Trek Madone 7.9 BB90 bearings for FSA MegaExo cranks (24mm)?

[BikeAnon]

I'm looking to install my FSA K Force crank on a 2013 Madone.

A quick search from Google shows two bearing sets available. Cheap, and expensive

Cheap
http://www.amazon.com/FSA-Bottom-Bracke ... B001GSKPDM

Not cheap:
http://www.amazon.com/gp/product/B00U6H0O9O/

Can anyone here tell me if they are the same dimension, just different materials/quality?

The issue I'm having is that the cheap one says it's "for alloy cranks" and the expensive set says it's "Compatible with K-Force Light and SL-K light cranksets 2010 model year and newer only".


I can't find anywhere online that gives the dimensions of the two different sets. I'll get the "good" ones, if I need them for fitting, but I'm not sold on the value of ceramic bearings.


The crankset is coming out of my existing BSA that has ceramic FSA bearings.

[Kayrehn]

I would say either should be fine. Dimensions of the crank shaft will be the same for a certain standard and I've never heard of the crank material being a factor before.

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[BikeAnon]

Thanks for the advice.

I pounded the bearings out of an old BSA MegaExo BB. It turns out they are the size needed to press-fit into the BB90 on the Trek (24x37x7mm).

These bearings are shot, so I've ordered a set of the steel bearings from Amazon. I'll keep this thread updated in case anyone else runs into this issue.

[BikeAnon]

I wanted to get back to this thread....

The cheap bearings from Amazon are FSA branded. I forgot to whip out a magnifier to read who actually makes them.

The size is 24x37x7mm. They come lubed, sealed, and with FAS dustcaps that fit well in the BB90 shell.

The lube seems fine, and probably is good. Whoever is making them isn't likely making them as BB bearings, they are just making bearing that meet a certain spec for industry. I chose to clean the grease out and lube them with Phil Wood grease.



They spin fine, and do a good job of letting me throw my MegaExo spindle into the BB90 frame. No adapter needed, just install bearing, slide in crank spindle.

[Valbrona]

I wanted to get back to this thread....

The cheap bearings from Amazon are FSA branded. I forgot to whip out a magnifier to read who actually makes them.

The size is 24x37x7mm. They come lubed, sealed, and with FAS dustcaps that fit well in the BB90 shell.

The lube seems fine, and probably is good. Whoever is making them isn't likely making them as BB bearings, they are just making bearing that meet a certain spec for industry. I chose to clean the grease out and lube them with Phil Wood grease.

They spin fine, and do a good job of letting me throw my MegaExo spindle into the BB90 frame. No adapter needed, just install bearing, slid in crank spindle.

Who'd have thought of it?

Cartridge bearings that come with grease and dustcovers!
And they 'spin just fine' too!

I would buy a load of those if I were you. They might run out if they are that good.

[jekyll man]

Alternatively, you could have just "wet n dried" the fsa axle to fit the stock Trek bearings- its fractions of a mm difference.
Going on my experiences of fsa bearings, replacement is something you'll be getting used to..

[BikeAnon]

Jeckyl man, what do you mean by "wet n dry"?

Also, there were no stock bearings. I bought the frame used with no bearings installed.

I agree about having spare sets. I already ordered a second. I did have great service life from my BSA MegaExo ceramic bearings (12,000+ km and still going when I switched frames). If these steel bearings don't hold up, maybe I'll spend the cash on the "good stuff" for this bike.

[prchew]

I realise this is an old thread but I am trying to fit a FSA SL-K Light crank onto a Madone 7.9 and have hit a few problems so I was hoping to get your advice.

I an using the existing bearings that I used for a Shimano HT2 crankset and I have found the FSA crank to be extremely tight to fit, so tight it needs several good blows with a mallet to get it through the bearings and when removing it needs enough force to unseat the bearings from the frame. Once seated and I torque up the crank bolt the crank presses against the bearings and adds a significant amount of friction when turning the crank arms.

So a quick couple of questions:
1. Am I correct in thinking that BB90 HT2 bearings are the same as the FSA megaexo or am I best buying new bearings?
1. Did you install the bearing seals on both the drive and non drive side of the bearings as designed?
2. From the previous comment regarding wet and dry it seems that a FSA crank may normally be tighter when using the stock HT2 bearings?

Any advice you can provide would be appreciated.

Thanks

Paul

[freestyl321]

Crankset I'm trying to use.

Crankset I'm trying to use.

Frame I'm trying to put it on.

@BikeAnon:

Were you successful in using those other bearings? I'm being told by folks at FSA that this solution will not work.

I'm looking to put a FSA Sl-K carbon crank on a Trek Emonda BB90 frame. I was told that because the spindle for the carbon crank is slightly shorter than the alloy crank, that when tightening down the leftside crank arm, that it will pinch the bearings and won't work properly. My initial thought was to use some shims or to use a slightly shorter 8mm hex head to tighten down the crank arm. But it's probably not that easy.

Any advice? Thoughts?

@prchew: Were you successful in your project? Did you get the frame, BB, crank combo worked out?

Thanks for the look folks!

[Fisherfreerider]

You are correct, the K-Force crank wont work. You will side load the bearings and kill them pretty quickly.

[Calnago]

I ran into a similar situation some years ago with that crank, not on a Trek, but I’m sure the issue was the same. The bearings aren’t located in identical spots on the spindle I believe... can’t remember the details now, so even though the owner would have liked to save a few bucks by using the crank he already had, we ended up with something else. Much happier as a result.