Primera vs. Speedster vs. Roadster

[Carbonfiberboy]

Did the search, read the posts, still have some questions.

300 lb. team, looking at buying a small size tandem. We enjoy sport riding. Not looking to tour. Our previous experience has been on a friend's Cannondale. Don't know the year, but the 8 speed cassette might date it for you. We liked that bike quite a bit, though it seemed a little clunky somehow.

Everything we've read and heard, combined with our riding style, has us thinking we want a Co-Motion, so we test rode a Primera. We didn't particularly care for it. We experienced "stoker steering." The bike seemed quite flexible, so that my stoker kept trying to correct for how the bike was jumping about, and of course that felt to me like the bike was really jumping around. :( On the Primera's side, the shop hadn't cut down the fork so the bars were much higher than I'm used to and the stem was a good bit too short, so that pushed my weight back, off the front wheel.

After a few miles we got that calmed down. Stoker was asked to ignore the fact that the bike was wiggling and just let it. After that, I had reasonably good steering. We are both quite smooth, high cadence riders on our singles and this didn't happen to us on the C'dale. We liked the Primera at high speed and at low speed and it cornered fabulously. It was mostly in the middle ring in the middle of the cassette when we were working hard that we had the worst of it.

I think we would get used to this eventually, but our first impression was not the best. Will the Speedster be stiffer? The Roadster stiffer yet? We didn't think that the C'dale was too stiff. It had a suspension stoker post, though. We are inclined toward the Speedster because of cost, but want the right bike. The dealer doesn't have a Speedster or Roadster in our size.

We'd also like to get the Wound Up fork. Will that have a positive effect on this stiffness issue? We'd probably run Vredestein 25 tires, but are concerned that the stock Dyad rims are too wide for a 25. Should we upgrade to Aerohead rims? Or put 28c Ultra Gatorskins on the Dyad rims?

Thanks for any comments and suggestions.

[Doggus]

We'd probably run Vredestein 25 tires, but are concerned that the stock Dyad rims are too wide for a 25. Should we upgrade to Aerohead rims? Or put 28c Ultra Gatorskins on the Dyad rims?

Thanks for any comments and suggestions.


We're running 23c tire on our front Dyad rim. I didn't think there was a rim width issue for that size tire, maybe I need to re-think this before we go down in a fiery crash.

Our first Speedster bounced like a trampoline. We now have the coupled version and it bounces less but still bounces. We are also a heavy team at 380.

[oldacura]

I'm not familiar with the Primera. I suspect the "flexible" feeling is just being new to tandeming. Tandems are not as stiff as single bikes. I think the bike would feel just fine once you get more miles under your belt. We have a Co-Motion Co-Pilot (about a 1998). It is just a Speedster with couplers. It is a steel bike. I don't notice any undue flexibility but maybe it's just what we've gotten used to.

[dbohemian]

First I would contact your dealer or Co-Motion directly. They should be able to tell you if one of there other models is substantially stiffer than the one you were riding.

Wound up forks are very ridged. I have had great luck with them on tandems. For my latest tandem I made a custom steel fork that is very beefy and I would say from the ol squeeze test and riding that the Wound up is just as stiff if not stiffer. It was just that I could not run a disk on a Wound up and therefore resorted to making my own.

The rim width should be a non-issue. It will slightly change the profile of the tire but will not reduce safety or ride quality in any way. I would recommend wider tires than you may be used to on your singles. 25-28 and wider. I could make a very convincing argument that wider tires on tandems are actually faster in real world riding than narrow ones, but that is another thread.

All the best,

Dave Bohm
Bohemian Bicycles

[TandemGeek]

We experienced "stoker steering." The bike seemed quite flexible, so that my stoker kept trying to correct for how the bike was jumping about, and of course that felt to me like the bike was really jumping around.

Not sure how recently you've ridden the Cannondale or any other tandems before this outing, but aside from the inherently "bouncier" ride of any tandem vs. single bikes and your prior experience / expectations from the Cannondale, what you were likely reacting to was the Co-Motion’s longer steering trail and not a noodly-frame. While the Cannondale frames are super-stiff, they also have less steering trail are like the Santana tandems in that they are more resistant to body lean or heavy pedal stroke induced steering inputs than the Co-Motions. Large teams, teams that push big gears, teams with tall stokers or stokers who move around a lot, or captains who ride with a death-grip on the bars will all exacerbate the Co-Motion's “twitchy” steering" (common street jargon with negative connotation, but not really an accurate description of what's going on and the "goodness" of long-trail) until such time as they correct those behaviors or simply adapt to the way the tandem reacts to their riding style or team size. Most but not all teams will adapt and those who are still fighting the handling characteristics of a Co-Motion are easy to spot: look for the arm muscle and fork twitching that accompany almost every pedal stroke when they’re pushing a big gear or climbing.

Will the Speedster be stiffer? The Roadster stiffer yet? We didn't think that the C'dale was too stiff.

Co-Motion's frames are all very stiff compared to most other production tandems. In talking with the folks at Co-Motion, you’ll find that they design their different tubesets -- the Reynolds 725 air hardened tubing (used on non-coupled Speedsters, Cappuccino, Mocha, & Supremo), the Reynolds 631 (used on Primera and all coupled frames), and Easton 7000 Series (used on the Roadster & Robusta) -- to deliver the same stiffness but with the inherent weight savings associated with the air hardened steel and aluminum tubesets. Therefore, any significant perceived differences are likely due to other considerations which include the weight, the sound, differences in wheels and tires, as well as rider expectations (the mind is a powerful thing). Remember, before the Reynolds 725 tubesets came along, the Speedsters that earned Co-Motion's reputation as a performance tandem builder were built using the same zonally-butted 631 framesets found on the Primera: we're talking topself heat-treated chromly. Also, bear in mind that while the Speedster/Supremo and Roadster/Robusta frames are lighter than the Primera's tubeset, the big weight reductions with the high-end Robusta and Supremo come mostly from the components used on those bikes (as do the associated higher costs).

We'd also like to get the Wound Up fork. Will that have a positive effect on this stiffness issue?

The Wound-Up fork (as well as the True Temper X2) provide you with weight savings without sacrificing stiffness vs. Co-Motion’s very robust steel forks; however, while Co-Motion’s stock forks are where that additional steering trail comes from, the Carbon forks have less rake which means even more steering trail. So, rather than nulling out the stoker-steering they could make it even more pronounced. Now, to be fair, any subsequent ride on the same Co-Motion that you test rode would yield a more familiar and comfortable ride than your first. As you discovered, the Co-Motion’s have some very desirable handling traits. However, for first time tandem teams or teams that have been riding Santana, Burley (non-Race models), non-carbon fork equipped Trek tandems, Cannondales, Bilenky, KHS, or just about any of the other tandems that have more conservative steering geometry, they can “feel” like a handful. We often joke that there are a couple tandem dealers out there who use Co-Motions to sell Santanas by putting first timers on the Co-Motion and THEN putting them on the Santana. Less I digress… go back for another test ride and see if you don’t come away with a different impression.

We'd probably run Vredestein 25 tires, but are concerned that the stock Dyad rims are too wide for a 25. Should we upgrade to Aerohead rims? Or put 28c Ultra Gatorskins on the Dyad rims?

As for rim widths, the Vredestein 25’s are about at the lower limit for the Dyad. Yes, 23mm tires can be mounted to the Dyad, but you end up with a very short tire and will be cornering on the sidewall seams which can be less sure-footed than the tread compounds, are unprotected by the PRS liner, and more susceptible to nicks and cuts. Again, they "work" but it's not an ideal, long-term match.

Looking at rim choices, we’re a 285lb team that has been using 23mm and 25mm Vredestein Fortezzas since 1997 on 36h wheels built with Mavic CXP30 and Velocity Deep-V rims: no complaints and never an inclination to switch to something else either. We have been using the 26” Aeroheat rims on our off-road tandems since ’00 which is very similar to the Aerohead as well as the wider Dyad and it too is a good wheel, but not my preferred design for sport tandems.Therefore, based on personal experience, I’d be more inclined to suggest the Deep-Vs over the Aerohead… although not as light as the Aerohead or the Dyad, the Deep-V is a more robust rim that builds up easier, stiffer, and stays true even over less than idea road conditions. However, that said, any of the three are very good rims for tandems: Aerohead for weight weenies, Dyad for touring or larger teams, and Deep-V for anyone who wants them that falls in between the two other designs.

[dbohemian]

Very thorough TandemGeek.

Your description of steering geometry on tandems is accurate. I would like to add just a few things.

Lower trial numbers as on the Co-motion are appropriate on tandems due to the increase in stability from their length. Most custom and semi production builders (Co-motion, DaVinci, myself and others) will use a lower trail figure on tandems than we typically would on singles meant for similar work. I typically design in the 40-45 range. This may feel a bit unusual in the beginning but makes for a better feel overall.

Also realize that tire width does contribute to overall stability with wider tires offering more stable steering. Although not nearly as pronounced as steering geometry, you tire choice can make a noticeable difference to steering feel.

Slightly overbuilt wheels are just a bit of insurance on a tandem. The extra 40 grms per wheel by using a Deep V or Dyad is probably well worth it. The larger tire 25-28c will increase comfort, stability, cornering grip and will not decrease speed one bit (may increase it....Talk amongst yourselves)

[TeamTi700]

In October of 2005 I e-mailed Velocity to ask about their Dyad rims and foldable tires. They recommended nothing smaller than a 28, particularly on a tandem.

[RickinFl]

I couldn't resist chiming in on this thread, and I'm not exactly worried about being seen as a Neo-Luddite for what I'm about to say:

I've been riding a Cannondale tandem for years now, and my current stoker (who is blind, and who also became my wife by virtue of the tandem [another story altogether]) has been riding with me for close to five years now. Somewhere along the line, we decided that we rode enough to deserve a "better" tandem, so we tried out several high end makes only to decide that we preferred the 'Dale over any of them. It wasn't a matter of $$$- we could pretty much afford whatever we decided we liked.

My blind stoker, who is quite sensitive to such things, felt that these other tandems were too flexible, and I agreed with her. We, and especially I, have been tandemming long enough to discriminate between quick steering and a flexible frame.

Stiffness is at a premium with tandem frames, especially if you like to climb, as we do (certain people who are aware that we live in North Florida are probably snorting and guffawing at the idea of a "climb" here, but we do have some pretty decent hills around Tallahassee, and we've also done quite a bit of riding in the Oregon Cascades and Coast Ranges, so we have an idea of what it's about). A stiff frame won't be as comfortable to ride, but if your riding style is "go-fast", you'll definitely appreciate the efficiency of a frame like the Cannondale has. The problem is that a Cannondale has no panache, or cache, so to speak- it just doesn't cost enough to have the glitz factor that a lot of tandemmists appreciate. What I say is that it's a lot of bang for the buck.

I would make a guess that the "clunky" C'dale you rode might have had the crappy stock wheels with 28 or larger tires on it. Give it a nice set of wheels with a 25 or narrower tire that can hold 120psi, and it's an entirely different machine. I've used 23's in the past, but have settled on Conti 25's mainly because they are about the only ones available rated for 120psi, and I like a little more rubber on the ground. They ride crisply. Also important IMNSHO are traditional style wheels built with 2mm straight gauge spokes to provide superior lateral stiffness (which they definitely do, but that's a battle I don't want to engage here because I've already skirmished with theoreticians on the subject and come out bloodied but unbowed). The point being that a wheel that is laterally flexible will give the impression of a noodly frame, especially when out of the saddle for a sprint. Nasty old squashy 28 tires do the same thing as well.

So- I'm clearly opinionated, but I *have* had many years and miles of experience with this bike (bought it in '92, Cannondale replaced the frame in '99), and I've yet to find anything else I like well enough to spend multi-kilobucks on to replace it. The cool side of this is that you can spend maybe $2k to get a Cannondale and have plenty of elbow room left for upgrades- to your heart's content. The Cannondale frame is definitely worth upgrading (again IMNSHO).

The end of my counterpoint view..... :)

Rick

[Dobe]

I had the same type of questions when I approached Co-Motion last year. I am 6'7" and weigh 230 lbs and my wife is 5'9" and weighs 145lbs. We decided to get a custom built Roadster with a WoundUp fork and have the standard 28c Gatorskin on 40 spoke Dyad rims. Since our bike is a little longer than most, Co-Motion did use a larger diameter top tube and down tube to retain frame rigidity.

Being new to using the tandem I found that with some practice the bike handles as good, if not better than my single bike, and that it is completely solid when we are both out of the saddle on climbs or accelerating on the flats. I don't feel that the larger tire size slows us down and I tend to agree that it adds to our comfort and stability. I have learned that the key to enjoying the tandem is to keep the stoker happy at all times. The bike that they made exceeded all of our expectations in terms of performance.

The staff at Co-Motion would be more than happy to answer your questions.

[zonatandem]

Experiencing 'stoker steering' is exactly what it says: the stoker 'steering' from the back seat; and yes, it will affect the captain's steering and bike handling.
Whether stoker tries to steer on a C'dale or Co-Mo, the results will be nearly identical.
So we suggest you two riding that same Co-Mo again. This time have the captain a bit more relaxed and have the stoker not attempt to steer or control the bike from the rear.
Yes, handling/steering a Co-Mo compared to to C'dale/Santana and some other tandems will be different. A bit touchier than what you are used to. Within a couple hundred miles you'll learn to appreciate the responsiveness. And, we are speaking from actual experience as we have ridden C'dales, Santanas, daVinci, etc. and also put 57,000 miles on a custom Co-Motion.
A c/f fork will be fine and add a bit of cushioning (and subtract a bit of weight) to the ride. A wider tire is not a bad thing and will let the front of the bike feel a bit more stable.
However, having said that, we used 23mm tires for well over a 100,000 miles and only recently have graduated to 'fat' tires: 25mm.
We are 50 lbs lighter than your team and use the AeroHead wheels, 32H front, 36H rear with 25mm Maxxis
Detonnator or Re-Fuse 120 psi tires. Currently have 14,000+ miles on those wheels. As Bohemian says, 40 grams more in rim weight could be a bit of insurance for an aggressive team.
Wish you luck with your next 2-seater!
Pedal on TWOgether!
Rudy and Kay/zonatandem

[TandemGeek]

My blind stoker, who is quite sensitive to such things, felt that these other tandems were too flexible, and I agreed with her. We, and especially I, have been tandemming long enough to discriminate between quick steering and a flexible frame.

Let me first say that I don't disagree with your observations on the stiffness of Cannondale's tandem frames: they are without a doubt the stiffest in all dimensions and directions. Our '98 MT3000 with its robust Moto FR fork was rock solid even when torqued in all of the various odd and bizzare ways that a tandem is subjected to riding off-road on technical single track.

The Cannondale's also remain an outstanding value. While it was disappointing to see them go from three levels of trim for both road (RT3000, RT2000, RT1000) and off-road (MT3/4000, MT2000, MT1000/900), the RT/Road model is very-well equipped (Ultegra/XT) for not a lot of money ($2,600-$2,700) and the "street" model @ $1,700 rivals anything else on the market for a 26" bike that is easily upgraded to premium trim with just a few drivetrain changes. Anyone who is in the market for a tandem should definitely look look at the Cannondale models, as well as Trek's offerings: they are by no means second class citizens and their pricing reflects huge volume cost savings on components which make them all that more attractive.

So, yes, if a Cannondale is your point of reference just about any other frame will have noticably more "bounce", especially for the captain and even some torsional flex depending on the year, brand, model, and material, some far more than others. The stiffness is often to blame for the old "harshness" rap that Cannondale tandems get which, frankly, I think is a bit of bunk and part carry-over from their single bike frame feedback that can easily be addressed or "tuned" via more attention to wheel / tire selection and tire pressure.

That said, there IS a reason that other tandem builders design in a certain amount of compliance to their frames and, again, you will find varying amounts of it across different brands, models, and materials. The whippiest better frames are the ones used by KHS for it's 700c Milano and they're actually a lot less whippy than many of the earlier premium grade tandems sold before the mid-90's. Burley's earlier frames were also a bit whippy and Santana intentionally makes their tandems a bit more compliant for added comfort whereas Co-Motion makes theres as stiff or stiffer than just about anything short of a Cannondale or a beefed-up custom frame built for a larger team, e.g., Dobe's Extra-Robusto / Roadster or SDS' Meridian "Moby". However, and in particular with the Co-Motion, the majority of the compliance is in the vertical plane and not side-to-side, and the S&S models are even less compliant in both planes: the same is true for just about every tandem fitted with S&S couplers.

But, getting back to the "first impressions", while the Co-Motion Primera may have exhibited more flex than the Cannondale, the biggest difference I've found when comparing any Co-Motion to other tandems continues to be the steering and handling characteristics. IF your stoker rides cleanly and is of average to small stature, it is not nearly as noticeable as it is with larger stokers or stokers who move around a lot. The latter is a very common thing for new stokers as they adjust to the rear riding position and the loss of positive steering/balance control, and often times try to see the road ahead by looking around the captain. Teams who are still working to get their act together as a team that works in unison, large-size teams, and teams that push big gears with lots of side-to-side body english will perturbate a Co-Motion's steering (or any other tandem with steering trail greater than 2" than the norm, e.g., Calfees, Ericksons, some Bushnells, etc...) far more so than the Cannondales, Santanas, etc... that use steering trail of 2" or less. Perturbating the steering on a tandem can get, well, perturbing if the team doesn't settle into good form.

From personal experience, I can without hesitation state that RickinFl's lovely wife Terri is a very clean riding stoker who doesn't exhibit any bad habits: she is relaxed, focused, and delivers lots of efficient power without any unnecessary body movements as they have the very well-refined, high cadence that most tandem teams strive for.

Bottom Line: Rick is correct; Cannondale makes the stiffest tandem frame. Steering differences alone will not define how a tandem "feels". However, IMHO and based on my experience in watching how people look and actually ride on their tandems (and I must say that some Captains would benefit from seeing themselves and their stokers on video early on in their tandem careers), newer and less experienced tandem teams will almost always find a Co-Motion tandem to be less "stable" feeling than a Santana, Cannondale, Burley, Trek, etc... That is, until a Co-Motion is ridden "fast" and pushed into corners and most of this is related to the difference in steering geometry more so than torsional frame flex. The latter would manifest itself as stoker lag contributing to poor handling during aggressive steering inputs/cornering and that's clearly not the case with the Co-Motions: in fact, aggressive handling response is their strong suite.

Parting Shots and My Shopping List:

1. Big teams in the market for a tandem or power riders should really consider the Cannondale tandems, new and not-so-new. As far as stock production tandems, nothing, and I mean nothing else will afford really big teams a better ride both with respect to the frame's inherent stiffness as well as the less aggressive steering geometry.

2. Even as a very small, lightweight team, if I was in the market for a time-trial specific or crit racing frame on a budget I would search out a pre-CAAD/99 model year Cannondale, strip it and refit the thing with go-fast parts. I say pre-99 because I'm not a fan of the stepped top tube design and because the older, smaller size C'dales had longer stoker compartment than the current models.

3. Short of that, and if I was not overly budget constrained, Co-Motion remains first on my list of premium tandem choices for teams in the market for a go-fast tandem, followed by Calfee (cost as the variable here), and then you're into the make-to-order / custom market, e.g., a custom-Calfee or open frame Co-Motion built around the dimensions of our Ericksons, etc...

4. If I was in search of comfort above all else, then Santana remains the pick of the day, followed by a Calfee with custom steering geometry (cost as the variable), followed by a Ti Seven (cost again being the variable) and other make-to-order, custom jobs.

5. Most bang for the buck? Cannondale, followed by Trek's T2000 which now has ALL the carbon goodies and finally, a fork with less rake to give it better handling. Yes, I am aware of the various different brands of imported chromoly, aluminum, and Ti tandem frames now on the market: however, I remain committed to my support of domestic frame fabrication and my recommendations follow suite.

6. If cost was no object, I'd have a (bigger) fleet of tandems from all the really good builders and I might even put an offer in on that $20k+ Bohemian Dave took to the hand-built show even if it was the wrong size just to hang as wall art.

[dbohemian]

6. If cost was no object, I'd have a (bigger) fleet of tandems from all the really good builders and I might even put an offer in on that $20k+ Bohemian Dave took to the hand-built show even if it was the wrong size just to hang as wall art.

Thank you for the compliment TandemGeek!:D

I know you know this but I do have to point out that the tandem is question is a one off show piece.

All of my other tandems have been custom in nature but no where near this price. My standard pricing is much in line with other custom builders product of similar quality and spec.

Dave Bohm

[Michel Gagnon]

Mr. TandemGeek has said a lot. I would suggest you go back and try again that Co-Motion Primera and Speedster. There are a few aspects that TandemGeek didn't cover:

– New stokers tend to look around their captain. So unless your wife is 1' taller than you, she will most likely try to look left and right around you, leading to lots of wiggling. Once the stoker learns that she (he) must not do that, you're OK. It doesn't take long to learn, so I assume that by your second ride the problem was solved, hence you had better trials afterwards.
I can tell you the problem is even felt with a 50-lb child stoker, and even more so on a trailercycle.
(P.S. There is another separate issue: whether she actually likes the stoker position or not.)

– Some cyclists like to take risks, like going too fast, staying too close to obstacles (curbs, cars, etc.), and if you are of that type, your stoker might be a bit fearful. Being conservative at the beginning helps.

– Handling a tandem takes a bit more upper body strength. Nothing horrible, but the first few times, you might discover some "new" muscles.

[TandemGeek]

Mr. TandemGeek has said a lot.

Mr. TG is cursed with the ability to type 120-130wpm....

[Ginny]

and my current stoker (who is blind, and who also became my wife by virtue of the tandem [another story altogether])
Rick
Rick,
Can ya open another thread and tell us? I REALLY need a good love story.

[Carbonfiberboy]

Thanks for all the input, folks. My buddy has sold the C'dale we borrowed, and purchased a Speedster, which he absolutely raves about. He also said there was a several hundred mile learning curve, but now they go like rockets on it. He's got the carbon forks and Rolfs. Pretty much what TandemGeek said. I didn't give that info to start with because I didn't want to prejudice further input. I can see that what I interpreted as twitchy is probably really responsiveness.

The stoker steering was more my fault than my stoker's. The steering was really different from the C'dale and I was probably steering too much, thus shaking up my stoker, rather than sort of pointing the bike and letting it go. I've got a good stoker. :)

OTOH, I can also see the cost differences generated by C'dale and Trek being able to buy components by the carload. More evaluation required, like realistically how many dollars per mile per year, and dreamwise, how many more miles per year might more riding pleasure bring?

[Jinker]

Mr. TG is cursed with the ability to type 120-130wpm....

Having read a lot of your posts in the tandem forum, fortunately, your brain seems to be able to keep up.

I type fast enough that sometimes the poor noggin falls a little behind. ;) (Still not quite 130wpm)

[fcatwo]

I will share our experience with a 98 Cannonale compared to our present 01 Co-Motion since no one has covered my perception of a slow-speed steering difference. I should mention that we liked the Dale and were only moving up to get S&S for airline travel. However, one advantage of the Co-Mo's steering geometry was obvious to me within a few seconds of starting the test ride. I had to make a tight u-turn at a dead end and experienced one of those revelations people talk about. The Dale had required a lot of attention in such situations in that it would resist turning initially and once into it it wanted to cut in on itself and dump us. It was not a big thing but I had to watch for the point when I had to stop forcing it and start holding it back. The Co-Motion by comparison made the turn smoothly with relatively light steering effort on my part -- as though it was no big deal. YMMV.

[Carbonfiberboy]

I will share our experience with a 98 Cannonale compared to our present 01 Co-Motion since no one has covered my perception of a slow-speed steering difference. I should mention that we liked the Dale and were only moving up to get S&S for airline travel. However, one advantage of the Co-Mo's steering geometry was obvious to me within a few seconds of starting the test ride. I had to make a tight u-turn at a dead end and experienced one of those revelations people talk about. The Dale had required a lot of attention in such situations in that it would resist turning initially and once into it it wanted to cut in on itself and dump us. It was not a big thing but I had to watch for the point when I had to stop forcing it and start holding it back. The Co-Motion by comparison made the turn smoothly with relatively light steering effort on my part -- as though it was no big deal. YMMV.We noticed the same thing in our test ride. We tooled slowly around a large parking lot and at slow speeds found that the bike made tight turns effortlessly, stably, and confidently.

[zonatandem]

In the end, it's your $$$. Our suggestion: buy the best you can afford, it's cheaper in the long run!

[ftsoft]

I wish I had seen this a few weeks ago. We ordered a new tandem 3 weeks ago (Co-motion speedster) and while I think we made the right choice, it would have been nice to see this input. We have been riding a 1982 Motobecane for 25 years, so we know a thing or 2 about flexible frames and stoker steer. I suspect any of the tandems mentioned would seem amazing to us. We are a 270 lb team and while we ride pretty fast, we are not power riders and rarely stand to climb on the moto (it is quite an adventure). I have to say that new 700C wheels and 25mm tires gave the moto some new life and really renewed our interest to the point of deciding on the new tandem. The big 27" 1 1/4 tires were pretty clunky and as our singles got better and better we mostly preferred to ride them. Thanks.

[CGinOhio]

I wish I had seen this a few weeks ago. We ordered a new tandem 3 weeks ago (Co-motion speedster) and while I think we made the right choice, it would have been nice to see this input.

We now have about 500 miles on our 2007 Speedster copilot. It doesn't seem to flex at all laterally, even when we are fighting each others movements learning to ride out of the saddle (I am bad to throw the bike:( ). We are about a 280 lb team. Now that we have the confidence, the downhill sweepers are a blast. :) We had only ridden a tandem three times (all LBS test rides) before putting in our order. We were pretty wobbly at first, but with some miles under our belt we are sure we made the right choice. I learned to be smoother with my steering inputs and to relax my grip, and my stoker learned how her various movements affect the steering. At TOSRV yesterday I was extremely pleased with the confidence we had at high speed, but also at low speed, negotiating through congested rest areas at a crawl. There is no way I would call this bike "twitchy". After a few rides you will love your co-mo!

We have noticed the phenomena noted in an earlier post regarding bouncing. On one of the frost-heaved roads in the area that has the right harmonic for the co-mo wheel base we get a pronounced bounce effect, but this is rare. TandemGeeks helpful post seems to confirm that more compliance vertical vs lateral is a design "feature". Having ridden the same roads on my harsh riding Giant TCR and taken a pounding I am willing to put up with an occasional bounce as a trade off for the great ride.

One thing I didn't see mentioned regarding reducing "wobble, bounce and twitch"....proper saddle height. I think we are smoother now that we raised the stoker's saddle height to correct level. Less rocking. Mine had been a little low as well. I think the same is probably true for too high of saddle.

[Artmo]

Great thread, especially as we bought a new 1996 Primera w/ Woundup, Bontrager tandem wheels!!

We love it (although I don't like the look of the Woundups -too much chrome) and didn't see the point in spending more for more expensive components and a minor weight saving. We are a 340lb team. See us in the 2007 Co-motion catalog.

[dfcas]

, "what you were likely reacting to was the Co-Motion’s longer steering trail "

TG seems to say increased trail makes for quicker steering

"lower trial numbers as on the Co-motion are appropriate on tandems due to the increase in stability from their length. ""

Mr. Bohm seems to say lower trail makes for quicker steering.

I understand single bike trail numbers,but tandems confuse me.

What are the rakes used by tandem companies?Since everyone claims 73* head angles almost universally,fork rake seems to matter.which way to go?Please dumb it down for me.

dan

[TandemGeek]

What are the rakes used by tandem companies?Since everyone claims 73* head angles almost universally,fork rake seems to matter.which way to go?

From previous posts and in regard to 700c road tandems:

Santana has defined 55mm of fork rake with a 73* headtube as the tandem standard. Burley, Trek, and others also adopted this as their "standard". This yields something like a nominal 1.9" of steering trail.

Co-Motion uses 50mm of fork rake with 73* as their standard for tandems fitted with their chromoly forks which yields more steering trail, something like a nominal of 2.125". The Wound-Up forks are built with 45mm of rake but are also a bit shorter which nulls out some of the added steering trail more on the order of 2.25" - 2.3" of steering trail.

It's noteworthy that Trek has been paying attention to consumer trends and also has a tandem enthusiast in their frame design team who has been influencing the design of their T1000/T2000 tandems. This past year Trek introduced a Bontrager carbon tandem fork on the T2000 that uses 50mm of rake. Before it's withdrawl from the tandem business, Burley had also introduced a True Temper CX tandem fork for use on their Racing kits that featured 48mm of rake (but also somewhat shorter) that afforded consumers "Co-Motion - like" handling.

At the other end of the spectrum is Bilenky 57.7mm fork rake and 73.5* head tube angles to achieve a nominal 1.65" of steering trail. This is the geometry that John Schubert, author of "The Tandem Scoop" had at one point advocated for tandems. You can see their geometry tables at their Web site: http://www.bilenky.com/tangeom.html I believe KHS uses very short steering trail as well.

Cannondale splits the difference by using 53mm of rake with a 73* head tube for 2" of steering trail.

You'd need to check with each of the other builders to find out what they actually used, but all will fall within the aforementioned range. In short, less fork rake (or off-set) = more trail. However, note that increasing tire diameter will also increase steering trail so none of these numbers are cast in concrete -- they're all variable to a certain extent.

Since everyone claims 73* head angles almost universally,fork rake seems to matter.which way to go? Please dumb it down for me.

As for which one to go with, that's a personal preference decision. None of them are "bad" unless you happen to find them either lacking in single-bike feel (that would be the short-trail tandems) or find that the amount of steering inputs needed to keep your team going in a straight line make you fatigued or your stoker sea-sick (that would be long-trail tandems). The only thing to watch out for are builders who try to apply conventional single bike geometry to tandems, e.g., going with lots of trail similar to a single touring bike to "increase stability" and make the bike easier to handle which actually does the complete opposite on a tandem. Just watch a big team on a Co-Motion who isn't all that smooth climb a steep hill and you'll see a lot of of twisting movements coming from the front fork and captain's arms, usually in sync with each pedal stroke.


Please dumb it down for me.

Actually, I believe the problem is confusion which stems from semantics surrounding words like "quick, fast, twitchy, and stabile" as well as a failure to put those terms into context when describing how bicycles handle. Stealing from my own writings, this is how I like to sum up how conservative and aggressive fork trail affect the steering and handling of tandems:

Conservative fork trail on a tandem (under 2") favors low speed maneuverability by providing lighter steering effort and faster steering responsiveness to handlebar inputs. Many teams will describe this as being "more stable" because, at least at slow speeds, it "feels" that way. Tandems with conservative fork trail take less effort and attention to steer in a straight line at slower speed and are resistant to inadvertent movements by the stoker, aka (stoker induced steering). However, conservative trail tandems also tend to understeer in aggressive or high speed cornering maneuvers which is not always desirable.

Aggressive fork trail on a tandem (more than 2") favors high speed cruising and aggressive cornering. This is because of their inherently greater straight line stability and smooth responsiveness to leaning inputs, noting that once at speed all directional changes on two-wheeled cycles are accomplished through countersteering with the handlebars in combination with leaning the bike in the direction of the turn. Many teams will describe tandems that handle well at speed as being "more stable" because, at least at higher speeds and for aggressive cornering, it "feels" that way. However, at slower speeds, steering tends to be heavier and less responsive which is often described as being "twitchy" by some and "solid" by others: look to the stoker for why there is a difference. Moreover, for teams with stokers that are exceptionally tall, or who tend to move around along or "rock" when they ride, a tandem with long fork trail can make for high-task load handling with lots of steering inputs which can also be undesirable.

Bottom Line: Tandems appear to defy conventional logic since everything is backwards... instead of the "racing models" having shorter steering trail than the models favored for touring or less aggressive riding, they have longer steering trail. However, "conventional logic" usually overlooks that 6' wheelbase and the added weight of a tandem. Moreover, a "racing tandem" is really defined by the handling skills of the captain and the combined power and efficiency of a team: you can't buy real speed. Therefore, just about any tandem can be a "racing tandem" if you put the right team on it.