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#1
11-29-2021, 07:06 PM
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A probably pointless discussion about watts/effort and bikes
Let me start this by saying **WARNING**, this will be long and there is a good chance it is utterly pointless.
Another **WARNING** is that I dont have a power meter on all 3 bikes, only one and therefore this will be tough to quantify properly if even possible. First, a few thoughts. I love Steel/Ti/Al(when done correctly) bikes. Not a big fan of carbon frames but carbon bits are cool - I subscribe to the propganda from Reneherse and others that big tires are not necessarily slow - I subscribe to the propoganda that weight is not the killer of performance under the right circumstances. Obviously climb fests through mountain passes will have a large effect - I live on the coast of Texas and it is LITERALLY PANCAKE FLAT with steady, predictable winds - I ride 99% of my rides solo and I ride them like they are hard training rides. I save interval work for the trainer - I have zero racing experience nor do I follow a lot of cycling racing if it isnt ultra endurance / gravel racing. - I have started racing last year and have found some early success (2x 1st Place - 30mile gravel, 2nd place in 280mile gravel) On to the questions, thoughts and utter rambling! I have had the chance lately (last 3 weeks) to run my same training route in similar wind, weather and on my 3 different bikes. What started as a speed and comfort comparison has now opened pandora's box for me. What I have noticed is that my gravel bike was easily the slowest of them. Most of you would say "yea, no joke" and exit this thread. But READ ON! The interesting part is that I could not get my HR to my normal (165+) levels, yet the perceived effort felt just as hard as the two other racier bikes. I know many outside variables can effect this but lets just try and roll with it for entertainment purposes. Lets toss out the stats for each bike really quick: - Bowman Pilgrims Disc -- frame type: AL -- groupset: Ultegra r8k 2x -- weight as ridden that day including water: 9.98kg -- tires: Panaracer GravelKing Slicks - 32c - 1985 Batavus Professional -- frame type: Columbus Steel -- groupset: Campy Chorus 2x -- weight as ridden that day including water: 11.22kg -- tires: Donnely - 25c - 2018? Black Mountain Cycles Monstercross Disc -- frame type: Steel -- groupset: Rival 1 (force 1 crankset) 1x -- weight as ridden that day including water: 13.58kg -- tires: Panaracer GravelKing SemiSlick 43c Comfort: The Bowman probably ranks last here but there is a good chance Im just running too much tire pressure (75psi f/r). Honestly, its a crazy comfortable modern aluminum frame. The Batavus caught me off guard yesterday as its 25c @ 95psi but omg, crazy comfortable!!! The BMC is just behind the Batavus, soaking up all the bumps but oddities about it throw certain things off for me, like the feeling of constantly struggling for speed. Speed: I was a little surprised to find that I could keep very similar speeds on the batavus as my Bowman, even with my total newbness with downtube shifting. That thing FLIES. The BMC can feel fast at times, but it usually FEELS like a much higher effort, yet my HR doesnt always reflect that effort. Other Variables to Consider: wind - Constant both days. Route is roughly headwind/tailwind, very little cross. My effort is usually the same upwind as it is downwind. elevation - pancake flat. I gain about 80ft on the whole ride and 60ft of that is a bridge. Im not joking. FTP - mix of zwift/strava est - ~235w The whole reason for all of this??? Will a larger tire bike, with a higher stack and all of those other "gravel" characteristics, ever be as fast a true road bike? As my interest in racing increases, I find myself wondering how long I can hold my ground on "steel is real" when I see people on gravel carbon wonder bikes running their mouths and doing 22mph, seemingly with ease. I know there are an absolute ton of variables here, so I just want to have a conversation about what I could be missing, ways to improve speed on the gravel bike and if ultimately, Im wasting my time with such thoughts. Are large tire bikes just slower? Is Jan at Reneherse full of crap? I am including screenshots from the 3 rides. They dont show HR so Ill write it beneath. HR from garmin hr strap. I can see now the HR from the Bowman ride is significantly higher and max was chasing segments, which throws it off a bit. BOWMAN IS ONLY BIKE WITH POWER METER. Rest are strava estimates from weights Batavus Ride: avg HR:143 Max: 173 BMC: avg HR: 142 Max: 174 Bowman: avg HR: 171. Max 189 
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#3
11-29-2021, 07:33 PM
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Just throwing it out there, but how does your position vary on these bikes? The biggest factor to overcome for speed on flat ground is air resistance. The fit on that black mountain frame in particular is very upright compared to a road race bike, as it has a long head tube and higher stack (and you see builds with spacers and upright stems for even higher stack). All things being equal, if you’re sitting more upright, you have more air resistance to overcome.
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#4
11-29-2021, 08:23 PM
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This brings my other musings to mind, rando bikes. I do the occasional brevet and admire the 650b 45c tire machines. Are they slow? Id love to build one but not if im throwing down 250w to hit 20mph. Perhaps I need to change my thinking? One last observation, I think Im struggling with 1x systems. My gravel bike is my 3rd one with it and it just feels "odd". I know it is because of gaps in the gear ratios but its more than that, like clunky almost. Meat grinder comes to mind. I typically spin at 98-105rpm and I tried today to hit and hold that and it just could not be done. The gap in the gearing required too much effort to hold 100rpm in comfort. This could also play into the "feels slow" effect.
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#5
11-29-2021, 08:50 PM
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#6
11-29-2021, 09:38 PM
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"Will a larger tire bike, with a higher stack and all of those other "gravel" characteristics, ever be as fast a true road bike?"
On pavement & category 1 gravel, the answer is a definitive no. Category 2+ gravel, yes most likely. Where you live (flat) It's all about position and kit to increase your speed! Position & kit can be 30++ watts, the faster you go the more important aero is! Last edited by adub; 11-29-2021 at 09:40 PM.
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#7
11-29-2021, 09:51 PM
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Good post, I love testing and observing while trying to figure out differences or costs/benefits.
What was the 280 mile race? If you're interested in competitive success, you need to find out for yourself. There's a lot of info out there, not a lot is relevant to the individual gravel racer. Lots of people have tried lots of different things and the past decade has selected for specific parameters of success for what is generally considered "gravel" in the USA. Namely 700cx42mm or smaller, aerobars, rigid bikes, and relatively narrow handlebars. Suspension seatpost and stems seem to be effective as well but not as clear. Droppers, front forks, 650b, full-suspension so far have been less than world-beating. If you've done a handful of races I think it is a little early to think your steel bike is holding you back. Weight matters a lot, but there are many racers out there who complicate their life and spend thousands of dollars to drop 2-3kg and improve their place from 35th to 32nd. Now if your early success holds and you are on the podium or close, but due to getting dropped on a climb X miles from the finish or at a selection point - definitely time to consider changes to both body and bike. I've been racing gravel for a while, and racing a lot, so I've tried all sorts of stuff to find success. Not much has worked other than the basics - body weight, aero, racecraft, route knowledge, and tactics are the things I've used to find the most success. Non-700c wheel sizes, overly large or small tires, different style bikes - have not.
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#8
11-29-2021, 10:03 PM
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txsurfer, here is something you might try to play your bikes against each other: climb a steep hill! IMO something between a 1 minute to 3 minute effort works well. If you like all your bikes, as I do, when you hit that hill you won’t want to let the bike down! So the climb on each bike will be done at your best max effort. After three or four attempts on the same climb for each bike, you’ll probably have a good idea of how the bikes stack up against each other.
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#9
11-29-2021, 10:29 PM
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Position will certainly come into it, but in terms of what's actually measurable without power meters on each bike... a 37c Panaracer Semislick will eat up 20.8 watts at 37psi while a Conti GP5000 is around 9 watts.
You'll notice that difference for sure, especially if you have a ftp in that 200-250 range. 10w is a decent haircut in percentage off your power.
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#10
11-30-2021, 03:51 AM
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On the road, a 35mm, 38mm, 42mm or 48 mm fat tire rando bike with lots of stack kitted up like a rando is about 2 hours slower than my racing bike kitted up with tighter clothing.....on a longer brevet for me. Thats with the extra legere tires vs GP5000/4000 with latex tubes. I don't subscribe to anyone who uses GPS top speed on coast downs to claim aero savings, this is not scientific. This difference in time is due to both more wind resistance and tires. On very rough roads or modest gravel, fat tires are worth it. But if you want to ride the flats at 35 km/h or higher, the aerodynamic drag is around 80% of what you are fighting. At about 20 km/h, it is half wind and overall half frictional losses (tires, chain, bearings). To put it in rough numbers, 35 km/h might take me 210 watts on the racing setup but the custom rando bike would take closer to 270 watts. I was able to do 210 for say 13 hours on a 400k but the 270 watts only around 3 hours until toast. So for illustrative purposes, if the more upright and fat tired bike measures 0.400 m^2, the racing bike can get to 0.300. The additional drag from the tires is like constantly riding up a 0.1% grade. I ride the rando bike plenty and in fact did TABR on it. If you have a steep hill, try coast downs to compare the bikes but only if you have a speed sensor on your wheel, GPS is not accurate enough. For gravel, it is more complicated and others can give better insight. Last edited by ripvanrando; 11-30-2021 at 03:55 AM.
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#11
11-30-2021, 05:15 AM
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I think you and everyone else here has hit on the difference. Wind resistance and tires, and your gearing probably plays a role.
I live in a very flat place as well, and I subscribe to the theory that a 2x drivetrain is MORE important for this type of terrain. I don't notice the gaps in the gears on my 1x mountain bike when terrain and speed are seeing significant swings. When on a road, with wind and only slight changes in elevation, you are going to notice those big jumps.
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#12
12-01-2021, 10:16 AM
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Presumably the first one is your road bike as the only way to see similar speeds with a 60 watt difference in power is with a radically different body position.
Aero is something like 80% (it goes up with speed) of your power consumption, so if you are sitting up, then you have to put out a lot more power to maintain speed. That makes me wonder based on disclosed HR if that estimate is just completely wrong. One other consideration is that while aero is everything, aero is not everything. There is a trade-off, as some people can't produce as much power when in an aero body position, and for those people a little more sit-up is helpful. In your case, for example, if you're losing an amazing 25% or more of your power when in a more compact position, maybe you'd go faster if you sat up a little bit. Another consideration is your muscular and cardiovascular physiology. You say that you like to spin at 100rpm, which is high. If you really are best at 100rpm, if your gearing is too tall you'll not be able to achieve good power. And then you have the interaction between body position and cadence, as well. A lot to consider there.
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#13
12-01-2021, 10:35 AM
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"Will a larger tire bike, with a higher stack and all of those other "gravel" characteristics, ever be as fast a true road bike?"
No, the aero and rolling resistance are the culprits here. I'm guessing my carbon wonder gravel bike which fits similar to my road bike and has 42c gravelking slicks would still be 1-2mph slower than my tarmac SL7 on a ride like yours. I'm pretty sure I am going 20mph on less than 200w on the tarmac.
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#14
12-01-2021, 01:17 PM
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All due respect, but I don't see how you can take anything from this.
- They are different (similar, but different) routes - one specifically mentions wind - they look like very different efforts. From my experience, the more similar/the same your positions on the bike, and if you're wearing the same clothing, and your bikes weigh similar (and wheels).... the differences in tires/wheels make very little difference in speed. Pretty much zero difference. Big or small, fat or skinny. Comfort is another story, but speed.... miniscule. Keep in mind, I cannot average 50kmph... nor 40kmph. I don't ride where it's flat... not even close to flat.
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cimacoppi.cc Last edited by rain dogs; 12-01-2021 at 01:26 PM.
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#15
12-01-2021, 01:59 PM
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| Tags |
| gravel, power, stupid, watts, weight |
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Due respect: maybe a link to the blog ? 
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