Test riding a true racing recumbent

[paco1961]

Glad the new bars are working out. I have often wondered if a different bar configuration on the cBs would be an improvement. I’m using the stock set up on my S40 but have always wanted to experiment with 2 things;

1) narrower bar - not too much narrower as I’m sure it would make for an unwieldy beast. But maybe drop a couple of cm from each side to improve aero and quite frankly to make it easier to get up the basement stairs.

2) try a flatfish bar rather than the stock drop/flair set up. Moving the hands to a lower position and getting those big hoods out of the air flow would have to be a good thing.

It seems a shallow mustache shape would actually enhance leg clearance and allow for a lower hand position.

 

[Osiris]

Glad the new bars are working out. I have often wondered if a different bar configuration on the cBs would be an improvement. I’m using the stock set up on my S40 but have always wanted to experiment with 2 things;

1) narrower bar - not too much narrower as I’m sure it would make for an unwieldy beast. But maybe drop a couple of cm from each side to improve aero and quite frankly to make it easier to get up the basement stairs.

2) try a flatfish bar rather than the stock drop/flair set up. Moving the hands to a lower position and getting those big hoods out of the air flow would have to be a good thing.

It seems a shallow mustache shape would actually enhance leg clearance and allow for a lower hand position.

When I joined the forum there was a thread about alternative handlebar designs for the Cruzbike. I don't know what came of it, but some of the designs looked very promising. I think the type of handlebar you see on a TT bike would work very well aerodynamically, providing you could work out the leg clearances.

 

[3bs]

i dont have enough time on the v20 to speak as competently as you guys, but i did not find a time trial bar to ever feel right for me, and i could not get the grip position i wanted for climbing.

larry has a narrow bar set up that he uses for certain racing and he did a huge article somewhere on his bar testing.

on the stock bar, i did find you can tighten the frontal area just by trimming the bar ends a couple inches on each side and then reset the hoods to match the hand size, and then work on the bar angle, which seems to angle the hoods more forward than down. i am using a bent top tube, so this brings the whole bar set up down.

 

[Osiris]

I was looking over the data from yesterday's test ride on my M5 and noticed that I got a PR on a Strava segment I wasn't aware even existed. I would have ignored it but for the fact that Ben Tomblin rode that segment at almost the identical speed (20.9 mph vs. 21 mph). I know Ben rides a completely stock V20 like mine, and he and I are about the same size, so how would his power output at the same speed compare to mine? It looks like the M5 has a considerable aerodynamic advantage over the V20, even at modest speeds. Ben's average power was 165 watts compared to my 137 watts on the M5. This is of course assuming that the results weren't contaminated by different weather conditions and that our power meters are giving accurate readings.

 

[Osiris]

I've just compared two area scans of my hand/wrist to get an idea of how aero the new handlebar setup is compared to the old. With palm facing forward (old handlebar setup), the total area exposed to the wind is 20.88 x 2 = 41.76 sq. in.
With the blade of my hand facing into the wind, the total area is only 10.9 x 2 = 21.8 sq. in.

So essentially turning my hands 90 degrees so that the palms/wrists face each other reduces their total area by about half. How that translates into watts is something I can't calculate, but I would expect that it's at least as significant as switching to a more aerodynamic helmet or wearing a tighter jersey.

 

[paco1961]

When I joined the forum there was a thread about alternative handlebar designs for the Cruzbike. I don't know what came of it, but some of the designs looked very promising. I think the type of handlebar you see on a TT bike would work very well aerodynamically, providing you could work out the leg clearances.

I was thinking something like this. Not sure how this would stack up on your aero meter.

 

[ed72]

I've just compared two area scans of my hand/wrist to get an idea of how aero the new handlebar setup is compared to the old. With palm facing forward (old handlebar setup), the total area exposed to the wind is 20.88 x 2 = 41.76 sq. in.
With the blade of my hand facing into the wind, the total area is only 10.9 x 2 = 21.8 sq. in.

So essentially turning my hands 90 degrees so that the palms/wrists face each other reduces their total area by about half. How that translates into watts is something I can't calculate, but I would expect that it's at least as significant as switching to a more aerodynamic helmet or wearing a tighter jersey.

It isn't just the hands. Your forearms should now be externally rotated and the narrower cross section exposed to the wind. Another advantage could be bringing the elbows more out of the air stream but this depends to a large extent on the overall bike geometry and leg clearance to the bars or at least for me.

Estimates can be made. My rule of thumb is 2 square inches = 0.001 meters squared. If the shape is like a brick (think mirror), I just double that to get the CdA. Plug 0.002 differences in Gribble and you can get a feel for the results to expect with a brick. Your hands are far more"slippery" than a brick and they interact with the rest of your body (face, neck). The coefficient of drag for your hands might be more like 0.4. So, maybe 0.005 improvement for the hands at the most. This would bring your hypothetical cruising speed from say 25.0 mph to 25.2 mph or in that ballpark. To be honest, I think of it a lot. My hands and brake levers really stick out in the air but only during certain times when the pedals are in the bottom position but when the pedals are in the top position, my leg is bent and it shields the hands and brake levers. My forearm and elbow are always exposed. This is where I think the gunner bars could make even more speed than the hands. (I think). I am going to guess you will gain about twice what I guesstimated. I'm thinking 0.5 mph improvement.....to maybe 25.5 mph from 25 mph. To some this might sound trivial but it would take 8-10 watts on the other side (your legs) and that isn't so easy when already pretty fit.

It will be interesting to hear of the longer range results. Between the skinsuit, gunners, and improved training.....you are going be killin it soon.

 

[Osiris]

It isn't just the hands. Your forearms should now be externally rotated and the narrower cross section exposed to the wind.

That's why I included the ends of my forearms in my area calcs. I probably could have included even more of the arm, but the further down you go, the more the arms are protected from the air stream by the rider's thighs. One thing I would love to get good data on is to what extent my exposed elbows and upper arms create drag. The fact that the air has to circle around my rear end and thighs before it even reaches that area mitigates the effect somewhat, but it's very hard to know just how much. I suppose the question is largely moot because there is no way to get the elbows out of the air stream completely without forcing the arms into a position which makes steering very difficult.

Estimates can be made. My rule of thumb is 2 square inches = 0.001 meters squared. If the shape is like a brick (think mirror), I just double that to get the CdA. Plug 0.002 differences in Gribble and you can get a feel for the results to expect with a brick. Your hands are far more"slippery" than a brick and they interact with the rest of your body (face, neck). The coefficient of drag for your hands might be more like 0.4. So, maybe 0.005 improvement for the hands at the most. This would bring your hypothetical cruising speed from say 25.0 mph to 25.2 mph or in that ballpark. To be honest, I think of it a lot. My hands and brake levers really stick out in the air but only during certain times when the pedals are in the bottom position but when the pedals are in the top position, my leg is bent and it shields the hands and brake levers. My forearm and elbow are always exposed. This is where I think the gunner bars could make even more speed than the hands. (I think). I am going to guess you will gain about twice what I guesstimated. I'm thinking 0.5 mph improvement.....to maybe 25.5 mph from 25 mph. To some this might sound trivial but it would take 8-10 watts on the other side (your legs) and that isn't so easy when already pretty fit.

That doesn't sound trivial to me at all. It's a pretty sizeable increase in speed or distance traveled at the same power level. Imagine the cumulative effect of reducing drag by 8-10 watts during the 24 hour race at Sebring, for instance.

One other thing that concerns me is the visor on my helmet. It occurs to me that the helmet was designed with Olympic sprinters in mind, not for recumbent racers whose heads tilt in the opposite direction. Is the air entering the visor from the bottom actually creating more drag? Would it be better to remove the visor, as some recumbent racers claim?

 

[ed72]

Helmet selection can be voodoo. Visors usually are slower on upright TT bike riders. On bents, I think the jury is still out.

I made the decision to always use a visor and often visor with clear glasses due to wind, rain, and insects pelting me at 35 mph. The Giro Vanquish works well for me, better than the Bell Star but the Bell star is my daily wear helmet. I doubt very much that a teardrop shaped TT helmet would be fast on the bent because it isn't like an upright with a huge transition from the back of the head to the shoulders and back. However, a well placed water bottle behind a headrest should help....maybe a lot at low yaw. I keep the Vanquish shield tilted down as much as possible and directed at the airstream, not like a scoop. It is pretty easy with that helmet but not as easy with the Bell. The Casco that Larry wears does look better but it was hard to find in the USA at the time and it was a very expensive experiment. I already have like 10 helmets. My two key criteria was comfort and weather protection followed by aerodynamics. The Vanguish visor has handled all manner of damp weather fairly well

Trust me, I appreciate the value of 8-10 watts. To put it into perspective, if I can average 120 watts over the course of Paris Brest Paris and if I stop just to control and find food and water, I will do a very fast time. This is a ridiculous idea for an old man but it keeps me busy planning. But, averaging (NOT NP) 120 watts for 45-50 hours straight might sound easy but is not. Improving the aero efficiency of the machine and rider interface by 10-15 watts would theoretically lower the power demand for my desired time to maybe 110 ish watts, which might be doable off an anticipated threshold of 285. So, yes.....we are 100% on the same page. I'm trying to up my power by 25 watts, lower my CdA by about 10-15 watts, and lose some more weight. 24 mph on 140-150 watts on the flats in warm weather on good roads is my goal.

I'll be following your progress with those bar quite keenly.

 

[Osiris]

Helmet selection can be voodoo. Visors usually are slower on upright TT bike riders. On bents, I think the jury is still out.

I made the decision to always use a visor and often visor with clear glasses due to wind, rain, and insects pelting me at 35 mph. The Giro Vanquish works well for me, better than the Bell Star but the Bell star is my daily wear helmet. I doubt very much that a teardrop shaped TT helmet would be fast on the bent because it isn't like an upright with a huge transition from the back of the head to the shoulders and back. However, a well placed water bottle behind a headrest should help....maybe a lot at low yaw. I keep the Vanquish shield tilted down as much as possible and directed at the airstream, not like a scoop. It is pretty easy with that helmet but not as easy with the Bell. The Casco that Larry wears does look better but it was hard to find in the USA at the time and it was a very expensive experiment. I already have like 10 helmets. My two key criteria was comfort and weather protection followed by aerodynamics. The Vanguish visor has handled all manner of damp weather fairly well

One of the TT guys I'll be training with claims he's got a Kask helmet that will allow me to pick up an additional 0.5 mph. I'm skeptical, but he offered to let me test it. It's not the typical teardrop shaped TT helmet, but a round one that I should be able to wear comfortably on any of my bents. The only problem is that at $500, it's not exactly cheap!

Trust me, I appreciate the value of 8-10 watts. To put it into perspective, if I can average 120 watts over the course of Paris Brest Paris and if I stop just to control and find food and water, I will do a very fast time. This is a ridiculous idea for an old man but it keeps me busy planning. But, averaging (NOT NP) 120 watts for 45-50 hours straight might sound easy but is not.

Easy? I can't even wrap my head around that. How is it even possible to turn the pedals for that long a time?

Improving the aero efficiency of the machine and rider interface by 10-15 watts would theoretically lower the power demand for my desired time to maybe 110 ish watts, which might be doable off an anticipated threshold of 285. So, yes.....we are 100% on the same page. I'm trying to up my power by 25 watts, lower my CdA by about 10-15 watts, and lose some more weight. 24 mph on 140-150 watts on the flats in warm weather on good roads is my goal.

That would be amazingly good on 140-150 watts. My best on the M5 so far is ~21 mph @ 137 watts over a 12 mile distance. If the crosswinds are gone, I'll be doing that same segment at 24 mph this weekend, but I don't see that happening at 150 watts. I did a two mile segment at 23 mph @ 164 watts, but the wind gusts were so crazy that day that I have no confidence in those numbers.

 

[ed72]

21 mph takes me 110-112 watts in warm, humid conditions if I have the fast stuff on and the lights, bell, Halt, junk, etc. off of the bike. 125-135 watts in cold dry air with wool tights and jacket.....maybe 0.205-0.215 CdA-ish?

I don't know if the Kask would help or not or to what extent. IIRC, this is the one Larry found to be fastest and he is the only bent racer to my knowledge who evaluated so broadly and shared his results. I was reluctant to buy the Kask because of reported fogging and my objectives did not put speed first. The shield looks correct for a bent. I am going to work on my homemade neck rest because it is so wide that it extends beyond the faceshield for example....small gains but it should help. The beauty of the Kask is you can try it free. If it really gets you 0.5 mph, it is worth $500 to me. How many hours of excruciating intervals does it take to get 0.5 mph? Is such an improvement in power even possible. For instance, the training software that I use "thinks" I can gain 21 watts in the next 14 weeks if I follow a 17 hour per week structured program. What is that 250 hours?

Riding 45-55 hours nonstop is certainly possible. I did 54 hours nonstop in 2015 but for some logistical issues shoulda/coulda/woulda been faster. With all the short punchy hills, I'd be better on a V20 but it is what it is. At that sort of epic effort, it ain't about the bike. Its the 6 inches between one's ears.

 

[Osiris]

21 mph takes me 110-112 watts in warm, humid conditions if I have the fast stuff on and the lights, bell, Halt, junk, etc. off of the bike. 125-135 watts in cold dry air with wool tights and jacket.....maybe 0.205-0.215 CdA-ish?

I'm going to remove the headlight and mirror, but that's about all the streamlining that's left to do on my M5. I doubt it will get me down to 110-112 watts at 21 mph, but we'll see. I did do one additional thing last night, and that was to make the chain run straighter by using a shorter spacer on the idler wheel. Unfortunately it hasn't eliminated chain rub on the inside face of the wheel track, but I can't push the idler any closer to the frame without the chain rubbing against the fork leg. I noticed this problem from day one, and wondered if I couldn't solve it by using a skinnier fork, like the one on my TT bike. That fork has the additional advantage of having the front brake fully enclosed and shielded from the airstream. Getting that to work on the M5 might not be possible, though.

I don't know if the Kask would help or not or to what extent. IIRC, this is the one Larry found to be fastest and he is the only bent racer to my knowledge who evaluated so broadly and shared his results. I was reluctant to buy the Kask because of reported fogging and my objectives did not put speed first. The shield looks correct for a bent. I am going to work on my homemade neck rest because it is so wide that it extends beyond the faceshield for example....small gains but it should help. The beauty of the Kask is you can try it free. If it really gets you 0.5 mph, it is worth $500 to me. How many hours of excruciating intervals does it take to get 0.5 mph? Is such an improvement in power even possible. For instance, the training software that I use "thinks" I can gain 21 watts in the next 14 weeks if I follow a 17 hour per week structured program. What is that 250 hours?

Given that I've already spent more than twice that on the SRAM etap system, $500 for an additional 0.5 mph isn't out of line. I'm sure that if the tests confirm it, I'll be able to talk myself into buying one. I'm even thinking of ditching my Vector pedals for a set of Speedplay Zero pedals, which I've had lying around. Phil said he prefers these pedals because they're the most aerodynamic. I've also put a much thinner pad on my headrest to decrease the angle of recline in the hope of saving a few watts. My head is so low now that I'm actually viewing the road through the space between my helmet visor and my face.

By the way, I found a local furniture shop that says they can make seat covers for any of my bents for $20 if I provide them with the material. I'd like to have one made for my M5's Railgun seat using the same closed cell foam that the stock seat came with. Kent only sells the 2" thick open cell foam seat cover, which is too squishy and is probably responsible for some power loss, as mentioned in your other thread. Now I just need to find a source for the foam.

 

[trplay]

Now I just need to find a source for the foam.

Go to Walmart in the kitchen section and look at kitchen mats. Cut to fit. When I used a cushion that's what I used under my cover. You really don't need a cushion. Especially if you are time trialing 10-30 miles. Try it before you discount it. Less weight, slightly more aero, no squish.

 

[Osiris]

Go to Walmart in the kitchen section and look at kitchen mats. Cut to fit. When I used a cushion that's what I used under my cover. You really don't need a cushion. Especially if you are time trialing 10-30 miles. Try it before you discount it. Less weight, slightly more aero, no squish.

I'll certainly have a look. It's bound to be cheaper than the stuff I've found so far, and if it works...

 

[trplay]

I'll certainly have a look. It's bound to be cheaper than the stuff I've found so far, and if it works...

Sorry, my post was poorly worded. The kitchen mat will weigh as much as the traditional cushions. I meant say try the no cushion method. You don't really need a cushion.

Here's a photo of the kitchen mat under a cover and the current no cushion method I'll be using in the upcoming 600K.

 

[Osiris]

Sorry, my post was poorly worded. The kitchen mat will weigh as much as the traditional cushions. I meant say try the no cushion method. You don't really need a cushion.

That's not going to work for me. I'm currently using a 1/8" thick pad made from a Yoga mat on my M1, and it's uncomfortable as hell. It's only there to keep me from sliding around on the smooth carbon fiber seat, so things would be even worse without it. What I like about the 1/2" thick closed cell foam pad that came with my M5 is that it provides just enough cushioning without being squishy. And it grips my body like flypaper, so that I don't slide around even during a hard sprint or a steep climb.

That's an interesting handlebar, BTW. Is it an aftermarket product?

 

[trplay]

Those are the stock bars that came in the box.

 

[paco1961]

Would love to know the name on the bars.

 

[trplay]

Stock Cruzbike bars. Robert Holler should be able to answer this.

 

[Osiris]

OK, so I just got back from the second test ride on my M5. It's definitely faster with the new handlebar setup, but I'll have to search through past test results to get a concrete idea of how much faster. The last time I rode this particular trail, I found a 12 mile long Strava segment that I thought might be ideal for this type of testing. It's not only very long compared to my other test segments, but it also changes direction several times, which should correct for any mild headwind or tailwind that would otherwise influence the results. The only imperfection in this segment is that it isn't perfectly flat. Even though Strava lists the average grade as zero, it does climb 25 feet from beginning to end. Very steep by Florida standards.

What I got according to Strava was an average speed of 25.2 mph @ 205 watts. This is definitely an improvement over my previous results. My endurance is poor, and at no time in the years that I've been riding the M5 could I have maintained 25.2 mph for so long at a modest 205 watts. That's only about 1 mph slower than my M1 lowracer can go at the same power output, and the M1 is a dedicated track machine.

No doubt I could squeeze even more speed out of the M5 by ditching the mirror and using a deep section aero front wheel in place of the aluminum one, but my only interest here was to see whether the new handlebar design would perform up to my expectations. It definitely does. My only remaing gripe is that the SRAM etap buttons require more thumb pressure than should be necessary to execute a shift. The shift buttons on the blip-box itself are far more sensitive, but I can't see any elegant way it could be mounted on the handlebar.