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what exactly is a "compact frame"?(7 posts)

what exactly is a "compact frame"?Jay18
Jun 9, 2002 1:46 PM
I have seen the expression "compact frame" used for various bikes, but have never seen it exactly defined. What exactly does this mean?

thanks,
J.
re: what exactly is a "compact frame"?Me Dot Org
Jun 9, 2002 2:26 PM
Compact frames generally have a shorter top tube, which is angled up from the seat tube to the head tube.

Shown below are pictures of a Merlin Extralight and and XL Compact. Note the top tube.
re: what exactly is a "compact frame"?jtolleson
Jun 9, 2002 3:06 PM
Actually, the actual and effective TT lengths of compact frames tend to be LONGER than their traditional geometry counterparts. The myth of the short tt has resulted in some smaller riders being steered to compact frames when they shouldn't be.

The MEDIUM Merlin Agilis, for example, has an effect TT of 55.5. That's pretty long.

The main difference with compact geometry is the shorter seatpost compared to the bike's overall effective geometry. That gives you a sloped top tube (obviously) which means you can have more standover clearance (good for the inseam-impaired) without having an overall tiny bicycle (no Shriners need apply).

Debates rage about whether it saves weight or stiffens the drive train, but some folks like the looks, and some folks like how it addresses the shorter legged/longer torsoed rider.

But don't assume you are getting a short TT; if anything assume the opposite.
Compact = short seat TUBE, not short seat post (nm)Kerry
Jun 9, 2002 4:00 PM
Whoops. My typo. As Pee Wee would say ...jtolleson
Jun 10, 2002 5:49 AM
I meant to say that.
The reason...sievers11
Jun 9, 2002 4:16 PM
Take your standard geometry for a 57 cm road bike. Chop of the seat tube 3-4+ cm without altering any of the angles chainstay lenth or effect top tube lenght. So a 57 cm fitting frame would look alittle like a 54 with the new geometry.This is similar to what the Mountain bike industry has been doing for a while.

As a previous person said the reasons are up for debate. I don't think there is any debate, many well respected frame makers have created these frames and a whole littering of european pro teams ride thes types of frames.

Reason 1: Stiffens up the frame, result more resposive stearing and rapid acceleration (good for climbing).

Reason 2: Makes the frame lighter, although marginally, it does make a frame lighter to make it smaller.

Smaller, lighter and faster - this is what drives racing technology, almost a no brainer. But, there is a down side. Do you need a lighter bike for $1000 more to save 2 oz? Do you really want a stiffer frame? Personally I am not willing to sacrafice the smooth ride of my current AL frame, for its wicked stiff brother.

I don't think that stand over height is an issue here, but there is definatly a traditional and conservative thinking that doesn't like the new frame type.

If you do a lot of hard climbing or race, then give them a look. Me I think they look goofy.
one more thing...sievers11
Jun 9, 2002 4:19 PM
carefull if you are ordering one without actually riding one...many of the frame makers are labling there compact fames in different ways. 1) a 54 is a 54 and this would be your size if say you are used to a 57. 2) a 57 bike measures out 54, the sizes are based off a virtual seat tube height.