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Can hybrid bikes be as fast as cyclocross bikes if we use an aero position instead?

There's quite a lot in common for both bikes. People claim that CX bikes are faster. It seems like the main reason is because they're more aerodynamic from the rider's posture. To have a more aerodynamic position on the hybrid bike, my guess is that the stem needs to be longer and have a lower angle.

Advantages of using a hybrid bike include not having to buy another bike if you already have the bike, lower cost for a bike with similar features such as brakes and drivetrain, better leverage for braking compared to that of the hoods position, more room for accessories on the handlebar compared to that of a drop handlebar, possibly more room for a front basket, more options for mirrors, less expensive combo shifters, etc.

On my hybrid bike, When I rotated my hips forward, I found it easier to pedal smoothly just like on my road bike. It looked more like the posture used for road bikes. When I was more upright, I found it harder to pedal smoothly and had to remind myself to do it more often. My heart rate seemed to be higher and I felt slower. Maybe smoothness of pedalling allows more power to be produced at a given heart rate.

On my road bike, my preferred position is on the hoods. I rarely use the tops or drops position. I find the drops position awkward. It's possible because my bike is one size too large. I'm 5'7" and my bike's 56 cm. Also, my commute is almost 9 km.

If a hybrid bike was fitted so that the posture was similar, wouldn't it be almost as aerodynamic? Is that not a popular alternative because with an aerodynamic position, our core and arms can get tired or stiff, and we don't have alternative positions available? For a properly fitted hybrid bike, is it supposed to be harder to pedal smoothly compared to using a properly fitted CX or road bike?

Update: I got my hybrid bike performance fitted. The fitter mentioned that the geometry was like a cyclocross'. My posture's more like a road bike's and was optimized for both aerodynamics and power transfer. Since there was a basket, it could only go so low. It's good to be able to have proper form. The next time I commute, I'll see whether I'm faster. A benefit of a longer stem is that there's more room for accessories.

Here are the details: SH: 737mm OS: 30mm Reach 545mm Drop: 75mm Handlebar: 45mm riser bar, 600mm wide Stem: 130mm +/-10°

  • Unless you have an extremely long torso and arms a 56cm size road bike frame for a 5'7" (170cm) is probably several sizes too large. Of course this depends on the dimensions of the frame, but you probably need a very short stem and the seatpost slammed in almost all the way. – Michael Sep 2 '18 at 11:49
  • BTW most people ride on the hoods most of the time. On a 9km commute, unless that's open road all the way, the bike speed is essentially irrelevant. Traffic lights and similar holdups will dominate. I do 8km each way and can't tell the difference between the hybrid (with child seat) and the tourer. The MTB is harder work but not really slower. – Chris H Sep 3 '18 at 7:58
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You're right to say that aerodynamics plays a big part. I'll assume the same tyres and saddle, and rigid forks.

The geometry of a hybrid may not lend itself to efficient pedalling if you increase the reach and decrease the stack, and handling may suffer from the longer stem.

The important part of the drag is CdA, the product of the drag coefficient and the cross-sectional area. The biggest effects come from reducing the area by getting lower as you suspect, but also by getting narrower, and there's a big difference there. I cut my hybrid's bars down from 640mm to 590mm and tilted them slightly forwards so the slight rise in the bars contributes as much to length as to height. My tourer (not a bad model for a cyclocross bike) has something like 450mm bars. The different hand positions also mean that any bend in your elbows tends to make you wider on flat bars.

To give you some idea of the difference, a 67km ride I've done quite a few times comes in at 3 hours on the hybrid but I've beaten 2.5 hours on the tourer, before I was really in training. Tyres were similar but not identical, and the load was no worse on the hybrid (backpack; I usually use a pannier).

  • Did your trips take 3 hours on the hybrid after making making the adjustments? – Han-Lin Aug 31 '18 at 7:07
  • @Han-Lin, yes. The tilt was done for fit/comfort years earlier and I cut the bars down when I started riding further. The first time I rode that journey (a slightly longer version) it took 4 hours, but the difference wasn't the uncut bars, it was fitness and navigation. – Chris H Aug 31 '18 at 7:15
  • If the ideal seat height and fore-aft are the same for all bikes, wouldn't the geometry be irrelevant for pedalling efficiency as long as you're able to get the ideal adjustments? For my bike, I couldn't get KOPS at the ideal seat height without exceeding the seat rail's max. I think it was missed by a cm. – Han-Lin Sep 3 '18 at 7:31
  • That's a big if, as these aren't independent of the rest of the setup, as I think you allude to in your question. Frame angles may also mean things like you mention in your comment. – Chris H Sep 3 '18 at 7:47
  • ... nominally equivalent bikes from different manufacturers will have different angles, meaning that you can't always acheive these ideals as you comment. By the time you say the frame is the same as well, you might as well think of it as a road bike with retrofitted flat bars (a friend of mine has one set up that way, so it can certainly work) – Chris H Sep 3 '18 at 7:56

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