Some older 6-speed freewheels (notably, SunTour Ultra-6) also have 5.0 mm spacing. You may want to replace the rear wheel because it is worn out or damaged in one way or another, but indexing is entirely possible even with an old rear wheel that accepts a thread-on freewheel.Īll common 7-speed freewheels, as well as Shimano 7-speed cassettes, have 5.0 mm center-to-center spacing of sprockets. That's part of the reason some bike shops will tell you to throw Old Faithful away and buy a new bike.ĭepending on what parts your bike currently has, you may have to replace many of these parts, but often not nearly as many as you might think. This can be prohibitively expensive on an older bike. If you believe the marketing info from the parts manufacturer, you'll think that you need to replace the shifters, derailers, and everything that touches the chain. With only two chainwheels, so the derailer's limit stops already provide indexing of a sort. Indexed front shifting, however, is of much more questionable value, especially Indexed rear shifting is a very worthwhile feature. Indexed shifting is one of the most popular upgrades to older bikes, and balky friction shifting is one of the most common reasons for discarding older bikes. With indexed shifting, there are click stops in the shifter so that the rider has a tactile guide as to how far to move the shifter to shift from one gear to the next. With older bikes, where the parts are often worn, friction shifting is often even harder to use smoothly.Īfter various false starts, the industry perfected "indexed" shifting in the mid 1980s. ![]() Correcting shifts was difficult when urban traffic or a racing peloton masked chain noise. Simplex Retrofriction, SunTour Power Ratchet and Shimano Light Action levers were better, with a spring to resist cable tension, making frequent adjustment unnecessary.įriction shifting required a fair amount of skill and practice even when the parts were new. A small D-ring allowed adjustment of friction while riding. Most levers were held against cable tension by friction alone, and would eventually slip as parts wore. The rider was expected to correct this by feel and by ear. It might also shift to the desired gear, but not line up quite right with the sprocket, so the chain would run rough and noisy. If the lever was moved the wrong amount, the derailer might shift the chain too far, or not shift at all. The shifter was a simple lever held in place by friction, and the rider was expected to learn to judge how far to move it for each shift. Up through the mid 1980s, derailer-equipped bicycles used "friction" shifting.
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