Test riding a true racing recumbent
- Thread starter Osiris
- Start date
Osiris
Zen MBB Master
Yesterday I tested the M5 pad on my M1, just to see if it would make the bent comfortable enough for long rides. I rode 38 miles on it, pretty much non-stop, so the experiment was a success. I may just decide to have it cut to perfectly fit the M1's seat pan. That way I wouldn't have to risk buying a similar material which may not work as well.
Osiris
Zen MBB Master
I performed several back to back coast down tests on consecutive days which confirmed that the new handlebar do indeed make the M5 faster. In my previous coast down tests on this particular hill, I achieved a top speed of 22.4 mph. The new handlebar configuration showed a marked improvement, with top speeds varying from 22.8 to 22.9 mph. That's much better than I expected. Any doubt that a mild tailwind might have contributed to the improved speeds was laid to rest when I turned around at the bottom of the hill and decided to do a sprint to the top. My PR on that climb was set back in 2014 on my TT bike, and I've never been able to beat that record on any of my recumbents. That all ended yesterday when I finally beat my five year old PR, moving up on the Strava leader board from 12th to 6th place out of a field of 5,890 riders. How much the new handlebars contributed to that is impossible to determine. All I can say is that I've never before hit 25 mph on that climb and been able to hold that speed for so long. And it's not because I was putting out more power than usual. My power readings were actually about 4 watts lower than my previous highs on that segment.
One interesting thing I did notice in later testing was that my strategy of placing the handgrips right behind my thighs in order to shield my hands as much as possible from the wind doesn't seem to work. I've been riding without gloves for the past couple of weeks so that I could feel how the air stream was hitting my hands, but I can't feel any difference based on thigh position. No matter where my knees are in the pedal stroke, the amount of wind hitting my hands seems unaffected. This certainly wan't what I expected, so while coasting downhill I moved my left hand around trying to find a spot behind my left thigh where it would be blocked from the wind. I couldn't find one. No matter where I positioned my hand, it was never out of the air stream. It's a bit disappointing, but at least I now know that very narrowly spaced gunner bars would not improve the aerodynamics much, if any.
Edit: I just got back from a 46 mile ride where I repeated one of the tests at much higher speeds (25mph+). I was riding into a headwind, so the effect was more like riding at 29 mph. It turns out that my thighs do block the wind somewhat, but it isn't noticeable at more relaxed speeds, and it only seems to happen at the top of the pedal stroke when the hands are very close to the thighs. Still, it's something.
One interesting thing I did notice in later testing was that my strategy of placing the handgrips right behind my thighs in order to shield my hands as much as possible from the wind doesn't seem to work. I've been riding without gloves for the past couple of weeks so that I could feel how the air stream was hitting my hands, but I can't feel any difference based on thigh position. No matter where my knees are in the pedal stroke, the amount of wind hitting my hands seems unaffected. This certainly wan't what I expected, so while coasting downhill I moved my left hand around trying to find a spot behind my left thigh where it would be blocked from the wind. I couldn't find one. No matter where I positioned my hand, it was never out of the air stream. It's a bit disappointing, but at least I now know that very narrowly spaced gunner bars would not improve the aerodynamics much, if any.
Edit: I just got back from a 46 mile ride where I repeated one of the tests at much higher speeds (25mph+). I was riding into a headwind, so the effect was more like riding at 29 mph. It turns out that my thighs do block the wind somewhat, but it isn't noticeable at more relaxed speeds, and it only seems to happen at the top of the pedal stroke when the hands are very close to the thighs. Still, it's something.
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Osiris
Zen MBB Master
Judging by my recent test results, it looks like your calculations might be spot on. Top speed on my coast down tests are 0.5 mph higher than before in the four tests I've conducted so far.
I'm thinking of getting rid of the front etap derailleur and selling it on e-bay. I don't need it for these flat roads, and ditching it will make it possible to put a plate on one side of the big ring to keep the chain from falling off, like my M1 has. Do you think getting rid of that bulky derailleur up front will result in any measurable aerodynamic gains?
joy
Well-Known Member
Go to clc.com and search for minicell foam. It comes in various sizes and can be easily cut and shaped. I use it for kayak seats and custom shape it with a wire brush held in a pair of grip pliers. It is firm foam. I could mail you a piece if you want to check it out first. Just message me your address.
Overall? Yes. How much depends on the angle of the wind (yaw). IIRC from some test reports in the wind tunnel, dumping both the FD and small ring is 2-10 watts depending on your speed and the angle of the wind, so, I can't give any more specific than that and it is from memory. Obviously none of these things we discus matter much at all at speeds in the 20-24ish mph range but up at 30 mph, small things matter. Just run a 56 or 53 ring in front and an 11-32 in the back. I am experimenting with a 56 now. Might go back to the 53. Not sure. I also thought of 50 if I could find one and going single ring. I can make it up most hills in 50x32.
I have to have a front light for randonneuring and it along with battery is huge waste of aero energy. I'm considering making a battery container and putting it inside the boom and making a cable to go up thru the FD hole.
Osiris
Zen MBB Master
I currently running a 53x28, but now that I know the 32T in back will work with the etap (despite what SRAM claims), I'm thinking of going back to an 11-32 cassette. I hardly need the small ring for the 1-2% grades I usually encounter. I found a place locally that does 3-D printing. I'm going to see if I can design a couple of plates to go on each side of the big ring to keep the chain from coming off and have them print it for me. I'm also looking at the possibility of mounting my Garmin to the frame like yours. The Edge 1030 I'm using is about as aero as a brick, so the handlebar is not the ideal place for it.
Somewhere on BROL (I think) I recall seeing nice bit of custom engineering where someone had cut a hole in the front of the boom of his M5. The headlight and battery were housed inside the boom, thereby keeping everything out of the air stream.
Osiris
Zen MBB Master
On the topic of streamlining our M5's, have you ever noticed how un-aerodynamic the stock fork is? The one on my TT bike has a much narrower frontal profile and the fork legs are shaped more like an airplane wing, with the brake built into the fork, rather than mounted on the front where it's exposed to the air stream. I found this interesting article about aero-forks, but unfortunately it doesn't address the question of the brake: http://biketechreview.com/index.php/aerodynamics/forks/460-do-aero-forks-work
WRT bike forks, I have thought about it some and have read on some forums that the aero gurus talk a lot about the interaction between the wheel and fork. They don't really discuss what is going on in terms of the interaction. I was watching CFD modeling of various front bike wheels and what stood out to me was the location of the null point or vortex varies a lot from wheel design to wheel design. I have thought of buying an OVAL Concepts Jetstream fork but those were made 10 years ago and not sure the full history. The older R900 is cheap on ebay but the new R911 is pricey. The following link....read post 4. It touches on the complexity of the wheel and fork interface. (I have a love/hate relationship with my fork)
https://forum.slowtwitch.com/forum/...Concepts_A900_Fork-__Myth_or_Miracle_P666778/
https://forum.slowtwitch.com/forum/...Concepts_A900_Fork-__Myth_or_Miracle_P666778/
Osiris
Zen MBB Master
The R911 certainly looks promising. But then I saw the price....
Too bad they don't have a "Try before you buy" policy. BTW, my recent speed/power tests on board the M5 reminded me of a conversation I had with Kent Polk in which he mentioned crossing a threshold at about 25 mph, where it feels as though the M5 is performing at peak efficiency in terms of the power to speed ratio. From a pure physics standpoint this doesn't make any sense to me, but on several rides I did get the sensation he described at speeds just above 25 mph. I don't have enough data yet to persuade me that it isn't just an illusion, though. Have you experienced anything like it?
I think I know what Kent means.
If you think about a Milan Sl velomobile with a CdA of perhaps 0.03, it might actually take more power to go 10 mph than a V20 at 10 mph because of higher weight and at those speeds, most of the forces against the rider are linear. The lower the CdA, the higher the speed that nonlinear wind effects show themselves so to speak. I have heard it said by a very experienced velonaut that a velo is just a slow, heavy trike at 15 mph. If you look at a curve of power vs speed for a velo, it looks somewhat linear until maybe 28-30+ mph. On a fast racing recumbent, that sweet spot might be 23-26 mph. On the power to speed curve (gribble is your friend), that knee or inflection point is indeed in the range that Kent mentioned, but it does depend on the weather and how I am kitted up. He might also be applying some physiology to it as well. Riding below the first ventilatory threshold, an endurance athlete is almost burning all fat and can ride for a long, long time. Kent has a lot of power, so, I suppose 25 mph for him is the overall sweetspot and I suspect he ain't working real hard to do it and can carry on for many, many hours at that pace.
If you think about a Milan Sl velomobile with a CdA of perhaps 0.03, it might actually take more power to go 10 mph than a V20 at 10 mph because of higher weight and at those speeds, most of the forces against the rider are linear. The lower the CdA, the higher the speed that nonlinear wind effects show themselves so to speak. I have heard it said by a very experienced velonaut that a velo is just a slow, heavy trike at 15 mph. If you look at a curve of power vs speed for a velo, it looks somewhat linear until maybe 28-30+ mph. On a fast racing recumbent, that sweet spot might be 23-26 mph. On the power to speed curve (gribble is your friend), that knee or inflection point is indeed in the range that Kent mentioned, but it does depend on the weather and how I am kitted up. He might also be applying some physiology to it as well. Riding below the first ventilatory threshold, an endurance athlete is almost burning all fat and can ride for a long, long time. Kent has a lot of power, so, I suppose 25 mph for him is the overall sweetspot and I suspect he ain't working real hard to do it and can carry on for many, many hours at that pace.
Osiris
Zen MBB Master
Kent's physiology couldn't be more different from mine, but I've noticed the same thing he reports at roughly the same speeds. Recently I won a relatively easy KOM on a 12 mile long segment, where the record was just under 24 mph average. The only reason I thought it might be a challenge was because of the length. I'm used to competing in 1-2 minute sprints, so I had no idea what to expect if I tried to go for a much longer distance at a modest speed. I began conservatively, just making sure never to let my speed drop below 24 mph. That didn't tax me at all, so at the halfway point I increased my speed to 25 mph, then 26 mph, and eventually picked it up to 28 mph for the final two miles. What surprised me was that the the stress on my body didn't increase very much once I crossed the 25 mph barrier. In fact, the lactic acid burn that I'd been experiencing from the beginning had completely vanished by the last three miles or so. Not sure why that happened, but I've experienced this several times since. Who knows, maybe it was just the dopamine blocking the pain.
When initially ramping up power to the pedals, the incremental power is always anaerobic. There is a delay until the heart rate, lungs, and the rest of the aerobic system catch up and start making increased power from aerobic sources. This delay is a lot longer exercising in the recumbent aka "supine" position than on an upright bike. The period also varies from individual to individual. I researched this in depth because I learned thru trial and error that a harder and longer warmup is essential on a bent and that it is always best to ease into a hard effort compared to on an upright. Otherwise, the initial anaerobic byproducts will thwart the effort.
After almost 2 years busting my butt, I am almost making as much power on a bent as I did on an upright 3-4 years ago. I had to learn a lot along the way.
3bs
whereabouts unknown
Another seat pad source is yoga and exercise pads from Dunham’s or Walmart. Different brands have different types of foam and thicknesses
My TiCa has a sweet spot somewhere in the 20’s that once I get the bike there and settle in, it is easier to hold the speed. It is a great thing when I just want to zone out and grind miles
My TiCa has a sweet spot somewhere in the 20’s that once I get the bike there and settle in, it is easier to hold the speed. It is a great thing when I just want to zone out and grind miles
Osiris
Zen MBB Master
Well, that clears up quite a few things I've wondered about, like why my PR's seem to be highest after I've ridden for quite a few miles than when I'm fully rested. From my own experiences, I would estimate that it takes me at least 6 miles at a decent pace before I'm warmed up. That's my guess based on the fact that after ~6 miles, the perceived exertion seems to drop quite a bit but without any decrease in power output. After about 10 miles, I feel very relaxed just holding a constant 25 mph. But what I don't know is how much of a warm-up is optimal to get me ready for say, a half mile sprint. I imagine that sort of thing requires a different type of warm up?
Osiris
Zen MBB Master
I think I saw the pad you're referring to at Walmart. It's the right thickness, but it felt a bit too squishy to me. It also has a smooth surface, which might cause me to slide around in the seat. I'm going to check out various stores and see if I can find more workout pads. Everybody seems to sell them. Maybe I'll find something that would be perfect for my needs.
Chain guard or catcher for 1x
https://www.aero-coach.co.uk/store/product/aerocoach-affix-1x-aero-chain-guide
https://www.aero-coach.co.uk/store/product/aerocoach-affix-1x-aero-chain-guide
Sprint is different.
If you do long hard warmup efforts well beyond threshold, the restoration of PCR and overall reconstitution of W' or so-called high intensity energy can take almost 30 minutes. You need to be warm and vessels opened but be careful not to do too hard of an effort. Several short bursts help but not like a couple of hard 1 minute efforts. Like three 10 second jumps or something like that at the end of the slower, more aerobic warming.....see attached.
https://www.peakendurancesport.com/...e-training/power-warm-ups-maximise-potential/
http://upupup.aboc.com.au/the-book/07-racing/warming-up
