Silly question
KevGuinness
Posts: 74
got a new bike computer, never had one before and was wondering, is there a standard wheel size for road bikes or do I need to measure my wheels? This presents a problem since I can not for the life of me find my tape measure!
^ft me and a frame size to match my height so nothing out of the ordinary for me, hopefully they are a standard and I can just shove that in without having to scrounge a free tape measure form ikea tomorrow
^ft me and a frame size to match my height so nothing out of the ordinary for me, hopefully they are a standard and I can just shove that in without having to scrounge a free tape measure form ikea tomorrow
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Comments
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Usually 700c. which will probably be one of the options your computer is asking you to choose from. 29 inch diameter otherwise 26 inch actually.Where\'s me jumper?0
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should default to 700's (or Pi *700) if you need the rim
i make that 2199mm as a quick mental calchttp://veloviewer.com/SigImage.php?a=3370a&r=3&c=5&u=M&g=p&f=abcdefghij&z=a.png
Wiliers: Cento Uno/Superleggera R and Zero 7. Bianchi Infinito CV and Oltre XR20 -
IIRC, Cateye information quotes 700cc wheel - 23mm tyres - 2196 .0
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Best to measure it yourself, instead of using default.
The actual measurement will vary depending on the tyre you use, the pressure you use and your weight.
Place your bike with the valve at the bottom of the wheel, mark the road, then roll forward one revolution, mark the road. Measure the distance travelled.
Start with a budget, finish with a mortgage!0 -
standard setting for 700x23 is 2096, depending on you're exact tyre could be slightly more or less, as suggested, better to measure.0
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700c wheels are only 700mm when they have a size C tyre on them, C being an old French standard width that doesn't exist any more.
A 700x23c tyre will say "622-23" on the side of it, where 622 is the diameter of the rim, and 23 is the size (width/height) of the tyre.
The circumference of the wheel as far as the computer is concerned is approx
3.14159 * ( 622 + 2*23 -2) = 2092mm
The "-2" is an allowance for the tyre squashing slightly when you are on the bike. This will depend on the tyre pressure you use and your weight.
If you don't make any allowance, it comes out as 2096mm, from which I deduce that when Lillywhite read his Cateye info sheet, he'd still got FeltSoGood's value in his mind.
Ideally, you would measure the wheel circumference. This would allow for tyres not being the size they say they are (I'm currently using a 25mm tyre that measures 27mm, and a 28mm tyre that measures 26mm).
Position the bike with the valve at the bottom, mark the road and with your weight on the bike, roll forwards one wheel revolution, until the valve is at the bottom again. Mark the new location, and measure between the two marks. You'll get a more accurate value if you roll several wheel revolutions and divide the measured distance accordingly.0 -
thanks for all the help folks, appreciate it and if I am sober enough to ride tomorrow I will follow your advice!0
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Although if you put a higher number in you can ride much faster and for a greater distance.....its like free fitness really..... 0
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ravey its much more fun to do silly stuff to make you feel like you are going faster without cheating cycle computers.
like going into a long dark narrow tunnel in Glasgow with very dark sunglasses on awesomely fast (you think) purely because you cant see a thing and just feel the wind rush past you!0 -
The best way to measure it is to put a blob of paint on your tyre then ride it. I did that and it was exactly what Sheldon Brown said it would be.Smarter than the average bear.0
