What Do I Think? Good Question. (Tandems & Composite Forks)

Let me confess that I really do enjoy getting comments when I post things.  Some of them come from friends who subscribe to our blog and stay in touch by sharing a compliment or an anecdote when something I’ve written inspires a reply and those are, well… awesome.  Others come from readers who have good follow-up questions or who just have something on their minds that they’d like to ask about, sometimes unrelated to what they are replying to.  That’s also pretty awesome, since that’s very much like the real world where at, say a tandem rally, a collection of folks are standing around talking about tandems and cycling and someone introduces a new topic.  Bottom Line: I’m a tandem cycling junkie, so all of this just feeds my passions for tandems, cycling and sharing observations and learning…. and it’s always a two-way street when it comes to learning.  I learn something from just about every interaction I have, even if it’s just what tandem enthusiasts have on their mind.

I recently received one of those questions that was unrelated to the blog entry that provided the impetus to comment and it was a good one. Jonathan asked,

“Just curious, have you written a review/primer on safety concerns (weight tolerances) of carbon forks on tandems…..specifically the Enve 2.0 that clearly states it is not Tandem approved? … Rodriquez Cycles posted an article in January of 2014 voicing some concern”

I replied to Jonathan with my own comment, but after penning it I thought that it might be worthy of its own blog entry, so here is what I shared:

—————————————————–

I’ve read most everything that Dan at R&E has written over the years and I have a deep appreciation for his insights and observations. R&E under Dan’s watch has always had the customer’s interests at the forefront and they don’t like to dabble at the ‘bleeding edge’ of bicycle or bicycle component design and engineering. Vanity ain’t worth a trip to the hospital. However, I had not read the new article on carbon forks, so thanks for sharing that. I would love to have R&E nearby as my local shop!

Anyway, I have lots of thoughts about lots of things and the one constant is that there are very few bicycle components designed for use on tandems. Therefore, unless a tandem enthusiast happens to have the right education or experience in engineering or materials development, they must look to the people who design and build tandems for insight into what works well and offers teams sufficient safety margins when it comes to tandem frame design and component selection.

So, when it comes to carbon forks there are only a few builders who have taken the time to work with composite component designers and manufacturing companies to develop or evaluate forks that MAY be suitable (within limits) for use on a tandem: it’s a short list. I’ve also spent some time talking with the engineers who developed some of the tandem-approved forks over the years and, clearly, there are ways to test forks to determine their limits and tweak designs to support the loads a tandem can generate, but within limits.

Therein lies the challenge and Dan does a good job of pointing out just how comprehensive the design requirements and testing needs to be when dealing with the loads a tandem can generate. So, as I said, there are a few tandem builders who have taken the time and made the investment to have composite forks proposed for use on tandems tested and/or worked with composite manufacturing companies to develop and produce composite forks that are suitable for their tandems (within limits).

You can probably do a little checking around and break the code on which companies these are and which forks have been deemed “suitable” (within limits), e.g., Santana worked with Reynolds early on to develop the very robust Ouzo Pro Tandem fork: we have one of those on our triplet… but then again, even riding three-up our triplet teams come in under 400lbs. Santana has also developed some house-branded forks made by 3rd parties that are very robust. Co-Motion used the tandem-rated True Temper Alpha Q X2 Tandem forks on their tandems until True Temper got out of the bicycle fork business. Co-Motion recently developed their own house-branded composite forks after doing some pretty extensive product testing and, oh… by the way, worked with Advanced Composites many years ago to develop the very robust and aesthetically-unique Wound-Up composite forks.

We’ve been riding Alpha Q’s since 2002 on three different tandems. They’re not nearly as robust as the Reynolds, but adequate for lightweight teams, whereas heavier teams will give up some handling. One thing that Dan hits on that also bears some attention is his observation that composite forks are more life-limited than a good steel fork: I tend to agree here. However, as to how long that service life may be will vary based on a lot of factors. Therefore, teams who have composite forks would do well to inspect them at least once a year, or more often if they ride a lot, and always after any type of impact that isn’t in line with the design use of a bicycle fork.

Your tandem builder — Calfee Design — knows composites about as well as anyone in the business: really. But, at the same time, Calfee is also all-about “lighter is better”. So, you’ll notice that they have always offered up a range of different forks for use on tandems. Unlike Co-Motion and Santana where the vast majority of their tandems are designed to work with a very wide range of riders (i.e., they tend to be very robust and built to a specification), most of Calfee’s tandems are built to order for a given team’s weight and riding needs. Therefore, having a range of fork offerings allows them to tailor recommendations to their clients.

So, all that said we have to ask ourselves, just how many tandem teams with what is now a limited field of composite fork offerings have had systemic or catastrophic failures? Frankly, I’m thinking if Santana, Co-Motion or Calfee had customers doing face-plants after fork failures we’d all know it in a New York minute and you’d see composite forks disappearing from the options list over night. That just hasn’t happened, at least to my knowledge and I keep my ear pretty close to the ground.

This then brings us to your ENVE 2.0 fork. If you provided Calfee with the usual design inputs for a tandem build — your weight, your stoker’s weight, how much luggage/gear you’ll carry and the like — then I would expect they recommended a fork that they have enough confidence in to put their reputation behind. And, if it helps, I can tell you that ENVE’s 2.0 forks have been tested against similar standards to what True Temper used for the Alpha Q X2 tandem forks, so the design characteristics are known. Therefore, the only variable becomes quality control and consistency…. and as I said earlier, I’ve spoken with some of the composite fork engineers in the past and that gave me the confidence I needed before fitting a composite fork to the tandems that our fairly lightweight teams use.

Disclaimer: These are merely my observations, and should not be construed as a recommendation or endorsement of any product. You will need to figure out how you can establish a level of confidence in the builders and component makers who you choose to provide you with equipment. There’s a reason it takes decades to build brand-name recognition in the bicycle business.

—————————————————–

Dan’s article on carbon forks on tandems is a good read that does offer up a lot of food for thought.  As always, it’s up to the reader to make sure they recognize that when they stumble on a subject that they feel is important and that could have a personnel connection they should pursue additional information and facts that will help them become well-informed enough to draw their own conclusions.

As someone who writes about tandem cycling I personally try not to tell people how they should think or try to suggest that everything they need to know on a given subject has been baked into my thought process and is therefore embodied in my brilliant article.  In fact, I usually try to stress the need to ask more questions and do more research so that readers will be able to make their own informed decisions vs. making too many conclusions based on a single data point or article.  It’s analogous to getting multiple quotes on home improvement projects, medical opinions when facing a serious health decision or shopping for a new vehicle; more information is usually good: just try not to get into analysis paralysis.

Without a doubt, cycling at the enthusiast level is all about passion and draws in passionate people.  Passion also has a habit of polarizing people with a common interest but different philosophies or biases.  You’ll find these divisions with sports car enthusiasts, wine aficionados, motorcycling enthusiasts, film & literary critics and tandem enthusiasts.  Want to start a passionate discussion at a tandem rally?  Introduce a discussion about something that a certain tandem builder has recently written about tandem technology; yikes!

And so it goes with all aspects of tandem cycling.  If you’re considering a large investment in a new tandem, or are shopping for a used tandem do your homework.  Call up and talk to the builders, noting that with the exception of the mega brands like Trek & Dorel (who in turn owns Pacific who in turn owns Cannondale: yeah, there’s a message in that) where you may be hard-pressed to find the person who actually designed your tandem never mind talking to someone in the mega-size factory that mass-produced your tandem, builders like Co-Motion, Santana, Calfee, Rodriquez, Bilenky, Seven, daVinci and other recognizable and reputable brands are very small businesses where the folks who design and fabricate the frames are very easy to reach and tend to be very happy to talk to customers about their products.

That’s all I’ve ever done when I’ve had questions about a specific product, along with making inquiries with the more experienced tandem speciality dealers who are also a wealth of information.  In fact, most of the dealers will help you sift through the fog of “facts vs. marketing spin” to arrive at a good decision on a tandem, tandem wheels or other components.  After all, the folks who’ve been selling tandems for 20+ years are still doing it for a reason: they take care of their customers and give them good advise.

If you think you’re smarter than dealers or builders are about tandems, then don’t waste their time: just go with your gut and do your own beta testing with the latest equipment.  Seriously, and that’s not a swipe.  I tend to fall into that category at times as there are things I’ve had builders do with our tandem designs that were not standard offerings because of my own experience and preferences.  There are also components or ways of rigging I’ve been able to learn and use on our tandems that are well outside the realm of conventional wisdom that work well for me, but not others.   Other times, not so much and I have the parts sitting in a box to prove it.  Thankfully, I’ve never found the bleeding edge, as I love my wife too much to put her at risk by putting a critical component on our tandems that I don’t have absolute faith in.

So, that’s what I think…. and I do a lot of thinking.

Advertisements

About TG

I've been around a bit and done a few things, have a couple kids and a few grandkids. I tend to be curmudgeonly, matter-of-fact and not predisposed to self-serving chit-chat. Thankfully, my wife's as nice as can be otherwise we'd have no friends. My interests are somewhat eclectic, but whose aren't?
This entry was posted in Advice & Commentary. Bookmark the permalink.

10 Responses to What Do I Think? Good Question. (Tandems & Composite Forks)

  1. jonathan says:

    Kudos! Another great read, informative, fair and balanced. As a matter of followup, Our tandem team on a 2014 Calfee Tetra (team weight 315 – 330 lbs) is equipped with the CoMotion carbon fork..as originally recommended by Mel of Tandems East…(not the Enve 2.0 as previously posted!….my bad).

    Thanks so much for the insight!

  2. David Roberts says:

    I got 404s on those links because of the inclusion of a closed quote. Using a 2003 WoundUp on our Speedster. 300 lb. team. I don’t understand the prediction of short life for carbon steer tubes. Ours has an aluminum mandrel with carbon over. Talked to WU who don’t predict a service life.

    • TG says:

      Links have been fixed; thanks for letting me know they were buggered-up.

      I think what Dan is most likely referring to are the all-carbon forks, along the lines of the early AME Alpha Q’s which did have some life issues. True Temper did a lot to improve the Alpha Q forks once they bought the product line that addressed the early issues. Advanced Composite’s Wound-Up forks and Co-Motion’s new house-branded forks are very much tandem-specific products as are the forks that Santana offers. I can’t recall hearing of any issues with those. In fact, despite ENVE’s warning about tandem use, I have yet to hear about any ENVE 2.0 issues from folks who have been using those.

      All that said, composite forks do bear some periodic inspection and attention, in much the same way that any other fork does. I’ve seen several of those AME Alpha Q forks that have developed cracks around the fork crowns… and have been both shocked and amazed at how they failed but also how they continued to stay together after they began to fail.

      Again, Advanced Composite’s forks and their seat posts are a different cat from many of the other all-composite products: the Wound-Up forks are far more robust and don’t have the deflection that I see in our True Temper Alpha Q’s and, on the triplet, with even the Reynolds Ouzo Pro Tandem.

  3. Dave Walker says:

    I read Dan’s blog post on carbon forks. His anecdotal story of “Jim” and his carbon fork failure on a tandem in 1995 is heartbreaking, but hardly relevant in 2014. When True Temper left the market a few years ago I spent some time talking to the engineers at Edge (as it was called then; since renamed ENVE) and was assured that their 1-1/8″ 2.0 Road fork was up to tandem duty; indeed, it’s been tested to be as strong and durable as the venerable and much-missed Alpha Q X2. If you read the disclaimer on the ENVE web site it all becomes clear: “ENVE’s forks are not approved for use on TANDEMS. While all of ENVE’s forks are EN certified for up to 350 lbs., currently there are no industry standards for tandem forks. As such, ENVE cannot recommend use on a tandem.” If there are no industry standards for tandem forks, then by that same logic not a single fork on any tandem from any manufacturer is “tandem approved.” Hmm.

    I am all for safety, first and foremost. We ride a Paketa tandem with an ENVE 2.0 Road fork on it (tapered 1.5″ in our case; also not “tandem approved” for the same reason as above) and feel every bit as strongly as Dan that I would never, ever risk my life, or that of my stoker (also my wife, usually) on a questionable fork. I assume the same level of responsibility for my customers, liability issues notwithstanding.

    Google “ENVE fork failure” and tell me what you come up with. I see ZERO results, and that’s even taking into account the approximately 1000X as many forks out there on single bikes as on all tandems from all manufacturers combined.

    And, yes, I understand the physics behind the forces involved, as Dan describes: my degrees are in physics and mathematics with a master’s degree in engineering. If one is concerned about the safety issues of the ENVE 2.0 Road fork that’s had zero reported failures, then the next logical step (and one that we recommend to any team over 300 lbs. total weight) is the tapered 1.5″ model. All else being equal, a 1.5″ crown is 316% stiffer, and comparably stronger, than the already-proven 1-1/8″ 2.0 Road model fork (the fork crown area is the usual point of failure on any fork).

    I also have to take exception to Dan’s closing comment on “eliminating the lateral stiffener tube,” which is completely unfounded. I’ve done the analysis and the testing that proves the Paketa’s open-frame design is far superior to any tandem frame made of any material using an internal lateral tube. But that’s a topic for another time and place. As for “honest bicycle weights,” our tandem is 23 lbs. with S&S couplings and pedals–i.e., rideable–and I have no problem showing anyone, in person, that that’s an honest weight.

  4. Andy white says:

    FYI, Niner makes a carbon disc brake for which states “no rider weight limit ” neat! I assume it has crown to axle height appropriate for a shock fork dimension. Still, nice to see a super beefy carbon fork.

    • Dave Walker says:

      While the Niner fork is probably just fine for tandem use, it’s still not tested to any tandem standard, thus falls within the same class as the ENVE forks for all intents and purposes. That’s the problem: until there’s an agree-upon industry standard for testing tandem forks this issue will be with us.

  5. Bryan B says:

    Hi all,

    A few of my observations to toss into the stew pot…

    While you may find a mfr that “certifies” their fork for tandem use, have you ever seen any data that shows where a legitimate CEN approved fork has failed and where the “tandem” fork has surpassed that failure and by what factor? I have not and would be interested in learning more if that info is available. Meanwhile, does a “tandem approved” fork make it safer, or simply make you FEEL safer?

    1. While Reynolds Ouzo Pro was one of the few “tandem rated” forks on the market, it was never certified by any defacto governing body. They could not market or sell any of their forks in Europe as they declined to invest in the testing to pass the CEN requirements, and so dropped out of the fork business. All the while, happy tandem users were thrilled that Reynolds labeled their fork tandem worthy… FWIW.

    2. We are currently using a ENVE 2.0 Tapered (1 1/8″ – 1 1/2″) fork on our Calfee. Based on the cursory research I did, the most critical failure area for a fork is the sharp transition between a steer tube and fork crown. A tapered fork is enlarged and shaped at the bottom, plus allowing much bigger bearing races to be installed. Load capacity of a 1.5″ Chris King bearing is far greater than that of cups used for a 1 1/8″ tube.

    While I was never sold on Santana’s “proprietary” 1 1/4″ upper steer tube, Bill M’s information about the increased steer tube strength over 1 1/8″ does hold true, and even more so when jumping that extra 1/4″ up to a 1.5″. Though I have not read reports of catastrophic steer tube/fork crown failures from tandem teams, that does not refute the fact that oversized/tapered forks are indeed a stronger design. Luckily, with the increased popularity of 29er/road bikes, oversized tapered forks are much more of a norm in the current market.

    3. Other manufacturers? 3T has the Rigida fork, CEN approved and it comes tapered too. They do not post rider weight limits on their forks because they defer to the very stringent CEN requirements and pass those. Their policy regarding tandem usage is actually the same as ENVE’s… officially it is not certified. The reason behind is that there are no official tests and the market is too small to develop tailored products or tailored tests.

    As Reynolds found out, meeting even the generic CEN requirements can be a deal breaker.

    Co-Motion? A reputable company, but what does a claim of tandem rated or certified really mean? Perhaps a heavier fork, overbuilt fork designed to accommodate harsher usages that are at or exceed a nominal 350lb threshold.

  6. Richard Entrekin says:

    Sorry to be so late to this thread. I want to throw in another bone to the stew. Unfortunately, my bride tried to put the Subie in the garage with our CoMo on top. Oops. The bike frame buckled at the top tube and the lateral tube. The down tube completely fractured. The Wound Up carbon fork was intact. I couldn’t believe it. I took the fork off and examined all of it with a magnifying glass for any cracks. I found none. My background was as a practicing engineer in both the composites and high performance fibers industry. I don’t intend this as a one data point endorsement of CF forks but the results really surprised me. Given the moment angles of the brake levers being the upper lever and the fork mount being the lower lever, I would have expected the fork to fracture at the crown juncture.

    Don’t worry, I destroyed the fork beyond use, and put it in the trash. You won’t see it on Ebay!!

    The silver lining was the replacement of the CoMo with a Calfee. Nicest tandem we have ever ridden.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s