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Bottom Bracket
 

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PLee
Joined: 08 Dec 2003
Posts: 3653
Location: Brooklyn, NY

9/8/19 4:20 PM

Bottom Bracket

So I decided to move the FSA 53/39 crankset from my lightweight aluminum Tommasini to my steel Tommasini. Well, I had my local shop do it. Then I had them order an FSA KForce Light compact (50/34) crankset for the aluminum.

I figured it made sense to put climbing gears on the lightweight bike.

Turns out that the shop had a heck of a time finding a bottom bracket that would fit the new crank and my Italian threaded bottom bracket shell. They found one, just one, that Rotor used to make. Luckily, they were able to find one on the back of one of their shelves.

I pick it up this week.

Does this mean I'm going to have trouble upgrading to Campy 12?

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Sparky
Joined: 08 Dec 2003
Posts: 17540
Location: Portland, OR

9/8/19 4:46 PM

Isn't that frame just threaded IT BB/Shell. IT Ultra Torque IT [or BSA] cups aren't going outta vogue as far as I know...

Didn't you consider a compact Ultra Torque chainset as an option?

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dfcas
Joined: 11 Jan 2004
Posts: 2618
Location: hillbilly heaven

9/8/19 5:48 PM

Campy Italian BB cups are readily available in Campy 12 speed or any other speed, so no problems going to Campy 12.

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PLee
Joined: 08 Dec 2003
Posts: 3653
Location: Brooklyn, NY

9/10/19 4:25 PM

I went for the FSA because it was lighter.

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Sparky
Joined: 08 Dec 2003
Posts: 17540
Location: Portland, OR

9/10/19 7:18 PM

You sure? Campy UT chainset weights include the bearings, the BB is just 35 gr. cups.

Isn't the FSA K-Force Light compact for 30mm crank axle anymore? BB386EVO? Or is there NOS of the 24mm stuff?

Some googling I seem to be seeing 11s Record 651s Grams [603 SR], Cups 49 gr. I was low on my guess on the cups.

I am seeing 150 gr for the MegaEXO BSA BB for the 24mm spindle cranks. 575-594 gr for crankset?

The 12s record chainsets are heavier than 11s it seems. Record=708/618SR

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Nick Payne
Joined: 10 Jan 2004
Posts: 2453
Location: Canberra, Australia

9/11/19 12:23 AM

This thread inspired me to weigh the SRAM crankset and BB that came with an Eagle AXS groupset that my wife bought - I didn't fit the cranks because she uses 160mm and SRAM don't make them that short. Total weight for 170mm cranks, chainring, DUB bottom bracket for English thread 68mm BB, and pedal washers is 560g. That's single chainring only, though. A dual chainring spider plus 2nd chainring would probably add another 150g or so.

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Sparky
Joined: 08 Dec 2003
Posts: 17540
Location: Portland, OR

9/11/19 10:13 AM

I'd say the lightest I have [or have had] is the 80th Ani SR 34/50 Chainset. 629 gr with bearings, and 43 gr advertised for SR cups. They have the ceramic bearings as well, what that does for weight one 'weigh' or the other, I dunno.

How much lighter can you get and maintain any reasonable stiffness? Something we Clydes need to consider perhaps a little more than the 130 climbing sort. ;)


I know some here have sported these at some point in time...

I know I was nibbling @ toplines when I built my first real weight weenie road bike. The Team Issue Scandium Fuji. I was 188lb then and was told forget it. Went with a carbon profile crank dejour.






Let me toss this link in here, now that the thread has taken this direction.

Weight, fine. Deflection [stiffness] there as well.

http://blog.fairwheelbikes.com/reviews-and-testing/road-bike-crank-testing/


And as always in my divergence, I have a few Force Carbon GXP cranksets. Which with the GXP BB are no big weight loss. But in my BB90 Madone where you just swap out the pressed non drive bearing for the 22mm and don't use the GXP threaded BB. Not to shabby low weight for low coin. And 145mm Q factor if you like that sorta thing. ;)

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PLee
Joined: 08 Dec 2003
Posts: 3653
Location: Brooklyn, NY

9/19/19 11:09 AM

The Rotor bottom bracket didn't fit. The shop thinks they found one that does. It'll take another 2 weeks - I wonder if the bottom bracket is being made as we speak . . .

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Sparky
Joined: 08 Dec 2003
Posts: 17540
Location: Portland, OR

9/19/19 12:00 PM

Did they specify what constituted not fitting?

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PLee
Joined: 08 Dec 2003
Posts: 3653
Location: Brooklyn, NY

9/29/19 12:54 PM

Got the bike back, fitted now with a Tripeak bottom bracket which, I was told, had to be machined to fit properly. I think the threads were longer than the ones in the shell and had to be cut back.

Well, I guess I now have ceramic bearings, not that I would be able to tell the difference.

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