It is important to note however, that in order to switch gears the chain must be moving forward. With both the front and the rear derailleur, when the shift cable is pulled, it will move the chain to a larger gear. When the cable is released, it will move the chain to a smaller gear. Just remember that larger gears at the rear mean easier pedalling but more torque, and larger gears at the front mean harder pedalling but more speed. The key element that will determine how hard you work is the difference in the number of teeth the wee pointy bits that hook through the gaps in your chain between the front chainring at the front and your selected rear cog.
That means the outer ring has 50 teeth and the inner ring has 34 teeth. The rear cassette is 11 speed The combination of your selected chainring and cog determine the gear ratio. The gear ratio, combined with the circumference of your wheel and tyre determines how far you will travel with each revolution of the cranks. To get our gear ratio we divide the number of teeth on the front by the number on the back:. This is expressed as 4. This is the gear I would use on the flat.
That said, some companies offer range expander rings which basically means that you lose the smallest gear from the outside of the cassette and replace it with a whopper on the inside. But dual front ring drivetrains are still available? Yes, and they are still very good and an extremely efficient way to offer smooth pedaling.
They can be programmed to automatically shift front rings independently so that you only need to run one shifter on the bars. Well, yes, yes they are but the performance is sensational and the sound of a servo automatically selecting your next ratio is so much posher than the ham-fisted crunch of chain suck.
Take heart though, Shimano have long stood by their policy of trickle-down tech through their product ranges and Di2 has already made it to XT level. Seems a bit daft to have all that technology getting coated in filth? This is one of the great riddles of modern mountain biking — the peril of the external drivetrain. In the very highest gear, the chain will be all the way on the right.
That stretches the chain and wears it out. Instead, shift the front set from the left to the middle 1 to 2. That keeps your chain nice and straight. Which brings us to…. Check our article. The ever-increasing number of gears on bikes is mostly marketing hype. For the most part, all the extra gears are useless. My childhood bike had just 10 gears. Then bikes went to 15 gears. Then Do you really need that many gears?
What you really need is a good range of gears. As you can see from our example, racing cyclists use gear set-ups with an emphasis on high gears and a relatively narrow range. That also means the steps between gears are close. For less serious riders, gear range is probably more important. How low a gear do you need? How high? The lower gear range you get from a compact chainset is why they have become so popular in the last decade.
With its WiFli transmissions, SRAM has taken this to its logical conclusion, combining a compact chainset with a very wide range cassette.
The advantage of a triple is that, done right, it can provide a very wide gear range with small gaps between ratios. The disadvantage is that even with the best indexed gears it can be a struggle to have the shift to the middle ring and down to the inner ring work perfectly. However, use the right components and you can go much lower. It's not usual for gear freaks to custom-blend set ups that go lower still.
My tandem has an 18in low gear, provided by a tooth chainring and a tooth sprocket. Single chainrings have become popular among mountain bikers for their simplicity. Racers like not having to think about front shifting, while for recreational riders who have adopted height-adjustable seatposts it declutters the handlebar.
Chainrings for double and triple cranksets are designed to make it easy for the chain to come off, so it can move to the next ring. That makes them unsuitable for use as a single rings. To get a wide spread of gears, single ring systems use 10 or 11 sprockets ranging in size from tiny to huge, as you can see in the above pic. The price for simplicity is that compared to other ways of getting a wide gear range there are some big gaps in there.
The middle sprockets do give you a useful selection of ratios for general riding though. If you like road. As a subscriber you can read road.
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