What is the relationship between block, gear speed and derailleur? With Pictures - Project Sports
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What is the relationship between block, gear speed and derailleur? With Pictures

5 min read

Asked by: Kimberly Brown

How do derailleur gears work?

Gears are changed on the cassette (a set of sprockets on the rear wheel) by the rear derailleur. This shifts the chain up or down the cassette. As the derailleur moves to change gear it forces the chain against ramps or steps, moving it onto a bigger or smaller sprocket.

What does a derailleur mean?

Definition of derailleur



: a mechanism for shifting gears on a bicycle that operates by moving the chain from one set of exposed gears to another.

What does 18 speed mean on a bike?

18-speed means you have 18 gears to choose from while riding a bicycle, offering you an extremely pleasant riding experience. These 18-speed bicycles are known for their strong construction and high performance.

Can you use a 7 speed derailleur on a 6 speed?

Shimano derailleurs marketed as 7, 8, 9 speed (and in addition, 10 speed road), can be interchanged in any of those speed drivetrains. Six speed is included in there as well, it’s just not common to see. So yes, a six speed rear derailleur will work correctly with 7, 8 or 9 rear speed systems.

Why is it called a derailleur?

‘ The left hand shifter moves the chain between these cogs using a… Derailleur – These are the very clever devices that move the chain between the cogs. So called because they ‘derail’ the chain – not as I thought for many years named after a French man called ‘Monsieur Derailleur.

How do I know what derailleur I need?

If you are replacing an existing derailleur on a bike, simply count the number of cogs on your cassette and you’re good to go. If your drivetrain’s speed is an unknown quantity, you can count the number of steps that your shifter runs through and add ‘one’ to determine the number of gears your drivetrain has.

What is the maximum speed of 21 gear cycle?

Maximum speed of 21 gear bicycle,



The maximum speed of gear bicycle can reach up to 110 kilometres per hour (68.3508 miles per hour), depending upon the surroundings and the experience and built of the rider. The shifting of gear at correct time makes a difference.

What gear on a bike is for hills?

High Gear = Hard = Good for Descending: The “highest” gear on your bike is the largest chain ring in the front and the smallest cog on your cassette (rear gears). In this position, the pedaling will be the hardest and you’ll be able to accelerate while traveling downhill.

Is a 7 speed bike good for hills?

The 7-speed bike is made for flat ground terrain and you can conquer good amount of incline. The 7-speed bike is great all-around bike. It has low enough gear to go up a pretty steep incline and also has a high gear to go pretty fast.

What are the parts of a derailleur?


Quote from video: So this is the upper pulley or jockey wheel or the guide pulley and then the the one at the bottom is the lower pulley or the tension pulley.

How do you align a derailleur?

Quote from video: We then rotate the tool hundred and eighty degrees. If this gap is larger than three millimeters. We know our hanger needs a bit of straightening. So we bend and we measure our distance to the rim.

What is a derailleur adjustment?

Turning the adjuster anticlockwise increases tension on the cable, bringing the derailleur closer to the wheel. Clockwise decreases the tension, moving it back towards the frame. If the chain seems hesitant to shift up, increase the cable tension by turning the barrel adjuster anticlockwise.

How much does it cost to fix a derailleur?

If you take your MTB into a local bike shop the average price to replace a rear derailleur is going to be $110. If you DIY replacing a derailleur will cost about $50 (plus your time) This price will depend a lot on the actual derailleur needed. Usually a bike shop will also take care of other problems.

What is a rear derailleur on a bike?

The rear derailleur is the mechanism that shifts the chain at the rear sprockets. There are many different models but they all share the same basic design and functionality. Derailleurs are secured to the bike with a mounting bolt to the frame’s derailleur hanger.

How do I know if my rear derailleur is worn out?

Worn Derailleur



All derailleurs wear out at some point. Check for wear by pulling laterally on the lower cage. Compare this movement in the linkage of a new derailleur. Sloppy pivot and linkages will produce inconsistent shifting, and the only solution is a new derailleur.

What is a derailleur adjustment?

Turning the adjuster anticlockwise increases tension on the cable, bringing the derailleur closer to the wheel. Clockwise decreases the tension, moving it back towards the frame. If the chain seems hesitant to shift up, increase the cable tension by turning the barrel adjuster anticlockwise.

What angle should derailleur be?

That means when using a road front derailleur on a bike with a significantly non-standard chainline (e.g. no chainstay angle to measure) then use an angle of about 71 degrees between the post and the chain line. If it’s a mountain front derailleur, something slacker to match a mountain bike’s seat-post angle.

How do you adjust a rear derailleur?

Quote from video: Set to increase this gap tighten the B screw. To decrease the gap loosen the B screw. If you made significant changes to the B screw double check the indexing adjustment.