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Aerodynamics of Gravel Bikes

renehersecycles.com

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Re: Aerodynamics of Gravel Bikes

#101

Post by wrycoder »

prmoustache wrote: post #42
pjc50 wrote: post #30

Earlier quoted context omitted.

The Dutch style bike is almost perfect for commuting, but for badly maintained roads I would occasionally want one with MTB suspension and tyres.

Dutch style bikes are perfect for casual city riding, sight seeing and well, riding slowly. Usually when you are commuting and you have more than a couple kilometers to ride you want to do it faster. Dutch omafiets are really bad in term of aero.

Would you happen to know the age at which Dutch commuters (shopping) start to give up cycling? Do people regularly cycle past 90?

Re: Aerodynamics of Gravel Bikes

#102

Post by prmoustache »

helsinkiandrew wrote: post #54

> The biggest part of a bike’s wind resistance is caused by the rider. Unfortunately, there isn’t much you can do with respect to the airflow around bike and rider There's lots of things you can do - apart from losing a lot of weight, clothing and helmet design is probably the simplest, there's some good references to things that can be done here: https://link.springer.com/article/10.1007/s12283-017-0234-1#... >I don…

The most aero time trial like position need training, especially the muscles in the neck area. Even in the pro racing world some racers do not train enough in that position and lose precious time in time trial because they are unable to keep it straight looking at the road constantly and move the head up and down constantly. The helmets manufacturers actually accounted for that and moved to time trial helmets with a much smaller tail as it spent to much pointing in the air.

Re: Aerodynamics of Gravel Bikes

#103

Post by prmoustache »

gergely wrote: post #99
prmoustache wrote: post #95

Earlier quoted context omitted.

I won a criterium once on a cyclocross bike while waiting for my team supplied road race bike. That so called nervousness is greatly overstated. I think this is a US thing actually.

But crit races are not like coming down from Stelvio kind of speed where nervousness counts. Crit races are exactly like cx races but on asphalt or at least where I'm in Europe ;)

I rode my cyclocross bike in the Swiss alps for months while waiting for my custom road bike. It was perfectly fine descending mountain passes.

As I said, that so called nervousness is overstated because people overthink it. BB height matter but for the most part we intuitively and inconsciously accounts for it and adapt. Also the difference is minute, from a 5 mm to 15mm. It is not like we switch from a road to a tall bike either. And guess what? A tall bike is pretty easily rideable, there are even people doing offroad on them.

Re: Aerodynamics of Gravel Bikes

#104

Post by wink »

pjc50 wrote: post #30
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…

The Dutch style bike is almost perfect for commuting, but for badly maintained roads I would occasionally want one with MTB suspension and tyres.

I think it's pointless to lump everything together as "commute" - sure, if you're lucky and need to go only like 4km without hills then basically every bike will do - but no, I don't want to do 12-15km one way with that, just because I can probably save 1/3 of the time (also gravel vs road)

Re: Aerodynamics of Gravel Bikes

#105

Post by brandmeyer »

prmoustache wrote: post #67
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.

> You can race cx with a gravel bike and race gravel with a cx bike.

Sortof. The key defining difference is that a cyclocross bike meets the UCI rules for cyclocross, while a gravel bike doesn't. In a sense, the gravel bike trend is the result of consumers rejecting the UCI's definition of what an off-road-capable drop-bar bike should be.

Re: Aerodynamics of Gravel Bikes

#106

Post by akgerber »

pjc50 wrote: post #30
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…

The Dutch style bike is almost perfect for commuting, but for badly maintained roads I would occasionally want one with MTB suspension and tyres.

A Dutch-style bike is perfect for Dutch-style commuting: riding maybe three miles max to the shops or public transit on a high-quality network of bike infrastructure where you won't be bullied by drivers for riding at 8-12mph.

Atrocious US land use & infrastructure makes this less practical for many trips in the US, where destinations are widely spaced to allow for free/easy car parking and evasive maneuvers are often required for safety, and steep/off-road shortcuts are often useful to avoid traveling miles out of one's way on a network of arterial roads designed for fast & easy car travel at the expense of everything else, including human life. A gravel or hybrid bike is better suited for this sort of riding.

Re: Aerodynamics of Gravel Bikes

#107

Post by MezzoDelCammin »

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…

oh, that's a good one. Explaining how brifters work never gets old :-D

On a more serious note, I don't really see the appeal of biking as a social / networking sport. Yeah, we do have a sort of a bike cabal at work too, but if I'd like to network, I guess there are much more efficient ways to do that. Biking as a sport has quite high barriers for entry both in material and in getting fit enough to be able to at least reasonably keep up.

Re: Aerodynamics of Gravel Bikes

#108

Post by metadat »

jackmott42 wrote: post #61
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 ou…

> I'm happy to run through some acceleration scenarios if you like.

Yes, please continue! I'm digging your analysis.

Re: Aerodynamics of Gravel Bikes

#109

Post by metadat »

prmoustache wrote: post #67
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.

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 conditions such as pavement, wooded trails, grass, steep hills and obstacles requiring the rider to quickly dismount, carry the bike while navigating the obstruction and remount.

https://en.wikipedia.org/wiki/Cyclo-cross

https://en.wikipedia.org/wiki/Cyclo-cross_bicycle

The cyclocross bikes appear similar to road racing cycles, the major differences between them being frame geometry, and wider clearances for cx bikes to fit larger tires and generally still function after accumulating large amounts of mud and other debris.

edit: Thank you @jerrycrunch! I've incorporated your bb info.

Re: Aerodynamics of Gravel Bikes

#110

Post by jerrycruncher »

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…

Bottom bracket, the part that holds the axle to which the cranks attach.
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