Way off topic E=MC2

Clockworkmark31

As you will notice E=MC2 is a constant, the same with the doppler effect, ohms law, farradays law, joules law, newtons law etc. They are all constant laws of physics that cannot be broken. If they were then our reality and perception of life would break down.

Since the laws of physics cannot be broken. why can't this knowledge be applied to bicycles.

Example if I weigh x amount and a suspension fork is applying an opposite force. Then why can't we use this data in a scientific way to get a rule or formula on how to setup a MTB given certain parameters.

Eg, sag, depending on where you ride 20-30% is suggested. But why?

Why could something like Newtons second law of motion not be implemented in to riding.

Surely if such a formula was "created" you would be able to apply it to suspension setup, rotor size and a whole host of variables.

Thus you would have the perfect bike setup based on the laws of physics that cannot be broken.

oodboo

Then every bike would ride the same, be the same and riding would be less fun.

Chunkers1980

Are you on drugs?

Antm81

Suspension settings are very personal, however at the higher end you can sometimes find recommended base settings to work from.

bob6397

It is in part due to the way that the physics principles are set in stone that there is a range quoted for setting a personal thing - some people like a softer fork, some people prefer their fork to offer more support at the sacrifice of small bump sensitivity. That's why there is no definite rule (besides the fact that the head angle of your bike/fork travel also have a huge impact on how much sag you want to be running)

bob6397

Clockworkmark31

I certainly am not on drugs, just a question (maybe through the wormhole with Morgan Freeman got me thinking), and partly due to the fact that every "upgrade" I have made has been a blind purchase.

Not only referring to suspension setup, but a whole range of parts you can chose from. If I were to put wider bars and a shorter stem on I could make the handling worse, or I could improve it. If I were to get wider wheels I would gain more grip but sacrifice rolling resistance. Going from a 160mm rotor to 180mm would I notice this just over replacing the calipers? The list goes on and on. Surely it would be better to see if there would be any positives or negatives in selecting components based on certain data.

I get that cycling and bike setup is a personal thing. But when you buy your next upgrade how do you know it will improve things? All you have to go on is doing lots of research and then you may find you don't like said purchase, when I look at upgrades it weight saving vs cost vs reliability. Anything else I would notice would be a bonus.

Only example that comes to mind right now. If I change stem length and handle bar width I am aiming for a certain "sweet spot" in steering, I may get stem length correct and width correct but overlook backsweep that would put me behind the front hub rather than inline with it. Equally if I used the same handlebar with a longer stem I could be too far forward of the front hub. Trying to work out stem length handlebar width rise and backsweep in relation to my bike has way too many variable for co*king it up.

To my mind, my reach and frame won't change so why couldn't they be used as a datum and I can select different components and work out if they would have a positive or negative effect or get a sweet spot, eg, you need between x&y stem length and handlebars within these parameters.

I know this sounds completely out there and whacky, but if you could use the frame and your body dimensions as constants then why couldn't you be able to see advantages and disadvantages of said future upgrades.

I am sure that if my AV amplifier can auto calibrate itself to room size, speaker levels, speaker placement, crossover ranges, in phase out of phase, time delays etc etc in order to work within a "sweet spot", why can't this be used with bikes. It would take away the guess work, headaches ,lost money in wrong upgrades and the list would go on. And why don't manufactures provide more help on this?

Clockworkmark31

Sorry if I seem too nerdy, but if I was looking at a top down view of me sat on the bike from my torso to reach and arm width surely I should be looking at mimicking an equilateral triangle?

bob6397

I am sure that, if you took into consideration body size (every dimension from inseam to arm length to shoulder width), frame size, geometry etc. then you would be able to do it all mathematically.

But that (unfortunately) is so impractical, not only due to the fact that there are millions of different frames out there all with slightly different angles (as well as being different sizes!) but that no one has exactly the same dimensions as anyone else makes it pretty much impossible..

bob6397

Clockworkmark31

Yes exactly true, and you can't argue with this. But for examples sake I have my bike now and I am looking to improve a certain area like steering then why couldn't I input said variables in to a formula to work out what size components would be an advantage or to put me within a "sweetspot".

Antm81

Clockworkmark31 wrote:

Yes exactly true, and you can't argue with this. But for examples sake I have my bike now and I am looking to improve a certain area like steering then why couldn't I input said variables in to a formula to work out what size components would be an advantage or to put me within a "sweetspot".

Because that sweet spot is different for every person, not just on dimension, but where you ride, how you like to ride, how you like the bike to feel etc. A lot of that can't be predicted in an equation.

Clockworkmark31

Antm81 wrote:

Clockworkmark31 wrote:

Yes exactly true, and you can't argue with this. But for examples sake I have my bike now and I am looking to improve a certain area like steering then why couldn't I input said variables in to a formula to work out what size components would be an advantage or to put me within a "sweetspot".

Because that sweet spot is different for every person, not just on dimension, but where you ride, how you like to ride, how you like the bike to feel etc. A lot of that can't be predicted in an equation.

But surely an equation would give you a good base point plus or minus a certain acceptable tolerance to keep you within a range that would work for you?

Clockworkmark31

Everyone here will have two constants frame and body measurements. If you were to compare this to a basic formula like ohms law, given x and y you can always calculate z with a tolerance limit.

Why can't this be applied to MTB to give you an acceptable (percentage) sweet spot that works for you?

Clockworkmark31

oodboo wrote:

Then every bike would ride the same, be the same and riding would be less fun.

The bike would perform to your given measurements.

FishFish

E=Mc**2 is not the full equation but you need to get involved with Hamiltonians. You need to include kinetic energy too.


E**2= (Mc**2) + (p**2c**2) M is the rest mass. In calculating the energy no need to bother with the negative root.

Clockworkmark31

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19620761#p19620761]cyd190468[/url] wrote:

The problem is the thing operating the bicycle. Designing a bike according to the laws of physics would only work if the rider was doing exactly the right thing at every stage. F1`is a good example. Two drivers in identical cars set them up differently because neither of them drive perfectly so each car is altered to allow for the drivers imperfections.

Yes and no, whilst I massively agree with this I also disagree too.

An F1 team will provide a good base setting based on certain parameters and they will have a "sweet" tolerance limit for what they can work within. One driver has a heavy right foot so they would look at fuel consumption and fuel preservation, the other driver has a tenancy to lock up so they would focus on braking to eliminate or minimize this, either way the team are aiming for a perfectly setup and balanced car according to the data or t elementary they are seeing.

If you took something like the new Nissan GTR and put any driver behind the wheel they could all experience the same effect but this is being governed by on board electronics that monitor 100s of things probably 100s of times per second. Could it not be said that they are trying to minimize the affect of the thing behind the wheel.

So why can't manufactures of bikes and components use data and the laws of physics and create a general sweetspot given a set of parameters of give more guidance on size selecting. All of the parts I am looking to replace just concentrate on weight saving benefits, I would rather look at a product or potential upgrade and see that it could be more beneficial other than weight or money saving.

Clockworkmark31

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19621273#p19621273]FishFish[/url] wrote:

E=Mc**2 is not the full equation but you need to get involved with Hamiltonians. You need to include kinetic energy too.


E**2= (Mc**2) + (p**2c**2) M is the rest mass. In calculating the energy no need to bother with the negative root.

quantum mechanics is way out of my knowledge but it seems like a interesting thing to learn. E=MC2 may be the short hand version but my point still stands, given a few parameters of data you can work out the unknown values, thus always having a stable mathematical formula to prove or disprove something.

My point is why can't this be extended to bike use, you enter your fixed data from your measurements and frame, then input said variables to see if the component you want to purchase or the parameter you wish to change would have a negative or positive effect.

Chunkers1980

Didn't you answer your own question when commenting on F1.

cooldad

There maybe a difference in ground as well. Sunny Wales is not in Utah.

Clockworkmark31

Okay having thought about this more now, I get the responses.

If you were to set the bike up to said X and Y data you would generate a Z datum, and this would require the rider to give a certain input to keep the formula in equation, if the rider deviated the formula would break down.

Black magic bikes, there I was thinking you could generate something to give you a good base setting, but was over looking the variable.

njee20

The manufacturers do the thinking on the "sweetspot" for you, it's bounded by the sizes they make...

Say you want a new stem. You can go between (say) 30mm and 120mm. That's the extremes of this "sweetspot" you're desperate to seek. Some people will want one extreme, others will want the other. You can apply a formula to it if you want, but unless you know exactly what is 'right' for you, and it will only be for you, then it's an utterly meaningless exercise.

Clockworkmark31

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19626364#p19626364]njee20[/url] wrote:

The manufacturers do the thinking on the "sweetspot" for you, it's bounded by the sizes they make...

Say you want a new stem. You can go between (say) 30mm and 120mm. That's the extremes of this "sweetspot" you're desperate to seek. Some people will want one extreme, others will want the other. You can apply a formula to it if you want, but unless you know exactly what is 'right' for you, and it will only be for you, then it's an utterly meaningless exercise.

Njee, you are exactly right and thankyou, I am not being sarcastic in saying this btw.

This is what I am wanting a formula you can apply given a few data inputs so you can work out what is the best solution for you.

How can it be conceivable to try every stem from 30mm to 120mm with god knows haw many degrees of rise.

If you were to look at a stem and for arguments sake and it increases 10mm each time and you have a zero to 5 degree rise in 1 degree increments you would be looking at 45 different stems. Then you have the handlebars and all of the rest.

How as a purchaser are you meant to chose the right fit for you without trying numerous variables.

Could the whole process not be simplified or categorized .

If you were to add the handlebars and you have 3 different width sizes and 4 different rise levels and 4 different backsweep options you would be looking at 48 different options.

So 45 plus 48 equals 93 different (if I have done my math correct) combinations you can try.

I get it is a personal thing, but I wouldn't try 93 different combinations in order to find the correct fit.

Hence my original question could it not be simplified more or a formula where you enter a few data points and you are given a few categories that would work well. Eg, I input a few data points I get four different results, each result could be categorized to a discipline, AM, XC Trail and DH all based on your individual data.

njee20

But what is the "correct" fit? There isn't one. You could do a bike fit on a jig to get the ideal position. But that's more about efficiency and comfort, not as relevant for MTB use.

I'm not sure how many more ways we can say this. There is no 'right' for everyone. Each individual may well have a 'right' position based on trial and error. You can't derive a formula.

stubs

I have thought of a radical solution to getting the right bike fitting. Go to several shops and try out some different bikes, some big shops even organise test days where you can get to try up to half a dozen bikes.

Throw your attempts to come up with a formula out there are too many variables you can change a bike radically by fitting a smaller or bigger tyre or even something as simple as a saddle can make big differences in your riding. You can get a bike perfectly set up for climbing smooth fire roads that will scare the brown stuff out of you when you go down hill.

A mate is big into road riding he even shaves his legs and wears strange gloves with no fingers. He had a big Alpine ride coming up so went for a fitting session at Ribble cycles sitting on a dummy bike whilst a bloke played with his protractor and laptop charging him £150. With his bike set up super efficent he went on a 100 mile training ride in the Lakes and ended up walking like a Hunchbacked Crab the next day. So even in roady circles there is no Formula that works for everyone

Clockworkmark31

Okay okay.

Yes I do get it and I know that it is a personal thing. Just with so many variables you'd think the bike industry would offer more support.

Rather than try it and see if it fits you.

njee20

Jesus wept. You're not getting it are you?

How can the bike industry tell you what you like?

I was in Sainsbury's the other day. The choice is bewildering. Why can't the supermarkets tell me what I want for dinner? :roll:

stubs

Wouldnt you be pissed off if you went with what the Industry told you to buy and you hated it

Clockworkmark31

I said I have got it, and I have got it.

Wasn't saying for the industry to hold my hand in selecting parts. But some guidance wouldn't go amiss.

njee20

They provide guidance.

You want a 190mm stem and 400mm bars? Well tough, you can't buy them.

stubs

If your worried about getting size just right buy some cheap stems of different lengths on the net you can get them for about £8 on ebay. Try till you find one that feels good then buy a nice shiny one in that size and sell the cheap stems on ebay or to your mates and likely you will get half your money back.

If your buying from a shop they might have some different used or shop soiled stems kicking about in a box ask nicely provide the spannermonkey with choc biccies and they might let you try out some different sizes.