rpm/speedo ratio

[dcil]

I saw a speed chart on here somewhere that told what speed u were going at what rpm in a certain gear. I can't find it now. Anybody know where it is located? My 750 is stock tire and stock sprockets, but everybody tells me my speedo is reading faster than I'm going.

[Steve]

I guess you will need to have another 750 rider to verify, but all my 850s seem to turn about 14 mph per 1000 rpm, so ...
2000 = 28 mph
3000 = 42 mph
4000 = 56 mph
5000 = 70 mph
6000 = 84 mph

Note that these are REAL WORLD mph figures from a GPS, not the speedometer.

.

[dcil]

thanks steve, will check it out

[Richsuz]

Hi guys, hope the weather isn being too merciless on you all. I have been able to get back on my bike since my accident, Just last Sunday I clocked 240 miles going to the beach and back.

I do have a problem with the bike. My speedo is broken and I tried using a bike speedo. The problem is, it reads 74 miles at 6000 rpm. I dont think it is right, but I dont have access to a GPS. Does anyone with a 650 GLD have an estimate as to how fast depending on RPM? I also noticed it is not linear according to the bycicle speedo. Should it be?

[verde]

I tried using a bike speedo. The problem is, it reads 74 miles at 6000 rpm.

Did you calibrate it? If you don't have a manual you can probably find it online. If it's a Sigma I can send you pics of the manual. The most accurate way to measure your wheel is to put a piece of tape on the ground and a corresponding piece on the tire, then go one full rotation and put another piece of tape on the ground that lines up with the tire tape. Measure the distance between the two pieces of tape on the ground and use that number to program the speedo.

[Richsuz]

Yes, I did calibrate. Marked the floor and tire with chalk and measured. When the odometer measures 1 mile on the sigma 509, I get almost 1.1 on the bike odometer which still works. I assumed that the sigma is the correct reading. But still, I think I am going faster than the speedo reading on the sigma.

[verde]

Huh. Is it the stock tire size on there? Stock speedo's usually err a little over(i believe manufacturers face fines if they err the other way). Not sure if this crosses over to the odo on your bike, but even so 1/10 of a mile/mile error is a bit much.

Keep an eye out for one of those radar trailers on the side of the road...