What is a "cassette cog" on a bicycle? Need to adjust front derailleur?

Question

I just bought a new Trek "Hybrid" bike for commuting to work. The town where I bought it is a 90 minute drive. As soon as I tried out the bike on hills, it became evident that it would not shift into the lowest gear possible for hill climbing because the chain will not engage the smallest front chainring.

I want to adjust it myself, but I am not certain of the following instructions, as taken from http://www.bike-manual.com/brands/trek/om/hybrid/index.html -


"- Front derailleur clamp

1. Shift the chain onto the smallest front chainring and the largest cassette cog."

I have never heard the terminology "cassette cog" when speaking of bicycle parts. From the context of the sentence I am guessing they are referring to the multiple gears/sprockets lateral to the rear wheel axel, but the name "cassette cog" just does not seem to fit this part of the bike. Why is it called a "cassette" ?

Answer 1

It's called a cassette because the whole cog set is a complete assembly that slides off the hub. The cassette can be dissassembled, depending on the model and manufacturer, and therefore specific cogs or clusters of cogs can be replaced as they get worn.

In the old days, the cogset was similarly attached to the free wheel, which contained the ratcheting mechanism. This freewheel then threaded onto the rear hub. Today, the ratcheting mechanism is integrated into the hub assembly. It's a much better system since the whole assembly can be rebuilt, as opposed to the old freewheels which you could replace the cogs on, but rebuilding the ratchet mechanism was exceptionally difficult.

One word of advice: IF convenient, take the bike back where you bought it and have the mechanic do the adjustment. If the bike is new, they should do it for free, and ask to watch.

If the shop is not convenient, the one thing you need to watch out for is backing off the small chainring stop screw too far. This will result in your chain dropping off on the inside. The danger here is two-fold:

You will suddenly be spinng the pedals but not going anywhere which may cause you to lose control,

The chain may become jammed in between the small chainring and the crank arm spindle shell (aka 'bottom bracket shell'). The worst case here is that the chain may become damaged and it may even be necessary to remove the crank arm to free the chain.

When adjusting the screw, test ride the bike on level ground and use light pressure on the pedals. Make sure not to back off the stop screw any further than necessary for proper shifting. Once the flat ground shifting works, try it on a hill. The added tension on the chain may require you to back off the screw slightly more, but never adjust in more than 1/4 turn increments.

Good Luck!!

Answer 2

The manual is correct but a bit confusing if you don't know about bike mechanics. The easiest way attempt to fix this yourself is to do the following. I will warn you though - you may need to bring the bike back to where you purchased it. This is a relatively simple adjustment and one that is very common.

Shift the rear derailleur (usually controlled by the right lever) to the biggest gear on the rear wheel. Try to shift to the smallest chainring. It should not go based on what you a saying. There should be two screws on the front deraileur. Onblocks the cage from climibng to far. The other blocks it from traveling to far down. Back the one that controls the lower adjustment off a half turn at a time until the bike shifts. Fine tune as you take your next ride.

This should do it.

Answer 3

the cassette refers to the rear gear assembly (the multiple gears on the rear hub)
it is called a cassette because it can be replaced as a whole, otherwise you can just replace the individual gears
the front gears are called chainrings, and are attached to the crankset (set of cranks and bottom bracket)
hope this helps

Answer 4

you could't only only purchase any Derailleur you like and set up it,you could desire to hunt around the community motorcycle keep's areas and ask them advice of what front Derailleur will paintings on your specific Compact Crank.So in end is this: you could desire to purchase a Derailleur which could paintings with 2 Gears on the front.