mtnbke

I thought I'd start a thread regarding big tandems (those that are bigger than 63cm virtual or otherwise for the Captain) and also to discuss available components for Clydesdale tandem cyclists.

So let's see some pics of some BIG tandems!

Lightning now offers tandem cranks, including up to 200mm. These have a 285lb weight limit. High zoot, featherweight tandem cranks. Curious to see the $/g saved ratio on these compared to other tandem upgrades. Notable here because they now make the tandem cranks to the aforementioned 200mm size, previously they had only been making 'em to 190mm.

Lightning Tandem Cranks

Zinn/High Sierra still make their square taper tandem cranks in sizes up to 210mm, I think.

daVinci makes cranks, but although they start their range at 150mm, they stop on the long side at 180mm. Until now. daVinci is going to do a limited run of 200mm cranks. You can get Tandem-Captain's cranks, road double, road triple, whatever you want. However, regardless of what pedal threading or interchangeable spider you select, you can only get 200mm, not any custom size.

However, at $220 these are going to be a steal for custom long Captain's cranks, let alone road double/triple or mountain triple for 200mm.

If interested visit the Serotta forum thread:

daVinci 200mm Special Order Crank Thread

mtnbke

I have a set of the Zinn/High Sierra Tandem Captain's cranks in 200mm, or I'd be getting a set of these myself. I'm still planning on getting a tandem set for my Dad, though.

Some info on Crank Length for those of you using clown cranks, who just might not understand:

Zinn of VeloNews and a 6'6" cyclist himself:
https://www.zinncycles.com/cranks.php

Some graphical data on length/spin from Customcranks.de:
https://www.customcranks.de/en/cranklength.html

And some (mis)information from Sheldon to boot:
https://www.sheldonbrown.com/cranks.html

Ritterview

The DaVinci's look like a good deal.

If you are comparing external bearing tandem cranksets, then the comparison is with the FSA.

• The FSA SLK Carbon Mego Exo Tandem Crankset weighs 1820 grams and costs $805.
  
• The Lightning tandem crankset weighs 1300 grams, and costs $1680.
  
• The difference in cost is $875. The difference in grams is 520, about a pound.
  
• $/gram is $1.7.

That is low hanging fruit.

Another thing, is that you aren't giving up something, or making a trade-off. The FSA doesn't have any other advantages over the Lightning that I am aware. Not so with many other weight savings, e.g. wheels.

The savings are in one fell swoop. No piece-meal gram shavings. One pound. Gone. Just like that.

Unlike items like wheels, saddles, etc., cyclists don't so often change out cranks. They become married with the frame, and never part. If together the frame and cranks are heavy, this will discourage any other efforts to make the bike lighter. You could strive mightily to save 50 grams here and there, but the extra 500 grams you put in the BB shell will forever mock your efforts. So, you'll not try, and heaviness will be the bike's immutable destiny.

mtnbke

I, personally, am not at all a fan of the external bearing crank.

I talked to Leonard Zinn about this (his shop is nearby), and while there are some significant advantages that come with the external BB such as allowing for a larger bearing and thus a larger diameter/stiffer/lighter crank axle, the disadvantage of significantly increasing the Q-factor has to be considered.

I think its silly that all these years later after the Magic Motorcycle crank introduced the external BB, that it is just silly that BB shells haven't increased in size to allow the advantages of the larger bearings but only inboard. Using a vestige BB shell designed for square taper and compromising the fit of the bike with outboard BBs just makes no sense to me. Its one thing to retrofit, but new bikes?

I like the press fit Klein BB back in the day as well, for the same reasons.

I think Lightning is the only external BB Tandem crank being made longer than 180mm (goes to 200mm now). All the other long armed Tandem cranks are square taper if I'm not mistaken (Zinn/High Sierra, and daVinci).

zonatandem

Back in the early 1990s co-designed a custom tandem for a guy 6'7" with a stoker that's 5'2".
Bullseye made us a set of custom 220mm cranks with a custom Bullseye eliptical cross over chainring for the pilot. Had the front BB on that tandem raised a bit so cranks would clear on corners.
Stoker's crossover chainring was same amount of teeth. Crossover chain did a bit of an up/down dance when they were pedaling but worked out great for both riders.

TandemGeek

From December when the long-crank discussion last came up, the still unanswered question to you [mtnbke] remains:

What's your inseam?

My question and curiosity as to your inseam length was prompted by your response to 6'1" tall Murf524 who reported doing just fine on 175mm cranks, to wit:

mtnbke

TandemGeek my cycling inseam is 99cm.

Using the one calculus (.216) I should be on nearly 215mm cranks. Using the more conservative approach (.210) I should be on 210mm cranks.

I use 205mm cranks on my touring bike, 200mm for the tandem captain's cranks, and 185mm (due to BB height) on the mountain bike. I'm building up another road bike and I'll probably use 200mm on it due to the Davinci deal.

To me its absurd that a 6'1" cyclist would believe that he was optimally efficient on the same crank length as some Basque climber who is 140lbs dripping wet and stands 5'7" in his dreams.

Over the course of the fifteen sizes from 49cm to 63cm, let alone the old touring frame size offerings from 17" to 27", I think its absurd to think that 170mm and 175mm cranks are appropriate. The real reason that 165mm, 177.5, 168.5, and 180mm cranks are no longer offered typically in the marketplace is because it increases complications in terms of production and the supply chain, not because these aren't a more appropriate fit for the range of cyclists purchasing the components.

For almost all tall people, they receive a disproportionate amount of height from their leg length than from their torso. It is very uncommon to find a man over 6'1" that has a proportionately longer torso than leg length. Which is why its absurd that frames 60cm and up come with 175mm cranks. It is laughable that a 63cm bike comes with 175mm cranks for any of the cyclists that fits that frame.

The reality is that most cyclists really don't understand bike fit. Most bike shops completely don't understand bike fit. The fact that most roadies spend 99% of the time on the hoods tells you everything you need to know, that their bike is completely the wrong size.

I'm the fattest cyclist I know, and I can comfortably ride in the drops. Then again, my bike actually almost fits, and the proportional length cranks allow for a 3cm drop in seatpost height compared to where I would be if I had clown cranks.

Thoughts?

TandemGeek

I'm happy to hear you've figured out what works well for you.

Dean V

What is your typical cadence with 200+mm cranks?

hairnet

3cm lower with the seat post but your feet come 3cm higher in addition, I can only imagine that feeling awkward. I too want to know how these long cranks affect cadence because I "should" be on 200mm cranks.

Homeyba

You'll probably have a slightly slower cadence. You could have the same cadence with increased foot speed. There's been a lot of debate about crank length. I'm kind of in the middle on it. For guys like Mike who are way out of the norm size wise they are probably quite beneficial I'm not convinced it's that big of a factor for the rest of us.

mtnbke

The absolutely staggering thing is how much more wattage a Clydesdale cyclist can put out with proportionately size cranks. I mean staggering...

With clown cranks (175mm) you can't effectively climb, and a ridiculous cadence is the only way to try and move the bike. If anyone has ever put bigger tires on a Jeep without regearing you'll kind of understand the problem with cranks that are too short. While the cyclist may have power, the cyclist/bike can't get that power to the rear wheel.

You have to be careful with proportionately sized cranks. I deliberately didn't choose 215mm cranks, or even 210mm cranks. I went kind of conservative on my touring bike, and even more so on my tandem.

The problem is that any bigger guy probably played a little competitive basketball or football, and has stronger legs. You can get yourself in trouble all of a sudden pushing ridiculously high gears, which isn't good for your knees. The trick is to realize what your natural cadence is.

The problem is that what worked for Marco Pantani isn't going to work for a Clydesdale that is at least 100lbs heavier and probably at least a foot taller than El Pirate was, in terms of spin.

Zinn now rents adjustable cranks on the website. You can take different rides and set 'em for all kinds of different lengths to figure out where you "should" be. The problem is that any serious cyclist will take at least a couple of weeks to figure out their natural crank length after a lifetime on clown cranks. The trick is to find that perfect length...

I think it would honestly take me a month with the adjustable cranks to settle in. Then again, I'm the guy that bought a Look Ergostem because I like to keep dialing in fit across different bikes (and its instrumental in fitting women and showing them that their frame is just WRONG for them - top tube length).

mtnbke

Really interesting graph from Customcranks.de related to plotting "shortcrankers" versus "longcrankers" from the historical Pro Peleton:

https://www.customcranks.de/en/cranklength.html

Homeyba

An interesting quote from that web site too.
"Better performance then ever before was reached about 14 days later (but for this it can not be ruled out, that psychological factors where not less important than the actual size of the crank)"

To be honest, I would say your on the right track mtnbke for you. With your 99cm inseam you are way out of the norm. I'm not too positive that it's that big of a deal for the rest of us. I'm pretty tall too at 6'3" but I haven't realized any major benefits from longer cranks. I have to admit I've maxed out at 180mm and most of my bikes have 175mm cranks on them (I can't tell the difference). According to that chart I should be between 180mm and 190mm. Don't forget the additional crank length can put additional stress on the knee. To someone who might be interested in this I'd say, do your research and make your decision based on that. I don't know if I could tell someone that this is a major benefit.