# 08 crank switch



## prschatt (Aug 19, 2007)

I found that TREK has an adapter kit to enable switching to other cranks. I have a SRAM Force crank on another bike that's just sitting, and want to switch it to the Madone, which already has a SRAM group. I can't seem to get any info on how the adaptors work, and my LBS is even getting mixed info from TREK rep. on what to order. Has anyone done this?, Is it a complete BB or an adapter for the stock BB?
Thanks


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## zac (Aug 5, 2005)

prschatt, from what I understand it is just the bearings out of the BB. I think Trek calling it an "adaptor" just adds confusion. But I certainly could be wrong. Maybe there is some sort of bearing adaptor needed to propery seat the bearings inside the BB shell of the frame for SRAM.

I have seen the breakdown of the BB on an Ultegra SL set, it was pretty simple.

But let me get this straight: you want to put on a Force crank on the '08 Madone that already has a SRAM group on it?


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## prschatt (Aug 19, 2007)

Thanks, that's a bunch more info then my LBS knows, but these are new so I'll give them some slack. The Madone came equipped w/SRAM Force RD-FD, Brakes, cassette and chain and a Bontrager crank ??. I have a Force crank that I already have on my crappy day bike that I want to swap to complete the group. Not real happy with the Bon crank.
Thanks


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## zac (Aug 5, 2005)

prschatt said:


> Thanks, that's a bunch more info then my LBS knows, but these are new so I'll give them some slack. The Madone came equipped w/SRAM Force RD-FD, Brakes, cassette and chain and a Bontrager crank ??. I have a Force crank that I already have on my crappy day bike that I want to swap to complete the group. Not real happy with the Bon crank.
> Thanks


That's right, I forgot that the 5.5 comes with the Bonty crank. From what I understand from my mechanic, you just pull the bearings on the Force BB and use them in the shell. But I can double check.

EDIT, maybe not

Direct from Scott Daubert at trek: http://trekroad.typepad.com/trekroad/2007/07/weights-and-tdf.html
scroll down to the July 31 post, #3 asks about the BBs and replacement bearings:

*The Questions:*

_1. The bottom bracket bearings are obviously sealed towards the outside. But are they also sealed against the inside? If water enters the frame through the top tube brake cable openings, as it most certainly will during long rainy rides or when washing, the bottom bracket bearings will be ruined pretty quickly. 
2. Replacement bearings I presume are only purchasable through Trek which is rather inconvenient and probably associated with long delivery times.
3. Also what’s the deal with using different brands of cranks? Do I have to use adapters for say FSA-cranks?
4. The integrated seat post design looks nice when new, but will the painted seat mast not get all scratched up and look real ugly in time?_

*Scott Daubert's reply:*

_Scott Daubert
Phillip Lust posted some questions above. 
1. The BB bearings are sealed on the inside by a plastic sleeve. The sleeve prevents any contaminates from pooling in the BB near the bearing.s. Additionally, there is a vent hole in the BB shell to let unwanted condensation and fluids out.
2. Since the 08 Madone allows for various cranksets, we will sell bearings for those cranksets. But Trek will not be the only supplier as most bearings are common to other industries or uses and can be found in any number of locations. This is especially convenient if you want to run ceramic bearings.
3. FSA and Campy cranks will require kits to be used on 08 Madone frames. Trek will sell these kits as aftermarket itmes.
4. Because the mast and cap are both made of carbon and clearcoated, we are not seeing significant maring or scratching. However, if you have to move your cap up and down repeatedly, you should expect some scuffing, just as you would with a tradtionally seatpost. If you can keep a normal seatpost from being scuffed, you can certainly do the same with Trek's cap and mast design._

I'd shoot him an email and ask. Sounds like just the FSA and Campy setups will require an adaptor. I wish I could recall the exact conversation I had with my mechanic, but from what I believe I understood (dancing around in the back of my brain) was that all Shimano, Bonty, and SRAM cranks are instantaneous installs. That Campy would require a special part and Zipp was a no-go. Can't recall anything about FSA. But I will double check.


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## prschatt (Aug 19, 2007)

Thanks for all the research zac, TREK is usually great about responding to questions. I like to try the local wrench first to keep them in the loop in the event of complicated fitting issue, a drop-in would be sweet.
I'll post the outcome of there's interest.
david


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## prschatt (Aug 19, 2007)

Well that was the easiest swap I ever did. Slid the bon off and the SRAM on, no adapters different BB etc., didn't even need to tweak the FD. 
Thanks for all the help guys, this site is better then all the repair books out there put together !!


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## zac (Aug 5, 2005)

prschatt said:


> Well that was the easiest swap I ever did. Slid the bon off and the SRAM on, no adapters different BB etc., didn't even need to tweak the FD.
> Thanks for all the help guys, this site is better then all the repair books out there put together !!



Good to hear, because that is how it is supposed to work. Thanks


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## Richard (Feb 17, 2006)

Yep. Bontrager's and Sram's are both Truvative designs and share all dimensions. FSA's use a proprietary method of fixing the left arm to the spindle and Campy has specific cups that the Ultra bearings fit into. Thus the need for specific parts.


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