skywalker, I know it’s yours (and others’) failure to get my point that’s kept this thread alive, here’s a chance to read some of the thread you seem to have missed, so you can let it go now?

cynic-al – Member

My points are 1. losing weight doesn’t make you significantly faster than the proportion of weight loss to overall weight on the climbs only…2. weight loss to wheels may make a little more difference, but not the 3x referred to in 1 touted in magazine articles…despite 3. your bike “feeling way faster” etc.

In other words, a mass on the tire has twice the kinetic energy of a non-rotating mass on the bike. There is a kernel of truth in the old saying that “A pound off the wheels = 2 pounds off the frame.”

Keep reading that til you understand it.

OP.. my 2p. Lighter wheels are a proven car-park bike-test winning tactic. They are noticed as soon as you try to accelerate. But much of the ‘lighter is better’ physics is more applicable to a track or road bike, MTBs are very different and although the physics doesn’t change, there are other factors that reduce the importance of lighter wheels on MTBs. ie the rougher the course, the less light + thin rims make sense.

For the last year or so I’ve been riding XC on the heaviest wheels I’ve ever used and I’m riding faster than I have done for a long time. (training effect? maybe but not really!) I found this suprising, but there’s some points that explain it –

Light wheels accelerate to a set speed in a set time with less power input. But once at that speed they have less intertia and are decelerated over bumps more easily.
So you spin em up to speed and think ‘wow, fast bike’ but you need to keep putting that effort in to maintain speed. A heavier wheel feels slower initially, but once rolling it should maintain speed more easily. One may well balance out the other. A bit like frame flex or the 26″ vs 29″ debates, it all comes down to the fact there’s no such thing as free energy, energy put in is just dissipated in different ways and we just want to use it effectively.

The other factor is that a heavier wheel is often due to a wider rim, and in my case also a UST tyre. Low pressure tyres on wide rims mean lower rolling resistance off-road, as well as grip and float that help maximise the momentum of the heavier wheel.

Combine this low rolling resistance and high momentum of these wheels and I can understand why they ‘feel fast’ despite being heavy. Your muscles quickly gain or lose strength based on the regular efforts you put in, so you get used to accelerating heavier wheels pretty quickly anyway.

Lighter wheels are good if all other elements are equal, but it’s not the most important factor. It’s the most easily measured and ‘sold as a benefit’ factor though.

In your case for endurance events I’d go for something light, while being happy to trade 50-80g a rim for a wider section and the ability use a lower pressure tubeless tyre. Comfort and efficiency count for more the longer you ride. Pacenti’s new TL28 rims (28mm width) are very light for the size and are tubeless ready.

skywalker – Member
Keep reading that til you understand it.

I understood it the first time I read it, shame you couldn’t even link to it 🙄

Why not use our brains? What you (and the article) ignore is, as ever, the relevant detail.

1. the effect of conservation of energy which means that the heavier wheel gives more energy back and takes longer to slow down when the bike decelerates (like the F1 KE system) and 2. that formula accounts for pure acceleration only – one does not spend an mtb race constantly accelerating.

You and I don’t know the extent of these effects…when I ride/race I am able to keep what I consider a fairly constant speed…and it’s established that at a constant speed weight at the rim has the same effect as non rotating weight.

Until someone’s attached an accurate acceleromter (sp) to a bike we’ll never know who’s right.

Here’s my take on things, based on races I used to do…80kg + 10kg bike, losing 500gm of (non rotating!*) weight = 0.55%, say I spend 70% of my race climbing, my time will be 0.385% quicker, which over 90m equates to 0.347% = 20 seconds

* We don’t have the info to do rotating, but even on your wiki formula, which is way too high as it ignores significant factors, that’s 40 seconds.

When I was racing (masters, the tightest category in Scotland) it would be pretty much unheard of for 2 places to be separated by 20-40 seconds, and it would be interesting to see what times separate riders in 12 hour events.

Finally I would say it’s pretty rare for anyone who’s serious about racing, and therefore finishing in the higher and more tightly packed positions, to be able to save 500gm off their wheels or bike affordably!

Keep reading that til you understand it.

Aw bless, gone quiet, probably bed-time.

You still going on 🙄

Ha ha, bored now you don’t understand?

I got bored of you ages ago mate.

Making up your own theories based on nothing, nice…..

Even better!

You’d have some credibility if you even tried to debunk what I’ve said, but you can’t.

Best thread outcome for a while! 😀

Can’t and can’t be bothered are slightly different.

Talking to you is like trying to teach a child that doesn’t want to learn, pointless.

Ha ha it gets better

Skywalker, you’ve proposed that you are a physics wizz, but seem incapable of dealing with any of the questions asked.

Give your mum a kiss and get off to bed now, there’s a good lad.

*high fives*

If you read that link from beginning to end you wouldn’t be asking such stupid questions and you would realise that you don’t actually have a valid argument. You are just making yourselves look stupid by thinking you know what you are on about.

It deals with everything you need to know.

Edit: Plus there is the analytic cycling site if you are still having trouble figuring it out.

I’ll tell you once more, then off to bed you young scamp.

Small changes in wheel weight and rotating weight are insignificant in bicycle performance. When you accelerate your wheels you also have to accelerate your bike, your camelback, your helmet and most importantly, you.

This is easy to demonstrate; if you don’t accelerate all these things, you will leave them behind.

Go and look at the article you quoted, and see what it says about lightweight wheels, then apply this to the real world.

And don’t forget to brush your teeth.

If you’re so clever and I’m so wrong it would take no time to destroy my arguments…but you’ve not advanced anything other than references to your article…which concludes against you from what I can see.

…you could do it tomorrow morning break time?

What am I supposed to be proving exactly?

That lighter wheels accelerate faster, handle better, stop quicker, and let your suspension work more efficiently.

Whereas heavier wheels accelerate slower, handle worse, stop slower, and cause your suspension to work less efficiently.

Do you expect me to show you all that in formulas?

And please stop trying to be offensive, it doesn’t suit you 😆

y time will be 0.385% quicker, which over 90m equates to 0.347% = 20 seconds

Doing the maths on this, that means 90m (metres?) originally took you 96 minutes?? (0.347% of 96 minutes is 20 seconds)?

🙁

Skywalker…You’re telling me I’m wrong without explaining why. Your last post shows you don’t even understand my point, no matter how simply I make it. That’s enough for me, you lose.

H…90 minutes.

Lighter wheels accelerate faster, we already agree on that right?

They handle better because of the reduced gyroscopic effect. You can notice this by simply putting on slightly lighter tires!

They stop quicker for the same reason they accelerate quicker.

They cause your suspension to work more efficiently because the suspensions job is to keep the wheel in contact with the ground. The wheel is forever being bounced up and down by rocks/roots/bumps etc. The heavier the wheel, the more work the suspension has to do to keep in contact with the ground. The less unsprung weight it has to deal with, the better it can do its job.

All this combined makes saving weight on your wheels worth while.

Not really much to argue about is there?

Gotta laugh at smart ass Al’s change of stance, it was only last year he was saying:

Look up moment of inertia.

If acceleration didnt matter then you wouldn’t know the difference between a light and heavy bike

do try harder!

LOL you are arguing this without even understanding the physics?
Let me help you. I’m not saying it’s significant – just that gram for gram you’ll feel weight loss more at the rim/tyre than static weight

you’re probably trolling anyway.

Most of your factual points are correct…you’ve also expressed a few opinions which are subjective and so incapable of being proved either wrong nor right.

But that’s not really against what crikey and I were saying, so you’ve changed your point 🙄

Being offensive suits you BTW…and it appears to be all you’ve got.

Run along now!

Nice selective quote these Doug, the older thread is actually a year old, and in it I even say the difference in time/speed is insignificant – my present position.

Flattered you’re spending time on it tho…haterz gon’ hate…

Be nice if you could contribute something to the thread other than attempts to bring of down…says all about you and nowt about me.

Most of your factual points are correct…you’ve also expressed a few opinions which are subjective and so incapable of being proved either wrong nor right.

No, they are all correct and can be proven so by simple physics.

But that’s not really against what crikey and I were saying, so you’ve changed your point

I haven’t changed my point, I was originally saying that you were wrong for saying this;

Rotating mass in bicycle wheels has an insignificant effect, however often the myth is repeated.
If anyone can show it makes a difference, rather than claiming it does, I’m open to having my opinion changed.

TBF crikey me sober chum, so does non-rotating weight.

And

Being offensive suits you BTW…and it appears to be all you’ve got.

I haven’t been offensive, you two were the ones being childish and resorting to insults.

Run along now 😆

skywalker
…All this combined makes saving weight on your wheels worth while

…is subjective. Problem is, so was my “insignificant” tho you chose to ignore my re-phrasing of my point.

Even then it’s all about degree and other factors which affect the simple formula in your wiki article (and even it later concede’s that’s balls…funny you’ve nothing to say about those eh?

Of course you have been offensive…calling someone “stupid” isn’t?…and you’ve been obnoxious from the start.

Oh well…at least I know what to expect of my first day volunteering in primary tomorrow…

Oh and Duggie…nothing to say? 🙄

This thread is great!

I would rather have light wheels if I could afford it end off! The only thing I would put it down to is how much stick I give my wheels. For and Enduro I would stick the lightest wheels my wallet could afford. Save weight on all the parts. It always comes down to money balls to the science.

Al you are wrong, face it.

I have said nothing that can’t be backed up by physics.

Lighter wheels are worth while, for the points I outlined up there ^

If you don’t believe me, buy the heaviest tires you can find, and some of the lightest ones, and see how much better your bike rides with the lighter ones.

Have fun tomorrow, being surrounded by 30 people of higher intelligence.

Nighty night, don’t let the bed bugs bite 😆

LOL…you still don’t even get it!

Anyway….why are you 2 so obsessed with putting me down? Did you get mixed up in the crossfire of some flame a thon?

Minnows like you really shouldn’t try to mix it with the big hitters until at least your voice has broken.

Al and Crikey:
a fairy comes along and you have a free wish to have either taken 500g from your wheels or from you frame. With no other than the weight effect. So no more or less flexibility, durability etc.

What would you choose?

LOL…you still don’t even get it!

No grandad, you still don’t get it. You must have forgotten to take your alzheimer’s medication for the past few days because you seem to have forgotten what you are even arguing about.

Anyway….why are you 2 so obsessed with putting me down? Did you get mixed up in the crossfire of some flame a thon?

You started it old boy, I have only been giving as good as I was getting.

It seems that when you don’t have the answer to the undeniable facts, you resort to petty name calling.

Minnows like you really shouldn’t try to mix it with the big hitters until at least your voice has broken.

Calling yourself a big hitter 😆 it gets better and better. Not only are you confused by simple physics, you have to resort to blowing your own trumpet because no one will do it for you.

😆

[video]http://www.youtube.com/watch?v=0Kz7YUdy-Cg[/video]

Al and Crikey:
a fairy comes along and you have a free wish to have either taken 500g from your wheels or from you frame. With no other than the weight effect. So no more or less flexibility, durability etc.

What would you choose?

It would make no difference where you lost the weight from.

How much faster are you with a full water bottle or an empty one?

How much effect does losing 500g from a total weight of 100 kg make you?

A big wee is about 250 mls; how much faster are you after having a wee?

You are assuming that changing the weight of your wheels will have a greater effect than changing weight elsewhere, please explain why.

You are assuming that changing the weight of your wheels will have a greater effect than changing weight elsewhere, please explain why.

It would make no difference where you lost the weight from.

Err, yes it does.

I explained all the reasons up there ^, if you care to read them again it would stop everyone repeating themselves.

Also the analytic cycling website has models and graphs which clearly show the benefits of lighter wheels in different situations.

What they don’t take into account though is the effect lighter wheels have on suspension performance, handling and braking.

If you add up all these benefits, you will find saving weight at the wheels is worthwhile.

Err, yes it does

Theoretically, there is a very very very small effect. In the real world? No.

The miracle of light wheels (compared to saving weight anywhere else in the bike/rider system) is hard to see.

This is a quote from the article that you are using to support your theory that you will find saving weight at the wheels is worthwhile.

Let me spell this out for you; the source for your theory says that your theory is not correct.

See?

No.

Like I said, you two are only looking at the effect on accelerating and maintaining speed. If you look at the whole picture (accelerating, braking, handling and suspension performance) it is significantly worthwhile.

Why do you think manufacturers try so hard to reduce the sprung and unsprung weight of downhill bikes? If you and Al were right, they would build heavier bikes to keep momentum, but like I said you are not looking at the whole picture.

Edit: That quote is taken out of context, read the whole thing FFS.
Plus it isn’t taking into consideration braking, suspension and handling.