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Are bikes with aggressive positions required to achieve high fitness levels when training on a bike?

My bike fitter claimed that a more aggressive posture is better for transferring power than a more upright position.

Janheine also agreed that a more aggressive position improves power transfer. https://janheine.wordpress.com/2018/02/12/myth-5-an-upright-position-is-more-comfortable/

If their claims were true, I would need something like a gravel, road, touring, or cyclocross bike to achieve high levels of fitness.

Interestingly, TrainerRoad doesn't seem to agree. https://blog.trainerroad.com/does-bike-geometry-affect-power-output-we-asked-an-expert/

Assuming proper fit, gearing, and training zones. If I use a city or hybrid bike, would it really keep me from pushing hard enough for fitness gains?

What if I get a hybrid bike fit instead of a road bike fit?

Imagine if Chris Froome trained on a city or Dutch bike. Could he have achieved a high VO2 max of 88.2?

Speed isn't the only benefit of fitness. Getting fit often improves our health and energy levels.

There are reasons for a more upright position such as comfort, the lack of room for an additional bike, visibility, cheaper brakes levers and shifters, more room for accessories on handlebars, better vision, room for a front basket as the handlebar needs to be higher and of the right shape to accommodate it, and even safely allowing high power output downhill. If your less expensive bike is less aggressive, you might prefer to leave it on a trainer.

  • My bike fitter claimed that a more aggressive posture is better for transferring power than a more upright position. That must be why you see high-level pro riders abandoning their aggressive riding positions and sitting upright for long, hard climbs. Translation: bollocks. – Andrew Henle Oct 30 '18 at 12:38
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    @AndrewHenle: Keep in mind that their upright position is still pretty aggressive and that they'll switch back to the hoods if more power is required (eg for attacking). From personal experience it feels as if I can't pedal powerfully on a cheap city bike but I don't have any power data to prove that in any way. – Michael Oct 30 '18 at 16:20
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TL;DNR - The bike you will ride most often is the bike that will get you fittest.

Fitness and power transfer are unrelated. Your bike fitter is presuming you want to make the most of the power you have, so is suggesting an aggressive position is needed. This is possibly because people who pay for bike fitting tend to also be competitive riders who want to go the fastest they can with the power they have. These customers are already close to peak fitness, so they are scratching for low single digit percentages gains in 'power to the ground' (1% faster over an hour's riding is 30 seconds – that is the difference between winning and not being in the leading peloton).

If, however, your goal is to get fitter, then a more comfortable position is arguably more suitable. The more comfortable you are, the more likely you are to ride more often and further. If the power you produce is the same on a hybrid at 20km/h as on a fitted racer at 30km, and hour of exercise produces the same results in terms of fitness, it's just that one bike lets you go further. If you are uncomfortable and quit riding the fast bike after an hour vs say an hour and five minutes on the hybrid, the hybrid will get you fitter.

As far as 'Bike fitness', training on a hybrid for a century on a racer would be unwise: your training would be sub optimal as a more upright position uses muscles differently, but that is a discussion about specific fitness vs general fitness.

How much difference it makes depends on you – some people find it demoralizing busting a gut to get 20km/h when they know they can do 30km/h on a better bike, and are better off on a faster bike. Others are happy to dial up a work output and accept the speed they get.

No one needs a 7kg $10K bike to get fit, many think they are fit because they can ride a 7kg $10K bike faster than the guy on the 20kg, $200 BSO. The industry loves selling $10k bikes, hence much of the promotional material around the need for a high end racer.

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    Mostly true, if your seating position on the "slow" bike is good. There are some factors which make road bikes better suited for training. They allow you to pull on the handlebars for maximum power, they are stiff enough to transfer that power, they have suitable gearing for pedaling on descents and the more aggressive seating position engages more muscles. I'd also like to point out that road bikes don't have to be uncomfortable and that going fast is fun and motivating. – Michael Oct 30 '18 at 7:13
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    @Michael excellent points. I actually find my best bike for the 'pedalling on descents' bit to be a MTB with knobbies on. The extra rolling resistance combined with being slightly less aero means i'm pedalling much more on moderate descents. I'd also add to your list that the road bike allows you to travel further and visit more places for a given duration/power which opens up more routes/variety, which for me is important for keeping motivation levels up. – Andy P Oct 30 '18 at 9:25
  • I should have noted my answer is based a perception the OP is a novice/causal fit rider rather than an experienced club rider. @Rider_X has an excellent answer with better advice for advanced riders. – mattnz Oct 30 '18 at 21:40
  • Can you still do Vo2 max intervals or HIIT properly on a hybrid bike if you're fit? I know that proper form is inportant. – Han-Lin Nov 1 '18 at 19:29
  • You can, but for HIIT training you need to be able to get into an aggressive riding position and utilize all your big muscles (see @Rider_X answer). If doing a lot of HIIT training, a bike with drop bars is far better. However you can do HIIT on any bike, or off the bike. – mattnz Nov 1 '18 at 19:58
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There is a lot to unpack here. So lets go through each

Are bikes with aggressive positions required to achieve high fitness levels when training on a bike?

There isn't a single answer because there are a lot of confounding factors

  1. Every bike has a fairly wide fit window now due to the wide array of components available. A bike with a more upright position can easily be made more aggressive by things such as negative rise stems
  2. What is "aggressive" differs greatly by each person. For example, a person with long legs and a short torso will find that a "regular" road bike geometry will fit more aggressively as the longer inseam effectively shortens the stack.
  3. If the position is too aggressive for your flexibility, body proportions or effort, it can impede gaining fitness due to discomfort and effects on biomechanics

Ideally to gain fitness the bike needs to be comfortable and put you in a position for good biomechanics. The bike fit required to get there can differ for each person.

Why do aggressive positions exist?

I believe there are two guiding principles, one is aerodynamics, which is more important for racing against other riders, than general fitness. The other is biomechanics, which is important for fitness. As you become more fit you will find you can sustain higher power outputs. Under sustained higher outputs you will find that you will naturally want to lower your body trunk so you can use gravity to resist each pedal stroke rather than just core musculature. If you take a very upright position and try to pedal as hard as you can you will find you have to hold tightly onto the bars to resist the pedal strokes. You will also find you may start to round your back which can affect how you pedal. None of these matter on a short-term basis. However, if you want to sustain a higher power output this can be less efficient as you need to recruit more of your muscle tissues (in this case more core) to resist the pedal strokes, which can be come unsustainable over longer duration of high output.

From Myth 5: An Upright Position is Always More Comfortable:

What is important is that our positions match our power outputs. A cyclist’s upper body acts as a counterweight to the forces of pedaling. The harder we pedal, the more inclined our upper bodies should be.

That is why racing bikes have low handlebars and stretched-out positions, while on cyclotouring bikes, the bars are higher, and the riders sit more upright. The extreme are some European city bikes where the riders sit bolt-upright. On those bikes, the riders’ power output is limited, and you won’t often see them in hilly towns…

The more aggressive position allows you to cheat by using gravity to resist your pedal strokes, meaning you are using less effort to pedal and can focus more of your concentration on effective pedal strokes. This also requires good flexibility at the hips and in the thoracic region of the back, which may not always be there or may need to be worked on. Also if you looking at pro racers, their low stretched out positions are on a much more extreme side than what I am envisioning.

That all said, an aggressive position also requires constant high power output to be sustainable. If you do not ride at a high power output (e.g., you are still working on fitness) then a more aggressive position may be inappropriate. When the position is appropriate for the effort you will find that your hands become unweighted, and you have a light touch on the handle bars. If you are too aggressive for your power output you will find that you place too much weight on your hands, and you may also be straining your back as you are likely not supporting your trunk weight from your hip and core, like you do when you have a light touch.

What is the best approach

The best approach is probably first to focus on just riding what ever you have, there is probably a big fit window you can explore with your existing bike. As you gain fitness try a slightly more aggressive, stretched out positions, see how that works for you, does it make it easier or harder to ride at a higher effort level. Once you run out of fit options, then start looking at a replacement bike. By this point you will have a much better idea of the type of fit you are looking for and therefore whether or not a particular bike will be suitable.

  • Under sustained higher outputs you will find that you will naturally want to lower your body trunk so you can use gravity to resist each pedal stroke rather than just core musculature. Not really. It takes about 50 N-m of torque at 60 rpm to generate 300W or so. Assuming 175 mm crank arms, that's a constant 286 N, or 64 lbs of force. At 90 RPM that drops to a mere 40 lbs of force. Under 200W at 90 rpm would be getting under 25 lbs of force. – Andrew Henle Oct 30 '18 at 18:01
  • (cont) Even if you double the peak force, you have to pretty strong and be mashing at a low cadence and quite a high power level to be pushing hard enough against the pedals in a pure aerobic effort to get much help from gravity. Gravity doesn't "help" because all the energy to move the bike still has to come from the rider. – Andrew Henle Oct 30 '18 at 18:01
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    BUT The best approach is probably first to focus on just riding what ever you have, there is probably a big fit window you can explore with your existing bike. This. A thousand times this. You need to ride a lot to know enough about how you want to ride to start fiddling with the finer points of how your bike fits. – Andrew Henle Oct 30 '18 at 18:03
  • What if we increase the saddle setback? Wouldn't there be less need to hold the handlebar tightly at high power outputs since the hamstrings are recruited more? – Han-Lin Oct 30 '18 at 19:04
  • @Han-Lin moving saddle backwards moves your center of gravity backwards, so you need to pull more. Which exact muscles you use to generate the torque does not matter. – ojs Oct 30 '18 at 19:12

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