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Aerodynamics of Gravel Bikes

renehersecycles.com

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Re: Aerodynamics of Gravel Bikes

#41

Post by rich_sasha »

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…

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 end components etc. Cometh the first hill, and we find ourselves waiting at the top. 2 mins, 5 mins, finally 10-15 mins in one guy turns around to check up.

The carbon bike cyclist figured how to shift up, but didn't know how to shift down, and was trying desperately to climb in a downhill gear.

Re: Aerodynamics of Gravel Bikes

#42

Post by prmoustache »

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.

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.

Re: Aerodynamics of Gravel Bikes

#43

Post by brandmeyer »

cdot2 wrote: post #2

"Some readers have suggested that the boxy shape of the bag could be improved. However, since the bag sits between the handlebars, a rounded shape was actually less aero when we tested it in the wind tunnel." I would not have guessed that. Could a more efficient shape be made?

The round-bottom shape that sits under clip-on aero bars is very good.

https://cyclite.cc/en/products/handle-bar-aero-bag-01

https://torstenfrank.wordpress.com/2021/12/07/aerodynamik-vo...

Re: Aerodynamics of Gravel Bikes

#44

Post by MezzoDelCammin »

benjaminwootton wrote: post #18

I bought a cool book yesterday which is all about gravel trails in the UK. I had never heard the term gravel bike until reading it. Silly question but can I do these trails on my full suspension mountain bike, or will I be mercilessly mocked and possibly chased out of town? I already have a mountain bike and a road bike so not keen to add a third!

"gravel" is more of a mindset. Yeah, granted, it's been taken over by most marketing departments trying to push people into buying new gear, but ultimately, it's about being able to ride both paved roads and whatever tracks are there in the outdoors nearby.

There's always the debate / meme of "are gravel bikes just 1990's hardtail mountain bikes with drop bars?" and ... the jury's still out on that one ;-)

AFAIK a full suspension is an overkill, but if it's what You got, go for it. You'll just be a bit slower.

If You're looking for some testing, perhaps try to just get yourself a new pair of gravel tyres that fit Your wheels. That's by far the biggest source of resistance. If it's fun, pick up from there. There are plenty of videos on youtube on how to hack into a gravel bike a cheap old frame (either hardtail MTB, or some CX / touring frames). Doesn't have to more than 100-200EUR / USD in the end.

Re: Aerodynamics of Gravel Bikes

#45

Post by bluecalm »

Steltek wrote: post #19
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…

Gravel bikes are good commuters, if you like drop bars. Many commuters prefer flat bars for the more upright riding position, which allows for a better field of view for misbehaving drivers. You still also have the classic problem that higher end bikes lose all the commuter friendly features. Carbon forks and frames often lose mounting points for fenders+rack. The marketing vision of a gravel bike is someone expectin…

I agree but there are exceptions. My carbon bike (from GT) has bikepacking mounts on both the frame and the fork. Mounting fenders wasn't a problem either. It also has outside cable routing but not a threaded BB.

I think Canyon is selling bikepacking gravel bike as well (Grizl). There are choices, you just need to look for them. It's true that these days availability is a problem but it's a problem with everything cycling related.

Re: Aerodynamics of Gravel Bikes

#46

Post by glenngillen »

ehnto wrote: post #27
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…

I agree, except on the electric part. Where I live e-bikes don't assist over 25/kmph, and I'm always above that... until, my ride home. Which is steep hill, and I'm tired, and I just want to go home. As an all-rounder it's been the best bike I've had yet, I can do just about anything with it. Very utilitarian. I ride a heap, I ride MTB, commute and also a gravel bike for fun, so I feel no shame getting that e-assist…

Depending on the bike/motor you've got, something like this can be very inconspicuously added to your bike to get past the 25/kmph limit: https://planet3.bike

I've one on a Specialized Levo and it works great.

Re: Aerodynamics of Gravel Bikes

#47

Post by jamesbfb »

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…

Unless we’re talking about climbing, weight isn’t _everything_. I would argue that being able to stay in an aero position (go on YouTube, but essentially, get on the drops, elbows in, etc) for longer periods is far more important, these aero gains similarly applies to deep dish rims.

All that said, I do agree with your sentiment that shedding a few bricks is going to be more beneficial than shedding a few thousand on a new bike (or rims!). Hell, you might save yourself a divorce in the process!

Re: Aerodynamics of Gravel Bikes

#48

Post by prmoustache »

Steltek wrote: post #19
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…

Gravel bikes are good commuters, if you like drop bars. Many commuters prefer flat bars for the more upright riding position, which allows for a better field of view for misbehaving drivers. You still also have the classic problem that higher end bikes lose all the commuter friendly features. Carbon forks and frames often lose mounting points for fenders+rack. The marketing vision of a gravel bike is someone expectin…

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 mind. Some are "racing" gravel with many lightweight high end components, other are made for bikepacking with provision for fenders, front and rear racks and usually more common standards. Those are commuters friendly.

Link: https://2.bp.blogspot.com/-hVZNsMpWmxk/V9rqVdtLBHI/AAAAAAAAQ...

Re: Aerodynamics of Gravel Bikes

#49

Post by wl »

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…

There's a difference between weight weenie carbon and using carbon to improve ride feel and aerodynamics. I've got an old bike made out of Reynolds 853 steel that's lighter than my recent vintage full carbon bike.

Re: Aerodynamics of Gravel Bikes

#50

Post by bbarn »

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's out there right now. I was flying past people on the hills, and while the ride felt very rough on the high speed flats, I was still going fast. If I were in my racing shape of a few years ago I think I would have been in the top 5-10% of racers, largely because nearly everyone was on giant heavy gravel bikes with massive tires loaded for friggin bikepacking from the look of it. My wife has a purpose-built gravel bike, and she commented on just how slow it felt going uphill (she is a former state cyclocross champion).

With the exception of the absolute professionals, most people "Racing" these events are just there to finish them, and the pros? It's basically just a road race. Gravel offers no significant challenge in handling your bike, and any reasonable set-up can win if it's light enough and the rider is fit enough. The Aero arms race certainly matters in time trials, but I remain unconvinced there's enough benefit for the actual racing. I know US Midwest gravel races are effectively flat, but acceleration is greatly improved with a light bike too.

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