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Old 08-11-17, 04:43 AM   #1
marciero
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Cannondale BB30 bottom bracket issue

Our 2015 Cannondale T2 has BB30 bottom bracket with a sleeve pressed into the shell that accepts standard FSA bearing cups. My understanding is that FSA developed the sleeve specifically for Cannondale for this application. I had the cranks off recently to check things out and discovered what appears to be non-factory welding or tacking of this sleeve to the shell. I described it in this thread and posted some pictures. This is not a tandem-specific issue, but I was wondering if anyone could shed some light or had any insights. The bike was sold to me as new. After two years I was getting creaking but greasing the spindles seemed to take care of that for a while. When creaking returned I discovered the bearing rough on that side and that one of the welds created a high spot that prevented a spacer from seating. I have machined the spacer where it was not seating flush against the sleeve and replaced the bearing. So far it seems functionally fine but the hack job on a new bike is unacceptable and I will be seeking to have the sleeve replaced and properly installed, or go another route. Options for tandem triples are very limited though. I wish Praxis made one...

On a related note, I replaced the bearing cups with FSA bb7000 instead of bb7000 TD (for "tandem"). Oversight on my part ordering the part. I uses the old bearing sleeve, which was shorter. (The new one would have required three spacers rather than two with this 68mm shell) The only other difference seems to be a small lip on the inner circumference of the bearing dust caps, protruding outward so it spaces the crank arm slightly farther away than if it were flat. The old ones were flat here. They are installed and seem to work fine, with minimal binding (they dont spin like old square taper bearings) though the wave spring washer is completely compressed, where it was not previously. I had to adjust the derailler slightly also, in the outward direction-no surprise. I do plan to get the correct bearings, but in the meantime, will my bike explode?


Thanks for any insights. (I've also checked with Mel at Tandemseast)

Last edited by marciero; 08-11-17 at 04:59 AM.
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Old 08-11-17, 05:11 AM   #2
marciero
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Update: Mel called it "Frankenstein engineering". Now it's down to getting the shop that sold it to me to do the right thing. Am really curious what the history is here. Supposedly was a special order that the would-be owner bailed on. It was discounted over $1000. Maybe the owner actually possessed the frame and returned after a short time, during which he had this done. But if he had an issue, would he not just return the frame? I am going on the assumption that the shop did not know about this-benefit of doubt. I live in a different state so may be a few weeks before I can get there. I did send photos and they did acknowledge that it's not right.
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Old 08-11-17, 10:22 AM   #3
OneIsAllYouNeed
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Sounds like there's a BB30 to threaded BSA sleeve that was pressed in with a hammer by an amateur.

With the BB30 frame, there are a host of better options for bottoms brackets than a pressed-in sleeve with threaded cups. Here are some that thread together (so they don't creak) and would fit 24mm FSA or Shimano BB spindles:

Praxis Works Conv BB
https://praxiscycles.com/product/shimano-conversion-bb/

Wheels Mfg BB30-OUT
BB30 Outboard Angular Contact BB for 24mm Cranks (Shimano) - Black

Wishbone BB3024
Wishbone enterprise co Ltd, Product:: Bottom Bracket, BB Parts, Pulley Wheel, Jockey Wheel, Wheel Bearings, Crankset, Chainring

Token Ninja
https://www.tokenproducts.com/bottom...bottom-bracket



Alternatively, you could source some BB30 cranks for the back of the tandem. You'd be stuck with press-in bottom brackets, but they'd be used as intended, which has a certain elegance to it. For traditional crossover drive, you'd need to piece together the crankset and get the left arm pedal threads repaired. SRAM BB30 crankarms and Cannondale SISL2 are good candidates, using a Cannodale SISL2 spindle (121mm for SRAM, 119mm for Cannondale for proper spacing with 145mm rear hubs and double chainrings -- 5-10mm longer spindle for triple chainrings). You'd use two right crankarms. The left would have to get a threaded insert to switch the thread direction (most established bike shops should be able to do this for you). Since the modified crankarm must be aluminum, it narrows your options down to SRAM Rival, older SRAM S350 (Apex), Cannondale SISL2, and Cannondale SISL2 Hollowgram.
We're using a Rival BB30 crankset on our tandem with a BB386 shell. It's been creak-free and pretty awesome so far.
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Old 08-12-17, 11:49 AM   #4
LV2TNDM
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Contact Cannondale

Your best bet is to go directly to Cannondale to inquire about this situation. You need to know if this was an OEM or manufacturer-authorized modification. Although it sounds like it wasn't, you need to get factual information. If it isn't a Cannondale-approved repair/remedy, then you have recourse with the seller you bought it from, since you say it was sold "as new."

I'll add that there seems to be uncertainty about whether or not the sleeve was tack-welded into place. (I couldn't log into the linked website, so I couldn't view the pictures.) If it were, I cannot imagine this would be authorized by Cannondale. For as long as I can remember, Cannondales have been heat-treated after welding and they CANNOT be welded post-production. Doing so negates the heat-treatment where welded and weakens the frame. And obviously, any such modification by a third party immediately voids any and all frame warranties. Although tack welds should have very little effect on the entire BB shell's integrity, it would be all Cannondale needs to relieve themselves of ANY liability if the frame were to fail.

And would you feel confident descending a road at 50 mph knowing your frame's integrity may have been compromised by some half-wit with a tack welder? I know I wouldn't! (And as a mechanic I would NEVER make such a modification to an aluminum frame.)

Again, talk directly to Cannondale. I hope you can find a knowledgeable person. If you have no luck calling them directly, perhaps find the largest Cannondale retailer nearby and ask to speak with their outside sales rep - if they have them anymore. Back in the day, this is EXACTLY the issue a good sales rep could advise you on. Good luck with researching this.
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Old 08-13-17, 11:18 AM   #5
marciero
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Thanks for the comments/suggestions.

My understanding is that the pressed in sleeve that takes the threaded cups was something that Cannondale worked with FSA to develop; that is, it is a factory-installed piece. Whether mine is that piece or not is still a question.

The other options-Praxis and Wheels Mfg in particular-look great. But there are a lot of questions as to whether they will fit. There are all kinds of caveats on the Praxis documentation. It would depend on whether this has the machined lip, has removable circlips, etc. If this requires different cranks I might as well get a new frame. At any rate that is for the shop to sort out. If this was not done by Cannondale they will either owe me a new frame or some sort of negotiated settlement.

As far as contacting Cannondale directly- I can try this also to verify but they seem to discourage this. They certainly dont make it easy. Also I waited for weeks on another inquiry about this bike a while back.

I will try to post pictures here-it does not look like a full-on weld. So the frame may not be ruined. But note the deformations...
Attached Images
File Type: jpg IMG_0113.jpg (86.9 KB, 21 views)
File Type: jpg IMG_0115.jpg (92.0 KB, 19 views)

Last edited by marciero; 08-13-17 at 11:26 AM.
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