Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Recumbent What IS that thing?! Recumbents may be odd looking, but they have many advantages over a "wedgie" bicycle. Discuss the in's and out's recumbent lifestyle in the recumbent forum.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 09-06-09, 09:49 PM   #1
brad3104
Guest
 
Bikes:
Posts: n/a
Mentioned: Post(s)
Tagged: Thread(s)
Quoted: Post(s)
Programming computer...

Just got a Cateye velo 5. Nice basic computer. Its all set up...but i have 2 questions. One where should the sensor be on the spoke? The pictures look like about 3/4 of the way up the spoke...closest to the wheel. Is this correct?

also my tire size is not on the chart....and the chart seems fishy.

Cateye chart says....
47-406 20x1.75=152cm
47-406 20x1-3/8=162cm

Mine is a 37-406 20x1.35=And it came out to exactly 150.5 cm when i measured it myeslf. How come my tire width is the smalles out of these but has the smallest circumference. The smallest out of the 2 listed above.....has the BIGGEST circumference. Does it have to do with the model or brand of the tire? note mine is a 37-406...whatever that means.

For my first ride i just used the standard "20 inch" setting. However i got home and entered as close to the exact amount as possible. I entered 150 cm...as there is no room for decimals. Should i stick with the 150 cm that i input?
  Reply With Quote
Old 09-06-09, 09:57 PM   #2
Jeff Wills
Insane Bicycle Mechanic
 
Jeff Wills's Avatar
 
Join Date: Mar 2008
Location: other Vancouver
Bikes:
Posts: 7,909
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Quote:
Originally Posted by brad3104 View Post
Just got a Cateye velo 5. Nice basic computer. Its all set up...but i have 2 questions. One where should the sensor be on the spoke? The pictures look like about 3/4 of the way up the spoke...closest to the wheel. Is this correct?

also my tire size is not on the chart....and the chart seems fishy.

47-406 20x1.75=152cm
47-406 20x1-3/8=162cm

Mine is a 37-406 20x1.35=And it came out to exactly 150.5 cm. How come my tire width is the smalles out of these but has the smallest circumference. The smallest out of the 2 listed above.....has the BIGGEST circumference. Does it have to do with the model or brand of the tire? note mine is a 37-406...whatever that means.
For my first ride i just used the standard "20 inch" setting. However i got home and entered as close to the exact amount as possible. I entered 150 cm...as there is no room for decimals. Should i stick with the 150 cm that i input
?
37-406 means it's 37mm wide and fits a 406mm bead seat diameter rim. These are the ETRTO numbers, which are less ambiguous than older measurements. Here's some good reading if you're an insomniac: http://www.sheldonbrown.com/tire_sizing.html

The chart is definitely weird. I think there's a typo- a 20 x 1 3/8" tire should be a 37-451 ETRTO size. It's the larger of the 2 20" tire size "standards" out there.

The Sheldon Brown/Harris Cyclery site is a wealth of bicycle information, both useful and useless. Here's some reference material on cyclocomputers: http://www.sheldonbrown.com/cyclecomputers/index.html
__________________
Jeff Wills

Comcast nuked my web page. It will return soon..
Jeff Wills is offline   Reply With Quote
Old 09-06-09, 10:22 PM   #3
brad3104
Guest
 
Bikes:
Posts: n/a
Mentioned: Post(s)
Tagged: Thread(s)
Quoted: Post(s)
Instead of using the standard 20 inch setting on the computer...do u think i should go with the 150 cm manually inputed in?
  Reply With Quote
Old 09-07-09, 12:32 AM   #4
accordionfolder
Senior Member
 
Join Date: Jun 2005
Bikes:
Posts: 214
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Put a piece of tape on a part of tire. Start on a line with the tape on the floor, roll the wheel forward until the tape hits the ground again. Measure the distance between the two lines, put that in your computer. All it's trying to determine is the outside circumference of the tire so it knows how many times it has rotated per time elapsed.

The position of the spoke magnet is completely irrelevant, like previously stated it just needs to know how many times the wheel has rotated per second to multiply that times the circumference of the wheel to find out speed and distance.
accordionfolder is offline   Reply With Quote
Old 09-07-09, 01:05 AM   #5
brad3104
Guest
 
Bikes:
Posts: n/a
Mentioned: Post(s)
Tagged: Thread(s)
Quoted: Post(s)
In my OP i said i measured the tire and it was 150.5 cm. I was just pointing out the Cateyes table of data seems fishy. So yes ill either enter 150 or 151.
  Reply With Quote
Old 09-07-09, 09:51 AM   #6
BlazingPedals
Senior Member
 
BlazingPedals's Avatar
 
Join Date: Dec 2004
Location: Middle of da Mitten
Bikes: Trek 7500, RANS V-Rex, Optima Baron, Velokraft NoCom, M-5 Carbon Highracer, homebuilt recumbent
Posts: 8,808
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 34 Post(s)
Pay no attention whatsoever to the numbers in the manual. The only thing they're good for is to verify that the numbers you come up with via roll-out are in the ballpark. If you measured 150.5, then enter 150. That'll get you within 0.3% accuracy, which is probably close enough for guv'ment work.

My method of roll-out is to line up the valve stem with a crack in the pavement. With weight on the bike, roll the bike 3 revolutions of the tire and mark the spot where the valve stem lines up. Measure with a tape measure. Divide by 3 to get the average circumference, then multiply inches times 25.4 to get mm.
BlazingPedals is offline   Reply With Quote
Old 09-07-09, 11:32 AM   #7
JanMM
rebmeM roineS
 
JanMM's Avatar
 
Join Date: Jan 2006
Location: In Central IN
Bikes: RANS V3, RANS V-Rex, RANS Screamer
Posts: 13,288
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
The 20 x 1.35 Primo Comet Kevlar on my front wheel rolls out at about 150cm. Actually, it rolls out at a bit less than 59" cause there are very few metric tape measures to be had in the American Heartland.
__________________
RANS V3 - Ti, RANS V-Rex - cromo, RANS Screamer - cromo
JanMM is offline   Reply With Quote
Old 09-07-09, 02:06 PM   #8
accordionfolder
Senior Member
 
Join Date: Jun 2005
Bikes:
Posts: 214
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
That'll learn me to half read a post whilst mostly asleep

Sorry for over explaining where it was unnecessary
accordionfolder is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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



All times are GMT -6. The time now is 06:00 PM.