Quandry, help needed before going mad...

[Sysagent]

Just had the delivery of my new Ribble road bike (previously been an ardent MTB'er for years n years) and I am now in the process of "fine tuning" the fit of it to me...

The frame is a 46cm sloping top tube, geometry here:-

http://www.ribblecycles.co.uk/content/images/FrameGeometrySloping.gif

and measurement chart to piccy here:-

http://www.ribblecycles.co.uk/content/images/FrameGeometrySlopingChart.gif

I have measured my inseam length to be 79.5cm using the hard-book method with my feet 6" apart in my cycling shorts.

Ok here is the dilemma when using the calculation:-

saddle height=0.883 x inseam I get the value 70.19cm

Doing a quick measurement now of my saddle height it is 75cm, this height was determined using the heel on pedal method, but the height just doesn't feel quite right, it is too low if anything...

Is it me? Am I an odd shape with legs longer than a giraffe, which is hardly probable being only 5ft 9" or am I completely missing the point here?

Oh also just for information the stem I have on the bike is 110mm in length with 46cm drop bars if that helps and 170mm crank arms, using Shimano 540 SPD's.

Many thanks in advance for any help or replies,

Russ

 

[Bigtwin]

Put the allen key in your back pocket, go for a ride, and adjust the saddle height till it's right.

Job done.

 

[Sysagent]

Put the allen key in your back pocket, go for a ride, and adjust the saddle height till it's right.

Job done.

Heh I was just going to do that...

Just curious though why the calculation throws up such a wayward result to what I am actually seeing.

 

[Bigtwin]

Heh I was just going to do that...

Just curious though why the calculation throws up such a wayward result to what I am actually seeing.

God knows - there as many of these calculations floating around as you can be bothered to find - it's all bollicks. So long as the frame is in the right ball park, it's trial and error. I don't even have the same set-up on all of my bikes due to different geometry and purposes.

 

[simon_brooke]

Just had the delivery of my new Ribble road bike (previously been an ardent MTB'er for years n years) and I am now in the process of "fine tuning" the fit of it to me...

The frame is a 46cm sloping top tube, geometry here:-

http://www.ribblecycles.co.uk/content/images/FrameGeometrySloping.gif

and measurement chart to piccy here:-

http://www.ribblecycles.co.uk/content/images/FrameGeometrySlopingChart.gif

I have measured my inseam length to be 79.5cm using the hard-book method with my feet 6" apart in my cycling shorts.

Ok here is the dilemma when using the calculation:-

saddle height=0.883 x inseam I get the value 70.19cm

Doing a quick measurement now of my saddle height it is 75cm, this height was determined using the heel on pedal method, but the height just doesn't feel quite right, it is too low if anything...

Is it me? Am I an odd shape with legs longer than a giraffe, which is hardly probable being only 5ft 9" or am I completely missing the point here?

Oh also just for information the stem I have on the bike is 110mm in length with 46cm drop bars if that helps and 170mm crank arms, using Shimano 540 SPD's.

Many thanks in advance for any help or replies,

Russ

Dunno where you get the 0.883 from.

However, the key point about the height of a saddle is that your leg is more efficient when your knee is less bent. So the higher the better with two limiting factors: your knee should not straighten completely even at bottom dead centre, and your pelvis should not rock in the saddle.

FWIW my inseam is 84cm, saddle to centre of bottom bracket is 77cm (mountain bike), 79cm (cross bike), 81cm (time trial bike).

 

[Sysagent]

Dunno where you get the 0.883 from.

From the Greg LeMond formula

 

[accountantpete]

Hi Sy - as the others say the positioning of the saddle is a personal thing but mainly the leg should not straighten out completely at the bottom of the pedal rotation.

Take a look at the Tour - some riders have a relatively low seat position where their legs don't quite straighten as much as others - it all depends on what style you feel comfortable with.

 

[Sysagent]

Many thanks for the replies, I went out yesterday for a 35 miler and seemed to have nailed the seat height issue.

All I have to sort out now is why:-

1) My right hand is experiencing numbness, more on the hoods than anything, so I have to shift hand positions to reduce it

(Saddle fore / aft position?)

2) Just below my undercarriage on the left hand and lesser to the right hand side feels like someone is trying rip it out with barbed wire after sometime in the saddle

(Saddle up / down position?)

Cheer's again much appreciated

Russ