Wobble or shimmy begins when some otherwise minor irregularity, such as fork asymmetry,
[76] accelerates the wheel to one side. The restoring force is applied in phase with the progress of the irregularity, and the wheel turns to the other side where the process is repeated. If there is insufficient
damping in the steering the oscillation will increase until system failure occurs. The oscillation frequency can be changed by changing the forward speed, making the bike stiffer or lighter, or increasing the stiffness of the steering, of which the rider is a main component.
The last bit is most important. Changing the speed...usually slowing down...or changing the damping so that the frame can't oscillate both work. You probably don't have to "squeeze" the top tube to stop it. Simply putting your leg against the top tube is sufficient.
And, no, steel bikes aren't immune from a death wobble nor are carbon bikes prone to it.