Weight Weenies
* FAQ    * Search    * Trending Topics
* Login   * Register
HOME Listings Blog NEW Galleries NEW FAQ Contact About Impressum
It is currently Fri Jan 20, 2017 11:10 am

All times are UTC+01:00





Post new topic  Reply to topic  [ 15 posts ] 
Author Message
PostPosted: Thu Dec 01, 2016 2:18 pm 
Offline
User avatar

Joined: Thu Nov 03, 2016 4:32 pm
Posts: 27
Location: North Carolina, USA
I freely admit I'm not the sharpest knife in the drawer.... so here goes,

(1) I ride rollers for training. Although the model probably is not relevant, they are Elite E-Motion B+ which are ANT+ FE-C controlled by TrainerRoad.
(2) I have two very similar bikes that I put on the rollers with identical frame geometry, saddle height, pedals, etc.

    (a) Pinarello GAN RS with RED Etap 11/28 and (temporarily) Vueltra Ultra Light wheels, wearing Gatorskin 700x25 @ 95psi
    (b) Pinarello GAN RS with Di2 11/32 and HED Ardennes Plus SL, wearing Continental GP 4000s II 700x25 @ 95psi.

Now, the meat of the question:

If I ride the exact same TrainerRoad program but swap the bikes, "Pinarello B" with the 11/32+Ardennes+GP4000 allows me to produce significantly higher watts for a longer period of time. Why?!? Is it the gearing of the 11/32 ? Doesn't make sense because I'm never in the 32 on the rollers. Is it the rim width of the Ardennes? Doesn't make sense because the rubber on both bikes is 25mm. Is it the rubber compound of Gatorskin vs. GP 4000 ?

Dozens and dozens of roller rides over the past year have confirmed this feel, and the TrainerRoad data backs it up --- I'm riding (no b.s. here) roughly 30 watts higher on a 1-hour workout when using "Pinarello B". Full disclosure, 5'9" 66kg, FTP 260

Educate a dummy. I don't understand.


Top
   
PostPosted: Thu Dec 01, 2016 2:29 pm 
Offline

Joined: Fri May 25, 2007 6:43 pm
Posts: 2965
Just the base tyres have a 10W CRR difference between them (per pair), if you add in rim width (wider = lower CRR) and different tubes plus a bit of drift/measurement error in the equipment and some slight errors in things like tyre pressure and position (though it's effectively the same bike by the looks of it) you won't be far off your 30W.

Also, doing slightly different sessions might affect the measured power output.


Top
   
Posted: Thu Dec 01, 2016 2:29 pm 


Top
   
 
PostPosted: Thu Dec 01, 2016 2:48 pm 
Offline

Joined: Thu Sep 29, 2016 12:45 pm
Posts: 81
Location: Newcastle, UK
I agree. You could work it out for sure by swapping wheels, then tyres, and maybe even cassettes.

You could get a more precise wattage by working out your virtual speed for a set power with different setups.


Top
   
PostPosted: Thu Dec 01, 2016 4:51 pm 
Offline

Joined: Wed Jan 22, 2014 11:48 am
Posts: 1785
Location: Vienna Austria
Rolling resistance is my bet too. It's exaggerated by the roller because the tire deforms more.

On my free rollers, the difference between already-good open tubulars at low-ish pressure and my fastest tire set - Turbo Cottons with latex tubes - pumped up hard - is absolutely massive, really hard to pedal vs. almost no resistance.


Top
   
PostPosted: Thu Dec 01, 2016 5:43 pm 
Offline
User avatar

Joined: Thu Nov 03, 2016 4:32 pm
Posts: 27
Location: North Carolina, USA
Wow... I never would have expected the difference between tires to be *that* noticeable on rollers, but clearly it sounds like that's the culprit. Tonight I'll put some new GP4000 rubber on the crappy Vueltra Ultra Light wheelset and see how it behaves. (The Gatorskins are great for long rides on lousy roads, but maybe that's the only place they're worthwhile)


Top
   
PostPosted: Thu Dec 01, 2016 6:06 pm 
Offline
User avatar

Joined: Fri Jul 23, 2004 8:24 pm
Posts: 1948
Location: Houston, Texas
Marin wrote:
Rolling resistance is my bet too. It's exaggerated by the roller because the tire deforms more.

While I now have a Tacx Neo direct drive trainer, my experiences with Kreitler Compact with hot dog rollers (2.5" diameter drums with 10" width) a number of years back seemed to support higher pressures yielding lower rolling resistance. I would even go so far as to say, assuming a radially true wheelset, training on the rollers is one of the times were super high tire pressures> 100 psi (6.5 bar) actually make since.

_________________
Michael - The Anaerobic Threshold is neither...


Last edited by ms6073 on Thu Dec 01, 2016 8:09 pm, edited 1 time in total.

Top
   
PostPosted: Thu Dec 01, 2016 7:03 pm 
Offline

Joined: Thu Sep 29, 2016 12:45 pm
Posts: 81
Location: Newcastle, UK
JackRussellRacing wrote:
Wow... I never would have expected the difference between tires to be *that* noticeable on rollers

http://www.velonews.com/where-the-rubber-meets-the-road-what-makes-cycling-tires-fast
http://www.bicyclerollingresistance.com/road-bike-reviews
According to the second link there's about 10w difference between a 4000s and gatorskin. Probably compounded because it's on a small roller.


Top
   
PostPosted: Thu Dec 01, 2016 7:48 pm 
Offline

Joined: Tue Jan 28, 2014 6:52 pm
Posts: 796
Isn't there some kind of calibration? Can you have two different calibrations for each bike?

_________________
Colnago C59


Top
   
PostPosted: Thu Dec 01, 2016 11:06 pm 
Offline

Joined: Tue May 23, 2006 4:33 am
Posts: 1036
Everyone understands that SRAM simply isn't as fast as Dura Ace. Haven't you heard?

Kinesthetic sense on rollers can cause quite a difference -- one tread feels different from another and you simply put out more or less energy because you're rocking it or hating it. Those two tires are pretty close to opposite ends of the spectrum, but not thirty watts worth. Put the same tires on both bikes and see if the differential goes away. I have a feeling it won't. Somewhere I suspect you have a setup or calibration difference that's throwing a tweak at you.


Top
   
PostPosted: Fri Dec 02, 2016 3:47 am 
Offline
User avatar

Joined: Thu Nov 03, 2016 4:32 pm
Posts: 27
Location: North Carolina, USA
11.4 wrote:
Those two tires are pretty close to opposite ends of the spectrum, but not thirty watts worth. Put the same tires on both bikes and see if the differential goes away.


Well I'll be a monkey's uncle! Tonight I put some fresh GP4000 tires on "Pinarello A" while retaining the same latex tubes and crappy Vueltra wheelset. The difference was indeed massive -- and the now the two bikes feel almost identical. GP4000 FTW :)

I'm stunned. I obviously knew that tire selection on the road was important, but blissfully ignored the role good rubber can play on rollers or a wheel-on trainer. I'll relegate the Gatorskins to my commuter. Thank you for everyone who responded.


Top
   
PostPosted: Fri Dec 02, 2016 5:48 am 
Offline

Joined: Sun Jan 01, 2012 9:58 am
Posts: 441
Just to clarify, you don't have a powermeter on either bike do you? power numbers are reported by the rollers, right?

Similarly, I run soft gatorskins and heavy wheels when on my rollers and can ride at or above FTP no worries. I recently did a warm down with nice wheels and wasn't really able to get far past 75% FTP. I also lost ~10kg over the last season and I had do reduce the pressure i normally run to hit the same power numbers.

Rubber, but i guess more importantly friction can make a significant difference on the rollers...


Top
   
PostPosted: Fri Dec 02, 2016 8:54 am 
Offline

Joined: Fri May 25, 2007 6:43 pm
Posts: 2965
TBH, for roller use it doesn't really matter, power is power, speed is of no importance whatsoever. And i'd not use anything fragile on rollers. The extra deformation caused by the small diameter roller, and the potential for extra heat in the carcase won't do the tyre any favours. Not as bad as a turbo though!

Jsut get some cheap nasties for rolling, or a couple of turbo tyres at £15 each.

And aren't trainer road programs based around power anyway? So you should be putting the same power out irrespective of how much mechanical losses the bike has.


Top
   
PostPosted: Fri Dec 02, 2016 10:16 am 
Offline
User avatar

Joined: Thu Nov 03, 2016 4:32 pm
Posts: 27
Location: North Carolina, USA
mentok wrote:
Just to clarify, you don't have a powermeter on either bike do you?

Power number is being reported by the Elite e-motion B+ rollers only.

(But, to answer your question -- both bikes *do* have a Quarqs. One has a DZERO and the other has a Red GXP. My full thread is about the power being reported to TrainerRoad from the rollers themselves, not the PM's on these bikes)


Top
   
PostPosted: Fri Dec 02, 2016 12:00 pm 
Online

Joined: Sat May 24, 2014 12:09 pm
Posts: 412
JackRussellRacing wrote:
mentok wrote:
Just to clarify, you don't have a powermeter on either bike do you?

Power number is being reported by the Elite e-motion B+ rollers only.

(But, to answer your question -- both bikes *do* have a Quarqs. One has a DZERO and the other has a Red GXP. My full thread is about the power being reported to TrainerRoad from the rollers themselves, not the PM's on these bikes)

In that case, my guess is that YOUR power remains the same, but, as the GP4000s have less roling resistance, you manage to reach higher speeds, and the e-motion 'thinks' you put out more power. That's a pure calibration issue, and a limitation of rollers showing power rather than a crank based system.

_________________
Canyon Ultimate CF SLX 2013
Scott Addict Orica Greenedge
Canyon Endurace CF SLX


Top
   
PostPosted: Fri Dec 02, 2016 7:40 pm 
Offline

Joined: Tue May 23, 2006 4:33 am
Posts: 1036
Delorre wrote:
JackRussellRacing wrote:
mentok wrote:
Just to clarify, you don't have a powermeter on either bike do you?

Power number is being reported by the Elite e-motion B+ rollers only.

(But, to answer your question -- both bikes *do* have a Quarqs. One has a DZERO and the other has a Red GXP. My full thread is about the power being reported to TrainerRoad from the rollers themselves, not the PM's on these bikes)

In that case, my guess is that YOUR power remains the same, but, as the GP4000s have less roling resistance, you manage to reach higher speeds, and the e-motion 'thinks' you put out more power. That's a pure calibration issue, and a limitation of rollers showing power rather than a crank based system.


I'd basically concur with this. This is about where roller-based resistance and roller-based power systems don't work as well as drivetrain alternatives such as a Kickr. I would have been comparing crank arm power measurements all along.

Use the heavy tires for training. Why not? Save the nice tires for use on the road.


Top
   
Posted: Fri Dec 02, 2016 7:40 pm 


Top
   
 
Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 15 posts ] 

   Similar Topics   Author   Replies   Views   Last post 
There are no new unread posts for this topic. a question on tire width...

in Road

rst72

6

602

Thu Jul 14, 2016 8:46 am

Marin View the latest post

There are no new unread posts for this topic. Is my math right? Aero bikes

[ Go to page: 1 2 3 4 5 ]

in Road

mbrider

72

4668

Wed Apr 13, 2016 7:21 pm

AJS914 View the latest post

There are no new unread posts for this topic. Rollers vs turbo

[ Go to page: 1 2 3 ]

in Training

buc

34

3957

Wed Jan 04, 2017 4:13 pm

JackRussellRacing View the latest post

There are no new unread posts for this topic. Getting rollers - recomendations please

[ Go to page: 1 2 ]

in Cycle Chat

Zak

18

1109

Sat Dec 10, 2016 11:59 pm

beatle View the latest post

There are no new unread posts for this topic. Wider is better? 23mm tire on 21c rim vs. 25mm tire on 15c rim

in Road

Beaver

5

887

Fri Jul 01, 2016 9:46 pm

crimsonbadger View the latest post


All times are UTC+01:00


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Limited