oboeguy

Anybody? I'd rather slap on decently accurate number than sweat out measuring it myself.

pharnabazos

1595 on the Speed 8, but Schwalbe stelvio tires on the Pro probably make a difference--why don't you just measure it?

af895

No kidding. It's SO easy! Mark a spot on your floor (or pavement) with whatever (chalk?).
Put the bike on the mark with the tire valve down for easy reference. Roll it until the tire valve makes a complete revolution. Mark that spot. Measure.

I did this the other day. Default setting for my tire was 1528. The actual measurement came out to 1550.
I'm 2% faster now! ;p

All kidding aside, measure it for the greatest accurcy in your speed and distance readings. Write the measurement down on the back of your computer and on your rim near the valve for the time when the computer needs a battery replacement. (or just gets reset)

oboeguy

I tried the "whiteout on tire" trick on my floor at home. I got only 1465, which I rounded down to 1460 to make-up for wobble. I think I'll have to try it again later to corroborate my original results. Maybe I read it wrong and it was 15xx? There's a ride that I do which is almost exactly 40 miles on my road bike's computer. I figure I go with whatever setting that's close, do the ride, and then adjust accordingly (do the math, that is). That way I can be pretty sure that I'm off by only a fraction of a mile per 40 miles. Not bad, IMO. For the moment, though, I want at least a decent estimate. I was always lousy in labs at school... (guess that's why I ended-up in math/computers instead of physics ).

Anyhow, I'm having a little trouble with the computer. It's a Sigma Sport 1600 (I think that's one of Ullrich's sponsors -- don't tell Lance!) wireless. I had it working after some tweaking of angles and whatnot, and it was even working when I got to my elevator. But on my way back from a little ride around the neighborhood (grocery trip), it registered a grand total of 0.06km. What gives? The distance between components is well within the max of 70cm, but the line of sight is pretty occluded. Could that be part of the problem?

af895

DEFINATELY line-of-sight is a possible problem. I have a Filzer wireless - low end model but it works just the same - and I had to reposition the unit so it didn't have a handlebar between it and the transmitter.

Same symptoms - little or no speed registering and, of course, the distance didn't work. Also: check the magnet and the sensor. They have to be VERY well lined up.

pharnabazos

I have one of the SigmaSport low end and I couldn't even get it to work consistently with my Surly unless I mounted it on the toptube. With the Dahon, I had to do the same, which means I'm going to run into a parked car trying to gauge my speed one of these days because the toptube is like three feet below me.

By the way, the central park loop is 6.1 miles according to the NYCC website--that might give you easier calibration than the 40-mile.

oboeguy

Hehe, yeah I know CP is like 6.1 to 6.2 miles. The way I see it, though, I want to really put the new bike through a long one to get a feel for everything anyway. Plus, the longer it is, the more accurate my final answer will be. If I don't get a chance to do the long one this weekend, though, I'll definitely be doing a lap around the park on my way back from work to improve the calibration!

I'm thinking I might move the computer a little further out on the bars. Maybe the occlusion by the fork will be mitigated at the cost of slight increase in distance.

farrellcollie

I have a speed8 (2005) and I am trying to get a sigma sport 1600 wireless to work on it - I put in the tire size for 20x1.75 mph=0988 according to little manual. Are you all using km/h? I realize that I am not good at this stuff - so I am trying to figure out if I have completely put info in incorrectly. Sorry to ask such a basic question - but I am very confused. Also not yet impressed with 1600 - it only works intermittently. My cateye astrale is much easier to work.
Thanks.

Dave Hickey

Check out Bike Friday's e catalog. Click on your tire and it will tell you the computer setting.

https://www.greengear.com/content/vie...50f622bf5c6755

farrellcollie

Thanks for the site - but my real question is - is there a different size if you have chosen mph versus km/h. Thanks

Dave Hickey

If there is one that requires it, I've never seen a computer that required a different tire setting to be entered for Miles/KM. I've used probably 20 different computers over the years and they all use the same setting. Even the computers that ask you to set miles vs km first, they still use the same tire setting regardless if miles or kilometers are chosen.

oboeguy

Doesn't make sense to me either, but how do you explain page 14 of this product manual?

oboeguy

I have a picture on my home PC of my setup. It was a little tricky to do it right. It suddenly stopped working a couple of days ago but then I realized that the sensor was a little off. This being my first foray into wireless, I must say I'm a bit underwhelmed by the delicacy of theset things. OTOH, I understand that the transmission can't be very strong to keep down interference.

FYI, I always do km on my computers, Euro-style.

Dave Hickey

Of course Sigma is one of the computers I haven't used

I'd be interested to see if you enter in mph instead of km/hr in the initial set up, it will ask you for the mph tire size.

I think since most, if not all, of the cycling computers are foreign(non US) made, the default setting is KM/Hr so the tire size is metric.

farrellcollie

Yes - it is page 14 that has thrown me off (well that and my total lack of mechanical ability) - when I put in the number for mph - everything was drastically off - not just the minor offness that I expected due to difference in their wheel size listed and my true wheel size.

I am probably going to switch over to the wired kind - I have only gotten the sigma to work three times in the last 4 days - folding it wreaks havoc on the sensor - which is very sensitive and if off the tiniest bit - is gone.

oboeguy

Before you give up, collie, let me send you a pic of how I set it up. It worked fine until a big bump unsettled the transmitter. I'm thinking of using something to keep that from happenning again (double-sided tape?).

farrellcollie

Thanks - a picture would be great -especially if you get the double sided tape to work - I am just very frustrated that the very few times I have managed to get the sensors correctly lined up - a bump or folding it or whatever can knock it out of alignment again.

oboeguy

Pic of transmitter placement

In short, I unhooked the brake and wrapped the rubber band around the break mount. That got closed the distance just enough for a clear transmission. The problem is that the sensor can only go so far up the spokes. I'm thinking now instead of double-sided tape, a little rubber cement might do the job of keeping the transmitter in place over bumps and such. Anybody know if rubber cements would react poorly with the frame paint? (I don't see how it could, but what do I know?)

af895

Check it for solvents. If it has petroleum distillates, toluene or anything like that, you'll dissolve paint with it. Careful about using an adhesive instead of a nylon zip tie or other "physical" restraint. The adhesive may wear through and you'll lose whatever you were trying to attach.

Nice ride BTW.

oboeguy

Thanks! I haven't had a problem since I adjusted the position again, so I'm thinking I won't need any "extra help".

lazurm

I use "Animal" ASM 1.95 20" tires on my Speed P8 and, with multiple measurements and excessively compulsive precision got 1547mm. Now, having written this, just do it man! If you don't care about on-the-dime accuracy, well, just put in 1565 and be happy!