Pain behind the knee after 2 hours of ride

Discuss light weight issues concerning road bikes & parts.
AllAboutFeel
Posts: 29
Joined: Fri Jul 13, 2018 6:04 am

by AllAboutFeel

Hello Folks,

I am new to this forum. Came searching for a solution to a problem I am facing for the last couple of months. Not sure I can explain it well but let me try.

My height is 163 cms. I am just a weekend rider. I have a high inseam and short torso. I used to ride a Pinarello Paris 46.5 and recently changed to Pinarello Dogma 65.1 46.5. The frame should be identical in size. The only differences from my Paris setup are:
1. Paris had a 10mm setback seatpost while Dogma has a 25mm setback seatpost.
2. Saddle on paris was a Selle Italia Flow, while on the Dogma is a Fizik Aliante Versus Evo

After this change of bike, I played around with saddle height for a few rides and one day I had a bad pain behind my left knee. I didn't know the cause and thought it could be a one-off case. I continued for another couple of rides only to realise that the pain comes back every time after about 50 kms of ride. I researched online and found that too high a saddle can cause it. I lowered the saddle quite a bit. Now my saddle height is right in the ballpark. I know it while riding. But still the pain comes back. So now I do not know whats going on. Few questions I am trying to get an answer
1. Is it that the injury I caused to myself has not yet healed hence the pain is coming back even after lowering the saddle ? I already took a 3 weeks break to let it heal but still it came back right after 50kms. And only in the left leg.

2. Could it be the 25mm setback on the seat post causing it ? Because of my short torso I always put the seat all the way forward. I have done the same on my Dogma too. Still is it too far back ? I would worry if thats the case because it is a stock pinarello bike, it should fit a normal rider like me. 

3. Could it be the saddle ? Are there saddles which can push you too far back or bring you forward ? If such saddles exist I can try one which helps me sit forward and offset the setback seatpost.

In general I am comfortable on the bike. I can happily do 120 kms if the pain wasn't there. So how to diagnose the cause of the pain ?
A zero setback seatpost could solve the mystery quite easily but it is rare to find and very expensive so I have kept it as the last resort.

by Weenie


TobinHatesYou
Posts: 4196
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Hyperextension. What is your inseam and saddle height?

AllAboutFeel
Posts: 29
Joined: Fri Jul 13, 2018 6:04 am

by AllAboutFeel

My inseam is 81cms
Exact saddle height I will measure today and post

TobinHatesYou
Posts: 4196
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

For comparison, I have around an 81.5cm inseam and my saddle height is 72cm from the BB with 165mm cranks.

AllAboutFeel
Posts: 29
Joined: Fri Jul 13, 2018 6:04 am

by AllAboutFeel

I use 170mm cranks for the last 4 years. Not sure if thats causing any problem.
Whats your saddle height from the floor ?

joejack951
Posts: 630
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

More setback effectively raises your saddle height (but where your saddle is positioned is what matters, not the setback of the seatpost). Longer cranks require more knee flexion and/or effectively raise your saddle height.

Saddle height should be measured from the crank center, not the floor, as bottom bracket drop can be different between frames, and saddle setback/seat tube angle will affect the measurement. If changing crank lengths, subtract the additional length from your saddle height measurement. This will keep your knee extension the same at the cost of more knee flexion (the flexion may or may not be an issue for you, it is for me).

Figure out where you sit on each saddle and confirm that that point is the same distance from the handlebar tops on both bikes. Depending on how far out your saddle height and setback currently are, you may need to adjust one or both a few times to get both correct.

Nixster
Posts: 93
Joined: Wed Oct 04, 2017 3:30 pm

by Nixster

The answers to your questions:
1 yes quite possibly
2 almost certainly
3 possibly maybe but better to resolve the seat post as that is fundamental

In order to get the same position as on your previous bike the saddle will have to be in the same position relative to the bottom bracket.

The setback of the seat post and the seat tube angle (STA) both are relevant here.

The easiest way to resolve this is to get the bike on a level surface and use a long vertical spirit level to measure the horizontal distance from the centre of the BB to a known point on the saddle on your old bike and then replicate it on the new bike. You can then set the saddle height by measuring along the seat tube to the top of the saddle and adjust forward and back until both measurements are correct.

If you’ve taken the old bike apart already you can compare STA on the two rigs and see if the new bike is giving you more setback through a slacker STA or less with a higher STA. if the STA is unchanged then happy days, you just need to get the saddle in the same position relative (horizontally) to the line of the centre of the seat tube. If not you need to do some math.

A post with greater setback will put you further behind the BB if you don’t compensate for it and by the sound of things you have the saddle as far forward as possible on old and new seat posts. This means 15mm more setback. My experience is that 5mm more than usual gives me exactly the issue you describe, so I can see why you have a problem! But then I am old :D .

Two things
1 don’t position your saddle relative to the bars. If you can’t reach the bars with your saddle in the right place change the stem, don’t move the saddle forward.
2 it definitely sounds like you would benefit from an in-line post to give you more options to fine tune saddle position. Plus it will look way cooler than slamming the saddle as far forward as it will go.

Internet bike fitting sucks though. Your best option may we’ll be professional help, particularly as you seem to be outside the standard range?

Hope that helps rather than confuses!

AllAboutFeel
Posts: 29
Joined: Fri Jul 13, 2018 6:04 am

by AllAboutFeel

TobinHatesYou wrote:
Mon Oct 07, 2019 7:34 am
Hyperextension. What is your inseam and saddle height?
Just checked, the height from bb to saddle along the seat tube is 70 cms. From pedal axle to saddle along the seat tube is 88 cms

AllAboutFeel
Posts: 29
Joined: Fri Jul 13, 2018 6:04 am

by AllAboutFeel

Thanks everyone for suggestions. My old bike is sold so I could not compare it to the new one. But based on your suggestions I dug out an old sheet of paper on which I had written down the measurements of my old bike settings. Guess what ? The BB to Saddle height on it says 685 mm whereas on this new bike (even after lowering the saddle to avoid pain) it is at 700 mm.

That is a big difference combined with a 15mm additional setback. I feel both stupid and happy that I have probably found the root cause of the pain. It also means I was riding almost 3 cms higher for the first few rides which caused this pain to start with. In my old bike the steerer tube was cut to max so there were no spacers below the bar whereas on my new bike I have 20mm spacers below the bar so even though I raised the saddle so drastically I was still comfortably reaching the bar.  All this and lack of measurements. 



Now I have lowered the saddle by 1.5cms and will ride over the weekend to see how it feels. 

TobinHatesYou
Posts: 4196
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

I find it unlikely that your inseam would be 81cm if 685mm BB->saddle feels ok to you. 81cm is also quite an inseam for someone 163cm tall.

icantaffordcycling
Posts: 440
Joined: Wed Jan 09, 2019 5:03 am

by icantaffordcycling

^ I am 163/164cm, all legs, no torso. My inseam is nowhere close to 81cm...
My saddle height is 68cm from center of bb to top of saddle measured vertically. Using 165mm cranks.

I am ALL legs, 70cm is a lot for people our height.
Specialized Allez Sprint
Instagram || Shitposting is a god-given right.

WorkonSunday
Posts: 119
Joined: Tue Jan 16, 2018 4:39 pm

by WorkonSunday

i too think it's crank arm too long plus saddle too high. im 170cm. my top of saddle to axle is 72cm. i tried 155, 165 and 170mm cranks, i found 165 is much better than 170mm for road use. for triathlon i use 155 but would imagine 160mm is better. 155 just means too little torque for me. do you have someone you know that can ride behind you and do some feedback sessions? if you hip is moving up and down excessively, thats an indicaiton you may need to look at lower saddle height/shorter crank.

my wife is 160cm, she also uses a set of 155mm cranks. saddle height is 63cm.

also worth noting where you are pushing down on the pedals. does your power transfer happens at the ball of your feet or you tend to use front/tip of your feet to pedal?
In the house: Colnago V1r, Colnago A1r, Wilier Cento1 Air, Scott Scale 700SL, Bianchi FSE, Colnago Concept, Colnago A1r, Specialized Ruze Pro, Wilier GTR, Argon 18 E117 Tri+, Brompton B75

AllAboutFeel
Posts: 29
Joined: Fri Jul 13, 2018 6:04 am

by AllAboutFeel

icantaffordcycling wrote:
Tue Oct 08, 2019 7:53 am
^ I am 163/164cm, all legs, no torso. My inseam is nowhere close to 81cm...
My saddle height is 68cm from center of bb to top of saddle measured vertically. Using 165mm cranks.

I am ALL legs, 70cm is a lot for people our height.
Shouldn't the height be measured along the seat tube ?

icantaffordcycling
Posts: 440
Joined: Wed Jan 09, 2019 5:03 am

by icantaffordcycling

roughly 71cm along the seat tube.
Specialized Allez Sprint
Instagram || Shitposting is a god-given right.

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wheelsONfire
Posts: 2963
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

I had something in those regions happen just at the start of the season.
I could walk and do all things normally, but from 9 o'clock to 3 o'clock my knee did hurt like crazy right at first spin.

I did however disappear after 10 weeks +.

* Have a look, one how your knees goes from downstroke to upstroke
* Have a look at Q-factor of shoes/ cleats/ pedals/ cranks
* Saddle position
Bikes:

Ax Lightness Vial EVO Race (2018.12.21)
viewtopic.php?f=10&t=156137
Paduano Racing Fidia (kind of shelved)
Open *UP* (2016.04.14)


Ex bike; Vial EVO D

by Weenie


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