Building Tandems the Rodriguez Way

At Rodriguez Bicycle Company, we build a lot of tandems. We’ve done it for 46 years now, and in that time we’ve learned a lot. Tandems require a different approach than single bikes. Every force put into a single bike during a ride is at least doubled, and sometimes tripled, when riding a tandem. This means every design decision has serious repercussions for ride quality as well as rider safety. In this article we are going to explain why and how we make these decisions when building a Rodriguez or Erickson tandem. We’ll take them in order of importance.

 

Fit – the most important decision

Every Rodriguez and Erickson tandem is built custom to the riders’ exact fit. Every one. This sets us apart from every other tandem manufacturer. We’ve learned that a tandem that isn’t comfortable to ride is a tandem that sits in the garage, unridden and unloved. Fitting one rider to one bike can be challenging, but fitting two riders to one bike requires the extra effort of a custom frame. This also allows us to build each tandem to perfectly suit the goals of each team of riders, whether that’s a 26 pound ultralight race tandem, or a double step-through tandem frame for an older (uh…wiser) couple that just wants to keep riding together as long as possible. We meet you where you need to be.

Fit is also the reason we rarely use a belt drive for our timing gears. We get a lot of questions about Gates timing belts for tandems these days. They work well to connect the two cranks together, but they are restrictive in one particular way: they drastically limit how long the stoker cockpit can be. A comfortable stoker is a happy stoker and forcing them into a cramped, short compartment is never a good idea. Although the timing belt looks cool, it will look less cool sitting in the garage because your stoker doesn’t enjoy riding the tandem.

We do build occasional tandems with belts if the stoker’s fit works out. If belts become available in variable lengths, and we can build without stoker comfort compromises, we will be happy to recommend them to more couples. Until then, consider what problem you’re trying to solve with a belt, if any, and whether the compromise is worth it.

The tandem above uses a belt for timing. As you can see the stoker’s handlebars end up almost directly under the captain’s saddle. The Rodriguez tandem on the bottom has a much roomier stoker cockpit, allowing for greater comfort and fit flexibility. Note the lack of stiffener tube in the top tandem as well.

 

Frame – the most permanent decision

To the untrained eye, tandem frame designs can look very similar, but to an experienced builder there are subtle yet important differences between designs. Our design choices can add complexity and time to the frame building process, but we think it’s worth it to our customers.

Designing a tandem frame is a formula that balances strength, handling, and rider comfort. The frame needs to be stiff enough to handle two riders putting all their weight and strength into it while still being compliant enough to give a smooth and comfortable ride. If a tandem is too stiff then it will be jarring to ride and therefore unridden. This is why we almost always start with steel. It provides a reliably smooth ride, fantastic strength, and can be made as light as the riders require for their needs. Desired riding characteristics can be achieved through tubing choices, tube shape, and geometry design all of which are fine tuned to the owner’s needs. These decisions build the foundation on which all the other parts rest.

One feature that almost all of our tandems have is a stiffener tube that transverses the length of the bike from the head tube to the stoker’s bottom bracket shell. (see the above image) Correctly mitering a tube to join the bottom bracket correctly is a difficult process, but one that we know is worth it. It stiffens the frame overall, but by joining the tube directly to the bottom bracket you gain a frame resistant to the twisting forces of the stoker’s pedaling and a frame much less likely to crack from stress. Our stiffener tubes are also one continuous tube, not two tubes welded into place. (see image below) Again, this is more difficult, but worth it for the strength and stiffness this method provides. A pierced tube will not flex at the captain’s seat tube the way a pieced together tube will.

Here’s an example of a junction assembled with pierced tubes. Piercing, rather than joining two separate tubes, maintains maximum strength and rigidity.

Most tandem builders have stopped using stiffener tubes in recent years. This is to save time in their build process. Time is money, after all. Some believe it makes the frame lighter, but is that true? Surprisingly, no. All the other tubes have to made stronger and heavier in this type of design so any weight savings is negated. Leaving out the stiffener tube also results in a frame this is less resistant to flexing at the stoker’s bottom bracket. The frame will be more likely to twist under load even if the other tubes are heavier because there is no triangulation. While we do offer lower priced Rodriguez tandems without stiffeners, they are not the main choice of our customers who want a high performance build. Leaving out the stiffener saves the builder money, but there is no getting around the fact that it is a performance compromise.

Fork – critical to both handling and safety

There’s no getting around how critical the fork is to tandem riders. It needs to be stiff and it needs to be strong. We have two styles of tandem forks and both are made from steel.  Unlike a single bike, where we can use aluminum or carbon fiber forks, tandems work better with traditional steel forks. We have a heavy duty fork that can handle the weight of the riders as well as a fully loaded touring setup with panniers and frame bags. We also build a lightweight steel fork for riders that want to save weight but still have a fork that they can rely on in difficult situations like sprinting and cornering under speed. Having a fork that flexes too easily, especially in regards to the steering tube, can ruin the handling of an otherwise well built tandem.

For these reasons we no longer use or recommend carbon forks in our tandems. While many carbon forks perform well on single bikes, they have proven to perform poorly on tandems. Carbon steering tubes flex more easily and are more prone to breakage than a steel steering tube. The legs of a carbon fork have the same issue and can provide a “noodly” effect even if they are built strong enough to stay intact. There are also few carbon fork manufacturers that will warranty or recommend their forks for tandem use. They know it’s not a good idea. Even so, many tandem manufacturers put these carbon forks on their tandems even though the fork maker has specifically stated ‘not for tandem use’. If the fork manufacturer says it’s not strong enough for a tandem, you should believe them.

Safety aside, the benefits of a steel fork in both handling and reliability for tandem use greatly outweigh saving a couple of ounces of static weight.

Components – fine tuning your needs

Tandem components go through a lot. Shifting gears can be especially challenging with two people applying force to the drivetrain. Stopping a tandem requires more than 3 times as much force as a single bike, thanks to the Inverse Square Law. Wheels on a tandem need to be especially strong to hold up to the forces of cornering, climbing, and descending under two adult riders and the things they carry with them. We can carefully curate a set of components for your tandem that will meet your needs and hold up for the long haul. These choices will be part of the conversation when you get a tandem from R+E. One size does not fit all and we keep this in mind when building your tandem.

Experience – the last crucial piece

All of this information and insight comes from building and riding tandems for decades. Every part of our design has been looked and revised over the years and we are confident that we are building the best tandems in the business. We build because we ride, and we don’t want to build something we wouldn’t want to ride ourselves. If you want to know more just give us a call or shoot us an email. We will be happy to have a conversation and go into as much detail as you need.

 

For more information on our history with tandems, check out the articles below:

Other articles on bicycles, tandems, and the bike industry can be found here.

 

Do you want a Forever Bike?

No Planned Obsolescence

What you don’t know can cost you thousands!

In our repair shop each year, we see several expensive bikes each year rendered useless! When I say expensive, I mean bikes that sold new for over $5,000. Sometimes they remain in the repair shop waiting for parts for most of the riding season, and sometimes they are off the road for ever. That seems unacceptable to me for bikes this expensive, and less than five years old. It’s amazing to me that the customers were unaware that the bike they purchased for such a large sum of money was designed to become obsolete after a few years. This is due to the use of proprietary parts, or parts that don not comply with ISO standards.

Proprietary parts are parts designed specifically for use with that particular bike. They are only made by that manufacturer, and they only sell them to dealers that carry that brand of bike. We’re seeing more and more of this in our industry. What this means to you, the customer, is that if you purchase a bicycle that uses proprietary parts, you are trusting that bicycle company will always manufacture the special parts for your specific bicycle. It also means that you have to take your bike to a dealer that sells that brand of bike in order to have the special parts serviced or replaced.

Part standards that are non-ISO compliant are phony ‘standards’ that are really just new designs issued by companies wanting to say that their bikes use standard parts. The difference between proprietary parts and these phony ‘standard’ parts is that they allow anyone to use the new ‘standard’ if they want to….so….somehow that makes it a standard. This is just another way to build planned obsolescence into an expensive bicycle.

Most people think that if they are paying thousands of dollars for a bicycle, it will last more than a few years. They are also under the impression that they can have the bike repaired in just about any bike shop. For most high-end bikes manufactured today, this is not true.

The Real Standards: For those of you who want to buy an expensive bike that will last forever, this article is a must read. ISO, or International Standards Organization, is a term that you need to familiarize yourself with before laying out the big dollars. I’ve written an article about ISO called Chaos that can be read here. If you want a bike that can be repaired by any bike shop around the world, for as long as you own it, then there are areas of the bike that need to comply with ISO standards, otherwise, it will become obsolete and may do so in just a year or two.

First, one real life example of what I’m talking about:

Can you imagine purchasing a $5,000+ bike and then just a few years later, having to purchase a new frame to replace it? Not because of wreck, but because the frame broke at the bottom bracket under normal use. This is an actual case that happened last summer in our shop.

Repaired Carbon Fiber Derailleur Hanger

A high end carbon fiber frame was brought in because the customer had shifted into the spokes and broke the derailleur hanger off of the bike. He was told by the manufacturer that his warranty would be void if he had it repaired. The local shop where he bought the bike told him he was S.O.L. Well, he had to have it repaired in order to ride the bike, so he hired us to machine an aluminum hanger and attach it to the frame (see picture).

A few months later, the frame broke at the seat tube, completely unrelated to the new derailleur hanger. The break was at the point where the seat tube meets the bottom bracket 18 inches away from the derailleur hanger. The manufacturer said ‘no warranty because the frame has been modified’. This is a common theme among big manufacturers these days. Really, these expensive carbon bikes are designed to last about 5 years. The trend is to design an expensive frame that is not repairable in any way, and then deny warranty because of some technicality. Can you believe that exposure to sunlight can void your warranty on some carbon frames?

The customer in this story now owns a Rodriguez lifetime bike that complies with ISO standards. He brought the carbon fiber frame in for us to cut to pieces and dispose of in our dumpster. He loves his new Rodriguez S3 frame, and says it rides even better than the other bike ever did. Another pleasant surprise, his S3 steel Rodriguez is also lighter than his carbon bike. He was surprised that it was lighter, but it is.


I’m trying very hard to get the word out about proprietary parts, and what they mean to you as a cyclist. The noise of cycling magazines filled with ‘experts’ telling people the benefits of XXXX company and their new design seems to drown out common sense.

So why are companies using non-standard parts?

I can’t read their minds, but I can think of several reasons that manufacturers can benefit by deviating from ISO standards.

  • Control of warranty costs
    Let’s say that a manufacturer wants to advertise that they offer a ‘lifetime’ warranty on their frame, but they really don’t intend for that frame to be on the road in 30 years. Simply design the frame to work only with a proprietary fork, or headset, or bottom bracket, etc. After 4 or 5 years, they just stop making that proprietary part and the ‘lifetime’ frame warranty is useless. They’re not going to give you a new frame because your head set wore out, or your fork broke right? Don’t think they would do that? Read the example above. They’ll look for any technicality they can to ‘opt’ out of the warranty. I think this is why some manufacturers that offer lifetime frame warranties only offer 5 year warranties on their proprietary forks.
  • Better design
    Let’s give them the benefit of the doubt and say that they’ve come up with a design that is better. I’m sure there are improved designs out there, but the fact remains that unless the part is compliant to ISO standards, you’re taking a risk. I’ve found that the “better mouse trap” usually has a big following for a few years, gets some great write-ups in magazines, and then it’s off the market again. It’s really interesting to read Bicycling magazines from the 1970’s and see all of the new designs that are going to revolutionize the industry, and then try and find one of those designs manufactured now. Unless you want to pay to be their product test subject, I suggest sticking with the 30+ year old standards.
  • Trickery in advertising
    Let’s say a company wants to advertise an honest frame weight that’s lighter than everyone else’s frame. It’s possible to make a frame even lighter with the use of proprietary or non-ISO compliant parts. The funny thing is, when the proprietary parts are installed, then the overall weight of the bike is actually heavier than a light bike with the ISO compliant parts. Don’t be fooled on that one. A frame weight for a bike using proprietary head set, bottom bracket, or forks is going to result in no weight savings when the bike is built up completely. All you end-up with is an expensive bike that is heavier, and will not last forever.
  • Profit for their dealers
    This one’s a no brainer right? If there’s no competition for the proprietary parts, then the profit margins can be really high. If you’re bike won’t work without a bottom bracket, and the only one you can buy for your bike is the one made for your bike, and it’s only available at the dealer……you get the point. This arithmetic is heading in one direction and that is higher, higher, and higher prices. Ouch! Not the direction that most of our customers want to go.
  • They don’t love their customers….
    …OK, maybe they do love their customers, I don’t know. What I do know is that they’re not doing their customers any favors by selling them non-standard parts. I’ve always said that when you purchase a bicycle, you’re purchasing a relationship with the dealer and the manufacturer of that bicycle. If you want that relationship to be a pleasant one that lasts, make sure that they share your philosophy and expectations you have before you spend the money.

no Planned Obsolescence
Avoid the chaos of non-ISO compliant parts! At Rodriguez Bicycles, we go out of our way to make life easy for our customers, and build them a bicycle that will last them a lifetime. We use ISO compliant parts so that you’ll be able to get your Rodriguez repaired at any shop just about anywhere. We love our customers, and they love their Rodriguez Bikes!

Thanks for reading