Tandem crankset options
 

I am starting to plan on building a high end road tandem, with a weight weenie theme. From what I can gather, the choices available for tandem specific cranksets are limited.

Assuming a standard tandem triple, with the timing chain on the right, the possibilities include the FSA and Stronglight.

FSA SLK TANDEM CRANKSET

http://www.webcyclery.com/product_image.php?imageid=512


The Stronglight Duolight Tandem

http://www.xxcycle.com/marques/stron...andemImgHR.jpg

Da Vinci cranks

http://www.davincitandems.com/images/crank4.jpg


The FSA has external bearings, the Stronglight an ISIS bottom bracket, the daVinci a square taper BB. None of these would be particularly high end on a road bike.

Are there any better options out there?

Timing chain on the right? That's not standard.

How WW are you trying to be?

None of the crank options are light, even if you go used Campy or Shimano. Either the weight is in the cranks themselves or it's in the bottom bracket. Your best bet might be the FSA SLK.

Save your weight in other areas.

Er, the other right. The left.

The last time I got an FSA crank, the left side crank arm had come loose and fallen off within 26 miles. FSA doesn't have the greatest reputation for their cranksets.

http://i43.tinypic.com/28i19qx.jpg

I'll get around eventually to fussing over the weight. First, I am interested in what options are available, especially besides the obvious FSA choices.

So, I'm suffering the same dilemma, only I was looking at the FSA Gossamer tandem cranks. I talked to my friend that owns a bike shop because he's been really critical of FSA gear in the past. He told me that recent FSA gear is better and that the current Gossamers are OK. We'll probably replace the BB bearings with Enduro stainless because he thinks the BBs are still not up to snuff and the Enduro bearings don't use the plastic bushings. I've got them on my singles and they are very smooth.

You could also try Tune cranks.

http://www.jdcycles.co.uk/files/prod...e%20cranks.jpg

and Middleburn also make their RS7 set for tandems. You can pair these with some really nice bottom brackets - Royce titanium for example.

There are some other options out there like Calfee CF cranks. Not sure who actually makes them.

We have DaVinci cranks, TA rings, and PW titanium BBs. They're fairly light.

Tune makes a lot of exotic weight weenie components. Their crankset, however, is considered dated. The crankset sold by jdcycles below is one demo in one size, and there doesn't appear to be any Tune triple tandem cranks for sale anywhere else. No tandem triple appears to be listed be listed at Tune's website. So, the Tune doesn't really appear to be available.

TUNE tandem x-over chainset

I did not know about Middleburn. It certainly looks robust.

MIDDLEBURN Tandem Chainset

http://www.jdcycles.co.uk/files/brands/midd.gif
http://www.jdcycles.co.uk/files/prod...set%201295.JPG

Any idea what a Santana chain line is supposed to be?

I'm measuring 52mm or so from the middle ring to the center of the boob tube and I got 55mm to the imaginary line between cog 5 and 6 on a 10 speed cassette.

The FSA tandem cranks claim to have a chain line of only 46mm which I don't think will work very well.

Any thoughts on this?

So after all this we are still left with FSA, unless you can have a set of cranks made. There is always the custom route, buy 3 old DA (7700, 1 triple and two double cranks) cranks have a shop helicoil one of the double cranks to swap them left for right, then take the second and third sets and throw away the non drive side crank arms and then helicoil the remaining double spider arm the opposite pedal thread. It will work but its expensive. Helicoil threads would be as strong or stronger than the original threads cut into the aluminum crank arms.

You could do the same with any Octilink or ISIS or square taper crankset. It would be unique and offer you a lot more choices.

Waldo, I'm intrigued by the idea. Especially since I have 1 Ultegra Octalink crank around already.

However, where did you get the coils? I only see the far more common 9/16 x 18 in the helicoil catalog and they don't mention left handed threads.

I've seen published weights that indicate the FSA Gossamer cranks are lighter than the SLK's.

We have the Gossamers. I would second the point about FSA cranks not being the most reliable. We trashed the BB's in 800 miles.

However, they're working nicely with the replacement ceramic bearings. Now if we could get the Captain's crank to stop creaking we'd be in business.

One other consideration if you're really thinking weight weenie. You might want to get a crank compatible with the Carbon fiber timing chain, which saves 10 ounces.

Not sure you can beat Ultegra for bang for your buck.

What's your definition of high end?

Better as in more expensive, more impressive brand name or what?

Successful installation of FSA's cranks requires the use of Loctite and a torque wrench with rigorous attention to the installation instructions.

Actually, the sleeper cranks in FSA's line up have always been the Gossamer models. They are lighter than the carbon models when mated with BBs of the same quality/weight, e.g., they really are 1820 grams vs. the Carbon models which are closer to 1900 grams.

Martec, same company that makes the cranks used by Santana with with a different BB interface (ISIS for Calfee, Octalink for Santana) and a range of crank arm lengths instead of Santana's spec of 175/170. They are purportedly in the same weight class as the FSA cranks, but not having weighed them myself I can't comment.

Actually, they're best characterized as very light at about 1,680 grams... much lighter than the FSA carbon jobs for a lot more money (try about $1k MSRP with Ti BBs), or a bit lighter than the FSA Gossamer ISIS for 3x the cost. That said, I've never found our daVinci cranks lacking in the stiffness, lightweight or high-fashion department and if you don't like the high-maintenance of polished aluminum you can always get them anodized for a few extra bucks if you time it right.

They're quite nice, but a scootch heavier than the daVinci. Alex Nutt of MTBTandems.com is one of their distributors and can tell you what configurations are currently available for road applications.

So, all of that said here are the real questions:

1. What's your weight target?
2. What's your threshold for pain when it comes to cost?
3. What brand / model of tandem frame are you using?
4. How will you use this tandem?

If cost is no object and you are building a Co-Motion, Calfee or a custom-job that can be fabricated with a 28.25" C-T-C boom tube you can mate a set of the FSA Gossamer or Carbon cranks up with the new Co-Motion / Gates Carbon Drive sync belt system sold by Co-Motion or WebCyclery. Sure it costs $520, but it'll reduce your 1900 gram FSA cranks to around 1,650 grams, or the 1820 gram Gossamer cranks (using the same BBs as the Carbon Cranks) down to 1,570 grams for some serious bragging rights.

And, yes, as WheresWaldo notes, you can get really creative by mixing and matching single bike cranks. Just be mindful to check and see what they're max weight rated for if you get into any exotic stuff. I contemplated making up a set of Campy Chorus carbon cranks for our tandem until it dawned on me that we'd seriously be exceeding their max weight limit as a double crankset, never mind being modified to accept a 32t granny which would have put some serious hurt on the carbon spiders.

I plan on it being a carbon frame, most likely a Calfee or Ruegamer.

If I am to claim the weight weenie mantle, I will need to use this Co-Motion/Gates Carbon Drive system, as a WW can hardly pass on 283 gram weight saving opportunity.

Co-Motion/Gates Carbon Drive Timing Belt System

http://www.co-motion.com/information...ges/CarbDr.jpg

http://www.co-motion.com/information...es/CdriveR.jpg

If I get a custom, such as a Rue Sports, I will need to make sure it has a 28.5" boom tube length. Calfee's tandem frame specs do not include this length. Aha, this boom tube length consideration shows I was right to start building the tandem out from the drivetrain.

The 130 mm BCD timing crankarm spiders are relatively common, and does not mandate FSA, although the FSA is the apparent default choice.

I've been trying to figure out why a Campagnolo drivetrain cannot be done. It must not be, because I can't find any examples save for the early 90's Campy tandem group.

Campy still offers a triple crankset, using its venerable square taper BB from the 2006 era. It is listed as being 788 grams, and being of Centaur level. 'New' 2006 Record triples and 200 gm bottom brackets are still available, and these for cheap.

Opposite the triple on the left side, the square taper could have a 2006 Carbon spider, with a timing chainring instead of a double.

http://www.chainreactioncycles.com/I...Full/25838.jpg http://www.excelsports.com/image200/...%20Bracket.jpghttp://www.jejamescycles.co.uk/produ...kset-19975.jpg

The captain's crank could use a Carbon record spider on the left, with the the 'left' crankarm on the right. The Campy UT has the same Q factor as the square taper, and possibly it could be used. This would save some weight (which the Campy triple/BB probably would not).

Perhaps Gates could be persuaded to make a carbon belt 'chainring' for the Campy 135 mm BCD (I emailed Gates, and their rep replied that they had no current plans for Campy 135 mm BCD, nor were they concentrating much on tandems at present. Dang.)

There must be some insurmountable problem here, and I'll soon find out what it is. I note, for example, that Rodriquez uses an FSA Gossamer on his otherwise Campy Record equipped tandems.

We got our Co-motion tandem less than six months ago, with FSA Gossamer cranksets and I then added the Gates carbon drive myself. We have about 1200 km (750 miles) on this setup so far, and are very happy with it. A bike shop mechanic told me to keep a close eye on the FSA cranks to check that they don't work loose, which he believed was a major flaw with all FSA cranks. We've already taken a couple of trips with the bike packed in suitcases, and I've been playing around with different chainring combinations, and so I've had the cranks off a few times. I re-install them with a torque wrench when in my workshop at home, but I tried to also learn the feel of the recommended torque so that I could install them at my destination without a torque wrench.

Their biggest test was doing 500 kms of lightly-loaded touring around Mallorca in March after doing an intuitively-guaged crankset installation in the hotel courtyard. By the end of that week, the cranks had not moved a bit, so I'm now expecting that the problem of them working loose that other people have experienced is not going to happen to this set.

As for the carbon belt drive, I never actually installed the regular chain drive, and so we really have nothing to compare it to. Again, I was originally watching it closely to make sure that the 'chainline' was straight, and that it didn't move across the rings to work itself off the inside. However, each installation has gone well and I've never needed to touch it after installation. The only complication with the belt drive is that the teeth are so small that getting the pedals perfectly in phase is not as easy as it might be with a chain drive. With the belt drive, there are about 71 'teeth' on a ring that is similar in size to a standard 42 tooth chainring. Therefore, it is pretty hard to tell whether the cranks are perfectly in phase or are one tooth off either way, and I would imagine that this would be easier to tell when the difference in angle is almost twice as much due to having only 42 teeth on the chain version. Because of this, I've often had to do several installations of the belt to get the timing right.

The belt drive has proved to have several advantages. The initially obvious one is the weight advantage, but there is also the increased longevity. Another major advantage for us is the cleanliness factor; there is no oil on the belt and it is completely clean, which is particularly useful when removing only the front section of the bike and then carrying it around in two parts to take it on Swiss trains and hanging each end on a separate ceiling hook in the train, which we do quite often (we don't own a car). The other advantage is the wow factor, which we hadn't expected to get to such a degree. There were a LOT of other cyclists in Mallorca when we were there, and they all enjoyed seeing a tandem, but it was surprising how many of them IMMEDIATELY commented on the belt drive, some of them were asking us about it before even saying hello to us. They were often disappointed when they found it that it wouldn't be so easy to put one on their single bikes.

Campy suggests a maximum rider weight of ~180lbs for it's components and therein lies part of the problem given that even lightweight tandems team will tip the scales at 230lbs - 280lbs.

Before carbon and black grouppos became all the range Rodriquez was fitting Campy cranks to it's otherwise all Campy drive trains. However, they were using the alloy Veloce and Centaur triple models which weren't subject to the more recent weight related cautionary / warranty-voiding language applied to the newer carbon cranks which bleed over to their alloy cranks whether or not it's really a true limitation for the alloy models.

The cranks and/or bottom bracket interface must also allow for chainline adjustment and FSA has added that feature to their MegaExo cranks. Most other oversized bearing cranks do not allow for this type of adjustment. Therefore, unless you are willing to use ISIS or square taper BB and cranks your options for oversized BB cranks are extremely limited.

Quoted from Ritterview
"If I get a custom, such as a Rue Sports, I will need to make sure it has a 28.5" boom tube length. Calfee's tandem frame specs do not include this length. Aha, this boom tube length consideration shows I was right to start building the tandem out from the drivetrain."

I know that at this time Calfee is designing their bikes around the carbon drive. If you want a stretched stoker compartment they will specifically tell you that this design change will make the bike incompatible with the belt drive system.

Standard Calfee boom is 28.5. I just got the Carbon Drive setup, haven't tried to install it yet, but looks like will have chainstay clearance issues for sure, will see if I can address via use of spacers, if not next winter will send frame back to Calfee for modification.

That's because it is not in the normal Helicoil catalog. I got a set from Bike Tools Etc. as I was planning on doing just what I outlined. I still may do it some day. Here is a link to the tools:

Sorry, but when R+E picked parts for their 26.8-pound steel Trillium tandem they chose a DaVinci crankset:

http://www.trilliumcycles.com/profil...liumtandem.jpg

http://www.trilliumcycles.com/profil...tandem_cu6.jpg

IIRC - DaVinci's are the lightest of any tandem specific triple cranksets outthere. I also like the fact that their timing rings are attached to the arms and will be "true" compared to the typical chainring on a spyder. My only dislike is having to use a square taper bottom bracket.

Another nice thing about DaVinci is that you can order the crankarm lengths that you want; ours has 170's in the front and 165's in the back.