How much does luggage slow you down?

[ChrisF]

Good to have all the responses but the discussion re rider weight seems to get away from my original question. The calculator that Brucey kindly linked to (http://bikecalculator.com/veloMetricNum.html) shows it all, really. So if a rider gains 10kg (of fat, not muscle) the effect on speed is exactly the same as adding 10kg to the bike weight (luggage). If the heavier rider has more muscle, then that will be shown by his/her power input which goes into the calculation. So, as a reminder for my original question, it was about a given rider taking more luggage, not trying to compare different riders which would bring in all sorts of unknowns!

[Mick F]

Unknowns eh?
How about WHERE the luggage is carried?

There's a bit of an explanation on the Carry Freedom website regarding "swaying" as you ride. The weight on the bike has to be balanced and steered plus swaying side-to-side as you ride. Putting it in a two-wheeled trailer behind isolates the load from the bike so is more efficient. This is a moot point IMHO because you then have to add the weight of the trailer plus friction losses of extra wheels etc.

However, if you take this idea as a good 'un, it suggests that weight carried low on the bike is better than being carried high.
Low riders vs saddle bag and 'bar bag for instance.

Personally, I prefer a two wheel trailer to panniers .......... having tried both over the years.

[Brucey]

It will vary with the rider but if you are doing around 10mph then it is likely that about 50% of your effort is going against rolling resistance.

50% sounds hugely high.

On a flat smooth road I reckon that at 10mph there is negligible rolling resistance (to me in my experience) ............. so long as you have suitable tyres.

Thick knoblies or soft wide tyres, I may agree with you.

Well you are just guessing. You don't have to do that.

Touring tyres can have Crr of 0.007 and a tourist can have a frontal area of about 0.5m sq. If you plug those numbers into the calculator you will find that on the flat you will do about 10mph using 50W (which is all some riders generate). If you set either the aero drag or the Crr to zero you will find that you will do about the same speed using about 25W instead.

If you use low Crr tyres then you can carry more load before you get to ~50% tyre drag @10mph.

cheers

[Mick F]

Thanks.
Good post (as usual) Brucey.

I was in one of our LBSs a week or three ago and they had a glass case with the Garmin pedals. I baulked at the price, but I'm very interested in the idea of looking at the power requirements. They appeal to my thirst for knowledge.

https://buy.garmin.com/en-GB/GB/sports- ... 93569.html

If I had these, I could ride my bike at 10mph and tell you how much power I needed. I could then tow a concrete block up Gunnislake Hill and report my findings.

[[XAP]Bob]

But would 30kg of feathers be harder or easier

[Mick F]

I was shifting logs the other day and stacking them up as firewood. Hazel mainly, and a variety of widths but similar lengths 15 or 16 inches. The diameters varied from 6" down to 1".

The weight of a barrow-load of logs ................. small logs are heavier then big logs.


........... oh, and a sack of sand is heavier than a sack of rocks.

[[XAP]Bob]

Unless the rock is barrow shaped

[Mick F]

Yep!

[robing]

Not a lot really. On my road bike unloaded I average about 15-17 mph. On my loaded tourer it's anywhere from 11-14 mph depending on terrain and particularly wind. With such a lot more drag the wind really makes a difference. But I'm usually enjoying the adventure of touring too much to worry about the extra weight