merlinextraligh

We're going to do a couple of time trials on the tandem for the first time this year; the State TT championship in May, and the Co-Motion Classic Tandem Race has a stage that's a time trial.

So are there things unique to Tandems that we should consider with regard to preperation, equipment, training?

With regard to equipment, we'll use clip on aero bars for the captain. For the stoker, I'm thinking we'll just go with the bullhorns that are already on the bike, perhaps lowered. Although I'm interested in the "drop in" bars pictured below.

For wheels, I think we'll use a HED3 front which I already have. Anyone else using this on a tandem (our team weight is around 340lbs.)

For the rear we'll probably just stay with the Rolf Prima. I have a HED disc. Does anyone know if you can swithc out the axle on the HED to get to 145mm spacing. (the bike in the pic below I'm pretty sure has 130mm spacing.)

I also thought about building up a Zipp 808 clydesdale rim with a Tandem hub. However, Zipp strongly recommends against this on the basis that the wider spacing results in the spokes pulling at an angle that will crack the rim. Also, I'm too cheap to spend the money for a couple of events.

Time Trial helmets. Data suggests that a TT helmet is one of the biggest energy savers you can buy. I already have one, but my stoker doesn't. Any thoughts on how important a TT helmet is for the stoker.

As for the race itself. Any thoughts on teamwork, and pacing unique to tandeming? Given that pacing off Power is not an option, our plan is to each gauge our effort off of our indivual HRM's

JTGraphics

No experience but sounds like your going to have a great time at it!
One thought that came to mind with the heart rate was also let the captain see the strokers HR so you can gage how the stoker is doing while riding so you can shift for cadence and keep HR's in a good Performance range.

CouchingTiger

My wife and I do about a half dozen tandem TT's a summer. I actually put together a tandem specifically for TT's with aero bars, bullhorns, bar end shifters and the lot. It's a Cannondale (same frame we normally ride). I put a Bontrager carbon road tandem fork that takes a long reach road caliper on it to lighten it and lower it. In the rear I still use a 6" rotor disc brake. For the captain's post I use a Profile fast forward and then use a standard post and bullhorn bars for the stoker.

One place I don't dare scrimp is on wheels though. Light and aero are great but flat out in the aero bars the bike can be a handful to control. You also go really fast. For the TT that we do (rolling 9.75 miles) we are averaging about 29mph and are doing almost 40mph at one point. No way I dare risk an issue with a carbon wheel (or most any other part) that wasn't designed for a tandem and the forces there of. My worst fear is losing a front wheel at speed on a tandem. It would be catastrophic and the captain would be lucky to survive, based on the low speed tandem MTB crash I had once where the stoker ends up driving the captain into the ground.

Mike

WheresWaldo

My daughter and I are planning on TTing on our new tandem when it arrives. We are on opposite coasts so now competition there.
We are planning on using clip on aero bars also.
That's the same frame that we are getting except ours won't be an uberlight. Brent usually builds to 130mm but will build 132.5, 135, 145 if the user requests. I would suspect that the frame pictured is 130mm.
We decided to do the two time trial helmets, Giro Advantage 2. The same generalizations apply start steady and build, trying to maintain a constant power output until the end. but you know all of this already. Anything you learn please pass on so that we can benefit also. Have fun with this.

zonatandem

Wheel suggestion: Topolino.

PMK

I mentioned the idea of us running a couple of the local tt's here in South Florida. She seems ok with the idea.

As for the setup, we won't be buying a third tandem. As for modding the one we have, maybe later after I see if she enjoys it.

29 mph average, very nice. Was the 40 mph on flat terrain or descending? Any details about the team?

Are you folks planning to use or do you already have ceramic bearings in your wheels and cranks? Good ones aren't cheap but if they work as well in a bicycle as they do in a road race motorcycle, it could be a worthwhile upgrade for those that can afford it.

PK

merlinextraligh

^ We use ceramic bearings in the cranks, mostly as a durability issue. All the data i've seen indicates that at best you're talking less than 1 watt power savings by going ceramic. (Leonard Zinn had a good article on ceramic bearings in Velo News awhile back.)

I'm not sure themotorcylce racing analogy would be applicable because of the different rpms involved.

As for Topolino wheels, they would be lighter than Rolfs, but just eyeballing themthey don't look very aero at all.

zzzwillzzz

a friend of mine runs the hed 3s front and rear on his cannondale tandem and has for years. he runs them in big fast groups rides with a male stoker. both riders are strong cat 3 and cat 2 masters racers. if he hasn't had any problems with the wheels i doubt you will either, especially if they're just for tt's

Red Rider

We do several tandem TTs a year. We have aero helmets, clip on aero bars for the captain, drop bars for the stoker, and the Rolf Prima Vigor wheels w/low spoke count that came with the tandem. We take off the rack and the water bottles (maybe the cages should come off too but is that effort worthwhile?). I use my HRM and a wired CATEYE so I can see any speed changes. We also communicate, enough to keep each other focused.

We really like racing the tandem. It's an added dimension that provides a lot of kick to our riding.

TandemGeek

Aero drag for Topolino wheels is probably no better than standard 36* wheels using Deep-V rims at average, non-TT speeds just based on my highly unscientific static spin-down testing. Rolfs did much better and were on par with my Campy Eurus G3 wheels. Crank up the speed to TT tempo and they probably become a liability.

The Topolino spokes have a very large cross section and the thermoplastic terminations (those black things at the end of each spoke where the carbon/kevlar spoke mates to the stainless steel threaded end of the spoke) also seem to contribute to drag. Again, as noted in other threads, these are excellent wheels if you're looking for improved ride quality / comfort, for steep climbing or just getting grams off the bike for bragging rights. However, they would definitely NOT be a wheel I'd use for a Time Trial.

TT = very deep section rims (40mm or better), tri-spokes or discs when cross winds and cost is no object. In fact, the set-up being used by the two gals on the Rue Sport Ying Yang is probably as good as it gets for a tandem TT.

Shayne

My daughter and I have done 5-6 TT's a year, over the past two seasons. This year she'll be 10. She doesn't come to all of them, which is fine as I can do 5-6 more by myself. We use a low end, steel Co-Motion. I've added clip-ons, rear wheel cover and we both use aero helmets. I got her's used from a fellow racer and she's thrilled to have it. For this year, I've built an aero wheel for the front, based around an Edge 68mm rim. We'll see how that works out. So far, I'm 2.5 - 3 mph faster when solo. Hopefully that will change as she gets older. Hopefully she'll still want to race with me. I'm sure there will come the day when it's not cool to put on lycra and hangout with your dad. For now, she loves winning those little trophies and medals, and since there aren't to many tandems racing, she usally walks away with something.

Good luck with your TT's. Sorry I didn't have much to add, but with a child stoker I'm just not that fast. Heck, I'm not that fast solo either.

PMK

Yes, but you are having fun. Enjoy every moment.

PK

sch

On our one TT effort, we had a pair of those stoker clipon aero bars
pictured in the dual ladies tandem, but on our bike the setup was such
that the bars were really close to the back of the pilot's thighs and
weren't feasible to install. Pilot has progressively moved his set up toward
the rear as time goes on and aerobar pushes him a bit further back.
We have noticed that pilot on the aero
bars is good for about 3mph increased speed at 30+ mph for the same
pedaling effort compared with the pilot on the drops or hunched a bit
on the shifters. Problem for the pilot is how long they can stay on
the aero bars-some people have breathing problems at high effort in
the aero position.

re HRM, we both have one but mine reads out the pilot HR when on the
tandem, so I have an excellent idea of where the pilot is in his effort
curve.

merlinextraligh

So far we've put clipon aero bars on for the captain, and Cane Creek Speedbars for the stoker.

As for wheels, we're going to run a HED3 tri spoke for the front, and use a disc cover for the rear. We have a HED rear disc, but the HED folks were pretty adamanant in their reccomendation not to put a 145 axle in it. (pics are with the regular wheels.)

colotandem

Merlin

That sounds like a great set-up! I need to look into those Cane Creek Speedbars and the a disc cover for the rear wheel. I'm gonna go out on a limb and guess that you can't use a disc cover on a wheel that uses disc brakes...

A couple more questions for the group regarding TT on a tandem:
1 is there an aero advantage to removing waterbottle cages (there are four of them)?
2 what about wearing aero booties?
3 is anyone racing with different tires or pressure than you would for everyday riding?

It seems that the areo position of the riders would be one of the first things to address (free), next would be helmets($) and wheels ($$$$$). I guess I'm wondering about the next items to address (I would guess that the benefits become smaller and smaller as you go down the list).

Thanks

merlinextraligh

As for waterbottles, the data for single bikes is somewhat counterintuitive. A single bottle on the down tube is faster than one bottle on the seat tube, or 2 bottles, or suprisingly no bottles at all.
https://www.slowtwitch.com/mainheadin...erbottles.html.

How this translates to a tandem would be anybody's guess (I've haven't seen any data) and trying to extrapolate wind tunnel results often doesn't work.

FWIW, we'll use a single bottle on the lateral tube for the captain, and a single Arundel bottle for the stoker (just because we've already got it from my single TT bike.) and remove the 2 extra cages.

I do use booties, they cost like $20, weigh nothing, and can't really hurt. (although you probably get more aero advantage from simply not wearing gloves, and certainly more from a skin suit.)

As for tires, if your team weight allowed 23c tires, or even a 21c on the front, there would be a wind resistence advantage. For us the 25c Continental 4000's we ride regularly are about as far as we can push it. An Attack/Force setup (22 mm fron 24mm rear) might be a good option for a lighter team.

As for tire pressure, there's a lot of data, that more moderate pressures have less rolling resistence in the real world. We need to run 120psi to avoid pinch flats. Above 120psi rolling resistence would increase not decrease, so we'll run the same presure as always.

PMK

I have to ask as this road time trial stuff is new to me, how does the rolling resistance increase after a certain inflation pressure?

Also, are you buying wheel covers or making them? One of the local guys here had mentioned wanting covers for his next tt adventure, and I agreed it may not be a bad idea for us on the tandem if we do another tt.

PK

WheresWaldo

Wheel Covers

merlinextraligh

Here's a piece from Leonard Zinn that explains it. https://www.velonews.com/article/7508

Essentially, very high pressures (like track riders have historically run on smooth wooden veldromes) are not fast in the real world because of the energy lost bumping over road imperfections.

Exactly what pressure is going to be the lowest rolling resistence would depend on the tire, tire width, team weight, and road surface. But I'm pretty confident above 120psi, in most every situation you're into the point of diminishing returns.

PMK

Sounds like more of a suspension concerns vs rolling resistance. A bouncing tire can't hookup.

He makes mention of this in relation to the "bump" causing an inertia change to the chassis. I'm not sure on the exact best psi number.

Almost sounds as if you'll need to check power in vs speed out for a series of tire pressure bumps by 5psi. Then narrow it down depending upon the actual race surface for each tt. With minimal turns, mechanical grip should not be much of a concern.

Seems there are a lot of test parameter variables to find a true optimum.

Frame compliance, tire size, weight bias, saddle/seat post compliance, wheel compliance and so forth.

As they say, racers earn their money the other six days of the week.

PK

merlinextraligh

The "bump" is about rolling resistence. When a tire bumps upward it's costing energy that could have been driving the bike forward, and on the rear tire is interfering with the transmission of power to the road. So a tire with less pressure will roll over small imperfections and actually be faster.

A number of people maintain that the least rolling resistence in most circumstances will be in the 90-120 psi range (Zipp, Continental, Zinn for 3).

Given that our risk of pinch flatting goes up much below 120psi, 120psi works for us.

mkane77g

We have a local tt here in Sonoma County. Roads are bumpy on some portions, and using Michelin Pro race tires inflated to 120psi made for a very unstable platform, now using 109psi which is much better. We use 12-23 gearing. Otherwise set-up standard, drop bars 4 both of us, Rolf wheels on a Co-Motion Supremo. Weve done the stage race in Oregon twice when it was sponsored by Burley, lots o fun. Combined age class, low key compared to the higher catagory classes.

Abram

...and the frame and the riders body absorbs that energy -- it is lost.

Two more for your list:

The March 2009 of Adventure Cyclist magazine had a good article on this, with a graph of optimum tire pressure vs. wheel loading and tire size. The article was written by Jan Heine, editor of Bicycle Quarterly, and reportedly based on testing. It states that the optimum "on an average road surface" corresponds to a "tire drop" of 15% -- where tire drop is the amount of deflection from the rim to the road when load is added to the bicycle. Their optimum is based on speed, not comfort. The curves of the optimum pressure were linear vs. wheel load, and steeper for thinner tires. (The optimum pressure vs. load varies more on a smaller tire than a bigger one.) A couple datapoints that may be of interest for tandem use: 28mm tire, 100lb load, 75PSI; 28mm tire, 155lb load, ~120PSI; 23mm tire, 100lb load, 105PSI; 23mm tire, 143lb load, 150PSI.

Last year I read an article in a cyclocross magazine that showed (via coasting trials on a hill) that 30PSI was faster than 70PSI on a grass surface. On a more bouncy surface, you want less bouncy tires.
To deal with pinch flats with low pressures, cyclocross racers move toward tubular tires and tubeless clinchers.

pablopsd

Revisiting this post while doing some tire research. Lobbying the stocker for some TT's this year. She is almost giving in! :-) Planning on doing the local club TT which starts in June. We have done it before, but want to, dare I say, train for it some this year. (She doesn't like the T word!) I am going to put on some aero bars, which I am comfortable with as I ride my TT bike a much during the season, and I picked up some wheel covers for our Race Lite Tandem wheels. Going to buy her an aero helmet to go with mine. What are you guys running for tires? Going with anything different that your usual rubber? How about training? She doesn't ride a single other than mountain biking, which with a young child, we don't get out and do much anymore. Stoker does like pushing and doing interval type riding, but not sure if there is anything else tandem specific to take into consideration for training. Thoughts?

merlinextraligh

For tires, we're going to run Continental 4000s 23mm in the front, and 25mm in the back. At our team weight the 23mm is probably pushing it, but with the trispoke front wheel the 23mm tire should be more aero.

As for training, lots of steady state intervals, such as 2x20, 3x20, 4x15 at or just below lactate threshold.

The only difference we've found in training is that a slightly lower cadence seems to work better for us, than I would ride on my single bike. I would typically do a TT with a cadence in the high 90's to 100. I've found, however, that my stoker tends to put out more power at little bit lower cadnece where she can feel the resistence more. So we'll be working with a lower cadence, around 85 rpm.

The challenge in any time trial is measuring the effort so that you don't blow up, but you also fully spend yourself. Getting this right would appear to be that much more difficult on a tandem, so that each rider is doing all the work they can, but not too much work.

Other than working with HRMs, the only answer I have for that issue is a lot of time in the saddle. (I refrained from using the acronym,given the more genteel nature of the tandem forum.)