jowong1

Hi, I am new to bicycle and I just got a low-end Iron Horse mtn bike for commuting and occassional off road riding. The commuting is about 5 miles a day. I have had the bike for about a week. Today i ride to work after having the bike sitting at home for its first weekend, i feel that my butt was going up and down which didnt happen last week when i was riding it. And I am not going thru some rough surface, just pavement. I am wondering if this can happen if the back tire is underinflated. If thats the case, what can cause a tire to be underinflated after 5 days of commuting (which adds up to be about 25miles)?


THanks

Landgolier

Any tire could go down in that time if it had a slow leak. Get yourself a good bike pump with a pressure gauge, and keep the tires within 10lbs of the manufacturer's reccomendation.

As for the bouncing feeling, spin the back wheel and see if it appears to move radially (i.e. does the position of the rim seem to move relative to the brake pads). If the wheel is out of round or there's a lump in the tire from a kinked up innertube, you'll see it pretty quickly.

demoncyclist

Tires lose air all the time, even without a leak. The air molecules simple permeate the tube walls. I pump my tires up before EVERY ride.

jowong1

How come the front tire and the back tire lose air at different rate? I feel my front tire is more inflated than my back tire.

Any recommendation of bike pump? Something quick to inflate and cheap.

Thanks

P.S. is it possible that there might be a little piece of glass stuck at the tire to cause leak? What are some signs that tires are underinflated?

THanks

Landgolier

If they lose air at different rates, one has a slow leak.

A basic floor pump should be $25. Be sure it works with both presta and schrader valves, the walmart ones sometimes don't do presta.

Glass causes most flats. Go over your tires once a week and dig around in any little cuts you see with something sharp and get the glass out. Get a patch kit and learn to use it, as well, and you will save a lot of $$$ on tubes.

The main sign that a tire is underinflated is that you put the pump on it and it takes more than a stroke or 2 to get it up to the correct pressure. So go get a pump and quit trying to guess about this stuff.

MichaelW

A 5 mile road commute may warrant some hiogh grade, high pressure slick tyres. Nothing upgrades a bike as cost effectiveley as better rubber.
The classic MTB road commuting tyre is a 1.5" slick pumped to about 80psi.