Computer set-up for 29'er: Use 700x...what?

Transfering my Cateye 'Strada' computer to my 29'er.

The set-up chart doesn't list a seperate code for 29'er size tires. Guy at the LBS said use the same "700" code as my roadie.

Question: there are twelve seperate codes for "700" size tires on the instructions, starting with 18c width up to 40c. Which one is closest to 29'er?

thx.

 

Do the rollout method. Put a tape measure out on the floor.....measure 1 full revolution of the wheel.....take that measurement and multiply by 25.4...you will then end up with your circumfrence in "mm".

 

I get 2286 mm (90"x25.4) and that's a figure beyond their size listings. Biggest size listed is 700x40c (2200 mm).

Suggestions? I can't pick off any of the math from the list - a jump from 25c to 28c increases the L(mm) by 31mm. But the same 3c jump from 35c to 38c only increases the L(mm) by 12mm ??

I still suck at math after all these years.:-k

 

Do the rollout....your 29er tires are quite a bit bigger than 700x38.

Start with the valve stem at the begining of the tape and roll out to the valve stem.....should be in the 87-90" area for a 29x2.35 tire.

 

If they don't have a manual override for size use the biggest listed. It's only 0.2% off. Besides that, did you ride the bike when you measured? (To compress the tire).

 

Yep, I did the rollout and came up with the 90" number. Biggest size they list is 700x40c (2200mm). My 90" tire comes in at 2286 mm.

The tires are 29x2.0.

Holiday today - the LBS is closed. I'll call them and/or Cateye for the number.

Thx.

Makes sense but, that's a good stunt by yourself.

I don't care much about my speed, I just want accurate distance count.

 

Then you have your number 2286. No need to waste the LBS time with the answer you have already figured out. They are more than likely not going to have this number just lying around. Different tire/rim combinations are going to yeild different dimensions.

Read the instructions to your computer....it should tell you how to enter your own number, usually after you toggle through all pre-set numbers.

If you don't have the manual, go to Cateye's website and download the manual.

Actually, I just checked the Cateye website and downloaded the manual for the Strada Wireless.......the number they give for 29x2.1 is 2288mm.

Keep in mind that there is always going to be a small tolerance/difference in the measurement.

http://www.cateye.com/sites/cateye/upload/manuals/en/CC-RD300W_ENG%2Bv3.pdf

 

Oh shit, I AM a dunce. I HAVE the number.

Cool. I got whacked by a car last week - still a bit foggy. Thanks.

 

If you want accuracy you'll have to measure it like you ride it. Make a chalk mark on the sidewall so it's closer to the pavement than the valve stem. Observe, measure, and repeat until you're sure of the value.

If you call Cateye they'll say - ??? We don't have figures for every brand of 29x2.0 tire. The number also varies with tire pressure and rider weight.

 

If you want to get that accurate..... Youll want to make sure your tire NEVER leaves the ground.

Bottom line, with a wheel sensor type bike computer, it will never be dead accurate..... Just not going to happen... YOu want the most accurate, get a Garmin.