[Alaska Mike]

<p>This is my first season riding my new/used Cervelo P3.  I did a long ride (106 mi) on Saturday and mid-way through the ride I started to have problems with my right leg, just below the back of the knee.</p>
<p> </p>
<p>One possibility is that my bike fit isn't quite dialed in.  Looking at my road bike, the distance between the center of my bottom bracket and my seat is the same as I have on my P3.  However, my tri bike has standard cranks and my road bike has compact cranks.  Which means that my leg on the P3 is more fully extended at the bottom of the rotation.</p>
<p> </p>
<p>So, my thought is to lower the seat slightly on the P3.  My only concern is what else that may affect.  Anyone have any idea of what I should be looking for when I do this?</p>
<p> </p>
<p>I'll probably schedule a re-fit sometime this trip home.  Unfortunately I'm racing this weekend and the LBS where I previously got my fitting done has gone out of business, so it won't happen until next week.</p>
<p> </p>
<p>Thanks in advance for any advice,</p>
<p>Mike</p>

 

[jroden]

<p>good question, i think your assumption about the crank is not correct, compact is just the ring BCD and the distance from center to pedal spindle is the same, assuming you are running the same length cranks.  Perhaps sliding the seat forward on a the rails a little will help?</p>

 

[Thor]

<p>Jr is right. Crank length should be the same. As for why the pain, I'm guessing something is different between old and new fit, as you have guessed, only it isn't always a matter of measuring the obvious points. If even the arm pads are in or out a nudge, that could put your torso at a slightly different angle relative to your hip, meaning your legs must do more work/less work to come around, which in turn could cause knee pain.</p>
<p> </p>
<p>There's a good website somewhere that details different pains in knees/hips/etc and what the cause might be. Maybe Google around a bit. That might at least give you an indication that, for example, your seat might want to go down a notch and forward a smidge.</p>

 

[Alaska Mike]

<p>JR and Thor - you are, of course, correct and I knew that and I feel a bit stupid for saying it.  Oh well, certainly not the first time and probably not the last.</p>
<p> </p>
<p>Actually, I do have slightly different crank lengths for the road bike and the tri bike.  The road bike has 170 cm cranks, the tri bike has 172.5 cm cranks.  I'm pretty sure the 2.5 cm difference is within my margin of error in measuring.</p>
<p> </p>
<p>I did lower the seat just a bit.  Didn't feel really any better or worse on the ride today.  My seat is pushed as far forward as it will go, so maybe sliding it back would help a bit.  I may try that after this weekend's race.</p>
<p> </p>
<p>Thanks for the suggestions.</p>
<p> </p>
<p>Mike</p>

 

[regiolanthe]

<br><br><div class="quote-container"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>Alaska Mike</strong> <a href="/forum/thread/74207/tri-bike-fit-question#post_2003157"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif" style="border-bottom:0px solid;border-left:0px solid;border-top:0px solid;border-right:0px solid;"></a><br><br><p>Actually, I do have slightly different crank lengths for the road bike and the tri bike.  The road bike has 170 cm cranks, the tri bike has 172.5 cm cranks.  I'm pretty sure the 2.5 cm difference is within my margin of error in measuring.</p>
<p> </p>
<p>Mike</p>
</div>
</div>
<p><br>
I believe that would be 2.5 mm .... Honestly, I doubt you'd feel much difference in crank length unless you went from like 165 to 175 (1 CM) ... or you might notice a negligble difference between say - a 170 and a 175 (5 mm) - but I wouldn't think it would throw fit off unless it was a full 10mm difference in crank length.</p>
<p> </p>
<p>Geo.<br>
 </p>
<p> </p>

 

[niemsco]

<p>After 100 miles and calculating all the rpms that would equate to, you never know if 2.5mm could do something.  I have same length on road and tt, best to keep them the same just in case </p>
<p> </p>
<p>On a different note, are you doing High Cliff this weekend?  I might go up there to race.  I wouldn't sign up until the day of the race (which is possible) and may actually leave here at 2:30 am Saturday morning.  Something stupid I would do.</p>

 

[Alaska Mike]

<p>Yes, I'm  doing High Cliff this weekend.  Assuming I can run by then.  Biked fine today but the run was a no-go.</p>
<p> </p>
<p>Mike<br>
 </p>
<div class="quote-container"><span>Quote:</span>
<div class="quote-block">Originally Posted by <strong>niemsco</strong> <a href="/forum/thread/74207/tri-bike-fit-question#post_2003189"><img alt="View Post" class="inlineimg" src="/img/forum/go_quote.gif" style="border:0px solid;"></a><br><br><p>On a different note, are you doing High Cliff this weekend?  I might go up there to race.  I wouldn't sign up until the day of the race (which is possible) and may actually leave here at 2:30 am Saturday morning.  Something stupid I would do.</p>
</div>
</div>
<br><br><p> </p>