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by roubaixtuesday
28 Mar 2024, 8:13am
Forum: Touring & Expedition
Topic: touring wheels upgrade
Replies: 66
Views: 2602

Re: touring wheels upgrade

531colin wrote: 28 Mar 2024, 7:52am It’s also important to hold on to some idea of the magnitude of the effect of extra weight at the rim.
An extra half kilo at the rim of both of your wheels might make 1% difference but only when accelerating; at least that’s what we said on the previous page.
…accelerating bike and rider, not just spinning the wheels in air.
Absolutely, and the physics helps this; rather than a vague "probably insignificant" or somesuch we can quantify it as you just have.

A kg extra probably does make a difference to "feel" of a lightweight bike, though of course such a bike will almost certainly already have lightweight rims and tyres. If you have such a bike and are considering eg carbon saddle and pedals, or even lighter rims and tyres, it helps understand where to get best bang for buck.

It probably would make a significant difference in a track sprint.

But for touring, where IMO hills when laden are the hard part, it makes no more difference at all compared to weight on the frame.
by roubaixtuesday
27 Mar 2024, 10:10pm
Forum: Touring & Expedition
Topic: touring wheels upgrade
Replies: 66
Views: 2602

Re: touring wheels upgrade

pwa wrote: 27 Mar 2024, 9:54pm
roubaixtuesday wrote: 27 Mar 2024, 9:47pm
pwa wrote: 27 Mar 2024, 9:43pm
So it makes no difference what wheels and tyres weigh? Imagine an extreme example, with wheels made as a solid disc of steel and each weighing as much as a man. Are we to believe that such wheels would be as easy to propel as normal cycle wheels? On flat terrain with junctions. Because if the answer is "No", weight does matter to some extent.
Sorry, you've lost me.

Per posts above, the physics dictates that mass at the rim of a wheel takes twice the effort to accelerate than mass on a frame. At steady pace, whether flat or on a hill, the mass has the same effect regardless of location.
My feeling is that the wheel weight thing matters on a route with lots of acceleration points, and not on routes where momentum can be held for long stretches. Does that make sense?

(Edit. It makes sense to me, but I am tired and I have downed a bottle of Old Peculier :lol: )
Yes, I think that's exactly what the physics shows.

Not had any OP for a long time, I shall have to rectify that!
by roubaixtuesday
27 Mar 2024, 9:47pm
Forum: Touring & Expedition
Topic: touring wheels upgrade
Replies: 66
Views: 2602

Re: touring wheels upgrade

pwa wrote: 27 Mar 2024, 9:43pm
roubaixtuesday wrote: 25 Mar 2024, 7:13pm
Thehairs1970 wrote: 25 Mar 2024, 5:03pm Surely on a bike, like any vehicle, you are either accelerating or decelerating most of the time and rarely at a constant velocity? So wheel weight will affect you all the time.

However, I think this is quite an irrelevant fact as toughness/reliability are more significant for tourers.
If you're accelerating and decelerating a bit all the time it will cancel out. The only real difference is when accelerating hard.

I agree it's all but irrelevant for touring, but it is good to get the facts straight IMO
So it makes no difference what wheels and tyres weigh? Imagine an extreme example, with wheels made as a solid disc of steel and each weighing as much as a man. Are we to believe that such wheels would be as easy to propel as normal cycle wheels? On flat terrain with junctions. Because if the answer is "No", weight does matter to some extent.
Sorry, you've lost me.

Per posts above, the physics dictates that mass at the rim of a wheel takes twice the effort to accelerate than mass on a frame. At steady pace, whether flat or on a hill, the mass has the same effect regardless of location.
by roubaixtuesday
26 Mar 2024, 7:28am
Forum: Campaigning & Public Policy
Topic: "Why is the right at war with cyclists?... "
Replies: 24
Views: 1197

Re: "Why is the right at war with cyclists?... "

Airsporter1st wrote: 26 Mar 2024, 6:46am I would hazard a guess that the author of that piece lives in or around London, where the majority of cyclists, especially commuters and delivery riders, seem to behave in such a way as to invite the negativity.
I'm in the North and any post on the local Facebook remotely related to roads immediately attracts random cyclist haters.

This in a town where in 25 years I've never once been even slightly inconvenienced by a cyclist.
by roubaixtuesday
25 Mar 2024, 7:13pm
Forum: Touring & Expedition
Topic: touring wheels upgrade
Replies: 66
Views: 2602

Re: touring wheels upgrade

Thehairs1970 wrote: 25 Mar 2024, 5:03pm Surely on a bike, like any vehicle, you are either accelerating or decelerating most of the time and rarely at a constant velocity? So wheel weight will affect you all the time.

However, I think this is quite an irrelevant fact as toughness/reliability are more significant for tourers.
If you're accelerating and decelerating a bit all the time it will cancel out. The only real difference is when accelerating hard.

I agree it's all but irrelevant for touring, but it is good to get the facts straight IMO
by roubaixtuesday
25 Mar 2024, 3:17pm
Forum: The Tea Shop
Topic: Just how long will it take to turn this ship around?
Replies: 103
Views: 2923

Re: Just how long will it take to turn this ship around?

reohn2 wrote: 25 Mar 2024, 3:02pm
pliptrot wrote: 25 Mar 2024, 1:53pm
al_yrpal wrote: 24 Mar 2024, 3:07pm The only thing that will turn us around economically is successful private business. Such businesses are lead by hard working, driven entrepreneurs. These folk must be incentivised. Heavy taxation out of line with world norms incentivises them to take their ideas and businesses abroad elsewhere.

Al
you mean like the water and rail companies? Or the steel industry? Or the banks? Just what planet do you live on? We would all be better off if the people who run -"run", I use the term in irony- these outfits did leave. Add to that the people who destroyed the UK car industry (Rover) ( now disqualifed as company directors) et.al and a clear picture emerges. Their ideas have only been disastrous. Which is the history of private business in the UK. All steps ahead in technology and health have been funded from Government through universities and national institutions. To think that the private sector does anything other than suck wealth from the many for the few shows a staggering misunderstanding.
Spot on!
However,there are those who claim it's all the fault of the British works,indeed Truss the loonie and a few others currently ministers in the present UK "government" :? including the present chance-ellor one Jeremy *unt wrote a book about how the plebs are lazy and don't work hard enough to fill their already bugeoning pockets!
The book you're referring to is presumably "Brittania unchained"

Hunt wasn't an author; these people were.

Kwasi Kwarteng
Priti Patel
Dominic Raab
Chris Skidmore
Liz Truss
by roubaixtuesday
25 Mar 2024, 2:11pm
Forum: The Tea Shop
Topic: Just how long will it take to turn this ship around?
Replies: 103
Views: 2923

Re: Just how long will it take to turn this ship around?

al_yrpal wrote: 24 Mar 2024, 3:07pm ...Such businesses are lead by hard working, driven entrepreneurs. These folk must be incentivised. ...
Guess they can't be that driven if they need extra incentives to avoid slumping into fecklessness.
by roubaixtuesday
25 Mar 2024, 1:42pm
Forum: Touring & Expedition
Topic: touring wheels upgrade
Replies: 66
Views: 2602

Re: touring wheels upgrade

531colin wrote: 25 Mar 2024, 1:38pm Numbers? I'm just a simple biologist with rapidly declining facilities, trying to make sense of the world.

Simple numbers for a simple man....

Say bike + rider + bag = 100 Kg

Say excess wheel & tyre weight at the rim = 1/2 Kg per wheel

Is it then the case that as accelerating the wheel rim "counts double" the excess for 2 wheels is equivalent to accelerating an extra 1 Kg?

....in other words an extra 1/2 Kilo per wheel is 1% when but only when accelerating.
Exactly correct.

[Edit: just to be precise, it's 1% more than it would be if the mass were on the frame, 2% more than if the mass were not added anywhere]
by roubaixtuesday
25 Mar 2024, 1:29pm
Forum: Touring & Expedition
Topic: touring wheels upgrade
Replies: 66
Views: 2602

Re: touring wheels upgrade

rareposter wrote: 25 Mar 2024, 1:05pm You don't really need maths to prove anything though. Put some 2.5kg wheels on a bike, go and ride up a hill.
Replace the wheels (keeping the same tyres/pressures etc) with a pair weighing 1.5kg , go and ride up the same hill at the same power.

The lighter wheels will feel better (which is a bit subjective) and will be measurably faster (which is purely objective).

There's a reason that performance wheels are lighter and it's not all marketing or snake oil!

OK, for touring I'd probably prioritise reliability and standard parts over purely lightweight but it'd still be a consideration even once a bike is loaded with touring gear.
As per above, it makes no extra difference where the mass is when cycling up a hill, that only matters when accelerating.

Of course the mass itself does make a difference on hills
by roubaixtuesday
25 Mar 2024, 11:46am
Forum: Touring & Expedition
Topic: Best tyres for touring
Replies: 27
Views: 1008

Re: Best tyres for touring

531colin wrote: 25 Mar 2024, 11:39am
roubaixtuesday wrote: 25 Mar 2024, 8:05am ..,,
It takes twice the effort to accelerate weight at the rim.
You can feel the difference between a heavy wheel and a light wheel when you are spinning the wheel on its own with your fingers.
However when you are riding the bike, in order to accelerate the wheel you have to accelerate the rider, bike, and luggage, so tiny differences in wheel or tyre are insignificant.
Sure, you can debate the significance, particularly for a touring setup. My own view of the significance for touring can be judged by the marathon plus tyres I tour with.

But, as a matter of fact, when accelerating, tyre mass has twice the effect of frame mass.

When climbing at constant speed, it makes no difference where the mass is.

These are the facts.
by roubaixtuesday
25 Mar 2024, 11:28am
Forum: Touring & Expedition
Topic: touring wheels upgrade
Replies: 66
Views: 2602

Re: touring wheels upgrade

There's no fallacy just maths.

Weight at the rim of a tyre takes twice the effort to accelerate than mass on a frame.

The reason is that you need to spin the wheel as well as moving it forwards, and simply because of the physics, it takes exactly double the effort.

The wheel diameter doesn't make any difference.

It's easier to show with energy than force and torque.

Physics of a spinning ring:

Moment of inertia I = Mr2
M= mass of tyre
r = radius of the tyre

https://unacademy.com/content/upsc/stud ... -cylinder/

Energy to spin an object E = 0.5* I*(omega)2
Omega = angular velocity

https://unacademy.com/content/jee/study ... ic-energy/

So E = 0.5 * M * r2 * (omega)2



But the tyre is rolling on the ground, so
V = r* omega
V = forward velocity
So omega = V/r, and substitute into the energy equation

E = 0.5 * M * V2

Which is exactly the same as you need to accelerate the mass if it doesn't rotate, and you need to do both to the wheel, hence double the effort.

Of course, even if your tyres are 500g each more than they would be with super lightweight tyres, that's still only a kg, ~a large water bottle, and it only applies whilst accelerating, not when going uphill at steady pace.
by roubaixtuesday
25 Mar 2024, 8:14am
Forum: Touring & Expedition
Topic: Best tyres for touring
Replies: 27
Views: 1008

Re: Best tyres for touring

Mtb tourer wrote: 25 Mar 2024, 8:11am Its still 1kg x 2 you are trying to pull up a col ,extra weight against gravity can be felt.
Yes, absolutely, sorry if that was not clear.
by roubaixtuesday
25 Mar 2024, 8:05am
Forum: Touring & Expedition
Topic: Best tyres for touring
Replies: 27
Views: 1008

Re: Best tyres for touring

simonhill wrote: 24 Mar 2024, 11:32pm

Although a recent thread said weight on wheels no more important than weight elsewhere.
Depends on the context.

It takes twice the effort to accelerate weight at the rim.

It makes no difference when going at steady speed on flat or uphill.

So pulling away at a junction, 1kg on a tyre feels like 2kg on the frame. However, crawling up the Galibier, it makes no difference.
by roubaixtuesday
17 Mar 2024, 6:44pm
Forum: Does anyone know … ?
Topic: Touring shoes for bunions and wide feet
Replies: 19
Views: 827

Re: Touring shoes for bunions and wide feet

Do you really need spds?

Touring I just use normal shoes or sandals.

Perhaps some leather walking shoes could work with flats?

Whalley warm and dry (best boots shop in the world IMO) will steam leather boots or shoes to fit bunions.
by roubaixtuesday
17 Mar 2024, 12:36pm
Forum: The Tea Shop
Topic: BEVs
Replies: 2135
Views: 109825

Re: BEVs

Jdsk wrote: 17 Mar 2024, 12:33pm
roubaixtuesday wrote: 17 Mar 2024, 12:31pmCaveat: back of the fag packet numbers, could be a fatal mistake in them.
Thanks

It's always worth including the numbers. Even if they're wrong we'll get to the correction quicker!

: - )

Jonathan
Again!