Sagan's bike at Paris Roubaix

Discuss light weight issues concerning road bikes & parts.
Post Reply
NiFTY
Posts: 1217
Joined: Sat May 26, 2012 11:26 pm

by NiFTY

Tobin I probably agree with you that tubulars have had their day. And I have a set of tubulars that ride lovely but they are a PITA to set up.

Your w/kg arguent is somewhat flawed though. I agree that in GENERAL a heavier rider putting out the same w/kg will be faster as for a given size weight increases more rapidly then drag/surface area. However this is not always the case. If the lighter rider generates his power in a more aero power that might well cover the wattage deficit. That is exactly the reason that people are willing to sacrifice some power for a more aero position.
Evo 4.9kg SL3 6.64kg Slice RS 8.89kg viewtopic.php?f=10&t=110579" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

by Weenie


NiFTY
Posts: 1217
Joined: Sat May 26, 2012 11:26 pm

by NiFTY

And Tobin if you are comparing a 45psi 2.4 inch MTB tyre to a 28mm road tire at 90psi you have bricks in your head. The air volume is completey different. And 45psi on a mtb is pretty high unless you are really heavy. In which case it seems you may have an ulterior motive for your fatties are fast argument.
Evo 4.9kg SL3 6.64kg Slice RS 8.89kg viewtopic.php?f=10&t=110579" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

TobinHatesYou
Posts: 1865
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

NiFTY wrote:
Tue Apr 10, 2018 5:24 am
Tobin I probably agree with you that tubulars have had their day. And I have a set of tubulars that ride lovely but they are a PITA to set up.

Your w/kg arguent is somewhat flawed though. I agree that in GENERAL a heavier rider putting out the same w/kg will be faster as for a given size weight increases more rapidly then drag/surface area. However this is not always the case. If the lighter rider generates his power in a more aero power that might well cover the wattage deficit. That is exactly the reason that people are willing to sacrifice some power for a more aero position.
5kg is not that significant in terms of cross-section, so I wouldn't expect or define a different body position. So yes for small differences, position matters, but position is also less likely to be an issue. For huge differences, say a 100kg rider doing 5w/kg vs a 60kg rider doing the same, the 100kg rider is pretty much always going to be faster.

And because this is more about the weight difference between tubulars and tubeless clinchers...the aforementioned ~300g in my other posts, cross section doesn't matter at all. :) 5w at 40km/h significantly outweighs a 300g weight penalty. 2.5w at 20km/h still significantly outweighs a 300g weight penalty. For the average weight rider, you pretty much have to go down to 8km/h as the breakeven point, which is a pretty unrealistic ride average. :)

TobinHatesYou
Posts: 1865
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

NiFTY wrote:
Tue Apr 10, 2018 5:28 am
And Tobin if you are comparing a 45psi 2.4 inch MTB tyre to a 28mm road tire at 90psi you have bricks in your head. The air volume is completey different. And 45psi on a mtb is pretty high unless you are really heavy. In which case it seems you may have an ulterior motive for your fatties are fast argument.

Who said anything about MTB? I rode 75mi 7800ft today on 28mm tires at 55psi. I go down to 40psi for some rides off the beaten path, but for general riding that is a little squirmy. It really seems like you guys have no idea about the capabilities of road tubeless.

Anyway, whatever. As I said earlier, if you guys want to die on the Altar of Tubulars, while also going slower in any situation, go ahead. :)

TurboKoo
Posts: 485
Joined: Wed Oct 29, 2008 7:55 pm

by TurboKoo

Image
Look what I found! Disc brakes have been here long time. This is from 1975 catalog.

Even if tubeless is faster I think pros will still use tubulars because of the possibility to continue riding until service car arrives.

I have not used tube in the last 7 years but I still feel that tubular offers best riding characteristics. Tubeless is getting there and in the end will replace tubular but not today or next year.
Scott Foil
Shimano 9150
Shimano FCR-9100-P
Shimano C60 tubulars

TobinHatesYou
Posts: 1865
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

TurboKoo wrote:
Tue Apr 10, 2018 5:46 am

Even if tubeless is faster I think pros will still use tubulars because of the possibility to continue riding until service car arrives.

I have not used tube in the last 7 years but I still feel that tubular offers best riding characteristics. Tubeless is getting there and in the end will replace tubular but not today or next year.

Did see what I wrote about tubeless clinchers being completely rideable at zero pressure? Calnago and others are just spreading FUD. <-- My major hang-up with discussions here.

tonytourist
Posts: 1231
Joined: Sat Oct 10, 2009 7:13 am
Location: 93306

by tonytourist

TobinHatesYou wrote:
Tue Apr 10, 2018 5:41 am
I rode 75mi 7800ft today on 28mm tires at 55psi. I go down to 40psi for some rides off the beaten path, but for general riding that is a little squirmy. It really seems like you guys have no idea about the capabilities of road tubeless.
On Zwift? :goodpost: :faint:

ome rodriguez
Posts: 340
Joined: Fri Feb 24, 2006 9:16 am

by ome rodriguez

Terpstra: tubulars or tubeless? 😂

Image

sychen
Posts: 341
Joined: Thu Apr 24, 2014 1:06 pm

by sychen

Tri guys wear socks? I call BS.

Even as a owner of a disc Tarmac, I don't see the point in disc for PR.
What braking is required in this race? not much.
Roval's already known to be notoriously bad in wet braking (on rim brakes) so if this was an issue for safety there would be a disc on the podium. There are never much braking in PR wet or dry anyway. Even if you were braking,, the dust/mud isn't going to allow you to slow much.

As for the Tub/Tubeless argument.. Tubs still make sense for road Pros with support teams. Lack of servicability isn't an issue and reduction of pinchflats/ better rideability when punctured /generally better ride(race) quality makes it a better race choice. Not to mention less issues of brakeheat failures in high mountains for rim brakes(yes i know off topic to PR).

Also servicebility / simplicity of Tubs for pro teams is an issue. They are pretty much glue and forget for the large amount of wheels needed for a race day. Pump them all (40-50 wheels per day) up to right PSI in the morning and thats pretty much it. Tubeless then have to mess with valves/sealants/bead seating/ Special pumps and etc... can't see pro wrenches wanting to deal with them other than TT days. Let me know if i'm wrong about any of it?

There are definatly technical merits to tubeless across many areas(like outright speed) but application of some technical superiority for racing is another issue for pro riders and teams.
Just because Tubs are old technology and Tubeless is new doesn't make the new "better" categroically for road racing purposes across the many iterations.

Can't use the new Campag Bora wheels as example of abandoning tubs... first they are only in TTish depths (for now) and for TT clinchers/tubeless have proven to be better (and pro teams use them).

jorisee01
Posts: 281
Joined: Mon May 04, 2015 8:22 pm

by jorisee01

TobinHatesYou wrote:
jorisee01 wrote:
Mon Apr 09, 2018 8:39 pm
TobinHatesYou wrote: 3) It’s not a broad claim, it’s simple watts/kg. A higher weight and higher w/kg is ALWAYS faster.
I'm confused.

Sent from my SM-G930F using Tapatalk

What are you so confused about? A 65kg rider putting out 5w/kg is faster than a 60kg rider putting out 5w/kg under ALL circumstances. Using Campy’s example. +5w is an additional 1.7% over 300w. +300g is .4% of say 75kg. If you gain 5w and 300g at pretty typical power outputs, you increase your w/kg. The only way this isn’t true is if you are a superhuman child that weighs maybe 30kg and puts out monster watts.

Come on weight weenies, this is pretty basic stuff.
That's is exactly what is wrong with your first statement.

Read it again.

It states HIGHER weight.

C'mon TobinHatesYou - that's pretty basic stuff...

Sent from my SM-G930F using Tapatalk


TobinHatesYou
Posts: 1865
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

jorisee01 wrote:
Tue Apr 10, 2018 6:50 am
That's is exactly what is wrong with your first statement.

Read it again.

It states HIGHER weight.

C'mon TobinHatesYou - that's pretty basic stuff...

Maybe NiFTY can explain it to you since you obviously think my statement is false.

jasjas
Posts: 135
Joined: Sun Aug 23, 2009 10:15 am

by jasjas

Why are soooo against the more traditional side of cycling? rim brakes or tubulars, you seem to be very anti, as if your whole world veiw would collapse if you were proved wrong?
Tubulars are pretty easy to set-up (you dont really need all those layers of glue) and i d bet you i can remount a spare and continue my ride whilst your are trying to get a tube in your tubeless/clincher set-up, oh and the pre used spare will stay on too.

and why was nt Sagon on tubeless and disk then?

User avatar
themidge
Posts: 892
Joined: Fri Jan 13, 2017 4:19 pm
Location: yer ma

by themidge

TobinHatesYou wrote:

What are you so confused about? A 65kg rider putting out 5w/kg is faster than a 60kg rider putting out 5w/kg under ALL circumstances.
No, it depends.

Before you ask, I will explain.
(remember that everything else is assumed to be equal here, I know things like rolling and air resistance can change with weight)

Uphill:
If I am 60kg (which I'm not) and you are 65kg (I dunno, are you?), and we are riding up a hill at 5w/kg, we will go exactly the same speed because we are both making 5w/kg, we just approach it from different angles. You may produce more power, but I am lighter, they cancel out. To look at it another way, if we both produce the same power, I will go faster because I am lighter, therefore my w/kg is greater than yours. (plug in numbers, re-arrange the formula, see for yourself).

Flat:
Same as above, 5w/kg is 5w/kg, it doesn't matter how you get there (less weight or more power).

Downhill:
You will got faster because of your greater weight (eventually; we will accelerate at the same rate).

I wish people would stop throwing 'watts per kilo' around as if it's some set power, it varies. 5w/kg is a lot more for me than it is for @Calnago (no offence).

CallumRD1
Posts: 130
Joined: Mon Apr 03, 2017 2:54 pm

by CallumRD1

themidge wrote:
Tue Apr 10, 2018 6:23 pm
TobinHatesYou wrote:

What are you so confused about? A 65kg rider putting out 5w/kg is faster than a 60kg rider putting out 5w/kg under ALL circumstances.
No, it depends.

Before you ask, I will explain.
(remember that everything else is assumed to be equal here, I know things like rolling and air resistance can change with weight)

Uphill:
If I am 60kg (which I'm not) and you are 65kg (I dunno, are you?), and we are riding up a hill at 5w/kg, we will go exactly the same speed because we are both making 5w/kg. You may produce more power, but I am lighter, they cancel out. To look at it another way, if we both produce the same power, I will go faster because I am lighter, therefore my w/kg is greater than yours. (plug in numbers, re-arrange the formula, see for yourself).

Flat:
Same as above, 5w/kg is 5w/kg, it doesn't matter how you get there (less weight or more power).

Downhill:
You will got faster because of your greater weight (eventually; we will accelerate at the same rate).

I wish people would stop throwing 'watts per kilo' around as if it's some set power, it varies. 5w/kg is a lot more for me than it is for @Calnago (no offence).

This is not quite true. While on the uphill you're essentially correct, on the flat it isn't true at all. If I'm 60 kg and you're 65 kg, our same 5 w/kg will give us powers of 300 W and 325W. We will have nominally similar frontal areas and aerodynamic profiles, so the extra 25 watts will mean that the 65 kg rider will go faster, just with a little more energy expendature getting up to speed. Once at a constant speed, body weight is almost insignificant; more power gives a faster speed even if the W/kg is the same. Similar logic applies to the downhill.

1415chris
Posts: 1109
Joined: Sat Apr 18, 2009 8:59 am
Location: Surrey UK

by 1415chris

What you are saying is that somebody pumping 300W on flats will be faster than somebody else with 325W?
Suerly you don't need extra 25W to overcome extra 5kg weight difference riding flats.

by Weenie


Post Reply
  • Similar Topics
    Replies
    Views
    Last post