A Geometry Question
 

This is a hypothetical question with regards to a comfort-geometry road bike vs. a racing-geometry road bike. Or endurance road bike vs. competitive road bike, etc....

For the sake of the discussion, let's assume that the two bikes are identical in weight and have identical (or comparable) components. And we won't flip or slam any stems, or do anything else to the factory configurations that would alter the bikes from their intended purposes (i.e., comfort vs. race). Finally, let's assume that a single, physically fit, experienced rider goes through a custom fitting to be properly fit to each bike.

Question: Would the rider be faster on the competitive road bike as a result of the more aggressive, "racing" geometry?

The 'race' bike will typically have a shorter head tube than the 'comfort' bike putting the rider in a more aerodynamic position. This should make him a little faster, as long as he is fit/flexible enough to ride in that position.

The handling of the race bike will usually be 'quicker', too, but some people would call it 'twitchy.

Yes, the cyclist on the race bike, all things being equal, is gonna be faster. As mentioned by canam73, the geometry, specifically the head tube height, mandates a lower "front", which results in a better aerodynamic stance.

The operative words are "all things being equal".

If the rider is in the exact same position, and using the same tires, and the same wheels, then performance will be nearly identical.

Hence we have Cancellara on the Domane in pro events, and a few others on endurance bikes in road races (including Sastre and Zabriskie).

The only way it'd make a real difference is if you can't get into a low enough position on the endurance bike.

Otherwise, I find the idea that a few cm of head tube generates a measurable increase in drag to be mildly amusing.

Many pros ride undersized frames with long stems just to get a head tube a few cm lower. Are you just as amused by them?

Cancellara rides a Domane to compensate for cobbles (and so trek a sell a few).

OP,
Take it from a guy that has owned both...me. I am faster on a so called comfort bike. Some won't understand this...in fact many won't.
OP...there is virtually nothing between the bikes in speed. You need to choose the bike that matchs your flexibility. If you are into bike racing and watched the TdF for example, top riders have the flexibility of gymnasts. Of course the general public all want to look and ride like pros and they go out and buy a bike with a short head tube and a low handlebar. They end up defacing the bike with their riding position. They strain in the drops with straight arms because their flexibility doesn't match the height of the bike. I see it all the time and ride with many like this. Almost everybody rides with a lower handlebar than me. I don't get dropped. My body position is many times lower than theirs. Aerodynamics on a roadbike isn't proportional to handlebar height as some would believe.
I believe you can simpify quite easily which bike to purchase. Call it a litmus test. If you can place your palms on the ground lock kneed, then purchase a short head tube so called racing geometry bike. If you can't, purchase a high performance endurance geometry like a Roubaix SL3 Pro or Sworks like I ride or equivalent. You will be faster on a bike that fits you properly and slower on a bike that doesn't. Simple as that really.

OP. Most comfort fit frames have about an extra 20 - 30mm of head tube length and sometimes a slightly different length top tube. If you went to get fit for both bikes, it is entirely possible to come out with exactly the same fit on both bikes by using different stem lengths and spacers. In which case both bikes would be very similar in performance.

If you have a short HT race bike with a whole bunch of spacers then you may as well be on a comfort fit frame. You wouldnt look as silly and it would be more appropriate.

Its a bit like getting a comfort fit frame with a longer HT becasue you want a high front end and then putting a 130mm stem on it - you may as well have gotten a larger frame with an even longer HT -You wouldnt look as silly and it would be more appropriate.

Now, a race geometry frame with few spacers and a long stem will result in a fit that can only be achieved by a race geometry frame - you need flexibility to make this work.

A comfort bike with lots of spacers and a shorter stem will provide a position that only a comfort bike can achieve. If you dont have flexibility then you may well make more power like this.

You wont notice much difference between any bike unless you are set up in one of the last two positions where the differences in each bike are maximised and you are comfortable on both. In which case the more stretched out bike with a lower front end may make you more aero and therefore quicker - provided as I mentioned above, you have the flexibility to make it work for you.

Edit: If you can almost touch palms on ground as you say then you probably do have the flexibility to ride a fairly big drop should you wish

Campag, I already have the SL2 Roubaix Rival, and I love it. I don't NEED another bike; just exploring some options should I decide I WANT another bike. I've only been on a road bike for eight months, so I'm still learning, but my limited knowledge thus far tells me that the shorter wheelbase would (should?) = quicker power transfer and faster acceleration, and that the more aero position achieved in a racing geometry frame would = better speeds on the flats and downhills, although the advantage gained from both factors may be minimal.

I understand your post above, and it makes perfect sense. My flexibility is such that with little or no warm up, I can get about halfway btwn fingertips and palm in your flexibility test. With a thorough warm up and good stretching, I can just get to full palm.

I certainly wouldn't want both bikes set up exactly the same, geometry-wise. I agree that kind of redundancy would be foolish. My thought was to get something like the Tarmac for my solo 20-mile after work "hard" rides, and continue to use the Roubaix for longer rides and events like RAGBRAI. Also, I'd continue to ride the Roubaix while riding w/ my wife on her Roubaix... usually a very easy spin for me.

Just thinking...

I'm amused by lots of things pros do. :D

More to the point, pros ride slightly smaller frames to get their bodies into a slightly more aero position. A difference in rider position will overwhelm almost any theoretical frame advantage.

By the way, the allegedly über-aero Cervelo S5 actually has a taller head tube (and a shorter fork) than many road bikes, including the R5. Care to explain?


He's been riding it in regular races as well.

While it is entirely possible he's doing it for sponsorship reasons, I can't imagine he'd ride it if he believed it would negatively influence his performance.

Problem solved. :D

It's a great bike. Seriously, unless you absolutely need a rider position that's a few mm lower, it's not going to matter.


Power transfer and acceleration will be exactly the same. The only difference is that the road bike will be a little more responsive, and absorb less road shock.


Now yer talkin'. ;)

You aren't going to get any more fit because you're riding a Tarmac instead of a Roubaix. If you want to get faster, then do some serious training. Then train some more. Then keep training. ;) Seriously, you are the engine.

Ignore the hype, ignore the marketing, and just ride your bike.

Cancellara may find it more comfortable/less fatiguing, especially for cruising in a peloton. But that is irrelevant to the original question.

Hypothetically, given perfect set up for a fit and flexible rider, a race geometry bike will be slightly faster than a comfort geometry bike. That doesn't mean that it's the best bike for Spartacus or the OP. It's just the answer to his actual question.

Depends a bit on the race too. A muti-corner technical crit might result in somewhat faster results on a race bike, due to the more aggressive goe and sharper handling. Might not as well. Campag makes a good point - if an individual is not comfortable they probbly won't be fast, regardless of bike.

No foul in considering other bikes for sure. More bikes is better. :) The thing is, many will come on here and share their experience but it is that...their and not your experience. The only true way to know is to have it be your experience. I believe you have to own several bikes to learn about fit and the best formula for 'you'. Again to look at pros, they are VERY different from average guys...even average guys out training on a road bike. Even within pros there is a pretty good range of fit...but you see more conformance than not because to be an elite rider you need it all really and that means riding very areo. Top riders literally fall to the handlebars. You see many in the peleton riding with their elbows over the bars. Most can ride that way comfortably but there are notable exceptions. Danno and Solo Assassin come to mind on here. There are pictures of their position on the bike in the archive if you look hard enough. They both have world class flexibility. No comfort bikes for those guys...they don't need 'em. No doubt there are many others here than don't need them either and don't ride them for good reason. But I would say more than not benefit from a taller head tube and why they are wildly popular.

So first things first. First slam your Roubaix position if you haven't already...purchase a long -17 deg stem. A common mistake is to lower the handlebar without ample reach. Pros do both for good reason. More drop is much easier to ride if you can stretch out. Danno has a good instructional on this if you can dig it out. If slamming your Roubaix works, I suggest you pick up another bike or start riding your friend's bikes to see how they feel. Again, I don't think you know until you own and live with different bikes. A test ride around the block isn't very telling.
Hope that helps.

Bacci, apparantly you've been talking to my wife. :rolleyes:

And Campag, don't take this the wrong way- I'm not ignoring your advice (or yours, Bacci), I haven't decided to buy another bike yet, but I may down the road... especially as my LBS looks to make room for next year's models. If I do... what is a fair price for a brand new SL2 Tarmac Elite Rival? My LBS has one in my size that he offered to me for $1900 yesterday. But knowing the SL4's are just around the corner, I wonder if a better deal could be had on the SL2?

FWIW, I'll be on the Roubaix again tonight.;)

Its even a bit more than that rob. Comfort is really a benefit of proper fit and not a symptom. A rider is faster on a bike that fits him aka fit's his flexiblity. One thing not often discussed here...is an inflexibile rider on a conventional geometry road bike will lose power in the drops do to closed hip angle. When a tight rider closes his hip angle by lower the handlebar, he can't lay down the watts. So an inflexibile rider on a more upright geometry bike will lay down more power. The common misconception and what I call a myth is...that a lower handlebar means a more aero rider. Not so. A rider can only get so low based upon his/her flexibility. Handlebar position is really incidental. An uber flexible rider on a comfort bike will ride in the drops with bent arms with a flat back. An inflexible rider on a short top tube racing geometry will ride with his back in the air, because he can't get low. So the bike really is incidental to how a rider rides. The most common mistake I see isn't in handlebar height as much as reach. Too short a cockpit is bad for everybody...flexible or inflexible riders.

Don't think you are ignoring my advice. I encourage you to buy many bikes. I even believe in horses for courses...including TT bikes...I am thinking about picking one of those up for the type of riding I do. Its all good really. Is there a best solution for anybody? Probably. But you don't know what that is for you until you live it and that means owning different types of bikes and bikes with different geometries. You can't virtually decide on best fit...you have to experience it.