Disadvantages Over Hub Dynamos
- Slippage: In wet conditions, the roller on a bottle dynamo can slip against the surface of a tire, which interrupts or reduces the amount of electricity generated. This can cause the lights to go out completely or intermittently. Hub dynamos do not need traction and are sealed from the elements.
- Increased resistance: Bottle dynamos typically create more drag than hub dynamos. However, when they are properly adjusted, the drag may be so low as to be trivial, and there is no resistance when the bottle dynamo is disengaged.
- Tire wear: Because bottle dynamos rub against the sidewall of a tire to generate electricity, they cause added wear on the side of tire. Hub dynamos do not.
- Noise: Bottle dynamos make an easily audible mechanical humming or whirring sound when engaged. Hub dynamos are silent.
- Switching: Bottle dynamos must be physically repositioned to engage them, to turn on the lamps. Hub dynamos are switched on electronically. Hub dynamos can be engaged automatically by using electronic ambient light detection, providing zero-effort activation.
- Positioning: Bottle dynamos must be carefully adjusted to touch the sidewall at correct angles, height and pressure. Bottle dynamos can be knocked out of position if the bike falls, or if the mounting screws are too loose. A badly positioned bottle dynamo will make more noise and drag, slip more easily, and can in worst case fall into the spokes. Some dynamo mounts have tabs to try prevent at least the latter.
Read more about this topic: Bottle Dynamo
Famous quotes containing the word hub:
“When I was growing up I used to think that the best thing about coming from Des Moines was that it meant you didn’t come from anywhere else in Iowa. By Iowa standards, Des Moines is a mecca of cosmopolitanism, a dynamic hub of wealth and education, where people wear three-piece suits and dark socks, often simultaneously.”
—Bill Bryson (b. 1951)