B
Bob Palermo
Guest
Hi,
I have a Trek 2300 with Bontrager race X-lite wheels and tires. The tires
are 700 x 23. I also have a Cateye cyclo-computer. To calibrate, I referred
to the table in the instructions, and used the value for 700 x 23. From my
first rides, I had the feeling that the setting was off. I thought I was
going faster than what I saw on my computer. I know that there are methods
to measure the wheel circumfrence, but when I tried these, I couldn't get
consistent results. I've had good success using roads with mile markers for
calibration, but the road I used for my mountain bike had removed them
during road re-paving. (After setting my mountain bike computer based on the
table, I monitored my distance across 5 mile markers. The miles came in at
1.00, 1.01, 1.00, 1.00, 1.01 on my computer, leading me to conclude that my
mountain bike computer was calibrated accurately.)
On my road bike, rides with friends had my average speed between .5 and .7
mph slower than theirs. (I guess they're just faster than me . )
Anyway, a few days ago I was on a road that had 10 mile and 15 mile lines
for a triathlon that was held recently. Riding the loop twice, I took note
of the readings on my computer as I crossed these lines. Both times, the
distance differential on my computer worked out to 4.88 miles. That's about
2.5%, which would explain a .5 mph average time difference. So now I know
how to adjust my computer.
Finally to the questions.
1) Has anyone else who has Bontrager X-lite wheels and tires found that
using the "standard" setting for 700 x 23 resulted in the 2.5% below true
readings that I have experienced?
2) Is it the wheel or the tire that is the main cause of the discrepancy?
3) What are the expected tolerances for Bontrager xlite wheels and tires? In
other words, if I had access to multiple Bontrager xlite wheels and tires
(700 x 23), and tried them all out, using the standard 700 x 23 calibration
setting, how different would the results on my computer be, for trials on
my 5 mile course? Would they all be near 4.88 mi or would they vary
significantly?
This is by no means a critical issue but I am interested in others'
experiences or insights on this subject.
Thanks,
Bob P.
I have a Trek 2300 with Bontrager race X-lite wheels and tires. The tires
are 700 x 23. I also have a Cateye cyclo-computer. To calibrate, I referred
to the table in the instructions, and used the value for 700 x 23. From my
first rides, I had the feeling that the setting was off. I thought I was
going faster than what I saw on my computer. I know that there are methods
to measure the wheel circumfrence, but when I tried these, I couldn't get
consistent results. I've had good success using roads with mile markers for
calibration, but the road I used for my mountain bike had removed them
during road re-paving. (After setting my mountain bike computer based on the
table, I monitored my distance across 5 mile markers. The miles came in at
1.00, 1.01, 1.00, 1.00, 1.01 on my computer, leading me to conclude that my
mountain bike computer was calibrated accurately.)
On my road bike, rides with friends had my average speed between .5 and .7
mph slower than theirs. (I guess they're just faster than me . )
Anyway, a few days ago I was on a road that had 10 mile and 15 mile lines
for a triathlon that was held recently. Riding the loop twice, I took note
of the readings on my computer as I crossed these lines. Both times, the
distance differential on my computer worked out to 4.88 miles. That's about
2.5%, which would explain a .5 mph average time difference. So now I know
how to adjust my computer.
Finally to the questions.
1) Has anyone else who has Bontrager X-lite wheels and tires found that
using the "standard" setting for 700 x 23 resulted in the 2.5% below true
readings that I have experienced?
2) Is it the wheel or the tire that is the main cause of the discrepancy?
3) What are the expected tolerances for Bontrager xlite wheels and tires? In
other words, if I had access to multiple Bontrager xlite wheels and tires
(700 x 23), and tried them all out, using the standard 700 x 23 calibration
setting, how different would the results on my computer be, for trials on
my 5 mile course? Would they all be near 4.88 mi or would they vary
significantly?
This is by no means a critical issue but I am interested in others'
experiences or insights on this subject.
Thanks,
Bob P.