Tandem Cycling - Co-Motion Frame Stiffness

After a lot of consideration I have decided to get a Co-motion custom bike; either the steel speedster with S & S couplers or their aluminum roadster. Has anyone had experience with these bikes and would there be significant difference in terms of frame stiffness between the two. I am 6' 6'' 230 lbs and my wife is 5'9" 150lbs so together that is 380lbs. Initially I was leaning towards the speedster co-pilot, but a friend of mine who has had a lot of experience (rides Paris-Brest with their tandem) said that I should strongly consider the aluminum frame for the added stiffness.

The steel S&S and aluminum rigid frame are pretty different machines... Are you sure you've nailed down your requirements, e.g., S&S for travel flexibility or aluminum for all out performance?

Given the differences in these two finalists, have you talked with Dwan Shepard, Dan Vrijmoet, or Alan Cline at Co-Motion to get their recommendations? Regardless of which dealer you are working with, I would still recommend speaking with the guys who design the bikes, let them understand your needs and expectations, and listen to what they have to say about the qualities of their respective frame choices.

Toll-Free Phone: 1-866-282-6336

There's no way we're going to be doing any Paris-Brest any time in this lifetime, so you may consider my opinion less expert than your friend. We ride a Trek T2000 and it's comfortable enough for our club rides, tours and metrics. It definitely accellerates much better than our first tandem, a steel Burley Duet, but if I was shopping for the last bike I'm gonna buy and carry around the world for short and longer rides, and choosing only between the two, I'd go with the coupled steel.

If you want stiff and coupled, you have to look beyond Comotion. I know Santana sells coupled steel, alu, ti and CF bikes. Not everyone like the Santana feel or geometry, but I prefer it over the "quicker handling" of other brands. Santan feels more stable which gives me a much better sense of control. I love my recently acquired coupled Santana Niobium, however being a lighter team (under 290 lbs.), I can't say how stiff the frame really is.

You should check with other frame builders to see if they can make coupled frames of materials other than steel.

Ira

Why do I keep reading that coupled tandem has to be steel or CF?
Whats wrong or less preffered in a coupled alu tandem?

S&S with alu frames is claimed to be an 'exclusive' Santana 'co-design.'
Santana charges $1200 for stainless steel couplers. $2000 for alu couplers on an alu or Scandium tandem. And $2600 for Ti couplers on Ti or Beyond tandems.
Both Calfee and ariZona Tandems will build *full* carbon fiber tandems, and triples, with $&S couplers, while 'tana's Beyond is a combo of ti and c/f/, not all c/f.
IF you want couplers for travel ease, get 'em.

S&S with alu frames is claimed to be an 'exclusive' Santana 'co-design.'

Initially, like for the first two years or something along those lines, it was true that builders who had an interest in using the Aluminum-specific couplers that Santana paid S&S machine to develop had to source them through Santana... which was basically because Santana owned the entire production lot. However, since then -- at least based on my last converstions with Bill McCready of Santana and Steve Smilanik of S&S -- the "exclusive" marketing arrangement has since expired any builders can source the couplers from S&S. Interestingly enough, no other builder has expressed an interest.


Why do I keep reading that coupled tandem has to be steel or CF? Whats wrong or less preffered in a coupled alu tandem?

This is where it gets interesting. Having talked with a few of the other builders about aluminum travel tandems, the widely held view is that aluminum frames once damaged are not inexpensive to repair and travel tandems -- by their very nature -- are far more prone to being damaged than the average tandem that never sees the inside of an aircraft cargo hold. Also, given that the major attraction of aluminum tandem frames is their light weight, once you add the extra butting (thicker) sections to the tubing for the installation of couplers and the couplers, the weight savings becomes pretty minimal. As for the added stiffness, coupled tandems are actually a bit stiffer than uncoupled models so, once again, the amount of added stiffness that a buyer normally associates with an aluminum frame is not as as significant when compared to a coupled steel or carbon frame. Finally, there is the cost. An aluminum travel tandem is more expensive than a steel S&S equipped tandem which is already a significant cost upgrade to a basic uncoupled tandem. Again, IMO once you start getting into buyers with that kind of money for a travel tandem, the stretch to the Ti or Carbon models (both of which are more durable and easier to repair than the Aluminum) usually isn't a big deal. Thus, the target customer for an aluminum travel tandem is someone who already owns and thoroughly enjoys an aluminum-framed tandem. Given that the most popular model of tandem sold for the past several years has been the Santana Sovereign / Team AL, I'd put money on the bet that says it was Santana's customers asking for the coupled Sovereigns that ultimately led to Santana's investment in the technology to deliver on that request.

This is where it gets interesting. Having talked with a few of the other builders about aluminum travel tandems, the widely held view is that aluminum frames once damaged are not inexpensive to repair and travel tandems -- by their very nature -- are far more prone to being damaged than the average tandem that never sees the inside of an aircraft cargo hold. Also, given that the major attraction of aluminum tandem frames is their light weight, once you add the extra butting (thicker) sections to the tubing for the installation of couplers and the couplers, the weight savings becomes pretty minimal. As for the added stiffness, coupled tandems are actually a bit stiffer than uncoupled models so, once again, the amount of added stiffness that a buyer normally associates with an aluminum frame is not as as significant when compared to a coupled steel or carbon frame. Finally, there is the cost. An aluminum travel tandem is more expensive than a steel S&S equipped tandem which is already a significant cost upgrade to a basic uncoupled tandem. Again, IMO once you start getting into buyers with that kind of money for a travel tandem, the stretch to the Ti or Carbon models (both of which are more durable and easier to repair than the Aluminum) usually isn't a big deal. Thus, the target customer for an aluminum travel tandem is someone who already owns and thoroughly enjoys an aluminum-framed tandem. Given that the most popular model of tandem sold for the past several years has been the Santana Sovereign / Team AL, I'd put money on the bet that says it was Santana's customers asking for the coupled Sovereigns that ultimately led to Santana's investment in the technology to deliver on that request.

ok, you have to excuse my ignorance on some points here bot how is a carbon fiber frame easier to repair than an alu? even a Ti?

for the weight factor, if you take a steel frame and add couplers, it will make it even heavier, granted the alu will be heavier with couplers but not as much as the steel.

Stifness, well I like stiff bikes but thats personal I guess, dont like flexy wabbly rides

just trying to understand here.

The steel S&S and aluminum rigid frame are pretty different machines... Are you sure you've nailed down your requirements, e.g., S&S for travel flexibility or aluminum for all out performance?

Given the differences in these two finalists, have you talked with Dwan Shepard, Dan Vrijmoet, or Alan Cline at Co-Motion to get their recommendations? Regardless of which dealer you are working with, I would still recommend speaking with the guys who design the bikes, let them understand your needs and expectations, and listen to what they have to say about the qualities of their respective frame choices.

Toll-Free Phone: 1-866-282-6336

I agree 100%, Talk to Dwan, Dan or Alan they are top notch guys and can give a guy the pros and cons about the subject at hand.

Good Luck,:)
Bill G

We also ride a Co-Motion CoPilot coupled steel frame built by Dwan et al and couldn't be happier. It is very compliant and lively on our less than perfect roads around here, is repairable, and lighter than you might think. They make these frames out of custom tube sets as specified by Co-Motion and they use large diameter thin walled steel tubes wherever they can. At any speed above 10mph it feels much like my single. I would recommend calling and talking with Dwan about it. He loves to talk about the bikes they build and is very accessible. He also is an avid rider and knows tandems! Don't buy a tandem without riding one of these first! Good Luck,

ok, you have to excuse my ignorance on some points here bot how is a carbon fiber frame easier to repair than an alu? even a Ti?

Remember, first and foremost, carbon and ti are very tough materials that don't need paint which means they resist damage better than aluminum. According to Craig Calfee, the ease with which carbon frames can be repaired is one of their advantages. We have some friends who have had the rear stays of their off-road Tetra Tetra replaced and it wasn't obscenely expensive nor is the repair visible. In fact, if you buy a carbon tandem and find that it's too flexy, they can rework the frame to make it stiffer and most rework is invisible after the clear or paint is reapplied to the affected area. Ti frames can be repaired in much the same way that a steel frame can be repaired; you rework the metal or replace the tube. If it was brushed or polished, you refinish... repaint the affected area if painted. With aluminum, after the repair is made the frame must be re-heat treated, realigned, and the frame repainted.


for the weight factor, if you take a steel frame and add couplers, it will make it even heavier, granted the alu will be heavier with couplers but not as much as the steel.

How much is 1lb - 2lbs worth to you?

Steel Co-Motion Speedster Co-Pilot w/S&S couplers is about 35lbs @ $5,200
Steel Santana Arriva w/S&S couplers is about 36.7lbs @ $5,395
Steel Santana Team Niobium w/S&S couplers is about 34.6lbs @ $7,095
Aluminum Santana Sovereign w/S&S couplers is about 34.5lbs & $7,300
Steel Co-Motion Supremo w/S&S couplers is about 33lbs @ $7,700
Aluminum Santana Team Scandium w/S&S couplers is about 32.7lbs @ $8,895

Note: Arriva & Sovereign have standard wheels, steel forks, alloy cranks, etc.. "Team" & Supremo models come with paired spoke aero wheels, carbon forks, carbon cranks, and other lightweight, go-fast goodies.


Stifness, well I like stiff bikes but thats personal I guess, dont like flexy wabbly rides

None of these S&S equipped tandems should feel "flexy". The least stiff would be the Arriva. Co-Motion's equivalent model -- the Speedster Co-Pilot -- is a bit lighter than the Arriva and should feel at least as stiff as the Santana Sovereign S&S.

. . . and a Zona open frame tandem with ti S&S, size Medium/Medium is shown on the website @ 27 1/2 lbs. . . and it'll cost less than an S&S Beyond.
And if you don't want couplers, the weight goes down (depending on component$) to an anorexic 23 lbs.
And as Mark stated c/f is easier/cheaper to repair (by a qualified builder), than aluminum.
'You takes your choices and pays your money!!!'

I have a steel S&S CO MO frame. It is very stiff, yet will give you the ride quality of good steel. Aluminum gives zero in ride quality.

I have a steel S&S CO MO frame. It is very stiff, yet will give you the ride quality of good steel. Aluminum gives zero in ride quality.

I disagree, my aluminum Co-Motion Robusta rides every bit as good if not better than my Co-Motion steel Supremo. Don't get me wrong there are some noticible diffrences the aluminum being stiffer gives the advantage to the tandem in climbing and hard cornering. Alan at Co-Motion along with me and Dwan talked about the aluminum verses steel ride quality debate. I found what they said to be true the Robusta aluminum frame will absorb the road viberation or transmited skock waves different but is designed to give a good stiff compliant performance ride and still be able to produce a comfortable ride for the captain and stoker, and that is does. My wife and only stoker prefers a normal seat post and does not care for a shock type seat post and her opinion is the ride is more performance but very compliant and comfortable. I feel the same way after spending 3 years on our steel framed Supremo but with that being said our Cannondale we had road a bit more harsh. I think the old myth of aluminum not being a good ride is not as true as it was at one time due to better materials and advanced design. Yes in general most aluminum frames ride stiffer and in general steel is a better ride but that is not allways the case. I hear that Burley spent some time to make there aluminum frame ride well as well. To date the Robusta is the best riding tandem we have ridden or owned I hear the Zona carbon tandem rides well also , I have not got a chance to ride one yet.

Take care an ride together,:)
Bill G

All metals and other frame materials have been "tweaked" to the utmost . . .
So steel frames from 30 years ago and alu from 20 years ago and ti-tandems from a dozen years ago are not the same as what's being built now. Along with OS tubing and carbon forks, light wheels and other tidbits, tandems and their riding qualities/weight/handling have greatly improved.
Got to test ride 'em to find out what suits your duo best!

Pedal on TWOgether!
Rudy and Kay/zonatandem