Bicycle Mechanics - shifting probs newb q's

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pbstar
03-03-04, 08:38 PM
ok I'm new to mtbing, and need to konw what to do.
ok the right grip has seven gears and the left has 3. when I go from 1-5 gear, and go to switch the left lever from 1 to 2, it grinds sometimes, and sometimes it will be ok and fit on the teeth right away. I dont 'konw what is the prblem though, but if it doesn't connect right I have to mobe the left lever back to one and try it again untill it get's on right. so any help would be appreciated.
Also, how much are your guys' rear tires filled? becasue I don't konw if mine should be all the way filled, or what, cause I'm trying to fill it up all the way so it doesn't move down at all, but it seems liek it nevcer happens, and it is always moving down somewhat. but I don'tr konw if they are supposed to be filled to the extrmee or what, casue if I look down on it from sitting on it, it looks worse than it is, but I can still tell that it isn't full enough to not go down at all, sorry if this is an obvious answered questions but I am new to mtbing.
thanks for your help, sorry for the long q's.

jeff williams
03-03-04, 09:16 PM
Cross chaining?
Think of the chain as a straight line,
High gear-large outer chain ring to the 2 smallest cogs outer as well!
Mid chain ring 3,4, 5th cog,
You guessed it! 6,7 to the small 'granny' chain ring.
If you run the outer chain ring to the largest inner rear you have crossed chain and it's stretching and your dérailleur is way stretched and doesn't like you. :mad:

Tire pressure is anything you like below max psi, garages pumps have a little pop up gage or buy one.
You generally decrease pressure for off road or ice traction and increase for speed (less contact with surface)
When I ride a ridged frame, I decrease the the psi front for a little give over bumps and increase the rear for a bit of speed and more weight is rear.
Hope some of this helps, perhaps post more info like tire type, and riding habits and more info can be provided.
peace.J
supcom
03-03-04, 09:57 PM
If you look closely at the sides of your tires you should see the maximum tire pressure, usually something like 60 PSI or so, depending on your tire. Get an air pressure gauge that can read higher than that number (some automotive gauges don't go up high enough for bicycle tires) and use the gauge when you fill your tires.

Even at the recommended pressure, your tires will flatten somewhat when you sit on the bike. They all do it so don't worry. Use the gauge and it'll all be cool. Too much pressure could cause a blowout so get the gauge.