BF2S Forums Bike explanation?

http://en.wikipedia.org/wiki/Gear_ratio
or:
http://en.wikipedia.org/wiki/Bicycle_gearing

Last edited by Morpheus (2008-08-30 10:06:20)

Wat? Never ridden a bike before

It's just like it is in a car. Once you cannot move any faster (or when your pedaling exceeds your comfort in a fast way) you change up a gear. As you would in a car, when you brake, change down a gear. For hills I find it is best to knock the bike down a gear or two until I am still pushing a bit but so that it isn't burning constantly.

Nappy wrote:

dont be scared when it makes an awful clacking sound, first time i rode a bike with gears i thought i mustve broke it, but it was just changing gears..

i was about 9 and i didnt ride my brand new bike again for about a month

It sounds like you are changing gears while still pedaling. You shouldn't be doing that, it increases the likelihood of a chain brake. You should briefly stop pedaling while simultaneously changing gears, and then continue again. At least, that's what I learnt!

Last edited by kylef (2008-08-30 10:12:53)

pretty much yeh

and yeh i figured that out after an hour or so of riding,

larger numbers - harder to pedal but more revolution of the wheel with less actual pedaling.  for going fast.
small numbers - easier to pedal, less revolution of the wheel, more pedaling.  for going up hills.

Ok good thanks. I went for a 2.5 hour bike ride today and i found it really hard going up the hills.
cheers thanks

When you're going downhill always go in the biggest ring at the front...it reduces the slack in the chain - less noise and less chance of it coming off.

what do the front gears do again?

simmy.uk wrote:

what do the front gears do again?

Think of the front gear as a multiplier. On a 21 speed bike, you'll have 7 gears in the rear and 3 in front. Gear 1 on the front gives you gears 1-7 in the rear, gear 2 on the front gives you gears 8-14 on the rear, and gear 3 on the front gives you gears 15-21 on the rear. Same principle for XX-speed bike.

I personally never leave gear 2 on the pedal ones (not sure what it's technical name is) and then just stick in 2's. 2, 4, 6, 8 etc.

It's also because my old bike, if I would land it heavy after something (even just a step), the chain would come off the pedal gear part and go down one. So if it was on 1, it would fall off completely.

I used to be an expert (ok not an expert, but I knew my shit) now you've reminded me that I've completely forgot how it all works. I haven't rode on a bike in years now, YEARS.

kylef wrote:

It's just like it is in a car. Once you cannot move any faster (or when your pedaling exceeds your comfort in a fast way) you change up a gear. As you would in a car, when you brake, change down a gear. For hills I find it is best to knock the bike down a gear or two until I am still pushing a bit but so that it isn't burning constantly.

Nappy wrote:

dont be scared when it makes an awful clacking sound, first time i rode a bike with gears i thought i mustve broke it, but it was just changing gears..

i was about 9 and i didnt ride my brand new bike again for about a month

It sounds like you are changing gears while still pedaling. You shouldn't be doing that, it increases the likelihood of a chain brake. You should briefly stop pedaling while simultaneously changing gears, and then continue again. At least, that's what I learnt!

lol, anyone who having problem with bike gears probably doesn't have a ton of manual transmission experience to draw on

You don't need to worry about what actual sprocket it being used as I doubt you gonna move the chain by hand, the gear shifters on the handle bars are all you need to worry about. 1st is gonna be the lowest gear, you can pedal like hell and go no where in this gear, but it will give you a lot of power to get the bike started or pull it up a hill. If its too hard to pedal shift down, if it feels too easy to pedal (like its almost not doing anything) shift up.

As you said, you have a set of sprocket at the pedals, and a set at the wheels....You should also have two shifters, basically one of the shifters is for the gear ranges in between the other... in other words generally you left shifter will make large changes in gear ratio, and your right one will make smaller changes. Start out with them both in 1st, and run through all the gears on your right as you accelerate. Once you need to go faster then the top gear range on the right will allow you put the left shifter into 2nd, and the right one back into first. Basically your going through every gear on the right for each gear on the left.


As far as what does a little gear and a big gear mean, ect.. Gears are basically levers, and levers change distance/speed for power/torque.
If you have a basic lever with 1 foot on one side of the pivot, and 3 feet on the other side of the pivot any force you put on the short side will move the long side 3 times as much, but with 1/3 the force. Oppositely any force you put on the long side will move the short side 1/3 the distance, but with 3 times the force.

The chain connects the two sprockets, and moves with both of them. One complete rotation of the sprocket means the chain moves the same amount as the circumference of the sprocket.  So if the driving sprocket is bigger then the driven sprocket one rotation moves enough chain to turn the driven sprocket more then once. Since they are connected by the same chain this takes the same amount of time, and the driving sprocket is moving slower then the driven sprocket, and so you pick up speed, but to do this you much sacrifice torque.

So anytime you have a gear, sprocket or pulley where the driving one is larger you will be increasing the speed driven one at the cost of torque. Any time you have a smaller one driving a larger one you will be increasing torque at the cost of speed.