It really is the engine
06-12-19, 11:57 PM
#52
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I'm pretty fast (when I want to be) on a gravelish bike. 33 mm rubber. But fast wheels and fast bars. And fast clothes too.
06-13-19, 12:01 AM
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Depends on which helmet and wheels you started with. That's particularly so for helmets, which tend to be much more individualized. That said, for most riders, in most common sizes, clothing matters roughly about as much as a helmet, and handlebars matter roughly about as much as wheels.
I had read that the bars are about 1/3 the drag of the whole bike minus the wheels.
Thanks for quantifying this stuff for us. (I don't have a proper speed sensor, and don't really want to put one on my pretty wheels.)
06-13-19, 05:29 AM
#54
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On the geometry tangent: What is the wheel base of the two bikes? Chainstay length? Head tube angle?
I've been of the mind that longer chainstays help with tracking a straighter line at the expense of a "feeling" of responsiveness. I have 2 bikes both with 20 inch (50cm) chainstays by design. I find they easily & deceptivly ride 18-22 mph on the flat/level but "feel" around 14 or 15mph.
Also the relaxed head tube angle may kick your front wheel further ahead (by comparison) making for a longer more stable bike that so you again, ride a straighter line. Also rough surfaces (which you say you ride on) is less likely to knock you to a new direction. Slacker HTA results in a bike that "rails" corners better (meaning at the expense of easy mid-corner corrections)...All this, of course, dependent on appropriate rake & trail being smartly chosen.
I ask because if your gravel bike does indeed have longer chainstays & slacker headtube than your aero bike it may help to explain your surprise. In short: In your particular situation, your gravel bike cutting through terrain may mean more than your aerobike cutting through the air.
I'm sure someone here will pipe in to educate me on my "wrongthink" but in anycase, for whatever reason, it sounds like you have a nearly optimal ride for conditions.
Rock on!
I've been of the mind that longer chainstays help with tracking a straighter line at the expense of a "feeling" of responsiveness. I have 2 bikes both with 20 inch (50cm) chainstays by design. I find they easily & deceptivly ride 18-22 mph on the flat/level but "feel" around 14 or 15mph.
Also the relaxed head tube angle may kick your front wheel further ahead (by comparison) making for a longer more stable bike that so you again, ride a straighter line. Also rough surfaces (which you say you ride on) is less likely to knock you to a new direction. Slacker HTA results in a bike that "rails" corners better (meaning at the expense of easy mid-corner corrections)...All this, of course, dependent on appropriate rake & trail being smartly chosen.
I ask because if your gravel bike does indeed have longer chainstays & slacker headtube than your aero bike it may help to explain your surprise. In short: In your particular situation, your gravel bike cutting through terrain may mean more than your aerobike cutting through the air.
I'm sure someone here will pipe in to educate me on my "wrongthink" but in anycase, for whatever reason, it sounds like you have a nearly optimal ride for conditions.
Rock on!
I still like my Fuji and have no plans to get rid of it, but the Giant def feels more stable/smooth. I have a feeling the Fuji will stay in TT trim while the Giant sees most of my miles.
06-13-19, 06:04 AM
#55
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Ok it is about the engine but I'll take this further. Unless you are paid to ride professionally this is just a cute hobby that's about increasing fitness and hopefully having fun. Don't be concerned with speed, just realize many of these cyclists out there are the basketball equivalent to a YMCA player dressing up as an NBA player. You will never be on that level regardless of what carbon bling gizmo you added. As long as you like your bike, and it fits properly, and you think it's fun to ride that's all that matters.
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06-13-19, 06:18 AM
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Bike parts meeting the earlier "clean air" before it's churned by other bike parts or body parts are more important to aero (excluding the body itself).
Most handlebars that are round are bigger diameter than your tires are, so probably present an equal or larger "A" in the CdA than your front wheel does.
I think the wheel gets addressed before the helmet, the kit, or the bars though because aesthetically it makes people happier.
What can make the most difference aero wise though is simply doing enough intervals and miles in an aero position. Reducing the power penalty for hunkering down. Or, doing some ab workouts to be able to hold the position longer.
It may feel aero with arms locked in the drops, but isn't optimal. You're probably fastest in a "gunner" position. Not everyone can hold their forearms flat for very long though.
I want bars but have been waiting for locals to buy/try a few because the reach on some aero bars gets funky (longer). Like an Aeronova gets a lot longer vs. an Easton not as much.
Most handlebars that are round are bigger diameter than your tires are, so probably present an equal or larger "A" in the CdA than your front wheel does.
I think the wheel gets addressed before the helmet, the kit, or the bars though because aesthetically it makes people happier.
What can make the most difference aero wise though is simply doing enough intervals and miles in an aero position. Reducing the power penalty for hunkering down. Or, doing some ab workouts to be able to hold the position longer.
It may feel aero with arms locked in the drops, but isn't optimal. You're probably fastest in a "gunner" position. Not everyone can hold their forearms flat for very long though.
I want bars but have been waiting for locals to buy/try a few because the reach on some aero bars gets funky (longer). Like an Aeronova gets a lot longer vs. an Easton not as much.
06-13-19, 07:11 AM
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@burnthesheep - I agree. I put a Syncros rr1 bar/stem on my Foil. I can feel the decrease in drag... kidding. I thought it looked cool 
Actually... the longer stem was part of the change from 61cm frame to a 58cm frame - my effort to get lower. It's hard to get low when your headtube is the size of a paper towel roll.
Actually... the longer stem was part of the change from 61cm frame to a 58cm frame - my effort to get lower. It's hard to get low when your headtube is the size of a paper towel roll.
06-13-19, 10:35 AM
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Bike parts meeting the earlier "clean air" before it's churned by other bike parts or body parts are more important to aero (excluding the body itself).
Most handlebars that are round are bigger diameter than your tires are, so probably present an equal or larger "A" in the CdA than your front wheel does.
Most handlebars that are round are bigger diameter than your tires are, so probably present an equal or larger "A" in the CdA than your front wheel does.
I think the wheel gets addressed before the helmet, the kit, or the bars though because aesthetically it makes people happier.
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06-13-19, 11:32 AM
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I suspect the CdA of my recumbent is lower than even a TT bike.
I'm still slow though, so it really is the engine.
I'm still slow though, so it really is the engine.
06-13-19, 11:36 AM
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You might be surprised. I've measured the CdA of several recumbent riders, and many riders on TT bikes. Most of the (unfaired) recumbent riders measure somewhere in the .17 to .35 m^2 range. Most of the riders on TT bikes measure somewhere in the .2 to .27 m^2 range (a few way under .2).
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06-13-19, 12:58 PM
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I'd have to agree, even looking at my Revolt, it looks like a pretty typical road bike, until you notice how much clearance the fork and chainstays have. Stack is only 26mm taller than my Fuji, so it's just a bit more relaxed. With the 28mm road tires, it's really just a comfortable endurance geo road bike.
06-13-19, 02:20 PM
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I can say with unwavering certainty it's the engine. I have made some really fast bikes go agonizingly slow.
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06-14-19, 07:27 AM
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Giant says 45mm. It comes with 40's and there is still a ton of clearance. There's a thread where a guy rubbed a hole in the chainstay with 45's, but it doesn't say what they actually measure out to, but Giant warrantied his frame, so that's good. Also can run 650b's, no official size specs, but I've read you can fit 2".
Fuji Transonic, tested about the same as the Cervelo S5, so it's pretty aero. I bought it because I liked the color and it felt good when I went for a test ride, I didn't know anything about bikes or aero when I bought it. lol
Fuji Transonic, tested about the same as the Cervelo S5, so it's pretty aero. I bought it because I liked the color and it felt good when I went for a test ride, I didn't know anything about bikes or aero when I bought it. lol
06-14-19, 10:23 AM
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Giant says 45mm. It comes with 40's and there is still a ton of clearance. There's a thread where a guy rubbed a hole in the chainstay with 45's, but it doesn't say what they actually measure out to, but Giant warrantied his frame, so that's good. Also can run 650b's, no official size specs, but I've read you can fit 2".
Fuji Transonic, tested about the same as the Cervelo S5, so it's pretty aero. I bought it because I liked the color and it felt good when I went for a test ride, I didn't know anything about bikes or aero when I bought it. lol
Fuji Transonic, tested about the same as the Cervelo S5, so it's pretty aero. I bought it because I liked the color and it felt good when I went for a test ride, I didn't know anything about bikes or aero when I bought it. lol
06-14-19, 11:01 AM
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I think we're agreeing. The bike's "aero" is what it is (which is pretty good), how "fast" it goes is entirely up to the rider.
06-14-19, 01:24 PM
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And then there are a lot of people that don't do USAC races, but a whole bunch of very competitive group rides?
Speed is pretty much all that matters in those situations.
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06-14-19, 01:36 PM
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Not to mention all the fondo riders, gravel grinders, grass roots CX racers, TTers and triathletes. This is a weird take that I see on BF all the time. Usually it's "if you're not racing, it doesn't matter." Now it's if you're not racing with a professional license, then it doesn't matter.
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06-15-19, 09:29 AM
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I've often heard people say that it's the engine, not the bike. Last night was a good example.
I took my gravel bike to the A group ride, because my aero bike is setup for a TT on Thursday and I didn't want to mess with it. So I put on my road wheelset with 28mm GP5Ks (measure at 30mm) and ended up setting nine segment PRs, riding my non-aero, 4lbs heavier, endurance geometry gravel bike.
I think part of it is the whole "comfort = speed" thing. Some of the roads we were on are pretty crappy, on a road bike you have to be careful and you get a lil beat up in some sections. On the gravel bike with bigger tires and compliance built-in to the seatpost and bars, I was very comfortable and had no problem pushing through the rough sections.
Yes, in a lab, aero trumps all, but in the real world, sometimes it's a lil different. That being said, I'm still riding my aero bike with 88mm wheels and clip-on aero bars for the TT.
I took my gravel bike to the A group ride, because my aero bike is setup for a TT on Thursday and I didn't want to mess with it. So I put on my road wheelset with 28mm GP5Ks (measure at 30mm) and ended up setting nine segment PRs, riding my non-aero, 4lbs heavier, endurance geometry gravel bike.
I think part of it is the whole "comfort = speed" thing. Some of the roads we were on are pretty crappy, on a road bike you have to be careful and you get a lil beat up in some sections. On the gravel bike with bigger tires and compliance built-in to the seatpost and bars, I was very comfortable and had no problem pushing through the rough sections.
Yes, in a lab, aero trumps all, but in the real world, sometimes it's a lil different. That being said, I'm still riding my aero bike with 88mm wheels and clip-on aero bars for the TT.
06-15-19, 09:40 AM
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I'm a very big pusher of comfort here. i mean if its not 100% comfortable then you cant go really fast no matter what. I have gone 2 minutes faster in 20 minutes on "lesser" aero and heavier bikes than my premium ones. and there is no denying that. you just have to accept it i guess. it is what it is.
20 minutes, is always 20 minutes.
06-15-19, 10:04 AM
#73
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2 minutes faster in about 20 minutes i mean.
and yes that is HUGE!!!
And i have no real way of explaining it. but i timed it.
about 10kg lynskey pro cross. vs all my other bikes. i have 4 other road bikes (and the pro cross is not even a road bike at all) ti and steel. and the pro cross was basically my beater/test platform. i used an up side down north road bar on it. maybe thats the magic potion?? kinda doubt it though. but it was very "optimal" in feel though.
All i'm saying is that it may not be up to numbers such as weight, angles, cd/cv, stiffness and so on. if one bike if faster or slower.
it could very well be:
all in your head.
comfort at speed
ergonomics at speed
and yes that is HUGE!!!
And i have no real way of explaining it. but i timed it.
about 10kg lynskey pro cross. vs all my other bikes. i have 4 other road bikes (and the pro cross is not even a road bike at all) ti and steel. and the pro cross was basically my beater/test platform. i used an up side down north road bar on it. maybe thats the magic potion?? kinda doubt it though. but it was very "optimal" in feel though.
All i'm saying is that it may not be up to numbers such as weight, angles, cd/cv, stiffness and so on. if one bike if faster or slower.
it could very well be:
all in your head.
comfort at speed
ergonomics at speed
06-16-19, 11:04 AM
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I'm a very big pusher of comfort here. i mean if its not 100% comfortable then you cant go really fast no matter what. I have gone 2 minutes faster in 20 minutes on "lesser" aero and heavier bikes than my premium ones. and there is no denying that. you just have to accept it i guess. it is what it is.
06-16-19, 07:14 PM
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I've often heard people say that it's the engine, not the bike. Last night was a good example.
I took my gravel bike to the A group ride, because my aero bike is setup for a TT on Thursday and I didn't want to mess with it. So I put on my road wheelset with 28mm GP5Ks (measure at 30mm) and ended up setting nine segment PRs, riding my non-aero, 4lbs heavier, endurance geometry gravel bike.
I think part of it is the whole "comfort = speed" thing. Some of the roads we were on are pretty crappy, on a road bike you have to be careful and you get a lil beat up in some sections. On the gravel bike with bigger tires and compliance built-in to the seatpost and bars, I was very comfortable and had no problem pushing through the rough sections.
Yes, in a lab, aero trumps all, but in the real world, sometimes it's a lil different. That being said, I'm still riding my aero bike with 88mm wheels and clip-on aero bars for the TT.
I took my gravel bike to the A group ride, because my aero bike is setup for a TT on Thursday and I didn't want to mess with it. So I put on my road wheelset with 28mm GP5Ks (measure at 30mm) and ended up setting nine segment PRs, riding my non-aero, 4lbs heavier, endurance geometry gravel bike.
I think part of it is the whole "comfort = speed" thing. Some of the roads we were on are pretty crappy, on a road bike you have to be careful and you get a lil beat up in some sections. On the gravel bike with bigger tires and compliance built-in to the seatpost and bars, I was very comfortable and had no problem pushing through the rough sections.
Yes, in a lab, aero trumps all, but in the real world, sometimes it's a lil different. That being said, I'm still riding my aero bike with 88mm wheels and clip-on aero bars for the TT.
28’s tires rock
