Bicycle Mechanics - tube size

Hi,

I have a Trek 1000 Series road bike. I'm trying to determine the tube size I need to get to replace a torn tube.

Here's the specs on my bike wheels I found online:

WHEELS: Alex AT450 rims w/stainless steel eyelets; alloy hubs; 15G stainless, black spokes
TIRES: Bontrager Select, 700x25c

WHEELS Alex AT450 rims with Bontrager Select tires are lightweight and reliable.

I was trying to figure out the size I needed but couldn't find it anywhere on the bike. Maybe this information can help you determine what size I need.

Thanks in advance!

Kevin Smith

You will want a tube that's marked 700 x 20-25 or so. If in doubt, go for the smaller size... for example, if you have a choice between a 700 x 20-25 and a 700 x 25-28, get the former.

Also, take a critical look at your rim strips, which lay in the bed of the rim and cover the spoke holes. Some problems to watch for are shown towards the middle of this page: http://www.parktool.com/repair_help/FAQtires.shtml If your rim strips are exposing your tube to anything sharp, replace them with the medium-width Velox adhesive-cloth rim tape (about $3 each).

Hi bluesource, welcome to the forums! Just ask the LBS for a 700X25 tube, they'll know what you mean. The tubes usually cover a range of sizes, so you might see on the box something like "fits 23-28mm", or something similar.

The 700 is the size of the wheel, and the 25 is the width.

I looked at my rim strips and did notice they weren't covering some of the rim holes completely. I also noticed that the tear was directly over one of the rim holes so good call on that one and I'll try to get some tape for it.

Just curious, what does 700 x 20-25 mean? Is that a measure in centimeters or something?

Thanks for the info.

You need to know if it is presta or shreader, as well as the size.

Thanks for the replies guys and enjoy the biking.