A good rule of thumb is, what crank length did the manufacturer spec? Hard to believe, but bike manufacturers often take things like what crank length is going to be used when designing a bike, as well as the expected height range of the rider. Those numbers on the geometry charts aren't just random numbers. A few mm doesn't matter that much, but several cm can really start to affect things.

As for going lower, the CPSC has our hands tied. There is a minimum cornering clearance required, throwing 200mm cranks on bike with a standard 70mm BB drop is way outside of that limit. There is one production bike that I know of that is designed for 200mm cranks (KHS Flite747), the BB drop on that bike is 25mm higher than on their bikes designed for 175mm cranks. So your ground clearance, and center of gravity, would be the same...

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"I'm thinking of a number between 1 and 10, and I don't know why!"

I only do about 2 hours a day now, wussing out.

But yea, as I was running, when I did not want to this morning, I just keep thinking my competition is out in the cold also, so it keeps me going.

But yep, frequency, consistency, duration will win for most folks.

At my age, not many race at all, let alone train daily. I am blessed and am thankful everyday. Today is not a dry run for tomorrow.

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

This would have been a great primer in post one.

I'd use your previous cycling experiences as a baseline to compare to the feel of the new fit. If you don't like going downhill at 30+ you don't like going downhill at 30+. No big deal there your comfort is your comfort.

I have never seen a mfg spec shorter cranks, have you?

I just went to the cervelo site, and looked at the P3 specs. Does not even talk about what crank length comes with the bike, let alone, different lengths
based on different sizes.

I had looked at having a bike made with a higher BB, but the building said it would mess up center of gravity and if built, would take no liability.

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

I will add to post one

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

Once Frank gives a suggestion for cranks to try, yep, I will somehow get on my race bike and take a ride a ride around my hilly community before I do my first race which is in some real tough hills. Good point.

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

QR goes slightly shorter, using 165s where most companies use 170-172.5, and 170s where others use 175. The big problem with production bikes is that the vast majority of OEM cranks produced are in the 170-175 range, with a few going down to 165. So production bikes get spec'd with cranks in that range, and frames are designed around that.

However, many tri bikes are being designed with lower BBs than before, even if they aren't spec'ing shorter cranks. Current Cervelo BB drop is 75mm, a bit lower than standard road geometry and 15mm lower than the older P2/P3.

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"I'm thinking of a number between 1 and 10, and I don't know why!"

Interesting.

Again, I just looked at one company, Cervelo, one bike, the P3, and it says nothing about crank length. Never heard from any bike shop I have been in that folks have a choice, it is what comes with the bike, and most are yep, around 170.

Interesting BB's are being lowered. Any idea why?

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

Okay, latest bike fit.

145mm cranks. 875 seat height from BB. 495mm from seat nose to AB edge pads. Seat nose is 95mm back from BB. Aero bars are 80mm down from seat

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

Was this the best crank length?

At least in the case of the last tri bike I designed, to bring the center of gravity down slightly. A little more stable regardless of crank length used, and a little bit better if going shorter. I'm assuming that is the same reason everyone else did...

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"I'm thinking of a number between 1 and 10, and I don't know why!"

Have not answered this yet. I would have done 150 but the Velotron to take video on is 145mm so thought that was close enough for now.

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

Makes sense. Guess I have not experienced anything I would relate to center of gravity issues yet, even though I maybe missing.
I know I have had the shakes on some other bikes before which scared the heck out of me. One of many reasons I will not allow myself
to go fast on down hills. Blowing out a front tire was another.

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

Here is a video with a decent bike top on.

145mm cranks. 80mm drop.

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

can you reproduce that fit on your real bike ?

Your cranks look too short

You are not taking advantage of the shorter cranks for a more aero flat back position. How much weight do you have on the arm rests.

I don't think there's a tri bike on the market that would allow for that exact position. Even an XL Shiv would be too long and low.

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"I'm thinking of a number between 1 and 10, and I don't know why!"

Is there a part of this fit to move to my race bikes I should be concerned with?

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

I was expecting this. When I see others post their video, I am looking to see if anyone makes comments on their backs, including Dan which seems to make fit comments
on all other threads. :) But I never seem to see anyone comment about flat back stuff most of the time.

I have a bad back. There is NO NO way I am going to ever have a flat back at my age. The shorter cranks have allowed me to get the cranks over the top correctly while in the
aero position. I was not able to do this with 200's, as proven with my testing with powercranks.

Not sure how to answer question about weight on the arm rests. How do I answer this?

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

Why do the cranks look too short?

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

What with this fit exactly would a bike not be able to reproduce? I have not tried yet, but if this is something missing before I try, I sure need to consider
how to deal with.

Thanks

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

Dave,

Here's a place where an experienced fitter might well help you out a great deal. Your back looks as if it's in a very comfortable orientation in the video and if you were able to just rotate your front end downward by how your pelvic rami interfaced with an appropriate saddle you could maintain that orientation and would not need to arch your back in a way that "hurt it" . As you get lower in the front end your neck strength and forward visibility will end up limiting things before your back ought to.

I suspect you're going to tell me your saddle is just fine but as a 64 year old with a really wrecked back I'll have to say that sitting on the "right saddle" the "right way" makes all the difference in the world in regards to getting low and not having back pain.

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

I also have a really bad back, and I've fit a lot of people with really bad backs. I'm a lot lower than you are, but I don't bend over any more than you are. The difference is that I'm rolled forward, while you're sitting back. Your saddle in these videos is mounted at about 72 degrees, as positioned you're riding a road bike, not a tri bike. Bolt a set of aerobars on a Specialized Roubaix and you'd pretty much have the same position you've got here. In fact, if this is the position you're going to race with, you'd be much better off on a road bike. It'll fit better, handle better, and as a bonus you'd now be able to get disc brakes at a P2 price...

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"I'm thinking of a number between 1 and 10, and I don't know why!"