My friend has a bike whose wheels are of the captioned specification. 38mm equates to 1.496 inches.
Was going though my computer user manual and found a conversion table (included below). None of these seems to equate to the size of the tyres. Does anyone know what mm setting I should program into the computer? Or should I try to measure the circumference manually (using a drop of oil or whatever on the tyre)?
Those figures are the rolling circumference in millimetres. You can measure it yourself.
Sit on bike with inflation pressure you are going to use. Put valve at marked spot on ground. Roll forward in a dead straight line (along some line) until valve is again at ground. Mark spot. Measure difference with a measuring tape. In mm = your figure.
I wouldn't worry too much about the accuracy of the initial messurement. Even a very accurate *one turn of the wheel*, will not be accurate out on the road anyway. I suggest you put approximate figures in the computer to start with, and make the adjustment based on messurements over long distances out on the road. Ride your bike on a road with milestone or km-stone markings and watch the deviation develop. Remember the deviation from a long distance - say 5 - 7 - 10 km - and when you come home you make a calculation to adjust your computer. Next time on the road you check the deviation again. In that way you will get a very precise and *realistic* messurement of how many turns of the wheel it takes to bring you a given distance down the road - riding in a not quite straight line.
Cheers Ivar
"Glm" <[email hidden]> skrev i en meddelelse news:Y5mOc.12095$zf3.4802@trndny03...
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"Gearóid Ó Laoi/Garry Lee" <[email hidden]> wrote in message news:[email hidden]...
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Those figures are the rolling circumference in millimetres. You can measure it yourself.
Thank you.,
Understood. Just not sure how much faith I had in my measuring ability
(or,
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for that matter, to roll the wheel in a perfectly straight line).
"Glm" <[email hidden]> wrote in message news:4dlOc.6384$FZ5.567@trndny07...
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My friend has a bike whose wheels are of the captioned specification.
38mm
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equates to 1.496 inches.
Was going though my computer user manual and found a conversion table (included below). None of these seems to equate to the size of the tyres. Does anyone know what mm setting I should program into the computer? Or should I try to measure the circumference manually (using a drop of oil or whatever on the tyre)?
Roll out about five revolutions, measure and divide. It will be very close. And certainly more accurate than you can do with measuring just one. Bill
You can do a rollout. But if your lazy like me and being within 1% is close enough, just do a little math. Since tire height is approximately the same as tire width...
Roll out about five revolutions, measure and divide. It will be very close. And certainly more accurate than you can do with measuring just one. Bill
Absolutely. I was shopping for pants last week. I had the tailor wrap his measuring tape about five times around my waist, measure and divide. I have never had pants fit so well!
Seriously though, did you just now make this garbage up? How did you determine your method is "certainly more accurate" than traditional methods used to measure objects less mysterious than bicycle wheels? Anyways, it sure sounds like BS to me.
My friend has a bike whose wheels are of the captioned specification. 38mm equates to 1.496 inches.
Was going though my computer user manual and found a conversion table (included below). None of these seems to equate to the size of the tyres. Does anyone know what mm setting I should program into the computer? Or should I try to measure the circumference manually (using a drop of oil or whatever on the tyre)?
Any thoughts appreciated. Thank you.
I'm showing a 700x38c as being 2170 from Nashbar and 2180 from Vetta. Taken from two different computer charts. --Don-- The beatings will continue until morale improves.
On Fri, 30 Jul 2004 17:14:56 GMT, Don Wagner <[email hidden]>
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I'm showing a 700x38c as being 2170 from Nashbar and 2180 from Vetta. Taken from two different computer charts. --Don-- The beatings will continue until morale improves.
Don
Thank you. Would it be awfully inconvenient if I ask you what mm length is implied by 700x35c? Seems that although the specs for his bike show 700x38c, the shop actually fitted 35c. (They put Shimano 23c on my Roubaix, although U believe the standard is Specialized 25c.)
Well, that is one way to set up a bike computer, and the basic method outlined on the site is sound, but the author of that page does not understand measurement very well, which leads to some silly statements. The last paragraph, in particular, is nonsense. Perhaps googling for "significant digits" would be a good place to start if one wished to fix this.
Thank you. Would it be awfully inconvenient if I ask you what mm length is implied by 700x35c? Seems that although the specs for his bike show 700x38c, the shop actually fitted 35c. (They put Shimano 23c on my Roubaix, although U believe the standard is Specialized 25c.)
If it's too much trouble, don't worry about it.
Sure thing... The Vetta chart is showing 2168 for the 700x35c.
Remember, this is the quick and dirty solution to the problem. Other folks have given excellent formula for much more precise calcs. --Don-- The beatings will continue until morale improves.
Thank you. Would it be awfully inconvenient if I ask you what mm length
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is implied by 700x35c? Seems that although the specs for his bike show
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700x38c, the shop actually fitted 35c. (They put Shimano 23c on my Roubaix, although U believe the standard is Specialized 25c.)
Why not just measure it? You've got the wheels right there. Measurement by Usenet is seldom as effective as direct measurement of the item in question. Phil Brown
