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

The 45 Degree Angle Rule

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!

The 45 Degree Angle Rule

Old 06-08-17, 08:55 AM
  #1  
Senior Member
Thread Starter
 
Join Date: Jun 2016
Posts: 116
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked 3 Times in 3 Posts
The 45 Degree Angle Rule

Hey Guys,

Its known that a torso angle at about 45 degrees is a good balance of aero and comfort. Good for general road cycling. I read an article that suggested your torso should be at 45 degrees to the top tube. However I always though it was to the horizon, or straight floor, which seems to make more sense since there are sloping top tubes. Maybe this article got it wrong?
ejewels is offline  
Old 06-08-17, 08:58 AM
  #2  
Senior Member
 
mcours2006's Avatar
 
Join Date: Jul 2014
Location: Toronto, CANADA
Posts: 6,198

Bikes: ...a few.

Mentioned: 47 Post(s)
Tagged: 0 Thread(s)
Quoted: 2009 Post(s)
Liked 405 Times in 231 Posts
Link?
mcours2006 is offline  
Old 06-08-17, 08:58 AM
  #3  
Senior Member
 
Maelochs's Avatar
 
Join Date: Oct 2015
Posts: 15,453

Bikes: 2015 Workswell 066, 2017 Workswell 093, 2014 Dawes Sheila, 1983 Cannondale 500, 1984 Raleigh Olympian, 2007 Cannondale Rize 4, 2017 Fuji Sportif 1 LE

Mentioned: 144 Post(s)
Tagged: 0 Thread(s)
Quoted: 7628 Post(s)
Liked 3,453 Times in 1,823 Posts
For optimal aero penetration you should be at a negative 45 degree angle, leaning way back over the back wheel, and steering telekinetically.

In the future, bikes will not have top tubes ... they will be made of sheets of glass, which are stronger than steel.
Maelochs is offline  
Old 06-08-17, 09:01 AM
  #4  
Senior Member
 
Maelochs's Avatar
 
Join Date: Oct 2015
Posts: 15,453

Bikes: 2015 Workswell 066, 2017 Workswell 093, 2014 Dawes Sheila, 1983 Cannondale 500, 1984 Raleigh Olympian, 2007 Cannondale Rize 4, 2017 Fuji Sportif 1 LE

Mentioned: 144 Post(s)
Tagged: 0 Thread(s)
Quoted: 7628 Post(s)
Liked 3,453 Times in 1,823 Posts
More to the point .... obviously the article was assuming a flat top tube. Otherwise it would make No sense at all, as every bike has a different TT angle .... you know that, and you knew it before you posted.

I am beginning to wonder if you use the correct chain lube. Do your socks match your bar tape....

Brothers ... I fear he is not .... One of Us.

We must purify the hive.
Maelochs is offline  
Old 06-08-17, 09:01 AM
  #5  
Senior Member
 
Gresp15C's Avatar
 
Join Date: Sep 2014
Posts: 3,893
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 1062 Post(s)
Liked 665 Times in 421 Posts
When I looked into bike fit, I realized that the rider has three points of contact with the bike: Feet, hands, and arse. What happens in between those points is important for the structure of the bike, but not for fit. Comfort is relative to gravity, and aero is relative to the air, neither of which are affected by the top tube.

So, at least that was my conclusion, without claiming to be a bike expert.
Gresp15C is offline  
Old 06-08-17, 09:11 AM
  #6  
Senior Member
 
Join Date: Jun 2013
Location: Bozeman
Posts: 4,094

Bikes: 199? Landshark Roadshark, 198? Mondonico Diamond, 1987 Panasonic DX-5000, 1987 Bianchi Limited, Univega... Chrome..., 1989 Schwinn Woodlands, Motobecane USA Record, Raleigh Tokul 2

Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1131 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I had no idea that was a rule. I change the fit on my bike until I'm "comfortable."
corrado33 is offline  
Old 06-08-17, 09:32 AM
  #7  
Senior Member
Thread Starter
 
Join Date: Jun 2016
Posts: 116
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked 3 Times in 3 Posts
Here is the link to that article:

https://www.cyclingweekly.com/videos/bike-fit-and-maintenance/handlebar-reach-how-to-get-it-right-video

Oh, and cocaine is a hell of a drug to that one poster.

Last edited by ejewels; 06-08-17 at 09:35 AM.
ejewels is offline  
Old 06-08-17, 09:32 AM
  #8  
Senior Member
 
wphamilton's Avatar
 
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 15,280

Bikes: Nashbar Road

Mentioned: 71 Post(s)
Tagged: 0 Thread(s)
Quoted: 2934 Post(s)
Liked 341 Times in 228 Posts
It might be a good starting point, but I think that 45° is not very aero.
wphamilton is offline  
Old 06-08-17, 09:39 AM
  #9  
Senior Member
Thread Starter
 
Join Date: Jun 2016
Posts: 116
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked 3 Times in 3 Posts
Originally Posted by wphamilton
It might be a good starting point, but I think that 45° is not very aero.
Agreed, I was asking more about where one should measure that angle to... (the top tube or horizon/floor).
ejewels is offline  
Old 06-08-17, 09:51 AM
  #10  
Senior Member
 
Maelochs's Avatar
 
Join Date: Oct 2015
Posts: 15,453

Bikes: 2015 Workswell 066, 2017 Workswell 093, 2014 Dawes Sheila, 1983 Cannondale 500, 1984 Raleigh Olympian, 2007 Cannondale Rize 4, 2017 Fuji Sportif 1 LE

Mentioned: 144 Post(s)
Tagged: 0 Thread(s)
Quoted: 7628 Post(s)
Liked 3,453 Times in 1,823 Posts
Originally Posted by ejewels
Agreed, I was asking more about where one should measure that angle to... (the top tube or horizon/floor).
One does not simply "measure" the "angle" ..... said Boromir. And he died, pierced by many arrows.

Seriously ... get on the bike. get comfortable. if you cannot get comfortable, move the movable bits.

Rules of thumb are fine ... if you are a thumb.

General ideas are great, generally. Only you know what works for you.

I would tell you my "Perfect Bike Fit Secrets™" but everyone here would disagree ... with me and with each other.

The last time I heard that "45 degrees" line was in a spin class ... where nothing but aero matters.

I tend to set up my bikes so I am comfortable after as long a ride as I can ride comfortably ... and then start removing spacers 5 mm at a time. At some point my girth or my age will force me to stop ... and then, over time, likely reverse that scenario.

That is the "system" which makes sense to me.
Maelochs is offline  
Old 06-08-17, 09:56 AM
  #11  
Senior Member
 
wphamilton's Avatar
 
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 15,280

Bikes: Nashbar Road

Mentioned: 71 Post(s)
Tagged: 0 Thread(s)
Quoted: 2934 Post(s)
Liked 341 Times in 228 Posts
Originally Posted by ejewels
Agreed, I was asking more about where one should measure that angle to... (the top tube or horizon/floor).
Along the line of the effective top tube, IMO. Parallel with the wheel axles.

Not the horizon, because the position relative to the bike affects comfort (more than orientation with gravity), and the bike's motion is always relative to the bike's frame (in line with the wheels basically) so aero is not with respect to the horizon.
wphamilton is offline  
Old 06-08-17, 10:02 AM
  #12  
Senior Member
Thread Starter
 
Join Date: Jun 2016
Posts: 116
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked 3 Times in 3 Posts
Right, so basically on level ground. The wheels would also then be level. Maybe I'm wrong, but isn't the horizon then level to all of that? I believe effective top tube is a horizontal/level measurement?
ejewels is offline  
Old 06-08-17, 10:06 AM
  #13  
Senior Member
 
mcours2006's Avatar
 
Join Date: Jul 2014
Location: Toronto, CANADA
Posts: 6,198

Bikes: ...a few.

Mentioned: 47 Post(s)
Tagged: 0 Thread(s)
Quoted: 2009 Post(s)
Liked 405 Times in 231 Posts
Originally Posted by Maelochs
One does not simply "measure" the "angle" ..... said Boromir. And he died, pierced by many arrows.
I've seen the film many times...I don't get the reference.


Anyhoo, OP:
The 45* rule of thumb may be for general riding with elbows slightly bent, sort of in cruising mode. If you want to get more aero you want to bend those elbows more, or get on the drops and bend those elbows to get the torso more horizontal. TT angle has little to do with either scenario.
mcours2006 is offline  
Old 06-08-17, 10:22 AM
  #14  
Senior Member
 
Garilia's Avatar
 
Join Date: Sep 2010
Location: South Park...ing Lot
Posts: 721

Bikes: Fantom 29

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 49 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by mcours2006
I've seen the film many times...I don't get the reference.
for reals?

Garilia is offline  
Old 06-08-17, 10:23 AM
  #15  
Senior Member
 
Garilia's Avatar
 
Join Date: Sep 2010
Location: South Park...ing Lot
Posts: 721

Bikes: Fantom 29

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 49 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
More Boromir, one does not simply memes
Garilia is offline  
Old 06-08-17, 10:43 AM
  #16  
Senior Member
 
Maelochs's Avatar
 
Join Date: Oct 2015
Posts: 15,453

Bikes: 2015 Workswell 066, 2017 Workswell 093, 2014 Dawes Sheila, 1983 Cannondale 500, 1984 Raleigh Olympian, 2007 Cannondale Rize 4, 2017 Fuji Sportif 1 LE

Mentioned: 144 Post(s)
Tagged: 0 Thread(s)
Quoted: 7628 Post(s)
Liked 3,453 Times in 1,823 Posts
Finally I have made a positive contribution to this site.

Savor it.
Maelochs is offline  
Old 06-08-17, 11:07 AM
  #17  
Senior Member
 
mcours2006's Avatar
 
Join Date: Jul 2014
Location: Toronto, CANADA
Posts: 6,198

Bikes: ...a few.

Mentioned: 47 Post(s)
Tagged: 0 Thread(s)
Quoted: 2009 Post(s)
Liked 405 Times in 231 Posts
Originally Posted by Garilia
Okaay!
mcours2006 is offline  
Old 06-08-17, 12:01 PM
  #18  
working on my sandal tan
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Posts: 22,625

Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)

Mentioned: 98 Post(s)
Tagged: 0 Thread(s)
Quoted: 3868 Post(s)
Liked 2,560 Times in 1,574 Posts
Originally Posted by ejewels
Hey Guys,

Its known that a torso angle at about 45 degrees is a good balance of aero and comfort. Good for general road cycling. I read an article that suggested your torso should be at 45 degrees to the top tube. However I always though it was to the horizon, or straight floor, which seems to make more sense since there are sloping top tubes. Maybe this article got it wrong?
The rule of thumb originated when just about all bikes had level top tubes. It's a decent starting position that is much more aerodynamic than sitting bolt upright, but not as tiring to the neck and hands as a more leaned-over position.

If for some silly reason we were going to go by the actual top tube angle, then I would argue for the inverse -- people on new carbon bikes typically want to be more aero, and folks still riding old steel bikes tend to be older and want to sit more upright.
__________________
Originally Posted by chandltp
There's no such thing as too far.. just lack of time
Originally Posted by noglider
People in this forum are not typical.
RUSA #7498
ThermionicScott is offline  
Old 06-08-17, 12:05 PM
  #19  
Old fart
 
JohnDThompson's Avatar
 
Join Date: Nov 2004
Location: Appleton WI
Posts: 24,936

Bikes: Several, mostly not name brands.

Mentioned: 153 Post(s)
Tagged: 0 Thread(s)
Quoted: 3571 Post(s)
Liked 3,368 Times in 1,916 Posts
Like most "rules of thumb," like "knee over pedal spindle" and "level saddle," this should be seen as a starting point to achieve best fit, not the end point. Your bike, and certainly your body are different from other peoples' bikes and bodies and may require deviation from these rules of thumb.
JohnDThompson is offline  
Old 06-08-17, 12:41 PM
  #20  
Senior Member
 
wphamilton's Avatar
 
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 15,280

Bikes: Nashbar Road

Mentioned: 71 Post(s)
Tagged: 0 Thread(s)
Quoted: 2934 Post(s)
Liked 341 Times in 228 Posts
Originally Posted by ejewels
Right, so basically on level ground. The wheels would also then be level. Maybe I'm wrong, but isn't the horizon then level to all of that? I believe effective top tube is a horizontal/level measurement?
Until the road slopes up or down. But we're only talking about a difference of 5° or so, so it doesn't make much difference in sitting. Much more than that, I'm either too slow to care about aero or coasting down.
wphamilton is offline  
Old 06-08-17, 12:49 PM
  #21  
Senior Member
Thread Starter
 
Join Date: Jun 2016
Posts: 116
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked 3 Times in 3 Posts
Gotcha. Thanks all.
ejewels is offline  
Old 06-08-17, 07:42 PM
  #22  
Senior Member
 
1Coopgt's Avatar
 
Join Date: Jan 2017
Location: Rochester ,NY
Posts: 103

Bikes: Mongoose Reform Sport

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 34 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Garilia

1Coopgt is offline  
Old 06-08-17, 09:16 PM
  #23  
- Soli Deo Gloria -
 
Join Date: Aug 2015
Location: Northwest Georgia
Posts: 14,782

Bikes: 2018 Rodriguez Custom Fixed Gear, 2017 Niner RLT 9 RDO, 2015 Bianchi Pista, 2002 Fuji Robaix

Mentioned: 235 Post(s)
Tagged: 0 Thread(s)
Quoted: 6844 Post(s)
Liked 736 Times in 469 Posts
Originally Posted by Maelochs
In the future, bikes will not have top tubes ... they will be made of sheets of glass, which are stronger than steel.
I'm going to print this and hang it on my wall.


-Tim-
TimothyH is offline  
Old 06-09-17, 04:51 AM
  #24  
Senior Member
 
Join Date: Jul 2008
Location: Minas Ithil
Posts: 9,337
Mentioned: 66 Post(s)
Tagged: 0 Thread(s)
Quoted: 2432 Post(s)
Liked 638 Times in 395 Posts
The more upright you sit the more pressure you put on your lower spine and sitbones.
Lazyass is offline  
Old 06-09-17, 05:09 AM
  #25  
Senior Member
 
Garilia's Avatar
 
Join Date: Sep 2010
Location: South Park...ing Lot
Posts: 721

Bikes: Fantom 29

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 49 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by 1Coopgt
I've got a bad feeling about this.
Garilia is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.