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Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

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Old 10-23-06, 08:49 AM   #1
Doggus
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Cracked Co-Motion frame!!!

We did it!!! We cracked our frame without going down in a firey crash. She's just barely a year old and we managed to crack her. Why so excited? Cause the whole bike shop where we bought it had to stop business and everyone came to see the Co-Motion with a DEFECTIVE crack in the frame!!! No one has ever seen a cracked Co-Motion frame without being in a crash.

Glad we have a Co-Motion with a lifetime warranty. This shouldn't cost me a dime to fix, we'll see how that warranty holds up.

On several past rides, I've noticed a little 'grease' running down the side of the stoker seat tube. First time I saw I thought maybe I had spilled something on it while servicing the bike. Cleaned it up and moved on. Then I saw the same marking again a couple weeks later. Thought to myself...what the hell am I doing to this bike. It seemed like I would spotted it after I would service the bike (I always wash it at that point too). Then this weekend, we were sitting at the feeding trough after the ride and I spotted the tale-tale lube running down the seat tube. So me and one other rider inspect it and low and behold and crack running horizontal across the seat tubing, across the weld and into the top tube. The crack is about .5" long. You can barely see it but we can tell it's all the way through since there is stuff seeping out of the crack. No one seems to know what the black is coming out other than it might be the seat post grease.

Not sure what Co-Motion is going to do to fix this. I'm assuming they'll be cutting and rewelding in some new tubing. Our LBS told us we could probably get the paint job we always wanted now since they're gonna have to repaint the bike anyway. Not sure if they'll just replace the frame. I'm no bike maker.

They're going to take photos this morning and I'll hopefully get hold of the images and post them here.

We we're signed up to ride our local tandem club's two-day overnight ride this weekend too. It was supposed to be a really cool ride

Last edited by Doggus; 10-23-06 at 08:57 AM.
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Old 10-23-06, 10:10 AM   #2
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Co-Motion should replace the frame instead of doing a fix like you're talking about. Can you imagine going down a long grade at 45mph on a bike that had a cracked frame and was scabbed back together? Scary!!!

Looking forward to seeing before and after pics. Hope you get that custom paint job.
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Old 10-23-06, 10:34 PM   #3
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scab patch it and let me see some booger welds .. ill ride it..... the ablitly to weld is a art that I do not have ... as long as its done right it will be safe. ever flown on a airplane ... your trusting someones welding
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Old 10-30-06, 08:21 AM   #4
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Yes you are trusting welding when you fly. What you're not doing is trusting something which has been modified or repaired without thought using unproven techniques. Normally modifications to original designs only take place with very careful though and testing by people who are expert in aircraft design. This is why people who want to design and build their 'plane either have to get inspected by the CAA and build it to the original design, or build it under a 'experimental' category, i.e. you're on your own when it comes to safety.

I wouldn't be very happy to fly in a jetliner registered under the 'experimental' category and wouldn't ride a commercially produced tandem on that basis either.
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Old 10-30-06, 10:59 PM   #5
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We've put 57,000 miles on our Co-Motion custom tandem. No problems.
If you are the original owner of the Co-Mo, it will be fixed.
In our 31+ years of tandeming, we've broken two tandem frames and one fork (not Co-Mo) and all were fixed gratis by the builder(s).
Sometimes stuff happens . . .
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Old 07-16-12, 12:30 PM   #6
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Hey,

we've developed a crack in our Co-Motion Speedster exactly like one you describe -- across the stoker seat tube, through the weld into the top tube. Ours is about 1" long, kind of squiggly.

Ours has not gone through the tube, yet. I thought it was a scratch at first, but on closer inspection, it's pretty obvious to be a hairline crack.

Question, what was the end result for your bike with Co-Mo?

I've dropped off the rear triangle of the frameset with our tandem dealer (College Park Bicycles, Md.) for inspection by the manager. We have couplers so I wonder if they'd try to remanufacture just that end of the bike.

thanks,
Ed
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Old 07-17-12, 06:13 AM   #7
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I've dropped off the rear triangle of the frameset with our tandem dealer (College Park Bicycles, Md.) for inspection by the manager. We have couplers so I wonder if they'd try to remanufacture just that end of the bike.
We had cracked our S&S'ed steel frame around the captain's seatpost clamp. Send it back to my builder. He replaced the whole frame. As he explained to me, a coupled frame is built by first building a regular frame and then cutting the built frame to install the couplers.

Good luck.
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Old 07-17-12, 08:25 AM   #8
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As he explained to me, a coupled frame is built by first building a regular frame and then cutting the built frame to install the couplers.
Some do it that way, but not all. Co-Motion, for example, incorporates the couplers into the raw tubes during the frame fabrication and lay-up process, before welding the frame's joints.

More info: http://www.co-motion.com/index.php/i...to_my_old_bike
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Old 07-17-12, 09:49 AM   #9
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Just curious if you bought your tandem from Richardson Bike Mart? We did. Did not know of another tandem dealer in Dallas at that time.
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Old 07-17-12, 12:57 PM   #10
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Just curious if you bought your tandem from Richardson Bike Mart? We did. Did not know of another tandem dealer in Dallas at that time.
We bought our CoMotion from Plano Cycling and Fitness in 2006. At that time we looked at Richardson Bike Mart and they only handled Santanas and not CoMotion.
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Old 07-19-12, 08:54 PM   #11
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Update on our ailing 2006 Speedster -- the frame definitely cracked at the stoker seattube/top tube junction. On close inspection, our shop found a crack inside the seat tube running away from the hole into the top tube, left-right. That's in addition to the crack on the exterior drive side. We've been hearing a ticking sound back there on and off for the last year or so but without any other evidence chalked it up to the seatpost & Brooks Flyer S combination.

Co-Motion has told our dealer to send in the entire frameset and they will fix it, but we don't know what all they plan to do.

Ed
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Old 07-20-12, 06:01 AM   #12
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If done well, it is perfectly safe to replace a tube on a TIG welded frame. If they choose to do so you will not be able to tell it from a new frame. One thing to consider if they fix the frame consider asking if you can change the color of the frame when they repaint it.
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Old 07-21-12, 07:23 AM   #13
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The question will be that the frame is coupled. Expect they will have to replace everything from the captain seat tube rearward. At that point, is it practical for them to cut and reweld, and will it come out straight? I'm interested in what they did for the original poster in this thread and how their repair turned out.
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Old 07-21-12, 08:01 AM   #14
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Co-Motion will do what ever's the most prudent approach to making the repair.... it's what they do. That the frame is steel makes it a bit less complicated vs. aluminum, but steel, titanium and composite frames really do lend themselves nicely to rework by skilled frame builders. But, we've seen a couple aluminum frames that have been reworked by Ventana for customers and you absolutely can't tell the frames have been reworked.

The key here IS being the original owner to whom the lifetime frame warranties apply, or with some builders subsequent owners who have re-registered the frames with the builder where they have "second life" warranties, e.g., Calfee offers a Second Life Warranty

Anyway, the key for original frame owners who have a program is to do exactly what our friend, the OP, did here. Contact their dealers who, in turn, will work with the manufacturer to establish if the observed condition falls within warranty coverage (that is to say, it was not caused by a crash or other external factors) and if so, how best to remedy the condition.
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Old 08-21-12, 05:46 AM   #15
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Co-motion replaced our frame under warranty. It took well over 6 months because we ordered a custom paint job on the new frame that they continually kept screwing up. I started riding my single, I got fast, got a power meter, started racing, my daughter started riding, she got really fast, she was asked to join the junior development squad of Exergy TWENTY12 (you've heard of them, Kristin Armstrong, Olympic gold medal in London), all we do now is travel to her races. Oh, the tandem, if I could light it on fire, I would. We are pretty much ex-tandem riders.
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Old 08-21-12, 05:51 AM   #16
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Co-motion replaced our frame under warranty. It took well over 6 months because we ordered a custom paint job on the new frame that they continually kept screwing up. I started riding my single, I got fast, got a power meter, started racing, my daughter started riding, she got really fast, she was asked to join the junior development squad of Exergy TWENTY12 (you've heard of them, Kristin Armstrong, Olympic gold medal in London), all we do now is travel to her races. Oh, the tandem, if I could light it on fire, I would. We are pretty much ex-tandem riders.
Sorry to hear that but at least you are both still riding. If you can get together you should be able to do some damage with your power on the tandem.

I am glad we have a backup tandem.
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Old 08-21-12, 09:40 AM   #17
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Oh, the tandem, if I could light it on fire, I would. We are pretty much ex-tandem riders.
Why not sell the tandem instead of keeping as a reminder of what is apparently an unpleasant memory?
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Old 08-24-12, 04:01 PM   #18
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Co-motion has our tandem and is ready to repair it for free under warranty. There were some welds from that year, 2006, that have not held up, they say.

We're also being offered a very low price for a full replacement, which we are considering. The Java 29er is our preference because we found our Speedster a little flexy when we stand up and way too flexy with four panniers.

It has a very long rear top tube. We'd also like more tire clearance.

Dwan says the Java will be stiffer than the Speedster even without a lateral, but we may add the lateral anyway. He says it will make the bike stiffer still. Thinking as a sport touring setup, do we get the lateral? This is a coupled tandem so we'd save a fair amount of money by leaving out two couplers with no lateral.
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Old 08-24-12, 07:38 PM   #19
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Co-motion has our tandem ...
There's no bad option in there that I can see.... Got with your gut!
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Old 08-24-12, 07:59 PM   #20
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... This is why people who want to design and build their 'plane either have to get inspected by the CAA and build it to the original design, or build it under a 'experimental' category, i.e. you're on your own when it comes to safety.
I wouldn't be very happy to fly in a jetliner registered under the 'experimental' category and wouldn't ride a commercially produced tandem on that basis either.
We've put over 10,000 miles on an "experimental" Co-Motion tandem.... it was the first triplet they ever built!
Then again I've been a member of the EAA for well over two decades now.
I affixed not only an FAA data plate to the boom tube just for kicks, but a "solo from front seat only" placard as well.
The company's tech folks were very easy to deal with during the design process, and since it has run flawlessly ever since we have had no further contact.
I'm sure they will make you better than whole again.
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