rdtompki

I'm wondering if other captains find themselves with a lower saddle height on the tandem versus single? My perception on the tandem is that the torque versus pedal rotation angle on the tandem is different; I have to create relative more torque at the extremes of the pedal stroke on the tandem and that seems "easier" with the seat slightly lower.

Of course the lower seat may help at the bottom of the stroke, but produce less torque at the initiation of the stroke.

Carbonfiberboy 

Nope. Sometimes each of us will remind the other, "Circles!" Especially on a hard hill, it's easy to fall into stomping without realizing it. Since it's you who notices this, you could try putting Stoker a link ahead of you. We find that even half a link off, sometimes unavoidable, is noticeable. In any case, it's an artifact of pedaling while attached to someone else,

Chris_W

It definitely sounds like you need to play around with different pedal phase combinations before you start playing with your saddle height.

jacks1071

Seat height should be the same as your single, assuming its set correctly on the single?

I use a plumb bob off the nose of the seat to measure how far the nose of the seat is behind the bottom bracket to ensure you get the seat in the right place in relation to the cranks.

merlinextraligh

+1 on same seat height. As much as possible, my position on the tandem duplicates the position on my single road bike.

Doing otheriwse, imho, risks injury, and is likely less efficient than trianing your body for one consistent position.

rdtompki

Can't really adjust the phase on our daVinci. Stoker has tried to go OOP, but automatically reverts in in-phase. I might try a more deliberate experiment on the flat, starting with the pedals stationary just slightly out of phase.

I do have the tandem set up identical to that on the single except for the handlebar height; this is constrained by the steel fork I'm using temporarily while my fork is getting new clear coat.

I think one of the things that's going on is that stoker has very short femurs. This may be affecting the torque curve causing more of a drop off at the bottom of the pedal stroke.

waynesulak

+1 I believe that more than one position for hard road riding presents additional physical challenges to the rider. Some can handle this for short time periods or at less than full effort or if the rider is highly functional. I don't need the additional challenge of different positions if it can be avoided.

obrentharris 

A few things that come to mind...
Are your crank arms the same length on both bikes? Same height pedals? Identical saddles or saddles with similar flex? Same saddle angle? Also jacks1071's suggestion is an important one: Relative fore-aft position of saddle and pedals can make a surprising difference.

Perhaps stoker needs shorter cranks?
Brent

Carbonfiberboy 

You're both running clipless, right? We consciously try to exhaust the quads and hams at the same rate. Ideally, one will cramp both muscles at the same time . . .

rdtompki

My tandem cranks are longer, this in an attempt to slow my cadence on the tandem. I've compensated my saddle position for the longer cranks (180mm tandem versus 172.5mm single). In retrospect, realizing that stoker's femurs are short and she needs her saddle way forward, might have been better to go with 160-165mm stoker cranks versus going up 5mm on the captain's cranks.

jacks1071

I'd been suffering with VERY sore legs on our tandem. I had the nose of seat to bar distance same as my single and when I got the plumb bob out it turned out due to a different seat angle on the tandem I had the seat 45mm further back on the tandem than on my single. Moved the seat all the way foward (still wasn't quite the same as my single but close), put a long stem on to get the seat to bar position right and WOW. Much more power, no where near as much fatigue and I've now got quite a long stem on there which gives me even more leverage on the 46cm bars.

Before this I really didn't feel like I was getting any fitness benefit from the Tandem, it was just hard work everytime I got on it.

Also I have 175mm cranks on the tandem, 172.5mm on the single so the seat height is 2.5mm LOWER to compensate for this.

StephenH

With both of the stokers I've had, I set up the tandem by measuring their single bikes. In both cases, the pedals on the tandem are farther in front of the saddle than on their single bike. So I can' adjust it where saddle distance from cranks is the same, distance from saddle to handlebars is the same, etc., but can't exactly duplicate the overall postions, either- it's just different frame geometry.

waynesulak

It is possible to flip a Thompson setback seatpost forward. This would compensate for a 73 degree seat tube angle on most tandems vs steeper seat tube angle on the stoker's single.

From FAQ on Thompson site:

– Can I flip my set back post around to be a “set forward” to use my road bike for triathlon?
A – Yes you may. You may need to turn the top clamp to face the front of the bike for saddle adjustment.

https://bikethomson.com/seatposts/elite/

If the stoker spends significant time on both her single and the tandem, I think it is well worth a try to get this right. A different setback changes the muscles most used while pedaling. If the stoker is going to get the consistent training the set back should be the same.

Onegun

Precluding any physical limitations on the rider's part, I have to disagree with you on the "risks injury" part. Ideally, your road bike will be set up differently than your time trial bike, which is different from your mountain bike which is different from your road tandem which is different from your mountain tandem which is different from your fixie, etc, etc. Yet we ride them all with no injury.

Generally, and within certain limits, pedaling is pedaling. There is certainly such a thing as a saddle that's too low, and also one that's too high. But between those two extremes are multiple settings that are perfectly comfortable, physiologically safe, and appropriate to that particular machine/riding style.

That having been said, note that it is also true that the more you train for competition, the more the validity of the above statement diminishes for you personally! Jacks1071 notes making an alteration of 2.5mm to compensate for crank length. That's tiny! Just shy of an eighth of an inch! But many racing or go-fast enthusiast riders I've worked with become that sensitive and more. To wit, how many times have you heard Liggett or Sherwin comment on the fact that even a rider's own "back-up bike", (which is an EXACT duplicate), just ain't the same? And that's where, (I believe), the majority of the anecdotal evidence for "one correct height" or "risk injury" is born.

So all of our bikes, (including our tandems), are set up initially as a reasonable duplicate of our singles, then adjusted from there to whatever "feels right" on that particular bike. And in this case, the saddle on our road tandem is ALSO lower than the one on my road bike.

merlinextraligh

Seat Height that is either too high or too low can definitely cause or contribute to problems such as Patellar Tendonitis, or Chondromalacia.

https://firstplaceosteopathy.com.au/page15/page15.html

So if you start with the premise that the seat height and position is optimal on your single bike, and then change it on the tandem, by definition its going to be sub optimal.

And by lowering it, you increase the potential to develop Chondromalacia.

Now the likelyhood of that is going to depend on how susceptible you are to the problem, and how far off your position is. However, it makes sense to figure out your optimal position and try to replicate that as much as possible.

Onegun

Agreed. As I said, there is such a thing as TOO high or TOO low. If your hips are rocking, it's too high. If you aren't getting a reasonable leg extension, it's too low. But between those is two is a RANGE of acceptable heights. To wit, racing cyclists of today ride as a matter of course with a saddle height much lower than we did back in the 70's. Neither setting seems to cause any more injury.

Disagree. The seat height and position is optimal FOR your single bike. I'm arguing that "optimal" varies by bike design and usage. Even IF your position on the tandem EXACTLY replicates the geometry of your single, it's NOT the same bike, and you DON'T ride it the same.

True. And there again it appears to me the problem is vastly overstated. In 15 years of working with racing cyclists in the bike business from the early 70s to the mid-ish 80s, I didn't know of a single one that developed any significant knee injuries. But, like plane crashes in this day of the internet and the competing 24 hour news channels, why, they happen all the time!

Agreed. As I said, that's the starting point, anyway. And I infer from what the OP said that he does that too, but wanted to know who rides more comfortably therefore more efficiently and without injury on a slightly lower saddle height on their tandem. That's me.

waynesulak

Here is where I feel that a lot of smart people with lots of time working with racing cyclist make an invalid assumption. That is that riders with various orthopedic and connective tissue problems that have accumulated over decades of paying sports have bodies that react to a long very hard ride the way that a 20 year old racing cyclist body reacts.

If an individual has a body that is structurally sound, flexible and reasonably strong then that body can adapt to a wide range of positions. Even such a cyclist however when coping with a less than optimal position will often produce less power as his body automatically uses some energy to stabilize itself while in a less familiar position on the bike.

Take out the structurally sound, flexible characteristics and you are left with a body that has a very small range of adaptability that will produce much less power and is more quickly injured. I don't know the OP but I believe that demographics of the tandem community tends to be more toward the empty nester than the 20 year old racer.

Carbonfiberboy 

Hanging out on the T&N forum, and from personal experience, knee overuse injuries are fairly common. I've had several myself. It's true that people in their 20's get them a lot less often and are less susceptible to these problems, but most of the folks on this forum are closer to 60 than 20, which for all the denial we may do, does make a difference. I've been able to eventually fix all my knee overuse problems through a combination of position adjustment and stretching.

Probably because I'm used to a particular bike position, I can absolutely feel when my saddle is adjusted for maximum power generation. It has to be within a few mm. I've gone up and down a bit over the years before settling on my current position. Hence I think it is very useful to use the same position for single and tandem. Lower injury potential is another benefit of correct positioning, but a lot of it is what you're used to.

The OP is using cranks 7.5mm longer than his road bike, so he has a 15mm larger pedaling circle. I think that's a significant amount. However that might be, it won't effect his ability to pull back at the bottom of the stroke, only perhaps his ability to push forward simultaneously with the other foot. So I don't think crank length is the issue, either for him or his stoker, though if he has a set of shorter cranks lying around, it'd be worth a try.

I'd try doing some one-legged pedaling on the single bike. If not on the trainer or rollers, then while climbing. I think that'd be most likely to fix the problem or help the most, anyway. My diagnosis is that it's just stoker drag. Easier for captain to deal with it than to fix stoker! I know a local team with the same problem. I think they've finally quit fighting about it. My stoker hates OLP pedaling drills, but that's OK. We pedal about the same anyway.

My method of setting saddle height is to put the heel of my bike shoe on one pedal at a time, and fully extend that leg. My legs should completely lock out with either no pressure on the pedal or up to 4mm clearance under the heel. No hip rocking. Most people get a slightly different result with each leg. I average them.

wheelspeed

I would also guess that, since you feel more resistance at the extremes, you should remind your stoker to try to pedal in nice, round circles.
I can't comment on matching my single to the tandem since the two bikes are too different to bother. My single is an old-skool racing bike that would be uncomfortable except for my being forced to stand up pretty often due to the old-skool gearing. Concerning the tandem- I'm scared to stand up on it, and it has a granny, so it's set up for comfy spinning.

StephenH

I'll have to look into that. I'm due to swap saddles out in a week or so anyway, and that would be a good time to do that. (Current seatpost is not a setback seatpost, by the way. And it hasn't been an issue with either stoker that I know of.)

zonatandem

Stats:

Saddle height on tandem is same as on my racing bike.
Stem is 1-inch higher on tandem than single.

Am 80 years old, still ride 100+ miles a week.

So far 300,000+ miles of bicycling since the early 1970s.

And, no knee problems . . .yet.

I must be doing sometthing right!
Can hardly wait 'til I get older!
Rudy/zonatandem

rdtompki

I did succeed in getting both single and tandem at the same height and feel with the tandem 5 mm lower due to the longer cranks. The seat height felt really good on our 100K this past weekend.

At this new seat height on both bikes I'm going to have to find something other than an SA saddle; the saddle is really too wide and I especially notice this when I'm working hard and the backs of my legs are really rubbing on the saddle.

Carbonfiberboy 

My problem, too. I need a T-shaped saddle. It would be nice to think it's because I have such powerful hams, but it's more likely that my legs are too close together, just like my eyes.

I use this saddle on all my bikes:
https://www.performancebike.com/bikes...30_-1___400195
This looks interesting, too:
https://www.performancebike.com/bikes...551_1086876_-1
and this one:
https://www.performancebike.com/bikes...12_-1___400195

When I was looking, I ordered three saddles at a time from Performance and sent back the ones that didn't work, usually all of them. I washed them and put them back in the original packaging with new zip ties. I never saw any scarring on the rails.

sine

Keep the saddle height and position related to kops the same as your single road bike. Crank length too and use the same saddle.

Work with your stokers (and yours) pedal stroke. Using something like spinscan (Computrainer) is a great start. Basically utilize many more muscles than you think including lifting legs over the top.

Cadence should be the same too.

ksisler

[;-) Wow; your stoker actually pushes on the pedals instead of just going 'round & 'round. That must really help on hills also!!!