Telkwa

I've got questions about maintenance/repair on our C'Dale tandem. Have read some unnerving comments on this forum about the Truvativ BB's and the rear hubs. Was hoping for some .pdf's at the Cannondale website but haven't found much of anything. I've got no idea how to get into those Truvativ's and that's not good.

Any suggestions to keep tandems running as well as possible? Do you guys completely disassemble BB, hubs, cassettes, etc. once or twice a year? And where do you go for manuals, guides, etc.? I found the Shimano website and that looks helpful for some things.

Forty years ago us kids in the neighborhood kept our heavy steel 10-speeds running without manuals or anything. We just shared our knowledge. I don't have my friends to lean on anymore but do have the internet and this forum!

BloomingCyclist

This link on the BikeNashbar site has links to many manufacturers - more than I've ever found anywhere else. I've used it many times to get to a manufacturer and the tech manuals. (I checked before I wrote this to see if they had a Truvativ link and they do and I followed it to the bottom bracket selection.) The list of companies in the pull-down menu box is much longer than the visual symbols you will see so use the pull-down menu. Hope this helps.

https://www.nashbar.com/tech/links_manufacture.cfm

Bloomington, IN

JanMM

Truvativ info should be available thru the SRAM website, also. (Parent company).
Our tandem doesn't get a lot of miles put on it and almost never in foul weather, so servicing intervals are really spread out. Hubs only get overhauled when they don't feel smooth and free with finger-turning. Same with the bottom brackets. Recently replaced the brake pads for the first time (on a 2000 KHS tandem). That's a long time. The simple answer is that parts need to be serviced when they need it. Pay attention to how things are working and if you aren't sure take it apart and see how it looks. Most frequent items needing attention on our bike are the chains and shifter cables.

zonie

40 yrs ago bikes were a bit simpler, and cheaper. Since it sounds like you "have a clue" about bearings and hubs and all that, invest in a set of Barett's Manuals. Covers specific's and general repair and maintance stuff. Prior to bicycles, I worked on my own motorcycles and thought a bicycle was too simple to bother with a manual. After reading thru Baretts, and the Big Blue Book from Parks tools, I was humbled. Also saved myself $$ replacing parts from over-torquing and wrong way assembly.

Also a sturdy repair stand comes in handy for a tandem....

Cheers

dubbelop

On our C'dale, the first Truvativ (rear) BB gave way at 2,500 kms, the replacement one at 3,500 kms. Then I was able to pick up a brand new Shimano tandem square-taper crankset for very little money (the fellow Dutchman who ordered it at Precision Tandems didn't realize it would never fit his Hase Pino ) so I switched to square taper.

I can imagine you'd prefer to stick to the original crankset. If the time comes to replace a BB, get yourself one from SKF. People in the cycling trade have ensured me that these are really really good - within the limitations of the ISIS concept, of course.

Telkwa

You bring up several points.
I'd like to know what's involved in switching to Shimano. Not going to rush out and do that, but makes sense to get a handle on it now rather than later.
If I found a good deal on Shimano parts would have no problem abandoning the original crankset. Don't know what's involved fitting Shimano to the C'Dale.
I know SKF as a bearing manufacturer, but entire BB's?
Where can I read up on the different kinds of BB designs? Would be great to find a discussion regarding the pro and con...

TandemGeek

It's not definitive by any stretch, but...

https://www.bikeforums.net/showpost.p...30&postcount=8

And just for kicks...

https://www.bikeforums.net/showpost.p...5&postcount=41

Telkwa

Thanks very much, TG -

I never really understand this sort of thing until I take it apart and have the mechanism laid out on the bench, if you know what I mean. I have to figure out what tools are necessary to disassemble/reassemble the C'Dale BB's.

Do you stand by the assertion that ISIS is a dead-end?

TandemGeek

It's not a dead-end; however, it's becoming a bit harder to find tandem cranks that are being made to work with the ISIS interface hence the reference to "headed for extinction" in my archived post. Of the very few tandem cranksets that they are producting these days, FSA and TruVativ seem to be limiting their offerings to the outboard bearing models. Santana's Martec carbon cranks & any remaining stock of Shimano tandem cranks use the Octalink design. daVinci and Specialites TA use square taper and while Middleburn offers ISIS, they still only offer MTB tandem crankset / spiders, not road-sized models. Calfee is just about to release a new carbon crank offering that is similar to the Martec cranks but with an ISIS BB interface and in a range of crank-arm lengths (170, 172.5, 175) for both captain and stoker.

Thankfully, there are A LOT of ISIS single bike cranks still on the market and a huge number of ISIS users so I suspect there will always be better quality ISIS bottom brackets available. The same is true of square taper, where the real gap only exists in 'better quality' / affordable BB's: the low-end is flush with all kinds of offerings and there are some really nice high-end models, but the $25 UN72 is gone.

So, if someone has or can get their hands on a set of ISIS cranks I suspect they will have a good section of brands and models of ISIS bottom brackets to choose from for many years to come. However, if someone's in the market for new production ISIS cranks it's slim pickings.