Cyclometer & Cable Questions

[glenna1984]

I have two questions.

1... I just bought a new cyclometer. My wife and I used to be within a tenth of a mile in synch for any distance ride. Now, on a 35 mile ride we are 1 mile apart.

Both cyclometers are properly configured for wheel size. Once I figure out the real mileage, I want to adjust one of the wheel sensors higher or lower to bring it closer in synch.

The question is: Which way do I move the wheel sensor to show more mileage? i.e. If the bike shows 1 mile and I want that same distance to show 1.1 mile, how do I move the sensor?

2...If I want to relax/loosen the cable on the front derailler, which way do I turn the barrel on the cable by the down tube?

I have a triple, and when using the middle ring in the front and the outside ring in the rear, the outside edge of the front chain guide rubs.

Thanks, in advance.
Glenn

 

[alienator]

I have two questions.

1... I just bought a new cyclometer. My wife and I used to be within a tenth of a mile in synch for any distance ride. Now, on a 35 mile ride we are 1 mile apart.

Both cyclometers are properly configured for wheel size. Once I figure out the real mileage, I want to adjust one of the wheel sensors higher or lower to bring it closer in synch.

The question is: Which way do I move the wheel sensor to show more mileage? i.e. If the bike shows 1 mile and I want that same distance to show 1.1 mile, how do I move the sensor?

2...If I want to relax/loosen the cable on the front derailler, which way do I turn the barrel on the cable by the down tube?

I have a triple, and when using the middle ring in the front and the outside ring in the rear, the outside edge of the front chain guide rubs.

Thanks, in advance.
Glenn

1. Don't move the magnet. The computer doesn't measure where the magnet is on the spokes, rather it "counts" how many times it passes the magnet over some interval of time. The difference between your wife's distance and yours is likely from
   • You both have different weights, so the effective circumference of your tires differ as a result of your contact patches differing in size.
   • The pressures in the tires aren't exactly the same.
   • Maybe the tires are different.
   • Weight bias on the bikes is different.
   To get a more accurate distance measurement
   • Inflate the tires in each bike to the normal pressure used.
   • Put a mark on the sidewall of a tire and align that mark so that it is at the center of the tire's contact patch. Mark the ground adjacent to the mark on the tire.
   • Get on the bike and roll the bike so the tire rotates 1,2, 3, or however many complete rotations. The more rotations, the more accurate your calibration number will be (Ten is prolly the most you'd want to do).
   • Place a mark on the ground where the mark on the tire meets the ground.
   • Measure the distance between those two marks on the ground and divide that distance by the number of rotations the tire went through.
   • Convert that number to the units the computer needs for tire circumference and put it in the computer.
2. Clockwise, but that won't change the fact that your front derailleur rubs. There are two screws on the front derailleur. Those "limit" screws limit how far the derailleur cage moves to the inside and to the outside. Go to Park Tool's front derailleur page for step by step instructions on how to adjust that deraileur properly. Then go to the Park Tool homepage and bookmark it. That website has repair how-tos for everything you could want to do on your bike.

 

[glenna1984]

Thanks...you are correct about the tires. Hers are 650 and mine are 700.

Regarding the limit screws...I understand what you are saying.
However, if the relax the cable with the barrel adjuster, what DOES that do?

Glenn

 

[alienator]

Thanks...you are correct about the tires. Hers are 650 and mine are 700.

Regarding the limit screws...I understand what you are saying.
However, if the relax the cable with the barrel adjuster, what DOES that do?

Glenn

That will change how far your shift lever moves when the front derailleur moves from one limit to another.

 

[barba]

Have you made sure that you have the right diameter programed in for the tire size you are using? It is my expereince that tires that are nominally the same size can actually vary somewhat between manufacturers.

 

[glenna1984]

I reset the cyclometer on both bikes based on actual wheel distance. I will test ride this weekend.

I am still a bit leery about playing with the stop limits, so will hold on that.

However, in the past, by rotating the barrel I would get back my micro shift adjustment. That seemed to work, so I will try that first.