Compact Framesets

GavW

Hi all.

I wish to tap the collective wisdom of the forum. What are general thoughts on compact frame geometry vs. traditional frame? My Felt has a compact frame, which I love the feel and fit of (I'm not the tallest), but I'm interested to see if people hold very polarized views on this.

If this has been asked elsewhere, I apologise

cheers

gavin

gavintc

Personally, I think it is just a structure. literally a frame. The positioning of the saddle, bars and pedals are independent of whether the frame is traditional or compact. I have a winter traditional frame and a compact carbon frame. I suppose, the traditional frame makes sitting on the top tube at traffic lights more comfortable, but that is as far it goes for me.

GavW

For me, the bike just feels comfortable, particularly over longer distances, but thats just me. Many, I'm sure, will have opinions on stifness, responsiveness etc, but I think its really just horses for courses.

pliptrot

There must be more to it than that. Lance Armstrong was insistent that his frames had horizontal top tubes, so I guess he had reasons. Before Giant came along and put compact frames under pro behinds the conventional wisdom was that frames should be custom made. I wonder why so much has changed? Colnago et al ask for silly money for their off the peg products, so going custom with them is going to buy their grandchildren nice presents at Christmas for sure, but for what value I'm not sure.

I have an off-the-peg Chas Roberts, which is the best fit. A custom made Pete Matthews, which is pretty close, and a Trek which is supposedly the same as used by LA and his team (in geometry at least). It's the worst fitting bike I've ever had, and as a result quite possibly the last from a major manufacturer. I wonder if going compact may have helped, with the latest Trek Madones, which are indisputably the ugliest bike frames ever made?

giant_man

Every compact I have ever tried has always fitted me, whereas a traditional frame geometry it seems you have to get right to fit you. Seems to be the reason why Giant only have a few sizes instead of specific cm sizing like the traditional top tube sizing.

markos1963

I have both, compact in 54cm and traditional in 58cm. and have no issues with either. The compact works better for climbing and the trad is more comfy on long runs.

redddraggon

The thing with Horizontal TTed frames is that if you get one too big - it's definitely too big, but with a sloping TT you can make it fit, even if the bars are slightly higher than what you really want.

meanwhile

pliptrot wrote:

There must be more to it than that. Lance Armstrong was insistent that his frames had horizontal top tubes, so I guess he had reasons.

It's always chancy generalizing from racing to any other use - very small edges in weight or pedaling efficiency can settle a race, so, yes, it might be worth spending £20k on a bike instead of £10K if it is 3 seconds faster over an eight hour race. A conventional frame will have less top tube showing, which might mean eg a shorter top tube, saving some weight, or marginally more efficient power transmission through greater rigidity. Or the guy could just have had his quirks.

But I'd certainly say that conventional frames usually *look* better!

aracer

redddraggon wrote:

The thing with Horizontal TTed frames is that if you get one too big - it's definitely too big, but with a sloping TT you can make it fit, even if the bars are slightly higher than what you really want.

If the bars are slightly higher than you want then it doesn't fit! Presumably the point you're making is that with a compact you don't have the problem of lack of standover height, but realistically with modern handlebar drops on a racing position that's not a problem until the bars are far too high.

Standover is the only difference a compact frame makes to fit - otherwise it's just the same as a normal frame apart from needing a longer seatpost, so it's a total non-issue.

redddraggon

aracer wrote:

If the bars are slightly higher than you want then it doesn't fit!

Hmm not really, if you are "comfortable" it fits, it doesn't have to be the most aerodynamic position. It might not be the "fit" for racing however - I'd be happy riding with bars slightly higher - you can live with that, but not if they are too low.

andrewgturnbull

Hi there.

In terms of geometry, there's no reason why a compact frame should be different from one with a horizontal top tube. Geometry is only truly measured from your contact points with the bike - saddle, bottom bracket and handlebars. How the bits in between are filled in doesn't really matter.

I'm of the opposite opinion to reddragon, as most manufacturers tend to offer compacts in less different sizes, rather than the standard 2cm increments. This can only increase the chances of ending up with a 'wrong bike'. This was Giant's original design plan, less sizes to bring carbon monocoques to the masses.

Also, if you get it wrong, better to have a smaller bike with a longer stem and more spacers than a too big bike.

My latest new bike is semi-compact, and I can't say I've noticed any difference due to the shape of the frame.

Compact are potentially stiffer (smaller main triangle), but then you have a longer seatpost which may be too flexy (integrated might help this). Testers will tell you horizontal top tubes are more aero.

Cheers, Andy

giant_man

andrewgturnbull wrote:

Hi there.

In terms of geometry, there's no reason why a compact frame should be different from one with a horizontal top tube. Geometry is only truly measured from your contact points with the bike - saddle, bottom bracket and handlebars. How the bits in between are filled in doesn't really matter.

I'm of the opposite opinion to reddragon, as most manufacturers tend to offer compacts in less different sizes, rather than the standard 2cm increments. This can only increase the chances of ending up with a 'wrong bike'. This was Giant's original design plan, less sizes to bring carbon monocoques to the masses.

Also, if you get it wrong, better to have a smaller bike with a longer stem and more spacers than a too big bike.

My latest new bike is semi-compact, and I can't say I've noticed any difference due to the shape of the frame.

Compact are potentially stiffer (smaller main triangle), but then you have a longer seatpost which may be too flexy (integrated might help this). Testers will tell you horizontal top tubes are more aero.

Cheers, Andy

I don't agree entirely with your comments Andrew. I think you have less chance of getting the size wrong if you go for a compact, hence exactly Giant's philosophy in sizing with it's compacts. Because of the traditional geometry sizing of 2cm increments or whatever, you can get it wrong if you don't get measured properly or know your measurements, and that could result in getting a frame which is too small for you, or worse, one which is too large for you. The compact geometry sizing is more flexible for fitting, hence exactly why Giant didn't offer many sizes in it's compact range, simply they don't need to.

Monty Dog

I have both types of frame and particularly for my smaller size I prefer compacts even for the additional clearance over the crossbar. The only problem with some compacts in smaller sizes is that they can have quite long headtubes and hence getting the bars low enough can be difficult - a 13cm headtube on a small frame isn't very 'racy'. The original Giant TCR wasn't that univeral - the size small had a toptube in excess of 53cm making it very long for anyone less than 5'6". The key thing with a frame is the relative position of the BB, saddle and bars and whether the tubes are horizontal, sloping or curved shouldn't make a difference. Ironically, the original Trek OCLVs were a geometrical abomination with all the frame angles the same regardless of size which made the handling of the small and larger sized frames a bit odd.

aracer

giant mancp wrote:

I don't agree entirely with your comments Andrew. I think you have less chance of getting the size wrong if you go for a compact, hence exactly Giant's philosophy in sizing with it's compacts. Because of the traditional geometry sizing of 2cm increments or whatever, you can get it wrong if you don't get measured properly or know your measurements, and that could result in getting a frame which is too small for you, or worse, one which is too large for you. The compact geometry sizing is more flexible for fitting, hence exactly why Giant didn't offer many sizes in it's compact range, simply they don't need to.

But given the only two measurements which are actually important for fitting on a bike are the top tube length and the headtube length, and these are just as fixed on a compact frame as on a standard frame, I don't see how a compact frame can possibly be made to fit a wider range of positions. Maybe you can get the right seat height and still have standover room on a compact frame which is too big, but that will still leave you with too long a top tube, which you can't necessarily fix just by fitting a shorter stem as that's liable to mess up the weight distribution and hence the handling. You're also liable to have too long a head tube which may mean you can't get the bars as low as you'd like, and just because it's still comfortable doesn't mean you have an optimum fit if you would still be comfortable (but also more aero) with lower bars.

I really don't understand what it is about a compact frame which is supposed to make it more versatile - as I said before, the only difference is more standover and you should have plenty of that on a standard frame which fits properly. It is all just a con to suggest that you don't need so many sizes and then have big jumps in top tube length - not something you can adjust with a longer seatpost.

andrewgturnbull

giant mancp wrote:

andrewgturnbull wrote:

Hi there.

In terms of geometry, there's no reason why a compact frame should be different from one with a horizontal top tube. Geometry is only truly measured from your contact points with the bike - saddle, bottom bracket and handlebars. How the bits in between are filled in doesn't really matter.

I'm of the opposite opinion to reddragon, as most manufacturers tend to offer compacts in less different sizes, rather than the standard 2cm increments. This can only increase the chances of ending up with a 'wrong bike'. This was Giant's original design plan, less sizes to bring carbon monocoques to the masses.

Also, if you get it wrong, better to have a smaller bike with a longer stem and more spacers than a too big bike.

My latest new bike is semi-compact, and I can't say I've noticed any difference due to the shape of the frame.

Compact are potentially stiffer (smaller main triangle), but then you have a longer seatpost which may be too flexy (integrated might help this). Testers will tell you horizontal top tubes are more aero.

Cheers, Andy

I don't agree entirely with your comments Andrew. I think you have less chance of getting the size wrong if you go for a compact, hence exactly Giant's philosophy in sizing with it's compacts. Because of the traditional geometry sizing of 2cm increments or whatever, you can get it wrong if you don't get measured properly or know your measurements, and that could result in getting a frame which is too small for you, or worse, one which is too large for you. The compact geometry sizing is more flexible for fitting, hence exactly why Giant didn't offer many sizes in it's compact range, simply they don't need to.

Hi there.

I'm guessing you ride a Giant...

Giant's philosophy was based around not having to make more than 3 or 4 molds (which are expensive), thus being able to knock out a whole lot of carbon monocoques at price point way below their competitors.

How can having less choice improve your chances of getting the right bike. You are more likely to end up with a compromise.

Cheers, Andy

ps Having said all that, the TCR was a design classic and a great bike!

meagain

Preference/aesthetics as much as anything I think. With a bit of bias thrown in.

On balance I prefer compact - altho' in recent months great majority of my pedalling been on a trad horizontal (not many compact frames for fixed available that have generous clearances, 'grds, long front-centres etc).

Monty Dog

I think Dave Lloyd's contribution to frame design goes unattributed - his Concept 90 preceded the Giant TCR by a number of years- probably the fact that it had 650c wheels was the reason for it's lack of popularity as well as the cost. Interestingly Giant now make 6 sizes of frame - and XS and XXL were added later. I used to help out at a Giant dealership and often saw the impact of their odd-sizing - fitting a 5ft woman with a bike that required straight-out arms to reach the bars was clearly wrong, but the marketing blurb said otherwise.

tenor

one advantage of the compact is that it allows a longer headtube (higher bars) for a given standover height, but this feature is not widely adaopted. A longer seat post is also said to add more comfort, but I find the 250mm Titanium Chorus hard to improve upon.

andrewgturnbull

tenor wrote:

one advantage of the compact is that it allows a longer headtube (higher bars) for a given standover height, but this feature is not widely adaopted. A longer seat post is also said to add more comfort, but I find the 250mm Titanium Chorus hard to improve upon.

One man's advantage is another's disadvantage... I prefer a shorter headtube for lower bars...

I'm still not sure how standover height is relevent on a road bike though?

Cheers, Andy

giant_man

andrewgturnbull wrote:

giant mancp wrote:

andrewgturnbull wrote:

Hi there.

In terms of geometry, there's no reason why a compact frame should be different from one with a horizontal top tube. Geometry is only truly measured from your contact points with the bike - saddle, bottom bracket and handlebars. How the bits in between are filled in doesn't really matter.

I'm of the opposite opinion to reddragon, as most manufacturers tend to offer compacts in less different sizes, rather than the standard 2cm increments. This can only increase the chances of ending up with a 'wrong bike'. This was Giant's original design plan, less sizes to bring carbon monocoques to the masses.

Also, if you get it wrong, better to have a smaller bike with a longer stem and more spacers than a too big bike.

My latest new bike is semi-compact, and I can't say I've noticed any difference due to the shape of the frame.

Compact are potentially stiffer (smaller main triangle), but then you have a longer seatpost which may be too flexy (integrated might help this). Testers will tell you horizontal top tubes are more aero.

Cheers, Andy

I don't agree entirely with your comments Andrew. I think you have less chance of getting the size wrong if you go for a compact, hence exactly Giant's philosophy in sizing with it's compacts. Because of the traditional geometry sizing of 2cm increments or whatever, you can get it wrong if you don't get measured properly or know your measurements, and that could result in getting a frame which is too small for you, or worse, one which is too large for you. The compact geometry sizing is more flexible for fitting, hence exactly why Giant didn't offer many sizes in it's compact range, simply they don't need to.

Hi there.

I'm guessing you ride a Giant...

Giant's philosophy was based around not having to make more than 3 or 4 molds (which are expensive), thus being able to knock out a whole lot of carbon monocoques at price point way below their competitors.

How can having less choice improve your chances of getting the right bike. You are more likely to end up with a compromise.

Cheers, Andy

ps Having said all that, the TCR was a design classic and a great bike!

No I don't ride a Giant, but this is what i believe based upon personal experience. We're all built differently.

giant_man

aracer wrote:

But given the only two measurements which are actually important for fitting on a bike are the top tube length and the headtube length

You're forgetting about a very important measurement and that's the seat tube measurement.

meagain

"I'm still not sure how standover height is relevent on a road bike though?"

For those with limited mobility - often simply a function of age - VERY! I know a couple of older riders - one who used to do long, long, distances - who now ride step-through frames. And still put in the miles.

andrewgturnbull

giant mancp wrote:

aracer wrote:

But given the only two measurements which are actually important for fitting on a bike are the top tube length and the headtube length

You're forgetting about a very important measurement and that's the seat tube measurement.

Hi there.

Unless it's an integrated post, then the seat height is generally adjustable.

Cheers, Andy

aracer

giant mancp wrote:

aracer wrote:

But given the only two measurements which are actually important for fitting on a bike are the top tube length and the headtube length

You're forgetting about a very important measurement and that's the seat tube measurement.

That's totally irrelevant for bike fit as you simply use a different length seatpost. You can't adjust the toptube in a similar way.

giant_man

No it's not totally irrelevant at all, especially on normal geom. frames. It's very important especially for those of us with shorter legs and longer torsos. You obviously haven't had this problem in the past so you wouldn't understand.