Scales for weighing bikes

[Minion]

I think the bathroom scale method is more likely to be accurate, than the kitchen scale one. So give it a try. Do you know why they make those WW scales only accurate to 10k's...cause you should not ride a bike any heavier than that!

Weight: 75.2kg (true weight, assuming accuracy is the same as resolution, 75.15 to 75.25).

Weight with bike: 82.4 (true weight with bike, 82.35 - 82.45).

 

Calculated weight of bike: 7.2kg (true weight range of bike 7.1kg - 7.3kg)

 

Potential error in bathroom scale method, just due to resolution: 0.2kg or one seatpost.

[Shebeen]

 

Potential error in bathroom scale method, just due to resolution: 0.2kg or one seatpost.

 

that is entirely correct. i'd be happy with that accuracy, because if i wanted anything finer, then i'd hope over to the LBS. but do excuse me, i'm a mtber so my bias got filtered in there. in fact my roadbike weighs more than my dual susser.

 

I only thought your suggestion was a joke because who the hell has a 5kg kitchen scale - dunno much about kitchen equipment! I (wrongly) assumed you meant bathroom scale. If you had an accurate kitchen scale with that range, then surely take the wheels off and measure all three items accurately separately?

 

I also was refferring to mtbs too, which generally weigh more than 10kgs, which would max out the 5kgs scales. in fact with a standard 40/60 split front/rear the minimum you could measure with your method is an 8.33kg bike.

[Minion]

I only thought your suggestion was a joke because who the hell has a 5kg kitchen scale - dunno much about kitchen equipment! I (wrongly) assumed you meant bathroom scale. If you had an accurate kitchen scale with that range, then surely take the wheels off and measure all three items accurately separately?

I had a pressing need to weigh my road bike and the LBS wasn't open: hence the kitchen scale. It does have it's limitations, as you say. Max theoretical weight would be twice scale capacity and max actual would be less due to weight distribution.

 

The main problem I had with weighing items separately was that I had no easy way to balance the frame (with all attached parts) on the scale (any supports pushed it over the 5kg mark) and the wheels were also fiddly. It's just easier to weigh a whole bike.

 

Hub friction is the biggest source of error (ignoring scale accuracy) with the method. Even with that, I calculate it still allows the true weight of my bike to be estimated to within +-5g. This is a similar accuracy to a bike scale with 10g resolution (again, ignoring scale accuracy). I wouldn't want to check UCI legal limits, but it's sufficient to satisfy my curiosity.

[Nialls101]

Got a true reading for my bike weight at SA Champs... glad none of the pros saw the weight of my brick