Carbon seat posts and tandems

In the summer of 2011, two days before the biggest ride of the year in our area, I received an emergency phone call from a customer. The couple had a S&S coupled travel tandem (not one of ours) and they were leaving on a trip to Europe in 2 days. The emergency was that the captain's seat post had broken off while they were trying to pack the bike, and they had no way of getting the remaining portion out of the frame. Realize that our repair shop was booked solid, and had been for over two weeks already. We'd been working past 10:00pm every evening, and that night was going to be no exception. Had this been a Rodriguez, I of course would've said bring it in right now, and we'll fix it while you wait.

But, it wasn't a Rodriguez, so I asked them if they had taken it to the shop that they had purchased it from. They told me that the shop had gone out of business. I asked them if they had contacted the manufacturer of the bike and they said they had. The manufacturer had told them to bring it to R+E Cycles. "Well", I said "bring it in and we'll see what we can do". I told them that I would do the repair myself that evening.

When they brought the bike in, I was amazed to see that a standard road bike carbon seat post had been used for the captain's seat post in this bike. The riders were strong, powerful riders, and certainly not the type that I would've ever sold a tandem with a carbon fiber captain seat post. If I had seen this couple on this tandem, I would've suggested to them that they replace the seat post immediately. None-the-less, the under-weight carbon seat post was broken off flush at the frame, and needed to be removed and replaced with an appropriate weight post before the end of the next day. To further complicate the issue, the size of the seat post was specific to that brand of tandem (check out my article on proprietary parts), and not a size that I had or could even get quickly. "What a pain in the ^&*^" I thought.

I stayed late, and crafted some makeshift tooling in order to remove what was left of the carbon post while trying not to destroy the paint job. I then had our machinist manufacture a custom sized shim so that we could install a seat post that we had in stock, and another shim to fit the stoker stem to the new seat post. It was a lot of work to solve two problems that never should've been problems in the first place. I wanted to put a picture of the seat post in this article, but I'm still looking for it. When I find it, I'll update this article.

A Second Story
In the summer of 2013, a couple brought their brand new (non-Rodriguez) titanium tandem in for some minor adjustments after purchasing it elsewhere. This bike also used a carbon post for the captain. When the mechanic sat on the captain's seat and started to pedal the bike through the repair shop to do a preliminary check of the brakes, there was a loud 'POP' sound. It sounded like a small gun went off, and the mechanic jumped off the bike and said something like "What the heck was that?" (except he used surprised mechanic language that I don't need to repeat). Upon a quick inspection, we discovered that the carbon fiber captain seat post had cracked lengthwise over about a four inch section. If this were to happen during a ride, it could've been very dangerous. We replaced it with an aluminum one, and all was well.
We want you to live
A captain's seat post has to be extremely strong. On a tandem, the captain's weight, as well as a good part of the stoker's weight is on that seat post. When a powerful tandem team is standing and climbing, the stoker is putting a lot of force on that seat post that isn't there on a single bike. A carbon fiber seat post is easily damaged by clamping things onto it.....such as a stoker stem. When a carbon fiber seat post has crack in the finish, it can eventually become a break. This process is accelerated when it is used as a captain seat post. I would consider that a captain seat post shearing off while riding would be a catastrophic failure, wouldn't you? For this reason, I believe that this couple was extremely lucky that this happened during packing the bike and not while riding the bike.

Fit to Finish
This couple's tandem should've been outfitted with appropriate components when they purchased the bike. The manufacturer is trying to impress everybody with a light tandem by using parts that are too light for tandem use. That being said, if the dealer was a good tandem shop, they would have employees that ride tandems and would know to replace these items before selling this type of product. I think the fact that they are out of business speaks to what type of dealer it was though.

With our Fit to Finish manufacturing method, we see what works and what doesn't. As the dealer, we know right away when our customers are breaking certain parts because they bring them directly to us. As the manufacturer, we can change that spec right now as opposed to next year.

Feel free to email me if you have any further questions about tandem appropriate parts. We're the oldest tandem manufacturer still producing our tandems in the United States, and we've seen just about everything. We have the experience of over 39 years servicing tandems, knowledge of over 39 years building tandems, and quick reflexes through our Fit to Finish manufacturing process. Rest assured that we will not sell you any component on your tandem that we feel is unsafe for tandem use.

Thanks for reading,
Dan T.