Saddle height comparison between Road and Tri Bike set up

[SwissVan]

As we know.... Road frame and Tri Bike geometry is quite different what with a tri seat tube being more vertical (closer to 90 degs) compared to a road seat tube.

 

On my road set up my saddle height is 1cm higher than my tri bike, measuring both using the same procedure.

 

Question for those with road and tri bikes: Do you have the same saddle height set up or are they also quite different, tri bike lower due to a more forward position?

 

Reason I'm asking, lately I've been riding my tri bike and noticed that my legs (quads) are feeling more fatigued compared to when I was training on my road bike.  Unfortunately I never made a note of my tri bike set up last year and now I'm not sure if the seat post has slipped down slightly. 

[fanievb]

not sure on the difference between road and tri setup.

but from experience, tired quads are usually an indicator of a too low saddle.

 

 

Quote (J Friel Training Bible 3rd Ed)

 

 Saddle height, because of its effect on power output, is the most studied aspect of bike fit, and there are scores of formulas for determining it. Perhaps the easiest way to make this adjustment is to sit on your bike, with your shoes off, in the aero position. Place your heel on the pedal at the bottom of the stroke (crank arm lined up with the seat tube). To set the neutral position, adjust the saddle height until your knee is straight. Notice that as the saddle goes up, it also moves aft, and as it is lowered, it shifts forward slightly. So you may need to make some small, correcting changes in the fore-aft setting. For every 2 centimeters (cm) it goes up, it must also move forward about 1 cm; if you lower it 2 cm, move it aft by about 1 cm

 

[SwissVan]

not sure on the difference between road and tri setup.

 

but from experience, tired quads are usually an indicator of a too low saddle.

 

 

Quote (J Friel Training Bible 3rd Ed)

 

 Saddle height, because of its effect on power output, is the most studied aspect of bike fit, and there are scores of formulas for determining it. Perhaps the easiest way to make this adjustment is to sit on your bike, with your shoes off, in the aero position. Place your heel on the pedal at the bottom of the stroke (crank arm lined up with the seat tube). To set the neutral position, adjust the saddle height until your knee is straight. Notice that as the saddle goes up, it also moves aft, and as it is lowered, it shifts forward slightly. So you may need to make some small, correcting changes in the fore-aft setting. For every 2 centimeters (cm) it goes up, it must also move forward about 1 cm; if you lower it 2 cm, move it aft by about 1 cm

 

 

 

Yup that's what I have always believed / done.

 

Last year i trained and did IM and had no problems like this, but somehow I never recorded my settings and now this year having issues and not knowing what my seat height was last year has left me wondering if the seat height would normally be the same even with different geometry.

 

I'm not sure if the problem is because I'm training a bit harder (higher intensity) or if its seat height related.

[davem]

Where you measuring you saddle height from?

 

Your tri geometry will rotate you forward. The triangle should not change. So your contact point on the saddle will be the same distance from the bottom bracket.

 

Depending on your saddle contact point, in my experience, you saddle will actually move up slightly.

[Red Zone]

My saddle height is the same on my road, tri and mtb, each bike with quite different geometry, but the distance between saddle and pedal remains the same

[Eldron]

My saddle height is the same on my road, tri and mtb, each bike with quite different geometry, but the distance between saddle and pedal remains the same

Agreed. In my opinion you're asking for trouble running different saddle heights.

[SwissVan]

Where you measuring you saddle height from?

 

Your tri geometry will rotate you forward. The triangle should not change. So your contact point on the saddle will be the same distance from the bottom bracket.

 

Depending on your saddle contact point, in my experience, you saddle will actually move up slightly.

 

I always measure using the same method - pedal at the lowest position to top of saddle above the seat post:

1. Left pedal at 6 o'clock, locate center of pedal axle = point A

2. Locate the place on left side top of saddle that would be directly above the center of the seat post = point B

3. Measure straight line between A and B = saddle height 

 

My logic tells me that the seat height should be the same on both bikes, hence the question / confusion when I found the tri bike is 1 cm lower.

 

I'm going to move it up a 1/2 cm and see if things feel better

[shawnvan]

Saddle height should be the same on both bikes, measured from the bottom bracket axel.

 

This is because given the different geometries, the "bottom" of the pedal stroke (ie the point at which the pedal is at the farthest point from your seat) will be at different places on the two bikes.  With the steeper seat tube angle of the tri bike, the bottom of the pedal stroke will closer to the "6 o'clock" position , whereas with the less steep seat tube of the road bike this will be slightly earlier - closer to "5 o'clock".

 

However, don't think its a major issue if they're not idential heights if you are more comfortable on your respective bikes and they're within a few mm of each other.

[davem]

It is also dependent on the saddles you use. I sit on my ISM on the tribike completely differently to the road saddle. One is geared for getting low and aero, the otehr for a more upright pose. My contact points are different.

 

The way I got my ISM fit right was doing laps of Kyalami doing adjustments every few laps. The comparability of the laps made the changes measurable. When I found the sweet spot, the difference was obvious.

 

The end result was a combination of both height and forward/aft positioning.

 

I also have effectively two positions on the bike, firstly where I am just doing the distance, comfortably on the saddle with good power at not too high an effort. Secondly I move right forward so my butt is just on the tip of the saddle. The saddle provides little support, more just for stability and that's when the fun power happens.