Go Back  Bike Forums > Bike Forums > General Cycling Discussion
Reload this Page >

Why do road bikes coast better than other bikes?

Notices
General Cycling Discussion Have a cycling related question or comment that doesn't fit in one of the other specialty forums? Drop on in and post in here! When possible, please select the forum above that most fits your post!

Why do road bikes coast better than other bikes?

Old 07-04-20, 10:39 AM
  #26  
genejockey
Klaatu..Verata..Necktie?
 
genejockey's Avatar
 
Join Date: May 2007
Location: SF Bay Area
Posts: 1,653

Bikes: Canyon Endurace, 105; Battaglin MAX, Chorus; Bianchi 928 Veloce; Ritchey Road Logic, Dura Ace

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 266 Post(s)
Liked 338 Times in 192 Posts
Originally Posted by BlazingPedals View Post
Not in my experience. At least not unless the heavy person is on REALLY crappy wheels. Downhills are all about weight and aero.
True. I'm a fat guy with good hubs. I pass a lot of skinny people on downhills.
genejockey is offline  
Likes For genejockey:
Old 07-04-20, 10:42 AM
  #27  
genejockey
Klaatu..Verata..Necktie?
 
genejockey's Avatar
 
Join Date: May 2007
Location: SF Bay Area
Posts: 1,653

Bikes: Canyon Endurace, 105; Battaglin MAX, Chorus; Bianchi 928 Veloce; Ritchey Road Logic, Dura Ace

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 266 Post(s)
Liked 338 Times in 192 Posts
Originally Posted by Leisesturm View Post
Hub drag is nearly irrelevant in real life. At any speed over 12mph, air drag is the dominant force ******ing the cyclist. The lower air drag of a 23mm tire vs a 32mm or more section clincher is real. The better aero position of being on the drops, even on the hoods vs. being sat upright ... ...
Don't overlook hub drag, though. One of my bikes coasts down the same hills a lot faster than the others, and they're all set up exactly the same, so there should be no aero difference. The fast one has Dura Ace hubs. Second fastest has Chorus. Slowest has Fulcrum.
genejockey is offline  
Likes For genejockey:
Old 07-04-20, 11:03 AM
  #28  
indyfabz
Senior Member
 
indyfabz's Avatar
 
Join Date: Jan 2010
Posts: 26,999
Mentioned: 192 Post(s)
Tagged: 1 Thread(s)
Quoted: 11413 Post(s)
Liked 3,053 Times in 1,697 Posts
Originally Posted by badger1 View Post
Pffft. What you (op) are noticing is the difference between a $500 and a $5000 bike. That, and clipless 'peddles' (sic) vs. flat 'peddles'.

Oh, and 'Drop Bars' vs. 'Flat Bars' ... that too.

These are all important considerations.
Drop bars are an illusion to most.
indyfabz is offline  
Likes For indyfabz:
Old 07-04-20, 10:40 PM
  #29  
Toadmeister
Senior Member
 
Join Date: Nov 2019
Location: Iowa
Posts: 308

Bikes: 2019 Jamis Renegade Exploit 1x11. Motobacne NX Fat Tire

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 82 Post(s)
Liked 79 Times in 51 Posts
This thread reminds me of an old tale:

Who’s going faster? The fat guy at 20mph or the skinny guy at 20mph?
Toadmeister is offline  
Old 07-06-20, 10:23 AM
  #30  
Notso_fastLane
Senior Member
 
Notso_fastLane's Avatar
 
Join Date: Dec 2011
Location: Layton, UT
Posts: 1,370

Bikes: 2011 Bent TW Elegance 2014 Carbon Strada Velomobile

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 396 Post(s)
Liked 375 Times in 227 Posts
Originally Posted by BlazingPedals View Post
Not in my experience. At least not unless the heavy person is on REALLY crappy wheels. Downhills are all about weight and aero.
And at some point, probably around 45mph or so, aero starts to dominate even over significantly more weight.

I can verify this with an experiment I did:
Run 1: Recumbent bike, pedal to about 48 mph, then coast down. Top speed achieved: 54 mph, sustained for about 10-12 seconds.
Run 2: CBR66RR sportbike (~400 lbs) start run at top of the hill ~50 mph, pull in clutch and coast. Top speed achieved: also 54 mph sustained almost the same time.
Run 3: Strada Carbon Velomobile (~80 lbs) pedal to about 48 mph. Top speed: 68 mph, sustained for about 8-10 seconds. Coasted MUCH further even after it started to flatten out than the others.
Notso_fastLane is offline  
Old 07-06-20, 03:37 PM
  #31  
rydabent
Senior Member
 
Join Date: Apr 2010
Location: Lincoln Ne
Posts: 8,039

Bikes: RANS Stratus TerraTrike Tour II

Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 1657 Post(s)
Liked 236 Times in 152 Posts
They dont always. My son and I went for a ride a couple days ago. He rode his skinny wheeled racing bike. I was riding my RANS Stratus LE. Every time we coasted down hill I would easily out coast him.
rydabent is offline  
Likes For rydabent:
Old 07-06-20, 03:41 PM
  #32  
rydabent
Senior Member
 
Join Date: Apr 2010
Location: Lincoln Ne
Posts: 8,039

Bikes: RANS Stratus TerraTrike Tour II

Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 1657 Post(s)
Liked 236 Times in 152 Posts
Originally Posted by 70sSanO View Post
When you are in the drops on a road bike you are always going down hill regardless of the actual terrain.

John
And on my trike with 20" front wheels, and its 26" rear tire, I too am always going down hill.
rydabent is offline  
Old 07-07-20, 02:55 PM
  #33  
Drew Eckhardt 
Senior Member
 
Drew Eckhardt's Avatar
 
Join Date: Apr 2010
Location: Mountain View, CA USA and Golden, CO USA
Posts: 6,156

Bikes: 97 Litespeed, 50-39-30x13-26 10 cogs, Campagnolo Ultrashift, retroreflective rims on SON28/PowerTap hubs

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 469 Post(s)
Liked 199 Times in 148 Posts
Lower rolling resistance from more supple slick tires and better aerodynamics.

Down hill sectional density of the rider is significant. Heavier ones are faster.
Drew Eckhardt is offline  
Old 07-07-20, 03:39 PM
  #34  
Wildwood
Veteran/Pacifist/Resister
 
Wildwood's Avatar
 
Join Date: Dec 2004
Location: Seattle area
Posts: 9,943

Bikes: Bikes??? Thought this was social media?!?

Mentioned: 218 Post(s)
Tagged: 0 Thread(s)
Quoted: 2329 Post(s)
Liked 794 Times in 492 Posts
Originally Posted by Drew Eckhardt View Post
Down hill sectional density of the rider is significant. Heavier ones are faster.
Density matters - the very heavy, very skinny guys usually win @ downhill.
Wildwood is offline  
Old 07-07-20, 08:01 PM
  #35  
ofajen
Senior Member
 
Join Date: Jun 2020
Posts: 199
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 57 Post(s)
Liked 83 Times in 55 Posts
Originally Posted by indyfabz View Post
Drop bars are an illusion to most.
Be careful not to reach for them, lest your hands pass thru the illusion and you will tumble forward and crash!

Otto
ofajen is offline  
Old 07-07-20, 10:32 PM
  #36  
ofajen
Senior Member
 
Join Date: Jun 2020
Posts: 199
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 57 Post(s)
Liked 83 Times in 55 Posts
Downhill terminal velocity in a freewheeling descent will be roughly proportional to the square root of M/A, the ratio of combined mass over combined frontal area of cyclist and rider. That generally favors larger cyclists.

Otto
ofajen is offline  
Likes For ofajen:
Old 07-08-20, 03:19 PM
  #37  
rydabent
Senior Member
 
Join Date: Apr 2010
Location: Lincoln Ne
Posts: 8,039

Bikes: RANS Stratus TerraTrike Tour II

Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 1657 Post(s)
Liked 236 Times in 152 Posts
In actual test a couple of surprising results came out . A wider supple tire out coasted a narrow hard tire. A 20" tire out coasted and 26" tire.
rydabent is offline  
Old 07-08-20, 03:52 PM
  #38  
genejockey
Klaatu..Verata..Necktie?
 
genejockey's Avatar
 
Join Date: May 2007
Location: SF Bay Area
Posts: 1,653

Bikes: Canyon Endurace, 105; Battaglin MAX, Chorus; Bianchi 928 Veloce; Ritchey Road Logic, Dura Ace

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 266 Post(s)
Liked 338 Times in 192 Posts
Originally Posted by Wildwood View Post
Density matters - the very heavy, very skinny guys usually win @ downhill.
So take calcium supplements and iron supplements, and wear a real gold watch.
genejockey is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.