124Spider

We're running up against a problem we really hadn't anticipated, and I'm hoping we don't have to reinvent this wheel; any help would be much appreciated.

We're really enjoying the tandem, and my wife is working hard to up her game to contribute more than 1/3 of the total power. Obviously, I don't really need a lot of help for level or downhill portions, but uphill on a tandem is not a lot of fun (and I'm a guy who enjoys charging up a hill on my half-bike), so I can use all the help she can give on the uphill portions.

When I'm going up a hill (or, indeed, when I'm working hard even on level ground) my cadence can go quite high, well into the 90s. On a long ride where I'm putting in a fairly maximal effort on my half-bike, I'll average 85-88rpm; when riding by herself, my wife will be in the low-to-mid 70s.

She's happy to spin as fast as I want, but she literally is doing all she can do to move her pedals at 98rpm; she cannot apply significant force to the pedal at cadence above 90. And I need the high cadence to comfortably put down high power.

We'll be experimenting on local long, fairly steep hills to see if perhaps we can comfortably slog up a hill at 85rpm (I don't mind going slowly, as long as it's fast enough to not fall over); we think that she'll be able to contribute meaningfully at that cadence.

Any other suggestions?

Thanks!

Mark

Carbonfiberboy 

My Stoker is just the same. The issue is VO2max/aerobic capacity. As you know, the higher the cadence at any given power (speed), the higher the HR. Respiration goes up with HR. Thus pedaling faster at a given power uses up more of the riders aerobic capacity. The folks who pedal 95 up steep climbs are all folks with exceptional VO2max. IOW, nothing to be done, really. One can train to increase cadence somewhat. A good way is to put the single bike on a trainer and pedal as fast as possible in a very tiny gear for as long as possible, increasing the interval to up 30 or even 45 minutes, as possible. This creates a slightly more efficient pedal stroke at higher cadences, which helps a little. Another thing is to go out on the tandem and simply pedal 100 cadence for a steady 30' or as long as possible, on flat or very slightly rolling terrain, holding the same HR and cadence by use of the gears. Doing that, Stoker has Captain's pedals to help guide her force production in different parts of the stroke, which helps with synching up.

However even with lots of careful work, the difference is still going to be there. So what I do is simply drop my cadence down until I can feel Stoker's power and leave it there. You can learn to pedal more slowly even more easily than she can learn to pedal faster. Try dropping it down to 78 on climbs. Watch Eddie Merckx videos. He didn't pedal any 90 cadence on climbs, of course that's the gearing they had back then. We can do multi-thousand feet climbs in the mountains, slowly and with a lot of hard work, but we can do them and both enjoy them.

surak

I have the same issue, my natural instinct is to spin up faster on climbs. If the bike has the gears, I will sometimes exceed 100 rpm on climbs. On the flip-side, going below 90 rpm actually feels horrible to me (I just started a thread in the Bicycle Mechanics forum asking how to deal with this on my road bike). Strangely enough, I've sucked at all other forms of cardio exercise my entire life, so aerobic capacity can't be the only reason for my natural cadence.

My wife only does casual rides and doesn't want to ride anything except our tandem anymore, so training her cadence up isn't feasible. For about a month, I trained to deliberately go 10-15 rpms slower than I would normally, in all conditions. It seemed to help a little on the tandem, at least when I pay attention. Probably not the best solution, but just throwing it out there to a fellow spinning captain.

mtseymour

The biggest factor in changing cadence is technique. I used to think that 90 rpm was high, but I've learned to vary my cadence from 60 to 130 for different situations. The best way to learn is at a spin class with power meters (eg. Cycleops) and qualified instructors. For example, a Cycleops Phantom 3 has accurate power meter, cadence, and heart rate. Don't waste your time on spin class with loud music and converted aerobic instructors.

There are certain exercises (eg. one-leg drill) and techniques (using core muscles) to increase cadence to 100, 110, and 120 rpm. There are also intervals to increase power at low cadence (eg. 60 rpm at 100% threshold). A good instructor can help with body position, pedal stroke, etc.

Every rider has a preferred cadence, but proper training will allow you to slow down a bit, and your stoker to speed up.

Alcanbrad

reburns

jnbrown

I also have the same issue, but notice it most when we are standing while pedaling. My wife has gradually adjusted to a higher cadence. I prefer 90 RPM or higher but I am willing to compromise and go as low as 80 RPM for periods. One thing you might consider is your stokers crank length. My wife feels better with 165mm cranks although her legs are almost as long as mine and I ride 170mm but she is 6 inches shorter than me.

OneIsAllYouNeed

Carbonfiberboy 

A very good way for a captain to train lower cadence technique is to get on a long 3%-4% hill on your single and put in in a big gear so you're turning 50-55 (yes, it has to be that slow) at your usual climbing HR or power. Keep your upper body completely still and just rotate the pedals with your legs. You'll have to pedal full circles, maybe even pulling up in the back. The object is to train your ganglia to fire your muscles correctly at lower cadences. Once or twice a week, say 3 X 10' repeats. I've done this every spring for a few weeks. Or if you're really cruel, do it on the tandem so your stoker can benefit, too.

124Spider

Yeah, this is essentially what we're planning to do. We have a half-mile hill nearby that's a half-mile long, and averages about 5%. If we can work out a low cadence in our lowest gear that works for both of us (especially during the 8% portions), that could help us learn how to do that.

lichtgrau

Does someone ever tried to work on that issue with different chainrings for the timing chain?
Crazy probably and disadvantageous in other ways but quite easy to test without huge modifications.
I just wondering if anyone ever tried...

prathmann

I converted our tandem to a 'kid-back' arrangement years ago when our daughter was little using a variety of miscellaneous scrounged parts. Her crankset was from a child's bike and had a different number of teeth than on the cross-over ring on my crank. So we had a constantly changing phase difference and people riding with us said it looked very strange. Not really a problem for a kid-back where the stoker isn't contributing much power but I wouldn't want to use the arrangement with an adult stoker. Another issue that would arise on a regular tandem is that the captain wouldn't know how to position the cranks in a sharp turn to avoid a pedal strike by the stoker. (On our kid-back the stoker crank was mounted up high on the rear seat tube so no issues with a pedal strike.)

PDub62

You may want to consider changing crank arm lengths. Specifically, go shorter for the stoker and/or longer for the captain. If you drop her crank arm length it will allow her to spin at a higher cadence; in essence, her foot speed stays the same but the cadence goes up. I have a triple w/ a child stoker kit and my 7 year old has no issues spinning at my typical 90-105 rpm cadence because her crank arms are so short. An alternative to buying new cranks would be to buy bolt on crank arm shorteners.

124Spider

I have 175mm cranks; she has 170mm cranks. I've offered to get her shorter cranks, but she's not thrilled about losing the lever-arm length. I don't want to go longer because I already have issues with my 175 crank hitting on sharp turns if we don't stop pedaling.

mtseymour

Crank arm length should based on the rider's body measurements, not on leverage. A good bike fitter can tell if 170 is the right length for your stoker.

Male track cyclist generally use 165-170mm cranks, and they can generate really high rpm and watts. I've done training rides with track racers, and they're not short on power or efficiency over long distances (50 miles+). Given the opportunity, most road racers will do some training in a velodrome to improve their pedaling efficiency.

Mainstream brands recognize that more cyclist can benefit from shorter cranks, and now offer 170 or 165 arms even on flagship models (eg. Dura Ace R9100, Sram Red).

prathmann

Has she tried shorter cranks? I regularly switch between 165, 170, and 175mm on my different bikes and they all feel fine - but I do naturally tend to pedal at a little higher cadence on the 165s. It doesn't seem as if the extra 'lever-arm length' is getting you anything useful if the result is that the pedals are moving too fast for her to contribute much power.

OneIsAllYouNeed

Lever arm length from cranks doesn't matter when the cranks are moving over 30rpm. That's a bit of old-school thinking like 23mm tires and 160psi being fastest for everyone all the time. It does take time to adapt to different crank lengths. The most pronounced difference is when launching from a stop.

For the captain cranks, is your eccentric in the "up" position or "down"? If it's down, you could gain a few mm of clearance to allow for longer cranks.

Simple maths related to you problem:
Change just one set of cranks:
87 rpm / 74 rpm * 175mm = 205.7mm
74 rpm / 87 rpm * 170mm = 145mm

Meet in the middle:
87 rpm / 80 rpm * 175mm = 190mm
74 rpm / 80 rpm * 170mm = 157mm

Your actual options for cranks depend on your gearing and bottom bracket configurations.

Carbonfiberboy 

Do stock 165 stoker cranks exist?

124Spider

Da Vinci has them, I think.

diabloridr

Beloved stoker only uses 165 cranks on all her bikes.

When we were building up the Macchiatto last year we identified Middleburn & Lightning as readily available sources for our needs (We opted for Lightning).

noglider 

You've received lots of scientific answers, and they are good. My advice is on the interpersonal level. Do whatever makes your wife comfortable, at the expense of your comfort. This will build harmony. My wife doesn't often ask me to shift or coast, but when she does, I do what she asks.

My hope, in getting the tandem, was that it would make riding easier for her. It's starting to come true. What I didn't expect was that it makes riding harder for me. So we are equalizing but at both ends of the candle at once. We recently took a short ride towing a cargo for errands. I was exhausted at the end. And it's a form of justice, so I'm getting used to it.

Mr IGH

I too am in the "make the stroker happy at all costs" camp. I am lucky to have a nice lady that enjoys my company and likes to ride together on my tandem. I'm a spinney punk that dreads low revs. Well, I manned up and I'm learning to slog it out at 70~80rpm instead of 90~100rpm. BTW, different crank length translate linearly to rpm. If you have 175mm and your stroker has 170mm that shifts rpm by 170/175 = ~3%. Every little bit helps!

LV2TNDM

Yeah, I wouldn't change crank lengths to address cadence incompatibilities. Femur length determines ideal crank length, so it wouldn't make sense to compromise crank length to force someone into a higher (or lower) RPM.

Has anyone tried using different timing chainrings to accommodate different cadence speeds & styles? I was so lucky to have fallen in love with a woman who naturally spins the pedals. She had such great technique on her first ride with me, I was amazed. I asked, "How did you learn to spin so well?" She replied, "What's 'spinning'?" I just told her to just keep doing what she was doing! Only later did I truly appreciate her leg speed when we got the tandem. Such is luck, I guess.

And I don't think I'd last very long on a ride opting for a much lower cadence for me up front to accommodate my stoker. Not being selfish here; I just KNOW it would just be a matter of time before I threw in the towel. I was on a climb a few years back on a bike with less than ideal low gear. The couple I was riding with was happy climbing at a certain speed; they could accommodate decent cadence whereas I was nowhere near where I needed to be. Although they were much fitter than me, I decided to ride ahead to give my knees some relief. I just couldn't tolerate the low cadence for much time. So I guess I'm saying that asking one or both parties to compromise their cadence is not the solution.

So I've been on a just a few bike and tandem forums over the years but don't really think I've come across a tandem pair using different timing rings. Out of phase, absolutely, but not different ring sizes. I realize this will present a potential serious hazard when it comes to cornering, as the crank positions relative to one another will keep changing. I wouldn't want to have to even think of that issue while riding. But if it were to allow two very different styles to ride together, then perhaps it's worth considering. But damn, I don't know about that still. You've have to have some pretty clear communication on crank positions for corners throughout the entire ride!

Anyone care to offer insight or experience?

joelcool

I'm in the "make the stoker happy" camp. I bought the tandem so my wife and I could ride together - not so I could somehow convince her to ride like I do. So I slow down a bit, and she tries to trust me a bit.

124Spider

To clarify, this is not about a power struggle between captain and stoker (as I'm pretty sure I made clear earlier). It's about how best to deal with significant physical differences causing problems.

If I could painlessly (and effectively) pedal uphill at 75 rpm, and get us there, I'd do it in a heartbeat. Likewise, if my wife could pedal at 95 rpm, and put down power, she'd be happy to do it. We're not fighting; we're trying to solve a systemic problem!