tri bike fit question- hip angle, etc.

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2011-01-14 9:09 AM

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Subject: tri bike fit question- hip angle, etc.
Quick question for BT'ers.  Had a retoul fit recently, and was messing around with kinovea software to check angles on my tri setup.  Can someone explain hip angle and how it affects the ride/power etc.  What is the downside of having an angle too closed vs too open.  Is there an ideal range of hip angle.  I read some of the fit articles on slow twitch but wanted more explanation.  And is it better to be more open vs. more closed relative.  I measured my angle at 100 degrees.  If that angle is too much what are the steps that the fitter would make in order to lesson that more towards. 

At my saddle height, my knee angle is about 148 degrees. 

Also, the angle of my forearms and my shoulder is at 104 degrees.  I will eventually post a pic, the one I have I am not dressed appropriately.    This angle I am not as worried/obsessed about as it gives me pretty good comfort. 

I understand that it is also base on a person's measurements, flexibility, and overall comfort on the bike. 

Thanks in advance.  Sorry I just like to understand the why's about fitting.

2011-01-14 12:37 PM
in reply to: #3299185

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Subject: RE: tri bike fit question- hip angle, etc.

1.  Did you just have the fit done on your tri bike?
2.  Are all the measurements you gave from your fit?
3.  What are you trying to achieve.
4.  What is your angle under your armpit? (this is the angle between the line from your greater trochanter and your A.C. joint and the line from your A.C. Joint to your elbow).

To answer a couple of your questions...hip angle is largely dictated by biomechanical movement of the person's leg.  Several angles will work for you.  You can always get tighter on the bike with an angle like 100, but that's a good starting point.  Your body can adjust and get closer to 90 as you go.  I wouldn't want to go too acute because it would impede my power.  You basically want to find the fit that meets the line where comfort and aerodynamics meet.  Looks to me like you have a good idea of what is important from your last statement.

That picture will help. 

2011-01-14 1:10 PM
in reply to: #3299846

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Subject: RE: tri bike fit question- hip angle, etc.
jgerbodegrant - 2011-01-14 12:37 PM

1.  Did you just have the fit done on your tri bike?
2.  Are all the measurements you gave from your fit?
3.  What are you trying to achieve.
4.  What is your angle under your armpit? (this is the angle between the line from your greater trochanter and your A.C. joint and the line from your A.C. Joint to your elbow).

To answer a couple of your questions...hip angle is largely dictated by biomechanical movement of the person's leg.  Several angles will work for you.  You can always get tighter on the bike with an angle like 100, but that's a good starting point.  Your body can adjust and get closer to 90 as you go.  I wouldn't want to go too acute because it would impede my power.  You basically want to find the fit that meets the line where comfort and aerodynamics meet.  Looks to me like you have a good idea of what is important from your last statement.

That picture will help. 



1.  The fit was done on my tri bike.  (original fit not precise, ended up riding w saddle little too low for bunch of months, so wanted to be dialed in a little better).
2.  I was using the Kinovea software that you can measure angles (I referenced the measuring points from Slowtwitch), so maybe plus or minus a few degrees.  Misplaced the paper work, will go back and ask for another copy. 
3.  Just trying to understand the idea of why person is set up open vs closed.  I also wanted to drop down a spacer or two to get a little lower on front (from previous thread, understand that it could affect things).  And how to get from open to closed, seems since it is angled at hip area, lowering front is one way of closing angle????  Any other ways such as saddle position etc??
4.  The angle under my armpit is roughly 87 degrees.

Very happy with the fit based on my current physical level.

I have been working on flexibility, stretching, yoga etc in hopes to have more aggressive position in future.  

Sorry, I am the guy who wants to know too much...
2011-01-14 1:16 PM
in reply to: #3299185

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Subject: RE: tri bike fit question- hip angle, etc.

Never used this software you're talking about, but 87 degrees seems a bit small.  Did they give you torso length?  If so, what's your top tube length and what is the length of your stem?  We're going to need some pictures of this asap.

2011-01-14 1:22 PM
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Subject: RE: tri bike fit question- hip angle, etc.
jgerbodegrant - 2011-01-14 1:16 PM

Never used this software you're talking about, but 87 degrees seems a bit small.  Did they give you torso length?  If so, what's your top tube length and what is the length of your stem?  We're going to need some pictures of this asap.



I will get a more appropriate picture tonight (me in boxers only, not a pretty sight...)

Stem length is 100 or 110 I believe, will check top tube dimensions as well.

2011-01-14 1:47 PM
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Subject: RE: tri bike fit question- hip angle, etc.
>>3. Just trying to understand the idea of why person is set up open vs closed. I also wanted to drop down a spacer or two to get a little lower on front (from previous thread, understand that it could affect things). And how to get from open to closed, seems since it is angled at hip area, lowering front is one way of closing angle???? Any other ways such as saddle position etc??

Have you asked your fitter? He/she would be able to tell you their rationale. How open I set up a rider depends on a number of variables including: flexibility (hamstring/glute/low-back and upper back/neck, experience (cycling in general as well as aero positioning), rider comfort. I will often position someone new to riding a TT bike in a more open position with the plan to lower them as they become more comfortable.

When lowering the front end of a bike you need to account for the lengthening of the cockpit that happens as the bars are lowered.

scott

2011-01-14 2:06 PM
in reply to: #3300040

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Subject: RE: tri bike fit question- hip angle, etc.
yaqui - 2011-01-14 1:47 PM >>3. Just trying to understand the idea of why person is set up open vs closed. I also wanted to drop down a spacer or two to get a little lower on front (from previous thread, understand that it could affect things). And how to get from open to closed, seems since it is angled at hip area, lowering front is one way of closing angle???? Any other ways such as saddle position etc?? Have you asked your fitter? He/she would be able to tell you their rationale. How open I set up a rider depends on a number of variables including: flexibility (hamstring/glute/low-back and upper back/neck, experience (cycling in general as well as aero positioning), rider comfort. I will often position someone new to riding a TT bike in a more open position with the plan to lower them as they become more comfortable. When lowering the front end of a bike you need to account for the lengthening of the cockpit that happens as the bars are lowered. scott


Thanks.  From what you have stated, sounds like my lack of flexibility in hammis and glutes, probably contributed to this.  I am a work in progress.  I will still try to post a pics to get better input..
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