I'm wondering how much (if any) I understand about how a tandem should ride in the wind.
First some background, in case it's relevant, then I'll try to describe what happened today.
I consider myself to be a pretty experienced cyclist, I've got well over 20k miles under my belt and at least 3k of those must have been in groups. I know the game, though I may not be as fit as I once was. I'm a fairly big cyclist at 6' and 215# (I can put out some wattage, but it takes some to get me up the hills too.)
My stoker is what I would call a fairly strong casual cyclist. She's probably logged a few thousand miles in the last few years. Most of her riding has been with me. She recently took up an interest in drafting and has at times been able to stick in my draft if I keep my HR down to low aerobic or healthy-heart. Recently, while my road bike was in the shop, I rode on the road with her on her road bike, and me on my full suspension mtn. bike. I got a pretty good workout that day.
Today, we rode with a group I had ridden with yesterday on my 'half-bike'. Yesterday, I didn't have any trouble staying with them, and almost claimed a few hills (2nd or 3rd to the top, and half a wheel back). Basically, I didn't have to worry about being dropped, and was free to play.
Today, on a flat course, we started off okay. I had to work pretty hard at times to keep us on the group, but we were running with them. We went about 25 miles down-wind then turned to work our way back. As soon as the course turned up wind, it was like the brake started dragging. It wasn't a bonk, but the group just walked away from us, and I couldn't feel much of the draft even when I put us right in the spot. I find this nearly amazing because I expected to be aerodynamically superior and to excel in the headwind. I've always thought that the 'downhill advantage' tandems have was almost entirely due to superior aerodynamics and can't figure out why this doesn't manefest itself in a headwind just as much.
FYI, the tandem is a Trek T2000, not exactly a beach-cruiser.
Also, for what it's worth, my stoker later mentioned that "she doesn't get as much of a workout on the tandem [as on her single]", but that's a post for another thread.
What is your experience with a tandem in the wind?
The BikeForums Team
-adv-
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Tandems heading directly into a wind have good aerodynamics. But look at your tandem from an angle and you can quickly figure out why the aerodynamics go down the drain in a quartering headwind; there are a lot of surfaces and 2 pair of legs making turbulence. Some winds are better than others and often it's difficult to figure out why one hurts more than another.
I've had quartering tailwinds that also caused turbulence problems in pacelines that I usually don't have on a single. In those cases, pulling seems to be easier than drafting. You'll see what I mean when it happens.
operator
I thought tandems went faster than a non-tandem into a headwind because there are 2 people putting wattage vs 1 on a roadbike?
zonatandem
Cross or side winds can be detrimental to a tandem team as far as aerodynamics go. Have actually had a strong crosswind blow us laterally by at least a foot on a ride years ago in Indiana. The winds were so strong that the telephone wires were "zinggging!" Lots of cyclist ended up quitting the event that day, but we stuck it out. Eventually the route changed and things were OK again.
Again, body mass on a tandem is better aerodynamically when faced headon or tail on than laterally.
boyze
I'm sure someone has done a study but I'm not sure that a tandem with 2 equally powered riders would be more aero efficient than 2 single riders. For a simple object the drag coefficient is a function of the aspect ratio of the object. For a cyclist its the width to length. For the same width a longer setup has less drag. Two riders are overall more aero than a single rider. A tandem is not as long as 2 singles and hence has a lower aspect ratio and possibly higher drag than a singles. I say possible because it's more complex than simply length because the rider and bike are not smooth, continuous objects relative to the air. As mentioned, in a quartering wind condition the tandem can't echelon like 2 singles and would have an overall disadvantage.
turtlendog
I was thinking about cross-winds as well, and can see how a tandem would suffer in a cross-wind. The echelon thing definately makes sense.
It was a straight-on headwind that was killing us though.
I wonder if it has anything to do with the fact that the bars on the tandem are quite a bit wider than my road-bike, and so I don't ride a headwind as well as I thought.
galen_52657
I would guess that your power-to-frontal area ratio was not up to the level of the better single riders. Also, regarding your stokers remark, she may have been a contibutory factor.
TandemGeek
I thought tandems went faster than a non-tandem into a headwind because there are 2 people putting wattage vs 1 on a roadbike?
Yes and no. All things being equal except for the bike, (and despite myths to the contrary) a tandem road bike with two riders is between 30% to 50% less aerodynamic than a a solo rider on a road bike. Therefore, in order for a tandem to maintain a constant speed that is as fast (or faster) than a solo rider, the team must produce a net power output that is at least 30% to 50% greater than a solo rider.
Moreover, consider if you will that power production on a tandem is not necessarily linear since either one or both of the two riders on a given team may at any given time fall victim to poor form, individually or collectively. Put another way, even if you have two strong cyclists (1+1), they will lose some efficiency due to the nature of a tandem and, if they are not able to work well together, their efficiency will fall way off. So, in reality what you will often times find with a tandem is that you have two riders of different abilities who can produce variable levels of output which may or may not be as high as they are able to produce when riding alone. This is why some tandem teams who are weaker riders individually than a team comprised of two strong riders are often times as fast (or faster) than the stronger couple when both teams ride their tandems. The place where a team's combined efficiency level is most obvious is when they get to the hills where you have the same math problem with percent grade being substituted for headwind MPH and the added factor of team weight having more importance than aerodynamic drag. Less I digress...
So, to answer your question, if you have a team who can produce at least 30% to 50% more power as a team on a tandem they should be able to keep up with a solo rider. However, if a tandem team can produce a net power output above what is required to compensate for increased drag, the tandem pulls the train.
TandemGeek
What is your experience with a tandem in the wind?
How long have you two been riding the tandem, alone or with your local club riders? Do you have a baseline for your performance on a tandem to which you're comparing this weekend's experience or was this group ride something new?
As for us....
Some days we feel great and can pull the train. On other days, particularly when one or both of us are not 100%, we often times carry home the 'lanterne rouge'. However, that said, it has been my experience that the worst place to be on a tandem in a long, single file line of bikes drafting one another is last. The second to worst place is anywhere in the back UNLESS it's a rotating pace line. My rationale has to elements:
1. Aerodynamics: The turbulence wake that follows a very fast moving line of bicycles just seems to really take a hold on the back 1/2 of a tandem. If you drift too far back into the turbulence or fall off the back and try to bridge, it really hits you like a wall.
2. The Slinky Factor: If there is one thing a tandem excels at it's pulling the train at a steady pace. If there's one place that's obvious, it's riding the the lone tandem in a paceline being pulled by solo bikes; I know of nothing that causes more fatigue and stress when riding a tandem. At least for me, I find we must constantly feather the brakes or accelerate to alter our heavier bike's momentum to stay in place with ever changing speed of solos.
SDS
My theory is your stoker ran out of gas on the way back. With insufficient power available, you just couldn't hang on.
I ride tandems for the challenge. I want to work HARDER without worrying about busting the pack up. I don't expect that we will go as fast as I can go on a single.
We can tell when we are having a bad day. It's written all over the heart rate monitors. If they won't go up and stay up, it's not gonna be a good day....and it happens. We're dehydrated, or maybe just worn from previous days.
The performance edge of a mixed pair on a tandem over a male on a single bike is thin at best. Of course this is highly variable, depending on their capabilities. Chasing a couple of fast club riders or slow racers in a paceline with a tandem with a mixed pair that is off the back can be very challenging.
We draft very well on flat ground, but grade changes make this more difficult because the power requirement is constantly changing. On rollers this is less of a problem, because uphill you just set the throttle on "eyeball bulge," and you will be right on. When you crest the hill you move over to the left, and everybody knows in a few moments the freight train is going to come by. With single bike riders who are accustomed to riding with tandems this is no problem.
One thing you can do is to reduce your power requirement when you have been dropped. Put aerobars on the tandem and your performance will improve. You can get in better shape. And you can dump the pie-pan cassette and get a tighter one that only has the low gear you use, with all the other gears having smaller splits that will keep your cadence closer to where you make your power.
turtlendog
I should clarify that my surprise is not that we couldn't hang with the group (I actually expected to get dropped) but that we were able to stay with them okay when running down wind, then were so obviously slower in the headwind.
It's true that we were near the font on the way out, and on (and off) the back into the wind. Maybe that was my fatal mistake. I know the slinky game, and I also observed that it's harder to keep the proper position in a paceline on the tandem.
turtlendog
2. The Slinky Factor: If there is one thing a tandem excels at it's pulling the train at a steady pace. If there's one place that's obvious, it's riding the the lone tandem in a paceline being pulled by solo bikes; I know of nothing that causes more fatigue and stress when riding a tandem. At least for me, I find we must constantly feather the brakes or accelerate to alter our heavier bike's momentum to stay in place with ever changing speed of solos.
I'm glad you brought this up Mark, it was actually something else that's on my mind. I thought the subject of maintaining pace-line position actually deserved its own thread so please look here: http://www.bikeforums.net/showthread.php?p=732909.
TandemGeek
Also, regarding your stokers remark, she may have been a contibutory factor.
My theory is your stoker ran out of gas on the way back.
Is it merely a coincidence that you two -- who to the best of my knowledge are gung-ho guys who don't have a spouse as your stoker -- seemed to zero-in on the stoker's performance as the weak link?
Just curious. I would note that harboring such thoughts when your stoker is your spouse could eventually cool your stoker's enthusiasm and/or willingness to share the ride, particularly if such thoughts manifested themselves in a Freudian slip or put you into an awkward situation when overheard by said stoker whilst you were sharing those thoughts to what would hopefully be a sympathetic captain.
BTW, I'm actually 1/2 jesting and and 1/2 serious. In reality, we all have strong and weak days on the bike and when you share a bike with another rider who you think isn't pulling their share of the workload you need to be mindful that as captain you've got to "manage the team output" to ensure you can get the ship back to shore. It has been my experience that if you try to "pull" the tandem and stoker you're just as likely to use yourself up "overcompensating" 3/4's of the way through a ride and leave your stoker to "push" you and the tandem home as you are to succeed. Some might call this resistance training which, if the stoker doesn't mind, is OK. In fact, I know of at least one team where both riders carry their own weight -- to a point. And, once they hit that point the stoker allows the captain to literally "knock themselves out" pushing as hard and fast as he wants. On more than one occasion we have heard the accounts of said Captain enjoying a good road-side hurl mid-way through an event whilst the stoker was still in good spirits, and fine form, and otherwise enjoying a good ride.
Just something to think about next time you're out enjoying a great ride with a great partner who's willing to share a tandem with you.
SDS
"Division of labor is what makes America great. I shift, brake, and steer, and she pedals REALLY HARD."
That's what I often say when we pass people and they say hello, and it almost always gets a big laugh, but the point is, I'm perfectly willing to put all the credit on somebody else, and I do it.
More to the point, tandems are about teamwork, and the credit is indivisible. WE do what WE can do, and I never put it any other way, unless I am heaping praise on the stoker as the strong member.
Communication is very important to riding tandems, though, and that requires objectivity. We're very honest with each other about what we can do and how we are feeling, in light of how many miles are left. It's a little bit easier to be objective with the data from the HRMs.
"As soon as the course turned up wind, it was like the brake started dragging."
Reading that sentence, in the context of the others, suggested to me that the stoker had gotten tired.
We manage the resources as a team. In my opinion to place all the responsibility for that on the captain is to relegate the stoker to a subservient position. You both have to communicate and say you are or are not comfortable with the pace for the remaining distance.
Trsnrtr
More to the point, tandems are about teamwork, and the credit is indivisible. WE do what WE can do, and I never put it any other way, unless I am heaping praise on the stoker as the strong member.
You and Mark have hit the nail on the head. My wife and I are A-type driven people and have been scorching singles with a tandem for over 20 years, but some days, it just feels like somebody threw an anchor out. It happens.
#1 rule... never, never, and I mean NEVER, ask a stoker if they are working or if they quit pedaling or the great wrath of all things evil will be wrought upon your soul. :eek:
TandemGeek
#1 rule... never, never, and I mean NEVER, ask a stoker if they are working or if they quit pedaling or the great wrath of all things evil will be wrought upon your soul. :eek:
Ain't that the truth... I've seen stokers walking and I've seen captains riding solo who didn't leave that way. I believe these are known as "watershed" moments or "critical junctures" that often times have a bearing on future tandem outings for the couple as well as the slighly used tandem market. That reminds me... there are two slightly used Large/Med Calfee Tetra Tetra tandems for sale at http://www.tandemmag.com/classified. Hard to know why the first one with 300 miles is for sale but it's pretty clear that #2 is on the market due to an incompatibility issue between the $9k tandem and the wouldbe stoker. Less I digress....
I have found that I can get away with "how you feeling honey" which is mutually understood to mean one of us is having a bad day or fading and I'm not exactly sure who it is. Being the sweetheart that she is, she takes it in stride and always lets me know if she's not 100%. However, if she says she's fine then we both know I'm the one who's not at 100%. You find what works.
turtlendog
Re: the stoker debate. I'm pretty sure that she didn't run out of gas because she was riding low-aerobic. She may have gotten tired of being in the saddle, but she didn't run out of gas.
We did a recovery-ride the next day (where we discussed the ride plan, and for the most part stuck to it) and I found that we worked much better and seemed to flow.
I'll be trying to replicate that ride in the future. I have more interest in riding with my stoker than in getting as much horsepower on the bike as I can. That said, I may encourage some high-aerobic (my favorite zone) efforts from time to time :)