Road bikes. Why in the main is the flat top tube retained?
Discussion
So other than a few manufactures road bikes still in the main appear to cling to the flat top tube. I say cling as back 20 years ago mountain bikes looked like that as well, but being a new idea people seemed happy to mess with tradition and go for practicality, top tubes dropped sloped as much as possible. Result, more clearance, less weight, stiffer and they look way better. Not going to pick on any road bikes in particular but a few people on here have posted pics of their pride and joy massively expensive bikes and I just think they are pig ugly normally due to the steep seat stays demanded by having a flat top tube miles away, just looks crap.
So why?
Just tradition and should be consigned to the history books or is there a compelling reason to retain it?
I was looking at my old Ribble (flat top tube) sat next to my Planet X (big slope) in the garage today and it really highlighted how s
t the Ribble looks, the Planet X is way more comfortable as well despite the Ribble being fitted and the Planet X simply being a medium off the shelf.
So why?
Just tradition and should be consigned to the history books or is there a compelling reason to retain it?
I was looking at my old Ribble (flat top tube) sat next to my Planet X (big slope) in the garage today and it really highlighted how s
t the Ribble looks, the Planet X is way more comfortable as well despite the Ribble being fitted and the Planet X simply being a medium off the shelf.Don't really know , I have a flat TTube Wilier that's 7 yr old Alu and a sloping newish carbon Wilier
I like the frame geo of both , truth be told I feel a lot more at home on the straight older Wilier , see it a lot with older Bianchis with similar geo
Not really bothered about looks
as I don't look at it when I'm riding
I always thought The sloping top tube was designed in to accommodate all the old golfers that switched to cycling when it got popular as they couldn't reach the drops hence the phrase "sportive geometry "
I like the frame geo of both , truth be told I feel a lot more at home on the straight older Wilier , see it a lot with older Bianchis with similar geo
Not really bothered about looks
as I don't look at it when I'm riding
I always thought The sloping top tube was designed in to accommodate all the old golfers that switched to cycling when it got popular as they couldn't reach the drops hence the phrase "sportive geometry "
TwistingMyMelon said:
I always thought The sloping top tube was designed in to accommodate all the old golfers that switched to cycling when it got popular as they couldn't reach the drops hence the phrase "sportive geometry "
Interesting, I'd not heard that reasoning :-)Could have essentially the same placement of contact points with either setup, are sloping tube bikes shorter generally?
The sloping top tube was designed primarily by Mike Burrows when he worked at Giant Bicycles in the 1990s, the sloping top tube meant they could manufacture only 4 different frame sizes Small Medium, Large and Extra Large that would fit the majority of customers therefore halving the number of different sized frames they were producing before in 2cm increments...Simple but it works
Are we on about 'horizontal' top tubes here?
They ought to be retained because they simply look correct. The world managed just fine without this modern fad for 'sloping' top tubes for over a hundred years, since the invention of the 'Safety' bicycle. We don't need any of this new-fangled, funny angled nonsense, thank you very much...
They ought to be retained because they simply look correct. The world managed just fine without this modern fad for 'sloping' top tubes for over a hundred years, since the invention of the 'Safety' bicycle. We don't need any of this new-fangled, funny angled nonsense, thank you very much...
47p2 said:
The sloping top tube was designed primarily by Mike Burrows when he worked at Giant Bicycles in the 1990s, the sloping top tube meant they could manufacture only 4 different frame sizes Small Medium, Large and Extra Large that would fit the majority of customers therefore halving the number of different sized frames they were producing before in 2cm increments...Simple but it works
Cheers for that interesting , I always wondered why older bianchis with flat tubes had loads of sizes and modern bikes had less options Fastpedeller said:
I await a photo of a 70 year old bike with sloping top tube 
, probably be along shortly!
No doubt there will be plenty of photos of sloping tubed bikes from many decades ago. Sloping top tubes have long been a feature of bicycles, almost exclusively to accommodate the voluminous skirts of something called "ladies"..., probably be along shortly!
See how all the bikes with sloping top tubes are ridden by ladies, whereas the gentlemen all ride bicycles with horizontal top tubes. To corrupt this ideal is to interfere with nature itself, and is most definitely wrong!
The larger the distance between the down & top tubes, the more torsional rigidity the frame is going to have (diminishing returns obviously). Seat stays do not need to come up to meet the top tube either - look at any time trial / aero type bike for a clue there, but equally a larger rear triangle is again going to have more torsional rigidity than a 'swinging arm' type arrangement.
(random grabbed image of t'internet for illustration)
As has been proved already, the aesthetics are debatable. A horizontal tube is likely to be less draggy (by some very small amount), and standover height is pretty much irrelevant for roadbikes, more important for mountainbikes where you can be raising and lowering the saddle, and laying the bike over on it's side - there are simply more situations where a 'conventional' top tube would get in the way, and moving it down has advantages. Let's also not forget that most of them have rear suspension of some kind, and a lot of thought goes into optimising that geometry - you've got to have somewhere to hang the pivots, shock etc, and that doesn't want to be in the middle of a long, unsupported tube - I can imagine that leading to some significant variation in frame design/tube placement.
In short, horses for courses..
(random grabbed image of t'internet for illustration)
As has been proved already, the aesthetics are debatable. A horizontal tube is likely to be less draggy (by some very small amount), and standover height is pretty much irrelevant for roadbikes, more important for mountainbikes where you can be raising and lowering the saddle, and laying the bike over on it's side - there are simply more situations where a 'conventional' top tube would get in the way, and moving it down has advantages. Let's also not forget that most of them have rear suspension of some kind, and a lot of thought goes into optimising that geometry - you've got to have somewhere to hang the pivots, shock etc, and that doesn't want to be in the middle of a long, unsupported tube - I can imagine that leading to some significant variation in frame design/tube placement.
In short, horses for courses..
Sorry to piss on your potatoes, I disagree, but it is very subjective.
Sloping top tubes just look lame to me, like there is something wrong with the bike, or there will be. Pig ugly and just look crap, in fact. And why does a sloping tube weigh less?
A flat top tube is a thing of beauty; that Canyon looks gorgeous; modern, at the cutting edge, it just looks fast. In fact, the Giant Propel that is my next bike looks fairly similar, and yes, it also has a flat top tube.
Gazza, on that Canyon, if I understand it right, it makes the rear triangle smaller, so stiffer and gives a bit of flex/deflection above that to help comfort or bump absorption.
Here's my random pic of a bike that looks wrong to me -
Not only has it got a bent top tube, it's got those inserts in the stays so they look wrong too!
Sloping top tubes just look lame to me, like there is something wrong with the bike, or there will be. Pig ugly and just look crap, in fact. And why does a sloping tube weigh less?
A flat top tube is a thing of beauty; that Canyon looks gorgeous; modern, at the cutting edge, it just looks fast. In fact, the Giant Propel that is my next bike looks fairly similar, and yes, it also has a flat top tube.
Gazza, on that Canyon, if I understand it right, it makes the rear triangle smaller, so stiffer and gives a bit of flex/deflection above that to help comfort or bump absorption.
Here's my random pic of a bike that looks wrong to me -
Not only has it got a bent top tube, it's got those inserts in the stays so they look wrong too!
Nope, smaller does not equal stiffer. Part height seat stays 'because aero': The further they protrude into the breeze and the more perpendicular they are to the flow, the worse the drag, plain and simple. There's not a lot of side load on the seatpost, potentially some bending between top tube/seat tube/rear triangle out of the saddle, but it's a pretty beefy seatpost and generally the aero frames compromise some out and out power transfer to achieve a more slippery shape.
... but sloping tubes allow for forces to be distributed and managed in different ways and curved surfaces allow for greater stress absorption through small amounts of flex.(To me at least, the idea of a relaxed (read forgiving/compliant)geometry compared to that hideous looking canyon thing shown above is way more preferable).
Daveyraveygravey said:
Sorry to piss on your potatoes, I disagree, but it is very subjective.
Sloping top tubes just look lame to me, like there is something wrong with the bike, or there will be. Pig ugly and just look crap, in fact. And why does a sloping tube weigh less?
A flat top tube is a thing of beauty; that Canyon looks gorgeous; modern, at the cutting edge, it just looks fast. In fact, the Giant Propel that is my next bike looks fairly similar, and yes, it also has a flat top tube.
Gazza, on that Canyon, if I understand it right, it makes the rear triangle smaller, so stiffer and gives a bit of flex/deflection above that to help comfort or bump absorption.
Here's my random pic of a bike that looks wrong to me -
Not only has it got a bent top tube, it's got those inserts in the stays so they look wrong too!
Aesthetically I much prefer a smaller frame with a sloping toptube (I'm a smaller rider anyway), but find that curved toptube (to me) looks utterly awful. I really don't like it. Sloping top tubes just look lame to me, like there is something wrong with the bike, or there will be. Pig ugly and just look crap, in fact. And why does a sloping tube weigh less?
A flat top tube is a thing of beauty; that Canyon looks gorgeous; modern, at the cutting edge, it just looks fast. In fact, the Giant Propel that is my next bike looks fairly similar, and yes, it also has a flat top tube.
Gazza, on that Canyon, if I understand it right, it makes the rear triangle smaller, so stiffer and gives a bit of flex/deflection above that to help comfort or bump absorption.
Here's my random pic of a bike that looks wrong to me -
Not only has it got a bent top tube, it's got those inserts in the stays so they look wrong too!
This is my own bike, straight sloping toptube. To me it just looks right:
I agree the Canyon looks dreadful but more due to the hump back top tube, OnOne do a MTB with a similar style frame it's called a Lurcher I presume after Adams family Lurch with the stooping hunched back.
Smaller frames must normally be stiffer, most flex you want to avoid would be twisting pulling on bars and pushing down with leading foot trying to twist the frame. A big open triangle with long tubes is sure to flex more than a triangle with shorter seat tube. Smaller frames have always been sold as the stronger choice for mountain bikes. Try snapping a broom handle - easy, then try and snap the shorter halves left over - really hard. Shorter means less leverage so stronger.
Smaller frames must normally be stiffer, most flex you want to avoid would be twisting pulling on bars and pushing down with leading foot trying to twist the frame. A big open triangle with long tubes is sure to flex more than a triangle with shorter seat tube. Smaller frames have always been sold as the stronger choice for mountain bikes. Try snapping a broom handle - easy, then try and snap the shorter halves left over - really hard. Shorter means less leverage so stronger.
You've got the whole thing a bit ass-backwards. Yes, a smaller frame will deflect less than a larger one, but the spacing of your contact points (hands, feet, possibly ass) don't change, so that's not really relevant. Simply moving the tubes closer together does not make it any stiffer, because that results in more poking out at the ends, giving you more leverage over that frame. For a given set of contact points, the stiffest configuration is to put the tubes as close to the edges of that set of contact points as is possible. The broomstick analogy doesn't work - if that were the case, all bikes would be built with a single torsion tube as the 'chassis', there would be no top tube at all (and they'd consequently be as rigid as a wet noodle).
Amazingly when folks like canyon or whoever design a carbon frame in the kilo to sub-kilo range, (which is pretty common for a road bike) they're working quite hard to make it as stiff as they can with the minimum material, not to satisfy one person's personal aesthetic - I rather doubt they give a monkeys what you think 'looks right', the engineering (FEA and the like) tells them what actually works. When they compromise stiffness it is generally done to gain another advantage - lowered seat stays are pretty much standard on any frame with aero pretensions, simply because it's a clear aero win, which gets compensated for by a bit more carbon in the relevant area - again, aesthetics are moot, the wind tunnel is very clear about such things.
At best, the dropped top tube is a stiffness neutral, and an aero disadvantage; i.e. an aesthetic gimmick. Sorry it doesn't gel with your aesthetic / what you believe, but there it is.. If you're interested, cervelo have some interesting articles with their ask the engineer series (biassed of course, but interesting none the less).
Amazingly when folks like canyon or whoever design a carbon frame in the kilo to sub-kilo range, (which is pretty common for a road bike) they're working quite hard to make it as stiff as they can with the minimum material, not to satisfy one person's personal aesthetic - I rather doubt they give a monkeys what you think 'looks right', the engineering (FEA and the like) tells them what actually works. When they compromise stiffness it is generally done to gain another advantage - lowered seat stays are pretty much standard on any frame with aero pretensions, simply because it's a clear aero win, which gets compensated for by a bit more carbon in the relevant area - again, aesthetics are moot, the wind tunnel is very clear about such things.
At best, the dropped top tube is a stiffness neutral, and an aero disadvantage; i.e. an aesthetic gimmick. Sorry it doesn't gel with your aesthetic / what you believe, but there it is.. If you're interested, cervelo have some interesting articles with their ask the engineer series (biassed of course, but interesting none the less).
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