HOT: Active* forum members generally gain 5% discount at starbike.com store!
Weight Weenies
* FAQ    * Search    * Trending Topics
* Login   * Register
HOME Listings Articles FAQ Contact About




Post new topic Reply to topic  [ 5 posts ] 
Author Message
PostPosted: Wed May 05, 2004 1:54 pm 
Offline

Joined: Thu Mar 25, 2004 8:34 pm
Posts: 501
I found this on 53x12.com Michele Ferrari's training site

"1. Light weight: It’s easy to understand what a determining factor the weight of your bike can be when you ride uphill: the force of gravity becomes the cyclist’s principal obstacle.
In truth, weight is also important during accelerations, not only for the obvious ones when you bolt from a group in an attack or to go into a sprint, but also for the ‘micro-accelerations’ that occur with every uphill pedal stroke, especially at reduced speed and pedal cadence.

Five hundred grams saved on the weight of the chassis and non-moving parts translate into an advantage of about 30” for every hour of climb; an even more determinant factor is the weight of wheels, crankset and pedals: every 100 grams saved correspond to an average gain of 20” per hour of climb.
The rotational inertia of the crankset, wheels, and pedals resists every angular acceleration of these same moving parts, with an added energy cost depending on their mass."

Pretty significant if it's accurate.


Top
 Profile  
 
 Post subject:
PostPosted: Wed May 05, 2004 4:18 pm 
Offline

Joined: Tue Dec 23, 2003 9:28 pm
Posts: 1769
Location: Unknown parameter
The micro accelerations have always been my argument too, though I have made no attempt to quantify them, and Ferrari's numbers seem pretty high to me.

All the naysayers maintain that once up to speed there is no more acceleration and rotating weight become no more important than static weight. However ever since I first went up a major climb on my computrainer and saw the kph flickering up and down with every pedal stroke it was pretty clear acceleration is always an issue even without wind, pavement, draft and other environmental changes.


Top
 Profile  
 
 Post subject:
Posted: Wed May 05, 2004 4:18 pm 


Top
  
 
 Post subject:
PostPosted: Thu May 06, 2004 4:45 am 
Offline

Joined: Thu Sep 04, 2003 6:33 pm
Posts: 1332
i would say those figures are absolute rubbish


Top
 Profile  
 
 Post subject:
PostPosted: Thu May 06, 2004 2:03 pm 
Offline
User avatar

Joined: Tue Aug 12, 2003 8:39 pm
Posts: 1234
Location: Holland
What's the problem with micro accelerations when climbing? With every pedal stroke your bike accelerates a bit. But between the pedal strokes it will decelerate..... With a heavier bike the speed will be more constant, that's all.... of course a lighter bike will climb better, but when riding uphill with constant speed it won't matter wheter you have a 1300 gram frame and 300 gram rims or an 1100 gram frame and 400 gram rims.

By the way, I have seen studies which show that even on a relatively steep climb a heavier, aerodynamic wheelset is faster than a light, non-aero set. (But LightWeigths are both light AND aero :D )

_________________
Whow! That's a pretty damn nice garage door!


Top
 Profile  
 
 Post subject:
PostPosted: Thu May 06, 2004 2:58 pm 
Offline

Joined: Thu Mar 25, 2004 8:34 pm
Posts: 501
According to John Cobb, Lightweights aren't that Aero. Although Drag may have a bigger effect than rim Weight as remember the top of the rim is travelling a twice the speed of the bike relative to the air, which if your climbing at say 15km/h the top of the wheel is travelling at 30'km/h where drag is a factor. Rim weight is still important as this is the mass you are accelerating. Extreme example would be two bikes with same shape wheels and same overall weight, however one bike has 1100 gram Tubs say lightweights with 115 Gram Tufo's and weight added to the frame vs. Cosmic Carbones with 300 gram training tires, I don't think anyone would disagree with the statement that the bike with the light wheels would be easier to ride up the hill. I know I can feel the difference going up a hill on the same bike with Supersonics vs Vittoria Open Corsa's (only about 75 gram difference).


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 5 posts ] 


Who is online

Users browsing this forum: Bing [Bot], Google [Bot], lilearl75, Orfitinho, Sjoerd, Yahoo [Bot] and 30 guests


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:  

It is currently Sat Sep 20, 2014 1:41 pm

All times are UTC + 1 hour




Advertising   –  FAQ   –  Contact   –  Convert   –  About

© Weight Weenies 2000-2013
hosted by starbike.com


How to get rid of these ads? Just register!


Powered by phpBB