Test riding a true racing recumbent

[ed72]

Someone on another forum claimed that swapping my relatively un-aerodynamic aluminum front wheel on the M5 for a carbon three spoke wheel would increase my top speed by about 1 mph. Does that sound reasonable to you? It sounds a bit optimistic to me.

Maybe realistic.....at 88 mph

I had a set of the original Dupont Specialized trispokes back in the early 90's ......fast wheel but punishingly stiff....pretty sure the HED is based off this wheel. Harsh.

It would take a total CdA reduction from around say 0.162 to 0.148 just due to the front wheel to get 1 mph. Just highly unlikely unless it also had too wide of a tire mounted making the transition to the rim poor. Unlikely but not impossible. The Parker's wind tunnel experience bears this out....alu to Boyd60 front and rear got about 0.006 IIRC. I got 0.003 reduction going from Flo60 to Two Spoke wheel although, the 2 spoke does relatively better in cross winds. The Flo60 would be faster than any typical alu wheel. Try the Flo60 front with a 23 mm GP4000 or 25mm max

 

[Osiris]

Maybe realistic.....at 88 mph

I had a set of the original Dupont Specialized trispokes back in the early 90's ......fast wheel but punishingly stiff....pretty sure the HED is based off this wheel. Harsh.

It would take a total CdA reduction from around say 0.162 to 0.148 just due to the front wheel to get 1 mph. Just highly unlikely unless it also had too wide of a tire mounted making the transition to the rim poor. Unlikely but not impossible. The Parker's wind tunnel experience bears this out....alu to Boyd60 front and rear got about 0.006 IIRC. I got 0.003 reduction going from Flo60 to Two Spoke wheel although, the 2 spoke does relatively better in cross winds. The Flo60 would be faster than any typical alu wheel. Try the Flo60 front with a 23 mm GP4000 or 25mm max

Good to know. I was checking on the price of carbon tri-spokes, and they don't come cheap. I once had a FLO 90 on the front, but heavy crosswinds persuaded me that it wasn't a good idea.

Now, as far as performance improvements from a fast rolling tire, what would a couple of GP5000's get me compared to the Gatorskins? Are we talking about just a few seconds saved during a 40 km TT, or is it more substantial than that?

 

[ed72]

Good to know. I was checking on the price of carbon tri-spokes, and they don't come cheap. I once had a FLO 90 on the front, but heavy crosswinds persuaded me that it wasn't a good idea.

Now, as far as performance improvements from a fast rolling tire, what would a couple of GP5000's get me compared to the Gatorskins? Are we talking about just a few seconds saved during a 40 km TT, or is it more substantial than that?

It depends on your speed.

At 20 mph, such tires might save 4-5 MINUTES over the Gators on a 40k TT

At 25-28 mph.....maybe 30-60 seconds

I'd have to look up the Crr test results and calculate but real world Crr might be 0.004 for the GP5000 and 0.006 or more for the Gators....

Tires are the cheapest speed

 

[Osiris]

It depends on your speed.

At 20 mph, such tires might save 4-5 MINUTES over the Gators on a 40k TT

At 25-28 mph.....maybe 30-60 seconds

I'd have to look up the Crr test results and calculate but real world Crr might be 0.004 for the GP5000 and 0.006 or more for the Gators....

Tires are the cheapest speed

I'm considering doing a 20k TT, so every little bit helps. Endurance is always going to be my Achilles's heel, but if I can bump up my average speed by 0.4 mph, I might be able to win it.

 

[LarryOz]

194 watts for 25 mph.....wasn't that also Larry's numbers when he did the 100 mile record.

On my "Frankenstein" bike (Vendetta front end, Thom Ollinger's proto-type rear end, with Kent Polk's M5 seat (nearly flat), and my stubby handlabars) , during my 100 mile record, I was able to go 25mph on about 150watts, but it was sure hard to make that 150watts laying flat. Looking at that data, I was able to average 26.7mph on 181watts - amazing - problem was - it hurt like 210, not 180.!! You can take a look at the "other" splits from my Strava data here: https://www.strava.com/activities/1120688099

This is where the "not all watts are equal" disclaimer comes into the picture. Just like it is easier to make more watts on an upright, it has also been my experience that the farther back you lay the harder it is to make the same watts. Maybe with years of riding (and training) at a certain incline you might have some adaptation to be able to make the same watts with same effort at a lower recline - it has not happened for me.
I had similar testing results with my S30 and my 1st Vendetta. Same fitness and all the same wheels, tires, pedals, cranks, etc on both bikes: I could ride 360watts for 5 minutes on the S30, (after over an hour of testing at other wattages), same protocol 3 days later and I could only hit 265 wattts on the Vendetta (but I was faster = 25.9mph). Here is all the data from that first benchmark testing which is quite interesting: https://docs.google.com/spreadsheets/d/1rF0wEX2WpNRJ42GzFw70Zk5nfN_H28AP0c8nLisuCxM/edit?usp=sharing
This setup did not have fast wheels, tires, etc - but everything was at least the same on both bikes. (Now with my current setup I can probably avg same speed on Vendetta on 60 less watts)

I remember setting up the "Frank" bike and getting those crazy speed numbers on such low wattages and being all excited thinking I was just going to crush the 1o0-mile time. (Since I could appear to ride 27+mph on well under 200 watts). Problem was, I could not hold those 2oo watts on Frank like I could on my Vendetta, which is what I had been training on most of the year. I can remember "fading quickly" after about 2 1/2 hours at close to 200watts, and then my power output just kept getting lower and lower and lower - until by the end of my attempt I was only able to push about 150 watts. Granted I was still going 25mph, but it was hurting pretty badly by that time.

 

[Osiris]

This is where the "not all watts are equal" disclaimer comes into the picture. Just like it is easier to make more watts on an upright, it has also been my experience that the farther back you lay the harder it is to make the same watts.

I think many of us have had the same experience. I was reminded of it when I took out the M1 a couple of weeks ago, just to do some power/speed testing. On one four mile segment, I managed to average 25.6 mph at 195 watts, which ordinarily I would have been very pleased by, but it felt more like doing 240 watts! I couldn't believe how taxing it was to maintain a power level that would have been so easy on the Vendetta. Hopefully my body will adjust to the more reclined posture on the M1 eventually, but I can't say how long that will take or whether it will ever happen at all.

 

[Balor]

That makes hour record highracers power numbers all more incredible. Of course, they are piloted by incredible people, and yet... I still think that that by 'playing around' with bracing points you may gain some power back, though admittedly perfusion problems seem a much greater culprit of 'recumbent-specific power drop' than bracing woes, all else being equal (seat and frame stiffness, etc).

 

[Robert Holler]

On every platform recumbent and upright it is my experience that everything is a bell curve. An ideal angle for a given BB height, an ideal weight distribution for great handling, etc etc. When you start to adjust out of whatever that curve is for that particular bike - weird things happen and you sail into the land of diminishing returns.

 

[Osiris]

I just got back from my favorite 25 mile dragstrip where I did some speed power tests on the M1 and Vendetta V20. The temperature was perfect and there was no wind to contaminate the results.

This time I wanted to see what kind of power output it takes to maintain 28 mph on the M1. Regrettably I picked the one spot on an otherwise perfectly flat trail which had a 0.1% slope. Even so, I averaged 28.2 mph @ 228 watts. That kind of power output would have been easy to maintain on my Vendetta, but I just couldn't manage it on the M1. My legs don't feel like they're working right on the M1, and I'm not sure why.

Next came the Vendetta. Right away, pedaling felt much more natural on it, and my power levels were considerably higher than they'd been on the M1. I hadn't rested at all after my two runs on the M1, so my legs were feeling pretty weak by the time I got on the V20. Nevertheless, I managed to hold a steady 23 mph, which occasionally went as high as 25 mph. My Strava upload is showing much lower power numbers than I remember seeing on the Garmin though. On a 1.2 mile stretch, it shows me averaging about 23 mph at only 200 watts. That doesn't sound right. Or maybe it is, and my recollections of the previous tests I'm comparing it to are faulty. I tried holding a speed of 25 mph long enough to get consistent readings, but after those previous runs on the M1, I just didn't have enough in the tank. I think one mile is about the minimum distance to ride at a given speed to get a reliable average, and I could only manage half that.

 

[ed72]

Osiris is sort of running into the same inquiry that I have been thinking about. Why does perceived effort and actual power vary so much from one bike or platform to another and especially seat angle. The device that I would like to have is called a "Moxy" and it uses near infrared sensors on the muscle(s) to measure O2 saturation and the inverse giving you a window into what is going on inside the muscles.

I don't think 1 mile test is nearly enough because the latency period is longer on a recumbent and varies by individual and likely by angle of recline. From a power to speed comparison of the bikes, 1 mile gives a rough reading that can be useful for big differences. When I am too "lazy" to perform VE Chung testing and want to compare two conditions, I do ABBA tests of 10 miles each way at a power that is comfortable to hold. So run 1 might be wheelset A for 10 miles at 150 watts. Run 2 might be wheelset B for 10 miles at 150 watts. Run 3 goes wheelset B and run 4 back to wheelset A (ABBA). Comparing a session like this to another day is rather futile due to changes in conditions (temp, wind, barometric pressure, humidity, etc.). A wind, cold front came thru in the middle of my ABBA testing once and it was really interesting to see the difference in data just due to weather.

Back to Orsis' lower power on the M1. Is it a matter of adaptation, ie. bent legs growing? I have my opinion.

An easy way to compare would be to allow a few weeks of adaptation and then general peak power, 5 minute power, and then a 20 minute TT on both bikes when sufficiently rested. Load into different athletes within GoldenCheetah and then generate a modeled PD (power duration curve). Could be done on other platforms but you'd have to pay for two different subscriptions. GC is free.

The lower CdA of the M1 more than compensates for lower power on dragstrips or steady state efforts on flat roads. I doubt it would beat the V20 in real world roads with climbing and lots of starts and stops. Horses for courses.

 

[Osiris]

Back to Orsis' lower power on the M1. Is it a matter of adaptation, ie. bent legs growing? I have my opinion.

Could be one of two things. I don't have the right measuring tool for the job, but I would be willing to bet that my hip angles are different on the V20 and M1. The M1 feels more reclined, and that has given me problems in the past. When I got Kent's Railgun seat, my max power numbers dropped considerably. Fortunately this power loss was more than offset by the improvement in aerodynamics. Eventually the power came back, but it took months for that to happen.

Another possibility is that my leg reach is too short on the M1. Phil's physical dimensions match mine, but I have to say that the M1 feels a bit cramped. It was especially noticeable when I jumped right on the V20 after an 8 mile ride on the M1. Unfortunately the portion my torso lies in fits me so exactly that simply scooting back a bit to get more leg room isn't possible. I've e-mailed Phil to ask him how to adjust the BB to see if I can increase my reach by about 1 cm.

The really odd thing is that on the trainer, I managed to average 312 watts for 8 minutes, and after a few minutes rest performed another 8 minute test where I averaged right around 300 watts. I was using the same Vector power meter and Garmin Edge head unit that's on it now when I obtained those numbers, so in theory I should be able to duplicate that performance on the road, right? Not even close. My power numbers on the M1 are pathetic. It looks like I can maintain about 200 watts for the 7 mile test segment, but that's it. What happened to the other 100 watts? FWIW, Mike Mowett tells me that his power numbers on the M1 at 28 mph are pretty much the same as mine, but he can maintain 28 mph for much, much longer than I can.

An easy way to compare would be to allow a few weeks of adaptation and then general peak power, 5 minute power, and then a 20 minute TT on both bikes when sufficiently rested. Load into different athletes within GoldenCheetah and then generate a modeled PD (power duration curve). Could be done on other platforms but you'd have to pay for two different subscriptions. GC is free.

The lower CdA of the M1 more than compensates for lower power on dragstrips or steady state efforts on flat roads. I doubt it would beat the V20 in real world roads with climbing and lots of starts and stops. Horses for courses.

The M1 would be a horrible choice as a general purpose bent. The leading edge of the frame is about 1 inch off the ground. Any time you encounter a sudden dip in the road, like when going off the trail to cross an intersection, you would be scraping the frame. It's also an extremely stiff frame, which, combined with that small front wheel makes for a punishing ride. Then there's the fact that the back of your head is practically touching the rear wheel. It's not a safety issue, but it makes for a very noisy ride and can become quite unpleasant after a while. As far as climbing goes, it's a non-starter. My M1 has only one gear in front, and climbing steep hills with a 53 tooth sprocket isn't something I'd want to attempt. For all it's straight line speed, there's no getting around the fact that it's an extremely narrow focus bent, not designed for anything other than racing on the track.

I've decided that what I want to do on the M1 is improve my endurance so that I can go after the long KOM segments that I've been avoiding. I've been doing nothing but sprints since I started riding recumbents, so I'm like a fish out of water when it comes to even a 10 mile TT. Physically I seem to be up to the task, but the mental torture of pushing hard for seven miles yesterday was brutal. It's something I definitely need to work on.

 

[3bs]

keep this thread going guys. totally enjoying the read. i have several overlaps and some projects in progress that your conversations help me think about.

 

[Osiris]

I've come up with a new tiller design for the M1. I already have most of the parts, and the mountain bike handlebar ends ($4.99 for the set) should arrive this week. I'll cut about 1.5" off the one on the right, which will be the perfect place to mount my Di2 TT shifter. This setup should be more aero than the present configuration, and allow for a more natural hand position, and allow me to brake and shift simultaneously if necessary.

 

[RojoRacing]

Etap clicks would be even better for that setup, like dual gunner buttons on the republic star fighter.

 

[ed72]

Nice.

I've thought about a similar setup. Reverse TT brake levers with e-Tap buttons. I have them already.

Just need to find a 22.2 mm "cross bar"

Let us know how it works.

 

[Osiris]

Nice.

I've thought about a similar setup. Reverse TT brake levers with e-Tap buttons. I have them already.

Just need to find a 22.2 mm "cross bar"

Let us know how it works.

I found a cheap source for the crossbar. A local bike shop has a whole collection of discarded handlebars in their parts bin, so they just gave me a couple. I'm going to make mine a bit wider than I think I'll need, just so I can experiment with placing the gunner bars at different widths. Once I find the optimal placement, I'll trim off the ends. Alternatively, you could probably buy aluminum tubing of the right diameter at a hardware store. I'm told that 22.2 mm (or 7/8") diam. is a standard size.

The e-Tap buttons shown above would be the most aesthetically pleasing, but I've already got all the Di2 hardware. I also have a set of the Di2 TT style brakes with integral shift buttons. That would be a cleaner solution, but the problem is that those are designed to have the brake cable running down through the tube they're inserted in, and there's no way to do that with the ordinary clamp-on bar ends I'm using.

Functionally, I was happy with the current setup. It works pretty well ergonomically and I have it dialed in to my dimensions, but one thing about it kept me up at night.

Notice the amount of surface area of each brake lever exposed directly to the air stream. They're facing exactly in the wrong direction. The thumb actuated shifter is also fully exposed. That's got to me costing me a few watts in extra drag, especially if my fingers are covering the brake handles. Turning the brake levers parallel to my direction of travel and angling the grips towards me solves this problem, and the TT shifter on the end of the right grip is a lot more aero than what I've got currently. It may not add up to much, but if it can save me a couple of seconds in a 20 km TT, it's worth doing.

 

[ed72]

Mounting your Garmin on the "downtube" would save more than the thumb shifters.

I epoxied my mount just below the brake cable holes into my M5 "downtube" frame. Yes, I have no respect. Bikes are tools meant to ride hard and put back wet.

 

[MrSteve]

Lemme echo Osiris' recommendation, re. your local bike shop.
One of my favourite handlebars came from my L.B.S.
The owner only charged me five dollars U.S. for it, used, and I still use it.

 

[Osiris]

Mounting your Garmin on the "downtube" would save more than the thumb shifters.

Done. My Garmin 520 now sits right on top of the handlebar clamp, where it's out of the air stream. It's a bit ambitious, but I'm considering designing an aerodynamic shroud to cover the entire tiller assembly. I have a friend who owns a high end 3-D printer who could fabricate it, but owing to it's size it would require designing it in separate sections.

I epoxied my mount just below the brake cable holes into my M5 "downtube" frame. Yes, I have no respect. Bikes are tools meant to ride hard and put back wet.

Sounds like the perfect place for it. I've seen an M1 where the Garmin was attached to the downtube with velcro.

 

[ed72]

Sounds like the perfect place for it. I've seen an M1 where the Garmin was attached to the downtube with velcro.

I was using Guerrilla Tape but got fancy with epoxy after upgrading from an 800 to a 1030 recently.

I haven't perfected hand and arm position. But. At this juncture with my current rig, very narrow hands is slower than slightly wider. I presume the legs shield the hands or it could be the elbow and forearm angle presents less surface area. Very counter intuitive. I guarantee this would be opposite for some riders. LOL