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compact geometery. why?
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what is the advantage? i really can't see one?

customerjon @gmail.com is where information happens.
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Re: compact geometery. why? [ultra-poser] [ In reply to ]
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some think it looks cool.
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Re: compact geometery. why? [ultra-poser] [ In reply to ]
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With my shorter than average torso (and shorter than average height), it makes finding a road bike a lot easier!

-J
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Re: compact geometery. why? [ultra-poser] [ In reply to ]
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I think (and this is just my opinion) that compact geometry started as a repulsive abomination of an experiment to reduce the number of frame sizes on bikes from somewhere between 6 and 12 different frame sizes to just three "T-shirt" sizes named small, medium and large. That I am aware of the concept was popularized by designer Mike Burroughs, who has a long list of impressive design innovations in the cycling industry. If consolidating sizes was the primary intention of compact geometry, it was a butt-ass failure. However: An unintended spin-off effect has been that compact geometry does facilitate body dimensions where a person has an extremely long torso and very short legs. For this person (Dan prefers to call them "long-body Roddy")the compact configuration affords a long top tube in concert with their long torso, but a shortened seat tube for greater standover height and an overall lower center of gravity on the bike, for their short legs. This also effects ride comfort since there is now more exposed seat post and the seat stays are at an angle more closely parallel to the ground- inducing a comfortable ride since the transmission of road shock energy is not as direct to the seat mast area. If you have a long torso and short legs compact geometry works. If you don't, there still is some marginal advantage (perhaps) since you may be carrying around "less bike" to a very minor degree. In any case, you are right, it is also a matter of fashion at the moment. Well designed compact frames (Cervelo Soloist, Orbea compact, etc.) ride well and come in a full range of well conceived sizes. I have ridden compact geometry bikes that were absolutely terrible: Too "light" in the rear end, too long in the front-center dimension, truck-like steering and poor fit. I have also ridden at least two (Orbea and Cervelo) that I really like. It is a valid concept in the right application but in no way "replaces" conventional, horizontal top tube frames.

Tom Demerly
The Tri Shop.com
Last edited by: Tom Demerly: Apr 10, 03 4:17
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Re: compact geometery. why? [Tom Demerly] [ In reply to ]
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not too pick nits with tom, but we have been down this road before. :) really, while mega maker giant DID popularize the look, A-N-D , to their shame, attempted to marry it to the bogus 3 sizes fits all concept the two ( sloping tt's and limited sizes) have nothing to do with each other in a pure sense. moreover, it was hardly a "developement" by either burroughs or giant and had been in widespread use , most notably by varied boutique mt bike builders, on road bikes for many years prior to giant busting lose with the concept on the mass market stage. but any issues of handling , again, have to do with the bike itself and not whether or not the tt slopes or is horizontal. really that is all it is, a look - it affects the swing weight side to side minimally. comfort is affect far more by the frame's tubing and geometry just as on a horizontal bike. apart from that whether or not there are issues related to the rear end, or front center, or whathaveyou those problems would also exist if the same bike had a horizontal tt.
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Re: compact geometery. why? [Tom Demerly] [ In reply to ]
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I didn't say it was a "development". I said it was "popularized" by Mike Burroughs. Not to be nit-picky of course :).

Tom Demerly
The Tri Shop.com
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Re: compact geometery. why? [Tom Demerly] [ In reply to ]
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good one, tom !! just trying to stay on my ( and your) toes. :) :)
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Re: compact geometery. why? [t-t-n] [ In reply to ]
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but, i think it was first popularized by the BMX-ers ( the horror) !!!
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Re: compact geometery. why? [t-t-n] [ In reply to ]
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Oh, additionally, I agree that the effects of having the top tube slope downward to the rear may be minimal. However, there is a substantial set of changes to the rear triangle of a compact geometry bike, and most people don't think about these. These DO radically affect the bike's ride characteristics and (if poorly designed) its handling. "Bad" compact desings have shortish chain stays and "light" feeling rear ends. My sense is that they are too "compact". The front of the bike is out of balance with the rear. How can you tell? Hit the bottom of a steep, difficult climb; jump hard out of the saddle in a big gear and give it five hard pedal strokes: OH! what the hell was that? The rear end of the bike is all over the place! The tire actually skipped off the ground! Now, try the exact same manuever on a well-fitted Orbea compact, Cervelo Soloist, Bianchi compact. Hmmmm, it doesn't do that for some reason. Also, as the seat stays become "closer to parallel" to the ground (i.e. more horizontal) this does affect the way you "feel" the road surface- a lot I suspect. I notice it substantially. And finally, the difference between having 250mm of exposed carbon fiber seat post and 150mm of exposed aluminum seatpost make a difference in how the road feels on your ass- mostly due to the carbon fiber I suspect, partially due to the additional exposed seatpost.

Tom Demerly
The Tri Shop.com
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Re: compact geometery. why? [t-t-n] [ In reply to ]
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Actually, I appreciate it. At least someone is reading my stuff.

Tom Demerly
The Tri Shop.com
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Re: compact geometery. why? [Tom Demerly] [ In reply to ]
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well on that we agree, tom. i have a custom compact bike made of ox platinum steel, built on the lighter side of things, with radiussed stays to boot. coupled with a ti seatpost it rides sweet in the extreme. could be we could have gotten a horizontal bike to ride equally well - the two guys i had working on it with me ( builders) certainly thought so. and, the other issues i could also go with you on, but again most of that you could say about a horizontal bike as well, if not bikes in general.

but, on the only real issue of merit - put me down in the " think it looks cool" camp. :) mine looks wicked a$$ cool, but then, i also like those new gold treaded hutchinson tires, so there ya go.
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Re: compact geometery. why? [t-t-n] [ In reply to ]
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Yup! BMX baby. My roots are there. My bikes had sloping top tubes. To my eye, that's how a bike should look, so... I ride a compact geometry bike. Simple as that. There are no advantages or disadvantages IMHO. I just simply like the way it looks better than a horizontal top tube.

You should see my wife's Schwinn (got it during their bankruptcy sale). I think her seat post is actually longer than the seat tube. Looks cools as hell, as far as I'm concerned. She puts down the bike splits too, so no complaints there. I guess some of the ONCE Giant bikes and maybe Lieto's Litespeed come pretty close to the same seat tube / seat post length ratio. I dig it.


----------------------------------
Justin in Austin, get it? :)

Cool races:
- Redman
- Desoto American Triple T
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Re: compact geometery. why? [t-t-n] [ In reply to ]
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I confess and agree: I too am a victim of aesthetics to a large degree. They do look cool. when they first came out I was like, "Oh my God! No way, those mountain bike looking things are repugnant!" But then I saw guys stomping up a climb in the Tour on them and I was like, "Hmmm, perhaps I should investigate these..." So yeah, I was taken by their looks. Speaking of looks, have you seen Miss May this month?

Tom Demerly
The Tri Shop.com
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Re: compact geometery. why? [t-t-n] [ In reply to ]
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I think they look like a big BMX bike. I don't like the look
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Re: compact geometery. why? [ultra-poser] [ In reply to ]
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In theory:

1) a lighter frame since the seat tube has been cut down. In reality this usually means no more than a few hundred grams at most.

2) Stiffness is improved because of the smaller frame size and paricularly rear triangle. The smaller triangle is supposed to be better for kicking up hills. However, too long a seat post could negate this advantage.

3) They lend themselves a better to a dual purpose road/TT bike such as the Cervelo Soloist. I couldn't imagine Cervelo trying to do this with a Prodigy.

4) Sizing/cost. No doubt this is why Giant came out with only three T-shirt sizes, although they now have four with their composite models.

You either love them or hate them. Tom D hates them but I love my TCR. Team ONCE loves their TCR's as well. Of course I'm fortunate enough to be a good fit on the meduim T-shirt size, so that does make a huge difference.
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Re: compact geometery. why? [Tom Demerly] [ In reply to ]
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The only time I've ever noticed a difference between my current Specialized compact bike and previous standard geometry bikes from various makers is when I'm climbing out of the saddle, and even the "benefits" are more feel than real performance. It just feels like the machinery below me has a lower center of gravity. Other than that, my current bike rides pretty much the same as my previous road bikes.

As for the looks, well...its like my new Honda Element....I wasn't crazy about it at first, but it grows on you.

But its still all about the ride. Whether compact or standard, does the bike ride and handle well? There's plenty of both types on either side of the performance fence.
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