CB Idaho

What are the advantages over traditional frames? I've been told I'm a candidate because my inseam is relatively short for my height (32 in at 6 ft. 1 in). Sound right to anyone?

SpongeDad

Many theories - some say compact handles better while standing (including esteemed frame designer Tom Kellogg), others complain that it's just a way for bike manufactures to make a smaller number of frames (e.g., S, M, L, XL vs 50, 52, 54, 56, 58, 60).

The rationale recommended to you is as good as any I've heard - you can get a large compact frame but still have enough standover to not wreck the family jewels.

I have both classic and compact framed bikes - I like them both.

ericm979

The main advantage is that they have a lower standover height for the same size (TT length) traditional frame. Besides that it's mainly looks. Having short legs and a long torso would indeed mean that you might fit better on a sloped top tube frame. But only if you have standover issues on traditional frames.

Manufacturers will make all sorts of claims that a sloping top tube frame is lighter and stiffer but I think that is largely bumk. The extra seat tube length will negate most of that. Perhaps with integrated seat tubes the extra seat tube can be lighter and stiffer, but I don't think it's much different. That said, I have a couple sloping top tube bikes that ride nice, and I think it looks more modern.

shakeNbake

Because compact frames makes the search button cry.

666

More profit margin for the manufacturers.

shabbasuraj

+1......

johnny99

Compact frames do give more fit options for short-legged cyclists. I agree that the main reason for compact frames is to reduce manufacturing costs. Some of that is reflected in lower prices from companies like Giant, which is well known for limited frame sizes.

Longfemur

I remember when so-called compact frames started appearing (Giant was a big booster of this), the big advantage was for the manufacturers who actually claimed that they could fit anybody with just 3 sizes. But marketing also played a role, with a whole generation who had been raised with sloped mtn bikes, and the increasingly funny bikes in competition (Olympics, etc.)... to the point that there was acceptance of the most inelegant, esthetically-unbalanced designs that would have been laughed off the market a few years before.

Manufacturers will still market the perfect fit advantages of compact designs, but it's really about the economics of mass production. They just don't have to make and carry as many sizes of frames to cover the market.

That being said, it is true that if you have unusual proportion, like I do, it might be easier to get a good fit from a stock, compact-frame... without having to go to a custom-built frame. It will be uglier, though. The lines are all wrong.

MartiniTime

I do not fit compact frames very well at all. Hence I don't like them a bit,

johnny99

Why don't they fit you? Lack of sizes from some brands?

operator

+30

In addition to looking like garbage over traditional frames.

Scooper

While there may be some advantage to compact frames in mountain bikes (think standover height and potential damage to "the boys"), many road bike framebuilders believe the trend to compact frames in road bike design is due mostly to the cost advantange compact frames provide manufacturers; fewer frame sizes are necessary. Richard Sachs, one of the great American framebuilders, explained the phenomenon in one of his blog essays. Personally, I think sloped top tubes are fugly.

dekindy

Here's what Cervelo says.

Answer - Traditional, sloping & compact frames
A sloping frame is a frame that has the toptube higher at the headtube than at the seattube, as opposed to a traditional frame that has a horizontal toptube. It really doesn't change anything important in the geometry, the headtube, bottom bracket and saddle, the only points you connect with on a bike, are still in the same spot.

There are however some small differences between sloping and traditional frames that can be exploited in design. If you have two frames that are made identically except for the sloping vs. horizontal toptube, then the following can be observed:

1) slightly higher bottom bracket stiffness for the sloping frame
2) slightly higher torsional stiffness for the horizontal toptube frame
3) slightly lighter frame with the sloping toptube
4) slightly lighter seatpost with the horizontal toptube frame
5) slightly more seatpost compliance with the sloping frame.

Issues 3 and 4 are a wash, and for us at Cervélo the choice between sloping and horizontal depends on what combination we are looking for out of 1, 2 and 5. For our Road bikes, which have plenty of bb and torsional stiffness anyway, we go with a sloping toptube (or a dropped toptube on the tri bikes which has the same effect) to get a bit more seatpost compliance.

Compact geometry is the use of a sloping toptube to convince people you only need to make 3-4 sizes. As is obvious from the above, nothing changes in the way a bike fits when you make the toptube sloping. So if you need six sizes in a traditional geometry, then you still need six if it is sloping. Henceforth we're not big believers in compact geometry. But the terms compact and sloping are really used interchangeably by many people, so make sure you understand what they mean. Bolding added to Cervelo original for emphasis.

https://www.cervelo.com/viewkb.aspx#3
Link to original if anyone is interested.

dekindy

Do you really think that a custom framebuilder is going to comment that you can do a good job with 3-4 frame sizes regardless if it is compact or traditional style frame? See Cervelo explanation. You need as many frame sizes with either design because the contact points end up in the same place. See the five contrasting characteristics of traditional versus sloped/compact for the real engineering reasons of traditional versus compact.

michaelalanjone

Because not everybody is a 6'5" Italian dude. I am 5'6", and my pants are 28" long -- is that inseam? -- I don't know - I have short, muscular legs. I bought a Giant OCR-1 with a compact frame, and it is the best fitting bike I have ever ridden. I can really kick a§§ on that bike. I don't know if manufacturers can save money that way (and I don't care). I just really like that type of frame, and if I ever buy another road bike, I will try to find a compact frame.

Scooper

Cervelo's explanation notwithstanding, Giant introduced compact geometry frames purely as a cost savings/lower inventory measure, announcing in Bicycle Retailer that by manufacturing only four frame sizes for road bikes instead of 48, 50, 52, 54, 56, 58, 60, 62 cm sizes in traditional geometry frames, they and retailers would realize significant savings. The pitch from Giant to the retailers was essentially, "carry our new compact geometry bikes and you only need to have four sizes to fit everyone."

Please don't shoot the messenger.

mezza

Fashion.