Sigma sport cycle computer - what tyre size

[Mike_GMT80]

Hi, with my cycle to work voucher picked this cycle computer up. First use comparing speed, distance, etc to Strava seems not aligned. The spec for my Triban RC500 bike details wheels as 622 x 17c and also 28inch front and rear. I understand that 622 = 700c, and this is what I have entered as the size into the computer. Would it be more accurate if I entered as 28inch?

I now see the reviews for this computer aren’t great, with limited stock in the store I didn’t have much choice so will see how I get on.

Thanks
Mike

[Mike_GMT80]

Quick 5 mile ride this morning with the wheel size set to 28inch showed a c3% variance to Strava for top speed and distance. Is that difference to be expected on a lower end cycle computer?

Cheers
Mike


I'm a trendy consumer. Just look at my wobbly bog brush using hovercraft full of eels

[PaulaT]

My cycle computer has the ability to enter the actual wheel diameter (including the tyre). I don't bother using it and it doesn't worry me in the slightest that speed and distance might be a few percent out. A nice day out on the bike isn't going to be any better or worse because your computer reads a few percent different to the distance you actually cycled.

[DaveReading]

Quick 5 mile ride this morning with the wheel size set to 28inch showed a c3% variance to Strava for top speed and distance. Is that difference to be expected on a lower end cycle computer?

Plot your ride on, for example, cycle.travel and see what that says.

[Mike_GMT80]

Quick 5 mile ride this morning with the wheel size set to 28inch showed a c3% variance to Strava for top speed and distance. Is that difference to be expected on a lower end cycle computer?

Plot your ride on, for example, cycle.travel and see what that says.

I’m using Strava, so assume that should be accurate. The 3% divergence is between cycle computer and strava. It’s not going to impact my enjoyment of riding, just wondering if 3% is what to expect and if 28inch is the correct wheel setting for my 622-17c wheels.


I'm a trendy consumer. Just look at my wobbly bog brush using hovercraft full of eels

[Jdsk]

Hi, with my cycle to work voucher picked this cycle computer up. First use comparing speed, distance, etc to Strava seems not aligned. The spec for my Triban RC500 bike details wheels as 622 x 17c and also 28inch front and rear. I understand that 622 = 700c, and this is what I have entered as the size into the computer. Would it be more accurate if I entered as 28inch?

If you want the highest accuracy possible without going to extraordinary lengths (!) I recommend finding a convenient place, marking the wheel and measuring the distance that corresponds to a known number of rotations.
https://www.sheldonbrown.com/cyclecomputer-calibration.html
...

Can't comment on using a Strava distance without knowing its provenance.

...

Sheldon Brown article
https://www.sheldonbrown.com/cyclecomputer-accuracy.html
It's not great on the metrology but it does list the errors of cycle computers.

Jonathan

[reohn2]

Make a mark on the wheel circumferance or use the valve as a reference,mark it on the floor,wheel the bike one revolution of the mark.measure the distance in mm.Enter that into the computer for wheel size.
Job done.

I've been using Sigma computers for years,they're the most reliable ones I come across.

PS,are you sure your tyre is 700 x 17c?

[Mike_GMT80]

Make a mark on the wheel circumferance or use the valve as a reference,mark it on the floor,wheel the bike one revolution of the mark.measure the distance in mm.Enter that into the computer for wheel size.
Job done.

I've been using Sigma computers for years,they're the most reliable ones I come across.

PS,are you sure your tyre is 700 x 17c?

Good idea, will give that a try, thanks.

My tyres are 622 x 17c. I understand that to be the same as 700c. Is this correct?


I'm a trendy consumer. Just look at my wobbly bog brush using hovercraft full of eels

[Jdsk]

Make a mark on the wheel circumferance or use the valve as a reference,mark it on the floor,wheel the bike one revolution of the mark.measure the distance in mm.Enter that into the computer for wheel size.
Job done.

Good idea, will give that a try, thanks.

It's more accurate with more turns, as above.

My tyres are 622 x 17c. I understand that to be the same as 700c. Is this correct?

"Tire Sizing Systems"
https://www.sheldonbrown.com/tire-sizing.html

Jonathan

[tatanab]

My tyres are 622 x 17c. I understand that to be the same as 700c. Is this correct?

the 17 is the internal width of the rim, nothing to do with the tyre which will be 23/25/28/32 etc. Ten years ago 18mm tyres were available but I've not seen them in some time, and certainly not 17. On your computer set up there are usually one of two ways of entering wheel size. I think all of my Sigma computers (I have at least 4) allow precise wheel measurements as others have said above. The other way some manufacturers use is you select the wheel size from a menu, in your case 700C by whatever the tyre size is (23/25/28 etc NOT17). You've not told us which model of computer you have so we cannot look up the manual online to tell you what method it uses.

[reohn2]

As per tatanab,I think you have the tyre size wrong,the 17 part not the 700,which will alter wheel size and give a false reading.

[Mike_GMT80]

As per tatanab,I think you have the tyre size wrong,the 17 part not the 700,which will alter wheel size and give a false reading.

I'm a trendy consumer. Just look at my wobbly bog brush using hovercraft full of eels

[Mike_GMT80]

My tyres are 622 x 17c. I understand that to be the same as 700c. Is this correct?

the 17 is the internal width of the rim, nothing to do with the tyre which will be 23/25/28/32 etc. Ten years ago 18mm tyres were available but I've not seen them in some time, and certainly not 17. On your computer set up there are usually one of two ways of entering wheel size. I think all of my Sigma computers (I have at least 4) allow precise wheel measurements as others have said above. The other way some manufacturers use is you select the wheel size from a menu, in your case 700C by whatever the tyre size is (23/25/28 etc NOT17). You've not told us which model of computer you have so we cannot look up the manual online to tell you what method it uses.

Hi, model is SIGMA SPORT BC 9.16 ATS WIRELESS BIKE COMPUTER.

Bike size taken from website:




I'm a trendy consumer. Just look at my wobbly bog brush using hovercraft full of eels

[Jdsk]

You've not told us which model of computer you have so we cannot look up the manual online to tell you what method it uses.

Hi, model is SIGMA SPORT BC 9.16 ATS WIRELESS BIKE COMPUTER.

Jonathan

[reohn2]

As per tatanab,I think you have the tyre size wrong,the 17 part not the 700,which will alter wheel size and give a false reading.

I'm a trendy consumer. Just look at my wobbly bog brush using hovercraft full of eels

Yep as suspected,the OP needs to measure the circumferance of the tyre to get an accurate reading.