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Thread: What´s the reasoning behind dropped top tubes on a road bike?

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    The classic horizontal top tube seems arbitrary to me. An aesthetic that has no functional purpose. Why not have more space between the groin and the top tube? In the 70s and 80s I sold bikes to people based in part on how much space was left between the groin and that damn top tube.

    Injuries can happen when things go south and you gotta land on your feet, but the top tube gets in the way. Reading thru this thread, I note this aspect of the top tube has not been addressed.

    I had a friend that had to go to the hospital for this. An extra inch or so of clearance may or may not have helped him, but I think he would have preferred to have it.
     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by cargonaut View Post
    The classic horizontal top tube seems arbitrary to me. An aesthetic that has no functional purpose. Why not have more space between the groin and the top tube? In the 70s and 80s I sold bikes to people based in part on how much space was left between the groin and that damn top tube.

    Injuries can happen when things go south and you gotta land on your feet, but the top tube gets in the way. Reading thru this thread, I note this aspect of the top tube has not been addressed.

    I had a friend that had to go to the hospital for this. An extra inch or so of clearance may or may not have helped him, but I think he would have preferred to have it.
    A 54cm Moots Vamooots has a slopping top tube but a slightly taller standover height than a run of the mill 54cm mid 90s italian stage race bike.
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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by e-RICHIE View Post
    The lines haven’t moved; the dots that connect are in a different place.
    sort of. only if the lines are the soft pieces that actually power the thing.

    listen everyone- the biomechanics haven't changed but race bikes have. the hoods are now far more of a primary riding position- saddles have completely different shapes- and most bike racers are on bikes that are designed to work adequately for people who are not bike racers.

    in my opinion- what this means is that most bike racers are on bikes that takes say- the position they would have used in the 1970s- and basically rotates the rider around the bottom bracket ever so slightly. some of this is because in order to get the handlebars in anywhere near the right position most people of moderate fitness who want to sit on a bike the most efficient and proven way- need to ride a bike that is smaller than what they'd have been issued were they riding for Gewiss. Small bikes have less setback- which generally means that most riders are sitting further forward than they were in days of old. this requires the bars to be lower in order to maintain the same hip angle. imagine taking a rider and rotating them around the bottom bracket. if the frame setback, seatpost design, and saddle setback are somewhat fixed- the athlete needs to put the bars in the place that allows for proper muscle recruitment and a comfortable flatish back and shoulders. this lower position also encourages a narrower handlebar set-up which we are also seeing at the elite level.

    here's the other thing- what works at the elite level in Europe has always informed the rest of the sport- and races over there by all accounts are a lot less controlled, a lot faster, and there is far less time spent riding at tempo or below. everyone is trying to blow the thing apart most of the time- and a good portion of the peloton is trying to blow it apart all the time. this allows riders to be supported less skeletally and be rotated further forward.

    i believe that most of this is dictated by the realities of stock geometry bikes that are generally too tall in the front end for most bike racers. but the kids today have never ridden anything but that.

    i'm building bikes for the Semper Porro team for next season. These kids are a good group who should win some big races next year and compete domestically with all the big pro teams. Their DS has them all on what everyone here would say are ridiculous positions. All these guys run short snub nosed saddles right at the limit of what is allowed by the UCI fully taking advantage of the morphological exception rules. They're also all running stupid negative rise stems bottomed out on the head tubes and their positions are still too short and high in the front end according to all the testing the coaches and DS (and me) have done with these guys.
    they're also racing domestically in races that tend to be far less controlled (due to big american roads in part- youth of the pro teams in part- and other variables) than what you'll find in Europe (and even over there things are far less controlled and the role of a peleton boss is almost extinct now.)

    Anyway- you guys will see soon the new Gaulzetti geometry that was informed by the demands of these client athletes. The team came to me and is buying bikes because they want that competitive advantage of having bikes built according to what works for their athletes. The long and short of it is that we're putting these kids on fairly steep bikes with lots of drop and super narrow bars. Since we're right up against the UCI's rules for saddle setback- these bikes can easily be turned into "regular" European style race bikes in the event that conditions change- or some of these guys just aren't faster in these positions- because it is more taxing on the body and does require effort to maintain the position. think about going slow on a time trial bike with no forearm pads- it'd be like doing a push up for as long as you're in that position- however as soon as you're recruiting your glutes and applying force to the pedals- you're no longer holding yourself up with your arms.

    we've already seen this fit philosophy take over on the track and increasingly on the road at the ProTour level. Objectively- our kids go faster when they're set up like this. in the same way that i was a proponent of all this- i was (and remain) also the most skeptical.... and we needed to see what happened on five or six hour hard training rides with motor pacing and other elements that allowed for race simulation- again. the numbers don't lie. The kids were going faster and were more efficient. recovery didn't seem to be effected- we'll see how it all works halfway through the calendar- most of these guys are young and it'll be their first foray into racing at this level...but the bikes i'm making them are allowing for these positions and will work well. that being said- throw a regular setback seat post on the things- shorten up the stem from a -17' 130-140mm to -8' 110-120mm and the bikes go back to putting these kids in the race bike position that has been dominant since the 1980s. (Which honestly- used marginally less setback and more drop than what was the fashion in the 1970s- which was again slightly steeper and had more drop than what was common in the 1960s- etc.

    This is more than I really wanted to say here- but suffice it to say- that I'm really happy to be working with a fairly high level team who think about this stuff and are doing everything their resources allow to win bike races. Keep an eye on the kids.

    oh- and they're all on aluminum round tubed bikes- most of which do have the right amount of top tube slope to make sure the bikes look good- because then people like you will hopefully think so too and buy one for yourself.

    it's amazing how vital bike racing is to making race bikes. it sounds obvious- but there's no way I could offer the things I'm offering without being embedded in the sport. My personal experience with going fast on a race bike stops sometime in the 1990s and guess what? working with these kids and listening to them- it's the same but it's also different. stuff evolves and changes and that's true about bike racing as well. my bikes aren't going to work with cinelli 65 bars and pointy 8spd ergo hoods or threaded headsets and -17' quill stems- nor are they going to work with 250mm metal seat posts and Turbomatic saddles- and to think that the frame would share the same geometry with some race bike that was designed to work with those components is absurd.

    go sit on a Specialized Power Saddle and feel how the thing takes all the pressure off your junk and allows you to maintain an ever so slightly more aggressive bar position- put on some 38cm bars and look at how all of a sudden your hoods feel too close and too high- look at how the new Dura Ace hood sits so high and flat on a Deda M35 bar- stuff is getting really weird- but also cool.



    ps: We are talking about very small tweaks here. to the naked eye- these bikes don't really look any different than any other race bike. We're also not reinventing the wheel here- there has been a change in how pros are sitting on their bikes- and it's based upon objective realities that the athletes are facing. And yes- when big tall goofy riders like Adam Hansen push it to an extreme- on a bike that isn't designed to be set up that way- it looks kind of dumb no matter how level or sloping his top tube is.
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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by jerk View Post
    sort of. only if the lines are the soft pieces that actually power the thing.

    listen everyone- the biomechanics haven't changed but race bikes have. the hoods are now far more of a primary riding position- saddles have completely different shapes- and most bike racers are on bikes that are designed to work adequately for people who are not bike racers.

    Thank you Craig. I enjoy your insights.
     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by jerk View Post
    sort of. only if the lines are the soft pieces that actually power the thing.

    yes. that is what i meant (while adhering to a low word count).

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    One thing i noticed is a slightly longer front end on production race bikes w/a bit less steep head angles.
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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by jerk View Post
    sort of. only if the lines are the soft pieces that actually power the thing.

    listen everyone- the biomechanics haven't changed but race bikes have.
    Nice.
    I came here for the socks.

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by jerk View Post
    i'm building bikes for the Semper Porro team for next season...
    This might be more of a Smoked Out type discussion, but I think a lot of us here would be really interested in learning more about what it's like for a guy like you to build bikes for a team like that.
     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by jerk View Post
    sort of. only if the lines are the soft pieces that actually power the thing.

    listen everyone- the biomechanics haven't changed but race bikes have. the hoods are now far more of a primary riding position- saddles have completely different shapes- and most bike racers are on bikes that are designed to work adequately for people who are not bike racers.
    [...]

    ps: We are talking about very small tweaks here. to the naked eye- these bikes don't really look any different than any other race bike. We're also not reinventing the wheel here- there has been a change in how pros are sitting on their bikes- and it's based upon objective realities that the athletes are facing. And yes- when big tall goofy riders like Adam Hansen push it to an extreme- on a bike that isn't designed to be set up that way- it looks kind of dumb no matter how level or sloping his top tube is.
    What you say is right but is only valid for a small fraction of race bikes. Also it is not necessarily a reason for the tube to be dropped. My guess is the primary reason is to have some aesthetic coherence between small sizes requiring some standover clearance and the bigger ones. Also if you look at the last trend of "aeroish" race bike we have seen quite a comeback of horizontalish top tubes. Canyon Aeroad, Merida reacto, Giant Propel have near horizontal top tubes in Large and XLarge sizes.

    If you look at bikes that really sells - i.e. those called "endurance" , "gravel" or "anyroad" - they have towers instead of head tubes and the riding position of most non race specific geo Specialized Roubaix/Diverge or Trek Domane is closer to a cross country MTB or omafiet than a race bike. Completely the opposite of your descriptions really and it gives me back pain just looking at those dentists pedaling those things on the road. In that case I can't see how you could make a bike with an horizontal top tube look decent.
    Last edited by sk_tle; 12-02-2019 at 04:49 PM.
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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    ^ for the first time, I now physically understand this problem. I just spent a couple of hours on a Canyon “Endurace” or whatever they call it. Now, I ride a 55-56cm too tube and for some reason that’s squarely in between the M and the L geo. I chose the M to get more drop. Even if I could have pulled the 2cm of spacers, it still wouldn’t be enough. This is how tall racers wind up on small frames with a mile of seatpost and 140mm -17° stems. Gross.
     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Jerks bike design likely shows how little riding at 30 mph has in common with riding at 18 mph.
    Nice to see that they include recovery time in the outcome of the design.
    I just wonder what riding grand tour stages, day in- day out, year in- year out, will make you feel on a steepish bike.
    Thanks for posting that.
     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by rabo View Post
    Jerks bike design likely shows how little riding at 30 mph has in common with riding at 18 mph.
    Nice to see that they include recovery time in the outcome of the design.
    I just wonder what riding grand tour stages, day in- day out, year in- year out, will make you feel on a steepish bike.
    Thanks for posting that.
    A bike for one who rides 4 hrs a day needs to fit different than a bike for the guy who rides on weekends. The more you ride the position on the bike changes. At least that´s my experience: if i am riding more i will grab a narrow handlebar and move saddle back. I am slow weak and old but i still like saddle to bar drop. The more i ride the lower it goes. Racing bikes are fun and that´s what i like but a racer will ride a different sized bike than me.
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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by nick k View Post
    ^ for the first time, I now physically understand this problem. I just spent a couple of hours on a Canyon “Endurace” or whatever they call it. Now, I ride a 55-56cm too tube and for some reason that’s squarely in between the M and the L geo. I chose the M to get more drop. Even if I could have pulled the 2cm of spacers, it still wouldn’t be enough. This is how tall racers wind up on small frames with a mile of seatpost and 140mm -17° stems. Gross.
    Quote Originally Posted by rabo View Post
    Jerks bike design likely shows how little riding at 30 mph has in common with riding at 18 mph.
    Nice to see that they include recovery time in the outcome of the design.
    I just wonder what riding grand tour stages, day in- day out, year in- year out, will make you feel on a steepish bike.
    Thanks for posting that.
    all of this... when i was racing i rode a “51”. -17 140mm setup, and doing 20hr training weeks on it. i’m 6’1.

    now i’m quite happy on a stock 56.
     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Not a builder, nor a physicist. But:

    I often wonder if the smaller frames are stiffer (Ceteris Paribus) is correct, especially if you look at the headtube. Logic implies a longer headtube would be more resistant to torque and deflection.

    If I get two broomhandles of 1.2 yard and one of 1.4 yard.

    - I leave on the end 1 yard free.
    - I grab it with two hands
    - My grip is 0.2 yard versus 0.4 yards. The most stable position would be wider grip.

    So for a fork/headtube combo, a longer headtube and resulting steerer most certainly would be more robust. In other words, Dario's approach probably is mechanically sub optimal (but I also immediately argue it's not important^^).

    I think people just imagine a tube and imagine a force on one end: In that case a longer tube will deflect more. But if the tube is fixed on two points and force come from different directions, a longer tube could be more resistant to torque. I think? ;)
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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    I don't think I'm saying anything in disagreement to what you're saying here.. Most stock bikes used in the ProTour are using taller head tubes than the bikes would use were they designed exclusively for professional racers- hence most of these guys are on small frames with long stems. Big bikes don't need as much slope because big bikes can have tall head tubes and high handlebar positions and still give the rider plenty of exposed seat post, standover height etc.

    Aero bikes generally have level top tubes because a level top tube presents less frontal area than a sloping one. Most manufacturer's aero bikes have shorter head tubes than their endurance road models and many have shorter head tubes than their "climbing" road bikes (that tend to have sloping top tubes). They're also generally using top tubes that are short and flat at least compared to the top tubes most folks use on their endurance and climbing bikes.

    Modern "Endurance" bikes are just ridiculous for most people of moderate fitness and proportion. It's really tough to get your hip angle right- and your back flat and shoulders relaxed on most of these things- Most of these things aren't really slack enough to rotate the rider back behind the bottom bracket enough for the bars to be as high as they end up being. I think a lot of this comes out of the fact that in a stagnant stationary positions most people are most comfortable sitting on a bar stool at a bar--- and most "bike fits" don't involve recruiting the muscles that drive a bike- not to mention demand the rider to position her weight over the wheels in a such a way that the bike will balance and ride intuitively.

    My descriptions involved the bikes that I'm building for our sponsored athletes and my observations of the positions and geometries and set ups of professional bike racers on the equipment their sponsors supply.

    For the scope of my interest in this conversation- I wasn't really talking about things like Roubaixs and Domanes...Those bikes are not race bikes, and these bikes are (generally) not used at an elite level. Even when the specialized sponsored riders are using "Roubaixs" or the Trek-Segefredo are on their "Domanes" those bikes generally are special bikes that have shorter head tubes than the stock offerings. That being said- they're usually built to mimic the geometry of the manufacturer's Tarmacs and Emondas- so the bikes are still small frames with long stems and steepish seat angles.

    Quote Originally Posted by sk_tle View Post
    What you say is right but is only valid for a small fraction of race bikes. Also it is not necessarily a reason for the tube to be dropped. My guess is the primary reason is to have some aesthetic coherence between small sizes requiring some standover clearance and the bigger ones. Also if you look at the last trend of "aeroish" race bike we have seen quite a comeback of horizontalish top tubes. Canyon Aeroad, Merida reacto, Giant Propel have near horizontal top tubes in Large and XLarge sizes.

    If you look at bikes that really sells - i.e. those called "endurance" , "gravel" or "anyroad" - they have towers instead of head tubes and the riding position of most non race specific geo Specialized Roubaix/Diverge or Trek Domane is closer to a cross country MTB or omafiet than a race bike. Completely the opposite of your descriptions really and it gives me back pain just looking at those dentists pedaling those things on the road. In that case I can't see how you could make a bike with an horizontal top tube look decent.
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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    I'm no geometry expert and to be honest I'm not even remotely interested in it either but to me the layman it's blatantly obvious that "endurance" bikes are a joke. I've lost count of the amount of times I've seen people riding them in the drops and they're bolt upright like they're riding on the tops. I think it's a shame too as they've probably spent a fortune on something that is not fit for the purpose they bought it.
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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by jerk View Post

    For the scope of my interest in this conversation- I wasn't really talking about things like Roubaixs and Domanes...Those bikes are not race bikes, and these bikes are (generally) not used at an elite level.
    I mentionned these because these are the bikes that sells. Outside of UCI sanctionned amateur racers you will see 10 roubaix or Domane on the roads for 1 tarmac or Madone.
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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    On a side note; i notice head angles became slightly shallower if i compare published geo numbers of todays x 90s pinarellos for example. At least half degr. Fork rakes seem to be the same along w/ setback so the front center should be getting longer. I can´t compare actual bikes w/ a tape measure so i ask if this is happening or it´s just geo table fantasy world.
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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    ^ anything to do with current standards for wider tires? In the 90s we all rode 21s, today’s 25-28s are taller as well as wider.
     

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    Default Re: What´s the reasoning behind dropped top tubes on a road bike?

    Quote Originally Posted by Loknor View Post
    Not a builder, nor a physicist. But:

    I often wonder if the smaller frames are stiffer (Ceteris Paribus) is correct, especially if you look at the headtube. Logic implies a longer headtube would be more resistant to torque and deflection.

    If I get two broomhandles of 1.2 yard and one of 1.4 yard.

    - I leave on the end 1 yard free.
    - I grab it with two hands
    - My grip is 0.2 yard versus 0.4 yards. The most stable position would be wider grip.

    So for a fork/headtube combo, a longer headtube and resulting steerer most certainly would be more robust. In other words, Dario's approach probably is mechanically sub optimal (but I also immediately argue it's not important^^).

    I think people just imagine a tube and imagine a force on one end: In that case a longer tube will deflect more. But if the tube is fixed on two points and force come from different directions, a longer tube could be more resistant to torque. I think? ;)
    A longer tube is less stiff. The example you've given isn't good because changing your grip changes the how much force you can exert on a structure.

    Let's say you have an 8 foot 2x4 supported at either end by a pole and you hang from the middle of it. You see a certain amount of sag in the middle of it. If you move the post in from 8 feet to 4 feet and repeat the exercise you'll see less sag on the board.

    The way to think about it is springs in parallel or springs in series. If you put two springs in parallel (by doing stuff like thickening the tube or board) the result is a stiffer equivalent spring. If you put two springs in series, you end up with a structure that's softer.
     

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