I have a 2012 Cannondale CADD 105 bike that fits like a glove. I just bought 2004 Trek 5500. Both are 54cm.

Are there measurement I can make on one bike and transfer to the second?

I now know why this got no response. Two bike can be 54cm crank to top tube, and still be totally different! I did get a professional fitting!

an article for you
https://www.stevehoggbikefitting.com...mentMethod.pdf

^this.

Good article and pretty much what I do to duplicate settings across bikes.

What I do differently though is I have a gyroscope app that measures angles on my iPhone. I place that on the seat with the datum at the point where the seat clamp rotates and use that to duplicate the angle. I first take a measurement on the ground and use that to null out the measurement to level. Works really well to a tenth of a degree. Other than that, I use the same methods as does Steve in his article.


J.

Yes, that's correct, and it's why the Hogg guide is not terribly helpful for bikes which are not identical. It'll get you in the ballpark, but you'll probably need to re-adjust as you learn to adapt the different geometry to your demands.

No it works fine for bikes that aren't identical, I've done it many times on different bikes.
What I would suggest though is to have the same saddle and handlebars though

I disagree. Particular geometries will require the rider to interact with the bike differently; maybe where your weight is centered on the frame (bars in/down, for example) or how much steering input is required as opposed to weight shifting.

Intended purpose is another factor, too: the bike you use for crit racing need not fit like the bike you use for TTs, randos, or commuting across town.

I suppose it comes down to how different the frames are and how demanding the rider is, but even Hogg set up the article on the example of two identical bikes, so jumping to diverse frame geometries doesn't necessarily follow in that sense, either.

Anyway, the OP has already realized that same size bikes "can be totally different," so I don't think you're going to convince either of us otherwise.

When setting up a new bike, I always transfer my old saddle, set the height, get the setback with a plumb bob to the BB. Then measure a triangle between BB, saddle nose, and stem clamp center. When I change saddles, that has to be done by feel.

Chaadster, the OP was talking about road bikes so I was discussing transferring the measurements for one similarly sized road bike to another. This also works for transferring measurements between two time trail bikes.
I'm Steve Hoggs mechanic so like I said I've done this more than a few times.

Well, I guess you played the trump card! Haha! That's cool, and yep, your expertise commands my respect.

We certainly agree that for similar bikes intended for similar purposes, that works fine, and It sounds like we also agree that for diverse bikes and varying uses, it may not.

Thanks Chadster :-)
We do agree.
It takes considerable care to get the adjustments right. We've had pros fly back from Europe after they started having problems and it's turned out that the team mechanic thought he'd put his own interpretation on how to do adjustments and caused the rider to have problems. They now measure and make sure everything is in the right place themselves

[MENTION=18039]geoffs[/MENTION],

That's a very impressive and precise methodology you all have there.

"Back when" we used a "build sheet" for every frame-up bike build detailing the frame make/model size/dimensions and component list.
All sizes of components from crank length through toe clip size were recorded from a pre-build fit assessment of the customer.
On the build sheet seat height/rail position, drop and reach etc were recorded from the "base fit" before the customer left the shop, and discretely marked.

It certainly is possible to duplicate a fit from bike to bike with carefully recorded data, your process makes our old school method look primitive.
Anyone who is satisfied with their fit would do well to use your methodology to record their fit data for future builds.

-Bandera