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Aerodynamics of Gravel Bikes

renehersecycles.com

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Re: Aerodynamics of Gravel Bikes

#141

Post by ActorNightly »

matsemann wrote: post #5

A gravel bike is the perfect commuter bike! At least if you're not going electric. Almost as light and fast as a road bike. But a bit more upright riding so it's more comfortable. Wider and more treaded tires means tram lines, pot holes, curbs etc. are less of a problem and can handle rough surfaces and not just asphalt. Mounting points and wider forks allow for mudguards / fenders so rain is no problem. The wider sp…

From a money perspective, there is no reason to buy an analog bike for commuting anymore given the current selection of ebikes, and even more so, aftermarket ebike kits like Bafang. You can buy a single speed beach cruiser for $200, add $1000 BBSHD kit that comes with a battery, and basically get everywhere faster than a top of the line aero road bike.

Re: Aerodynamics of Gravel Bikes

#142

Post by wmorein »

762236 wrote: post #88
pharmakom wrote: post #28

I’m sorry but Jan Heine has unscientific methods and his products are of questionable reliability. You can drop 200usd on his tyres. It’s like hifi nerdy but for rubber.

Where are the supposed alternative people with scientific methods?

Two of the best people who are not selling anything are Tom Anhalt (http://bikeblather.blogspot.com/) and Robert Chung. They both post a lot in various forums like Weight Weenies (which is more about rolling resistance and aerodynamics now that we know that they are more important) and Slowtwitch (more triathlon focused but has a lot about general bike tech).

Josh Poertner from Silca is also good but has things to sell.

Of course what everyone is saying above is right -- fitness and rider weight matters the most. But it is fun to look at this stuff especially once you have achieved some level of fitness.

Re: Aerodynamics of Gravel Bikes

#143

Post by Dave_Rosenthal »

762236 wrote: post #88
pharmakom wrote: post #28

I’m sorry but Jan Heine has unscientific methods and his products are of questionable reliability. You can drop 200usd on his tyres. It’s like hifi nerdy but for rubber.

Where are the supposed alternative people with scientific methods?

bicyclerollingresistance.com

Re: Aerodynamics of Gravel Bikes

#144

Post by ben7799 »

jackmott42 wrote: post #128
ben7799 wrote: post #124

Earlier quoted context omitted.

I'm a former racer too and this constant equipment arms race and arguing is just so fatiguing. People can argue about analytics around equipment till pigs fly. It's all still just an order of magnitude smaller than the differences between being fit and not fit and a stronger rider versus a weaker rider or a coached rider versus un-coached rider. The sport has separated into riding enthusiasts and equipment enthusiast…

You are right I had the gradient off by 10x, sorry that should have been obvious, it has been a while Actual time savings of 1kg of weight reduction: 1 second And personally I've used aeroweenieing to podium in a cat 3 road race, and my wife has set state records and won pro races. You can make fun of fat guys doing a professional job if you like but it isn't just them.

If spending lots of money to win a Cat 3 race and knowing you did it with money and equipment instead of fitness and smarts is OK with you more power to you. But if it means thousands of dollars spent on a race that likely paid This isn't really funny, it's a fundamental problem with cycling as a sport that limits who participates in the sport and hurts the sports ability to find and develop the best riders. It seems particularly bad in the US. Rules which helped control the equipment arms race would be good for the sport at the competitive level. Many promising athletes never try the sport because the costs are so prohibitive. On top of that in road racing if expensive equipment raises the speed of everyone in the field it accomplishes nothing other than increasing the risk of severe injury as speeds go up.

If someone made $10k shoes that gave a competitive advantage in soccer or basketball, or a $10k baseball bat that offered significant advantages, etc.. that equipment would very likely be outlawed right away. Cycling has let everything get very out of control. Baseball obviously has already banned lots of bats that offer competitive advantage, whether it's banning metal bats after a certain level or limiting the power of metal bats below that level.

Re: Aerodynamics of Gravel Bikes

#145

Post by evandale »

elliottkember wrote: post #80
lm28469 wrote: post #68

Earlier quoted context omitted.

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

I've been circling the fountain pen reddit for a little while now and it's a similar thing. They spend thousands on pens, import ink from Italy, buy fancy paper, but their handwriting looks like a doctor's scrawl.

I almost went down that route! I settled for a $5 Platinum Preppy instead for a few years and picked up a Procyon recently. Don't think I'd spend anything more than that though. I tested out some $250-500 pens and didn't notice a difference but from Preppy -> Procyon is huge with how much smoother the Procyon is.

Re: Aerodynamics of Gravel Bikes

#146

Post by nradov »

ben7799 wrote: post #133
nradov wrote: post #16

Earlier quoted context omitted.

It makes no sense to optimize the bike in isolation. There is complex airflow interaction between the bike and rider. There are changes that aerodynamicists could do to reduce bike drag that would actually increase drag on the complete bike plus rider system. The problem is that there are so many variables with riders. For example, just a slight change in head position can increase drag more than any improvement in f…

For sure, and the bike industry tricks huge numbers of slow people into vastly overspending on their bikes with no real benefit. They basically never test these aero bike gadgets on a rider. Aero helmets and clothes are probably the only ones that get tested on riders in a valid way.

Just be careful not to use "illegal" aero socks.

https://www.cyclingweekly.com/news/racing/check-illegal-sock...

Re: Aerodynamics of Gravel Bikes

#147

Post by prmoustache »

metadat wrote: post #109
prmoustache wrote: post #67

Earlier quoted context omitted.

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.

So much bicycle acronyms and initialisms makes for a challenging read for the uninitiated (like myself)! I've researched the terminology and happily share in hopes you too will find it useful: 1. "lower BB" references a lower bottom-bracket , the part that holds the axle to which the cranks attach. 2. "CX" , or cyclo-X is short for cyclocross , which is a style of bicycle race which takes place over varied terrain co…

Sorry for that. I am a hardcore cyclist, I don't always realize that people are not as accustomed to the terminology.

Re: Aerodynamics of Gravel Bikes

#148

Post by ActorNightly »

bbarn wrote: post #120
jackmott42 wrote: post #61

Earlier quoted context omitted.

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 ou…

You're forgetting the effect of exertion on the rider under heavy loads like climbing. I've ridden heavy bikes, and I've ridden light bikes. Light bikes feel better, rotational weight mattering more than anything else.

Rotational inertia matters extremely little for bike feel compared to the overall weight of rider+bike. The torque required to accelerate a wheel by itself without any resistance is minimal.

Re: Aerodynamics of Gravel Bikes

#149

Post by prmoustache »

CobaltFire wrote: post #90
prmoustache wrote: post #48

Earlier quoted context omitted.

Drop bars can be set as high as you want. There are even off road drop bar bikes built with stems looking like goose necks to put the bar high enough (see example in the link). It is more about the position in which you want to put your hands/wrist that matters. Gravel bikes are sold in many different kinds, and different materials. Steel, alu, titanium, carbon, you name it. They are also build with different use in…

I cut my stem long and run my bars high due to a back injury. It does mean that I essentially had to learn how to build my entire bike from scratch since noone builds a bike that way, but I'm happy I did.

For what its worth there are custom builders that do bikes in any geometry. There are also a number of small bicycles companies that may not have a shop in every city but that provide bikes with various kind of geometries.

Re: Aerodynamics of Gravel Bikes

#150

Post by kevin_thibedeau »

dc-programmer wrote: post #84
prmoustache wrote: post #67

Earlier quoted context omitted.

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.

Cyclocross bikes also have higher bottom brackets

Larger road frames are designed to accommodate longer cranks and their BB drop approaches that of traditional CX which is itself dropping to lower heights as fashion changes.
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