> >
>

# Tire size conversion help

General Cycling Discussion Have a cycling related question or comment that doesn't fit in one of the other specialty forums? Drop on in and post in here! When possible, please select the forum above that most fits your post!

# Tire size conversion help

09-16-08, 03:14 PM
#1
acuteot
Newbie

Join Date: Aug 2008
Posts: 3

Bikes: Trek 7.2 FX

Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Tire size conversion help

Hi everyone, I'm a newbie biker, and I just bought myself a new computer (even managed to install it with no problems!). I'm trying to figure out what my wheel factor is.

I have a Trek 7.2 FX and it says that I have a wheel size of 700 X 35C. The data point I need to enter is the wheel factor, or the distance in millimeters per one turn of the wheel. Per the instructions, a 700 X 32C has a wheel factor of 2155, so I'm assuming that it will be just a bit higher than that. Any help would be greatly appreciated.

09-16-08, 03:34 PM
#2
cyccommute

Join Date: Nov 2004
Location: Denver, CO
Posts: 20,940

Bikes: Some silver ones, a red one, an orange one and a few titanium ones

Mentioned: 82 Post(s)
Quoted: 2194 Post(s)
Originally Posted by acuteot
Hi everyone, I'm a newbie biker, and I just bought myself a new computer (even managed to install it with no problems!). I'm trying to figure out what my wheel factor is.

I have a Trek 7.2 FX and it says that I have a wheel size of 700 X 35C. The data point I need to enter is the wheel factor, or the distance in millimeters per one turn of the wheel. Per the instructions, a 700 X 32C has a wheel factor of 2155, so I'm assuming that it will be just a bit higher than that. Any help would be greatly appreciated.
That's about right for a 700C x 32mm. You won't be off by much. If you really want to be accurate, get on the bike, mark the tire with something and ride in a straight line until the mark shows on the pavement. Measure the distance. Perhaps do several tests and average the results. But I'll bet they come out around 2160 +/-0.5
__________________
Stuart Black
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
An Good Ol' Fashion Appalachian Butt Whoopin'.

09-16-08, 04:46 PM
#3
Bill Kapaun
Senior Member

Join Date: Feb 2007
Location: Mid Willamette Valley, Orygun
Posts: 10,559

Bikes: 86 RockHopper,2008 Specialized Globe. Both upgraded to 9 speeds.

Mentioned: 4 Post(s)
Quoted: 583 Post(s)
Your tire diameter would be 6MM more, so that times PI would be about 19MM more.

I just "lasso" my tire with a string, and measure the string.
Even if you are off by "a few" MM, remember that's in over 2000 units. 20 "parts" off is only 1%, which is far more accurate then your car!

09-16-08, 04:52 PM
#4
acuteot
Newbie

Join Date: Aug 2008
Posts: 3

Bikes: Trek 7.2 FX

Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Thanks for your help! The exact number is 2173.8, so 2174, I had initially but in 2175, so I got pretty close!

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off