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Aerodynamics of Gravel Bikes

renehersecycles.com

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Re: Aerodynamics of Gravel Bikes

#61

Post by jackmott42 »

bbarn wrote: post #50

I am an out of shape former racer who has ridden his bike 10 times in the last two years. I have a dad belly and rarely work out at all. I recently did The Rift this summer - a 200km gravel race here in Iceland that people come from all over the world to race. I did it on a carbon cyclocross bike from my racing days with file treads. I felt like the light weight of my bike outweighed just about every gravel fad that'…

Why don't you actually do some math, or experiments, rather than just telling us you have doubts?

This is all really easy stuff to answer. For instance. 75kg rider + bike. Make the bike 1kg lighter. Go up a 8% grade for 1 kilometers at 300 watts Time saved by 1kg weight reduction? 30 seconds out of 40 minutes.

Or suppose we add 300grams to the frame to make it aero, which is typical. If that reduces the CdA by .02 out of .25, you are at about a breakeven point. JUST during the 1km climb. Then you save time on all the flats and non technical downhills.

Acceleration is even less affected by bike mass. People forget that bike mass is a tiny % of total system mass (our fat asses). And mass is only one of 4 major components that affect acceleration. I'm happy to run through some acceleration scenarios if you like.

Re: Aerodynamics of Gravel Bikes

#62

Post by prmoustache »

wyre wrote: post #37
hi wrote: post #13

> the fastest riders in the 200-mile Unbound average 20 mph (32 km/h) across the Flint Hills of Kansas. Let’s not forget that the most important aspect of averaging 20mph on grave roads: drafting, low body weight and high fitness. If you watch footage of the unbound gravel race they mention, the winners are with a group of riders until the very end. The fastest riders are professionals sponsored by the companies tryi…

This post feels very dismissive of pro cycling, aerodynamics engineering, and what TFA is about. Any pro cyclist is going to use drafting, a low body weight, and have high fitness regardless if they are racing on gravel or not. An upgrade of only 3% for a pro cyclist could be the difference in making podium or not. Long distance gravel cycling is a relatively new sport and technology and engineering is still in its i…

In fact there are already some changes in the way gravel is raced and there have been some waves in recent races. When reaching an optionnal resupply/refill point it used to be the case that if the leading 4-5 riders were calling for a pitstop the whole group would stop and wait for anyone to take food and drinks. Now some riders will decide they carry enough and not wait for those that decided on carrying less and stop more often and some additionnal strategy is being put in place. Also some elite riders are calling for a ban of aero handlebars, at least for the fastest ones who fight for the win, in the ground of safety reason. Many stopped using aero bars to set an example but others despite agreeing on the safety issue will continue to use them until a rule is set in place to ban them because they don't want to give up any possible advantage.

Re: Aerodynamics of Gravel Bikes

#63

Post by Zigurd »

They milk the topic. This could have been 2 pages at most: Aero bars are dorky, doubly on gravel, but they will make the most difference. Heck, clip a fairing to those aero bars. But nobody uses them because you look like a dork. If you can't get over looking like a dork, and you are susceptible to bike marketing GCN you'll spend thousands on an aero frame. And then you'll put a hipster handlebar bag on it.

Re: Aerodynamics of Gravel Bikes

#64

Post by jackmott42 »

hi wrote: post #13

> the fastest riders in the 200-mile Unbound average 20 mph (32 km/h) across the Flint Hills of Kansas. Let’s not forget that the most important aspect of averaging 20mph on grave roads: drafting, low body weight and high fitness. If you watch footage of the unbound gravel race they mention, the winners are with a group of riders until the very end. The fastest riders are professionals sponsored by the companies tryi…

Lubricated chains and aerodynamics save you energy in a group too.

Re: Aerodynamics of Gravel Bikes

#65

Post by jackmott42 »

MezzoDelCammin wrote: post #32
hi wrote: post #13

> the fastest riders in the 200-mile Unbound average 20 mph (32 km/h) across the Flint Hills of Kansas. Let’s not forget that the most important aspect of averaging 20mph on grave roads: drafting, low body weight and high fitness. If you watch footage of the unbound gravel race they mention, the winners are with a group of riders until the very end. The fastest riders are professionals sponsored by the companies tryi…

Personally, I'd change the order. Coach first, body weight second. If there's one piece of equipment to buy first & ASAP, it'd be a powermeter and something to display the readout on. Riding in a group is of course great, but first You got to have the legs to catch up and then the body weight / metabolism to keep up. Having the core / flexibility to be able to spend hours in somewhat aero position doesn't hurt either…

Carbon frames don't really cost especially more money than a nice aluminum bike any more.

Re: Aerodynamics of Gravel Bikes

#66

Post by chitowneats »

qwertox wrote: post #58

I started biking around three years ago. Lots of biking, like 5000-8000+ km a year. As long as I don't weigh my ideal weight and aren't planning on becoming a machine myself, I have zero interest in spending anything in optimizations which will make my bike a better one. I don't care if it could go faster or be more lightweight, spending 600€ for the bike was enough. The cheapest 30€ Schwalbe tires are good enough; I…

I appreciate your approach but the reason people like optimizations is for speed. The thrill of riding fast is what keeps a lot of us coming back.

Re: Aerodynamics of Gravel Bikes

#67

Post by prmoustache »

bbarn wrote: post #50

I am an out of shape former racer who has ridden his bike 10 times in the last two years. I have a dad belly and rarely work out at all. I recently did The Rift this summer - a 200km gravel race here in Iceland that people come from all over the world to race. I did it on a carbon cyclocross bike from my racing days with file treads. I felt like the light weight of my bike outweighed just about every gravel fad that'…

There is actually very little difference between a cyclocross bike and a lightweight gravel bike. Slightly lower BB, slightly longer wheelbase, sometimes slightly different headtube angle, flared handlebars. Actually the first gravel bikes were rebadged cx bikes. You can race cx with a gravel bike and race gravel with a cx bike. The rider makes most of the difference.

Re: Aerodynamics of Gravel Bikes

#68

Post by lm28469 »

qwertox wrote: post #58

I started biking around three years ago. Lots of biking, like 5000-8000+ km a year. As long as I don't weigh my ideal weight and aren't planning on becoming a machine myself, I have zero interest in spending anything in optimizations which will make my bike a better one. I don't care if it could go faster or be more lightweight, spending 600€ for the bike was enough. The cheapest 30€ Schwalbe tires are good enough; I…

Reminds me of this bicycle subreddit where they spend thousands on bikes and cosplay attires to get smoked by 60+ years old dudes on 40 years old bikes

As a casual rider you'll be the bottleneck for years before your gear matters even the slightest

Re: Aerodynamics of Gravel Bikes

#69

Post by lm28469 »

chitowneats wrote: post #66
qwertox wrote: post #58

I started biking around three years ago. Lots of biking, like 5000-8000+ km a year. As long as I don't weigh my ideal weight and aren't planning on becoming a machine myself, I have zero interest in spending anything in optimizations which will make my bike a better one. I don't care if it could go faster or be more lightweight, spending 600€ for the bike was enough. The cheapest 30€ Schwalbe tires are good enough; I…

I appreciate your approach but the reason people like optimizations is for speed. The thrill of riding fast is what keeps a lot of us coming back.

Lots of people optimise because they fell in the rabbit hole of optimisation and it became an addiction. Like in every hobbies some people completely lose touch with reality. I've seen videos of people comparing weight of bicycle seats and how to shave like 13 grams of weight of the bike, meanwhile the dude had a dad bod and shaving his torso would have shaved more weight than his $$$ seat

Re: Aerodynamics of Gravel Bikes

#70

Post by pmontra »

rich_sasha wrote: post #41
MezzoDelCammin wrote: post #32

Earlier quoted context omitted.

Personally, I'd change the order. Coach first, body weight second. If there's one piece of equipment to buy first & ASAP, it'd be a powermeter and something to display the readout on. Riding in a group is of course great, but first You got to have the legs to catch up and then the body weight / metabolism to keep up. Having the core / flexibility to be able to spend hours in somewhat aero position doesn't hurt either…

Yeah but carbon gives you cred, and basically _buys_ you speed. Losing weight is effort. Sarcasm over, one of the funniest cycling stories i ever encountered. My work had a little low-key "bike club", a few guys cycling on warm evenings. One of the partners was a key member so over time non-bike guys started wiggling in for networking purposes. One guy, with no clue how to ride, drops 2k++ on a full carbon bike, high…

I quote your sarcasm.

> Losing weight is effort.

I knew a guy that was training to run an amateur marathon in under I don't remember which time. He went asking to a coach and came back with a long list of training exercises and runs or, the coach told him, lose 3 kg. He lost those 3 kg.

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