Halp Plox: Bicycle Computers, Tire Size, Fat Bikes

[yuckfoo]

I have a Lixada bicycling computer. It comes with a chart to set a four-digit number that goes with your wheel size. The chart does not include a number for my 26 x 4 tires. You can measure it yourself to get millimeters of travel, but I think the numbers given in the chart take into account estimated compression of the tire with a rider and if I enter the millimeters myself it will be off. I'm looking for the proper number for this tire. Here is an example of the chart.

 

[DieselTech]

Go with the 75-559 should get you close. You should be able to measure your tire & input that in your computer.

 

[yuckfoo]

Go with the 75-559 should get you close. You should be able to measure your tire & input that in your computer.

Yes I've measured it before but it's really a two-person job if you want to get it right.

 

[DieselTech]

Use a sewing/tailor's tape to measure your tire. You will get the most accurate measurement that way.

 

[Sidewinder Jerry]

Completely forget those charts, they're useless.
Find true OD.
1) Get somebody to help you.
2) Hold the front tire perpendicular to the ground.
3) Take a level then place it in the center of the top of the tire.
4) Level the level.
5) Measure from the bottom of the level to the ground.

This will be your true outside diameter.

Now find the circumference
TOD × ⚻ = circumference.

Convert standard to metric

circumference in inches × 25.4 = mm

My Kendra 838's true outside diameter is 26.25. To get the circumference number this would be how I'd get that

26.25 × ⚻ × 25.4 = 2095 mm

Therefore, the number I enter into my bicycle computer is 2095.

 

[Wrench]

Tire circumference , Use a level to plumb from axel to floor and mark the tire and floor Then roll the bike forward until the mark on the tire is plumb with the axle again then mark the floor, Measure the distance

 

[Axl Myk]

Lay a tape measure on the floor. Put the valve stem at the end, and roll the bike until the valve stem is back at the bottom. That's the diameter of your tire.

 

[Sidewinder Jerry]

Lay a tape measure on the floor. Put the valve stem at the end, and roll the bike until the valve stem is back at the bottom. That's the diameter of your tire.

That would be the circumference of the tire not the diameter.

 

[Axl Myk]

Oops

 

[yuckfoo]

Completely forget those charts, they're useless.
Find true OD.
1) Get somebody to help you.
2) Hold the front tire perpendicular to the ground.
3) Take a level then place it in the center of the top of the tire.
4) Level the level.
5) Measure from the bottom of the level to the ground.

This will be your true outside diameter.

Now find the circumference
TOD × ⚻ = circumference.

Convert standard to metric

circumference in inches × 25.4 = mm

My Kendra 838's true outside diameter is 26.25. To get the circumference number this would be how I'd get that

26.25 × ⚻ × 25.4 = 2095 mm

Therefore, the number I enter into my bicycle computer is 2095.

I was trying this when I discovered something strange. My "26 x 4" tires measure 29 inches. Now I'm really confused.