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#31
12-02-2021, 07:52 AM
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At 20 mph, going from Crr of 0.003 to 0.006 would cost me 25 watts total on steel drums.
But, we do not ride on steel drums. A GP5000 on very good roads would be around 0.004 and a gravel tire would be more like 0.008 for a power differential of closer to 35 watts or a drop in speed by 1.5mph at the same power. At 12 mph, the speed difference is closer to 2 mph. I am always amazed how many riders claim these differences are not noticeable or that they are not significant when in fact, there isn't much freer and easier speed than in tires. 
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#33
12-02-2021, 08:38 AM
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#35
12-02-2021, 08:52 AM
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Here's what I observe:
The "steel drum" or diamond plate rolling resistance tests may not show actual performance but do show a relative difference. Over time, the "preferred" gravel and road tires have gotten wider and pressures have gotten lower. Gravel racers seem to have gone from ~32 to 35/38 to around 40 now, with some riding even wider depending on terrain. In longer or rougher rides or races, I find that wider suits me better as traction is better and fatigue is reduced (I've "raced" Battenkill on 25s, but it's not really gravel). I find sometimes wider doesn't equal slower (I found my WTB "slicks" slower than some wider small knob tires). Within the confines of "road width" and "gravel width" there is more variance between tire brands and relative speed vs width alone (25 gatorskins feel slower than 32 5k TLs for example) Personally, I haven't regretted going wider on road or gravel, but I have found some slow feeling tires regardless of width. If you're riding 30mph on a gravel bike on flat ground routinely, I'm afraid I don't have much input though!
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#36
12-02-2021, 09:57 PM
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wow! sorry, finally caught a break and caught back up.
I tried to run the same route the other day on the gravel bike with my road wheels/tires (Hunt Aero 34 with gravelking slick 32c) but as I swapped to take off, disc caliper was hitting the inside arm of the rotor and I needed to shim, which made it way too late to head off. This will happen though! My work centers around observability and metrics, so data control, within my means, is paramount to me. I agree, lots of variables at play here. To the poster who commented about the wind changing, that does happen but like I said, its NW/NE to SE on my routes. It can be a crazy headwind to start, or tail, but always the same essentially and I go same effort, Nbound or Sbound. I do avg higher speeds in lighter winds because I think I can maintain the effort longer in the head wind vs fighting 20+, which is common here. I also want to say that I LOVE my BMC. I would never blame a bike, almost always the rider. This whole post was to start the conversation that im highly enjoying with everyone about basically, is the higher effort real or just perceived? What IS a good gravel speed? I take my gravel bike on road rides often to compare and honestly, I find myself putting forth a lot more effort than on my other bikes. What I would like to establish is just how much a different component can make, stack height vs wheels vs whatever unknown variable. To the poster who talked about racing and the effort and the willingness to suffer, etc. EXACTLY. That is why I seem to prefer endurance racing is due to the variables. Power gets you nowhere. If you miscalculate a water stop, you're screwed. No manned stations to save you here. I called all the gas stations 2 weeks in advance and wrote down the hours of operations... did you? The 2 other gravel wins were night races. I found that I have a distinct lack of fear of crashing, especially at night, so I went full gas in the dark and finished ~5m ahead of everyone else. Was it power? Was it bike? Was it variable X,Y,Z? Im happy to see that other riders have experienced the same things, bigger tires/less-aero setups are indeed slower. I highly respect Jan and others and I honestly make it a point to roll bigger tires in fast group rides to screw with people. However, when I ride the same routes on 3 different bikes in similar conditions and find myself fighting the hardest on the big tire gravel monster, it starts making me wonder about everything, hence this post. Does this mean Ill stop racing on 43c slicks in hardcore mud or 50c GK SKs on hero gravel? Hahaha, no. Where is the fun in that?!??!
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#37
12-02-2021, 10:03 PM
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Shots of ETS (East Texas Slowdown) this year after 10hrs of rain the starting day + ~3 hours the morning before.
In these conditions, just to keep pedaling wins. I rode 38hrs straight, minus food/water stops... hardest thing I have ever done.
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#38
12-03-2021, 05:25 AM
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__________________
It's not an adventure until something goes wrong. - Yvon C.
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#39
12-03-2021, 06:19 AM
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Wow. That gravel looks like cement.....probably need a fat bike on that.
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#40
12-03-2021, 08:53 AM
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Variables
surfer pal,
thank you for such a thoughtful reflection, I really appreciate it. You touched on a key word here: Variables. There are many variables at play, some play a bigger role in certain situation than others, it just depends. And they are in constant flux. Nothing is fixed. And sometimes one variable can counteract or contradict or conflict with another. It's finding the balance. Luck plays a big part too. Every time we have a discussion like this, we can get into an argument or a loop. Someone would say A that seems to contradict what the other person who says B. When in actual fact, both are correct. Most folks can't handle tension very well. Two seemingly opposing concepts can coexist in tension but we insist on "one" truth. Seven blind mice and the elephant. One touches the ear and concluded that it's a fan. The other touches the leg and insists that it's a tree trunk. Both came up with their own conclusions based on their personal experience and observations. Both are "correct" and "wrong" at the same time. But they refuse to listen to each other and is adamant in sticking to their story. It's a losing proposition. Let's talk about endurance/gravel racing for a sec... I immediately thought of Lael Wilcox, Ted King, Peter Stetina, Colin Strickland etc. Lael bursts into the scene of long distance endurance cycling events many years ago. To many people, she seems to come from nowhere, with very little background in bike racing and very elementary knowledge about equipment. But she won. She won because of her "human" abilities, not because of her choice of bike equipment. And one can argue that the year that she won the biggest event of her life, she doesn't have the best selections and preparations in terms of nutrition and bike equipment compared to her competitors. But she won despite of that. Because other "variables" come into play and they made the biggest difference. In subsequent years, she continued to develop as an athlete and a competitor. Her racing IQ and knowledge, level of equipment improved over time from experience and sponsorship. And her times of completing these events also followed suit and improved dramatically. Every variables count. But if she hadn't continue to improve or maintain her "human" abilities, none of these would have mattered and she wouldn't continue to perform and excel. I mentioned top gravel racers like Peter Stetina, Ted King, and Colin Strickland earlier.... It's easy enough to google this yourself. You can go back and search for pictures and details of equipment they have selected to participate in all the different gravel events over the years. You will see a trend and some patterns. These are world-class gravel racers who are on top of their game but they did not win every time. In fact, every now and then, a dark horse would take the top step. Why? Is it because of the lack of proper equipment? No. Lack of preparation or racing fitness? Sometimes. Life gets in the way occasionally. Luck plays a big part too. You can read race reports and interviews of the racers who ultimately won. There are too many variables to list. Tire widths is but one of many. To win a race, you got to be able to manage and balance all the different "variables" and do it consistently, year after year after year. It's not easy. Some people can do it better than others. Marianne Vos. Alejandro Valverde. Mathieu van der Poel.
__________________
 🏻* 
Last edited by weisan; 12-03-2021 at 09:29 AM.
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#41
12-03-2021, 10:06 AM
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I did not mean to stir the pot of bike variables, though. Im just looking for feedback and thoughts regarding avg speeds and what others experience and what I might be able to do to improve mine.
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#42
12-03-2021, 02:19 PM
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Just a quick timing point about wind. In a higher wind, for the same effort, and assuming you start and end at the same point with equivalent elevation etc. - you'll always be slower than light wind, and no wind is fastest of all.
The reason is that, for the same power, you'll spend more time on the leg into the wind than you'll save on the leg with the wind. Suppose you have a 20MPH average speed on a course with no wind. With 5MPH wind on the same course, for the same power, you could maintain about 16MPH into the wind, and 24MPH against the wind - for an average speed of 19.2. For a 10MPH wind, it'd be about 16.8MPH - reason being that you spend more time at a slower speed. This is a rough calc., but windy days for rides that finish where they started (assuming the wind stays the same!) are slower.
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#43
12-04-2021, 06:21 AM
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I find this whole thread very interesting. For a number of reasons, I have registered for 5 gravel races next year. I purchased a new gravel bike in September and have been riding it on road with 32MM slicks (which ballooned up to 34's when inflated) to get my fit and feel dialed in. Plan to ride it outdoors as much as possible this winter. So, with slicks on and 50/34 - 11/32 gearing I've been riding with friends on their road bikes. I gotta say, it feels like work to keep up. I'm absolutely positive my average and normalized power would yield me another 1 mph if on road bike. But, the purpose of getting comfortable should also improve strength and ultimately more speed when on my road offerings. I guess I'll find out....
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#44
12-04-2021, 09:13 AM
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Take a close look at the gearing on your gravel bike in gear inches with the slicks vs. your optimum gear inches on a road bike with 700 X 25. Note the differences and swap out the (likely) middle cogs to get the same cadence/mph ratio as the road bike.
Bet it will seem like less work. I make all my own custom cassettes using loose cogs and spacers so that all of my bikes (road, gravel, touring), regardless of crankset combo & rim/tire size, have pretty much the same gear inches in the combinations I use the most. Careful record keeping of all rides over years and years of doing this shows that my speed/elapsed time for the same course is very similar on all of them. Yes, some have larger/more big cogs to be used for climbing rides, but MOST of my riding is done in the middle five cogs & that’s where most of the cog swapping occurs, even on the ones with larger tires.
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#45
12-04-2021, 08:35 PM
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| Tags |
| gravel, power, stupid, watts, weight |
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