The steering difference with my Dymags on the motorbike (and binning a brake disk) was immense, to the extent I almost crashed first ride out. But that's gyroscopic forces with a much heavier assembly spinning at much higher speed so really difficult to make any meaningful comparison. I can't feel any steering difference going from my lightweight wheels and tyres on one bike to the dualplies and 721s on the other bike.
A word on placebo effect... Don't underestimate it. If your bike feels faster, there's a good chance you'll become faster.
Still... There's a whole industry of racers, and these days it's a science as much as a sport. When you look at the lengths they took to lighten Steve Peat's world champ winning bike, I think it makes sense to ask why they'd do that if it wasn't effective- the risk they took there was huge, they lost strength, punctureproofing... And then look at every single race bike at an XC event, if there's no meaningful difference shouldn't at least some of those riders be on beefier rims?
A word on placebo effect... Don't underestimate it. If your bike feels faster, there's a good chance you'll become faster.
And I say it again to you, as I do to skywalker....evidence?
You must be kidding? These guys might play your silly games...
Where is your evidence Al? So far all you have done is disagree.
Yes al - you tell yourself you are always right so you don't have to think critically. Your argument on this one is full of flaws but as usual its pointless to debate with you,
Northwind - loosing a kilo off the front tyre on the tandem ( a very extreme case and obviously other effects such as profile as well) was an obvious difference to steering at speed.
skywalker - Member
Where is your evidence Al? So far all you have done is disagree.
No, that's you.
I've accepted much of the argument is unsupported by evidence on either side. You've not even commented on my 500gm = 20s on a 90min race or produced any mathematical analysis of your own.
TJ - shame you have to reduce it to personalities so quickly, up to you, [s]how you can say the speeds re similar is beyond me[/s]*. And I too see flaws in your arguments...your 1kg lighter front [s]wheel...same tyre/pressure/terrain?
[/s] the other factors would have too much influence for your judgement to be worthwhile IMO.
And Northwind - without evidence it's pure conjecture...as some of my points are...but at least I have some arguments/analysis to back them up.
EDIT TJ didn't say *!
Cynic al- shame you don't want to think critically - two misquotes / falsification of what I said in one post. Nice
loosing a kilo off the front tyre on the tandem ( a very extreme case and [b]obviously other effects [/b]such as profile as well) was an obvious difference to steering at speed.
Speeds are similar[b] magnitude [/b]not similar speeds.
See my edits - apols for speed-reading.
Night all, soft toys are waiting...
I just put Crest stickers on my Flow rims and so everyone thinks that's why I'm faster when in reality I am a cycling Ninja
This thread really is the point where Al jumps a shark (on a homemade fatbike obviously). It's hard to believe anyone has so much free time they'd choose to waste it like this... Ah well.
You've not even commented on my 500gm = 20s on a 90min race or produced any mathematical analysis of your own.
I'd say that your analysis is very partial.. It doesn't attempt to quantify the effects of unsuspended weight on rolling resistance. It's valid on a smooth track, but not many mountain bike races are.
Although I don't pretend to know any maths to show the significance of the effects, I'd certainly say that the following points are true:
1. Having less unsuspended weight (or less unsuspended inertial mass, as it's spinning) will allow the suspension to react quicker to bumps.. So less deformation of the tyres and wheel, less energy transfered to the ground, and less rolling resistance... So less slowing down over bumpy ground.
2. Having more reactive suspension (because of the above) will have the effect of sticking the tyres down better, giving the wheels greater grip on the corners.. So carrying more speed. After all, suspension is about traction, not comfort.
These could each be equally as significant as the accelerative effect that you mention (well, actually they're the same effect!) so if 20s became 60s over 90 minutes.. what then?
Last thing..
If the wheels are constructed the same, then the lighter ones will be less stiff.. So might deform more due to pedalling forces and losing energy that way. Most light wheels aren't built like that though.
lose some weight. You'll ride faster. oh, and ride more, further, faster. I think that's it. and cut out the pies and beer. oh, and your expensive wheels will wear out. sorry it's not about the wheels.
I'd say that your analysis is very partial.. It doesn't attempt to quantify the effects of unsuspended weight on rolling resistance. It's valid on a smooth track, but not many mountain bike races are.
Why not look into the data on rolling resistance and see if it helps? Schwalbe published some research IIRC.
Northwind...shame no one can match my big hit stamina or analytical skills....
One thing that is confusing me is the fact that everyone seems to be saying that they can tell when they are on a bike with heavier wheels but with some saying it makes no difference to speed while others are saying it does.
I guess they best way to test this (since as far as I can tell there have been no tests done on technical off road trails) would be to fill the tyres with water for one run then do the same run without the water in the tyres but with an equivalent weight added to the frame taking care to keep weight distribution the same for both.
Ideally the bikes and riders should be fitted with full data acquisition systems measuring heart rate, cadence, torque input, wheel speed, GPS speed, and suspension velocity.
This test should be repeated using at least 10 different riders with five doing the increased wheel weight first and the others doing the increased frame weight first. The test should also be blind so the rider doesn't know whether he or she is riding the bike with increased frame weight or increased wheel weight. Comments from riders should also be taken into account and all riders should have similar fitness and technical ability.
Anyone out there doing a Masters degree in sport science or engineering and looking for a thesis?
Actually, my original thought when I decided to post was about the sprung weight vs unsprung weight. I've been thinking a lot lately about how important unsprung weight is for mountain biking. Obviously in motorsport it is very important since the majority of the suspension is provided by the shocks.
In mountain biking you have at the most 8 inches of travel provided by the suspension plus 12 inches provided by your arms and legs effectively turning the entire bike into unsprung weight.
I've had a look but I can't find much information on this on the net, anyone read anything that talks about this?
What goes round in circles more easily, a light wheel or an internet argument?
(Amedius, well said)
In mountain biking you have at the most 8 inches of travel provided by the suspension plus 12 inches provided by your arms and legs effectively turning the entire bike into unsprung weight.
Fair point.. your body can't react as fast over repeated impacts in the way a damper can, so the whole bike's not really suspended in the same way. You want suspension to free your arms and legs to simply control / steer the bike, or pedal, more of the time. But you're right that a lighter bike is easier to hop and float over the trail too, it is unsprung then. Certainly is if it's a rigid bike.
Lowering unsprung weight is probably more easy to show as a benefit than lowering wheel weight, as unlike the wheel weight point, it assumes the suspension is working ie you're not on the lab-conditions smooth surface. But it assumes you already have dampers and pivots that are sensitive enough to react faster if the wheel and swingarm is lighter (ie Propedal would cancel out a lot of that I think)
A low pressure tyre deforming over a rock should reduce momentum less than a damper allowing the wheel to move over the rock, and certainly has less reduction in momentum that the impact lifting the weight of (a rigid, high pressure tyred) bike and rider over the rock. This is why a heavy fat-bike tyre can have suprisingly low rolling resistance - in this area it has super-low unsuspended mass - but it won't pedal up the hill so easily.
This is why I think rolling resistance and grip / comfort are worth considering even at the expense of reduction in weight. There's a balance point somewhere but I won't pretend to understand the maths there.
oh my god, are you lot still at it?
the thread that keeps on giving....
I think its about time for.........
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😆
two hundred!
I'd just like to say that i no longer care whether it'll make a difference or not...... I'm just pleased to have my 1st 200 post thread. 😳
Thanks to all that made it possible...... You know who you are 😉
:glee:
You are assuming that changing the weight of your wheels will have a greater effect than changing weight elsewhere, please explain why.
Hi Crikey,
you answer a question with a counter-question, do you?
I didn't assume anything in that post. I asked a simple question:
Would you choose the lighter wheel or the lighter frame?
If you care, give a simple answer to my question and we can take it from there.
If you don't, keep arguing for the arguments sake.
Cheers!
