raria

Hi,

One of my bikes has a FSA Vero Triple with a square bracket mated with Tiagra 4500 (9 speed). It works great.

But I wanted to upgrade to a two piece crankset and the Shimano Sora 3503 Triple (9 speed) and Hollow Tech II bottom bracket can be had for under $100.

But a few compatibilty quetsions arise in particular:

a) Will the chainline be correct with the 3503 Crankset?
b) The FD is Sora 3503 so I don't see any issues there
c) Anything else I should be aware of?

dsbrantjr

What do you expect to gain with this change? Sounds tough to improve upon "great".

FullSpeedAgain

You would get some more stiffness while stroking the left pedal and save some weight but maybe it has more sense to save that money to upgrade to a 2x11 105 groupset in a future.

raria

I should hae articulated better, to say "it shifts great".

Yes, I was hoping for stiffness.

cpach

That should work fine. Charline and der compatibility should be the same.

raria

Will update you when they arrive

shoota 

Dang man, that is not an upgrade at all.

hermanchauw

pressed001

If you're sensitive, you'll notice the change between the two types of bottom brackets dramatically. Especially depending on how many miles you have on the old one. I would spend the extra 25 bucks for a dura ace level BB.

It is good to keep in mind that the outboard BB's are meant to be changed out more often. But at the cost of $25 I find it is more than adequate.

shoota 

That's baloney, there's no way he'll notice any difference at all except placebo.

pressed001

Do, enlighten us.

TallRider

My guess is that most differences in feel will be placebo, although a well-constructed blind test wouldn't be too difficult to execute. Or even without blind tests, you could combine a pedal-based power meter with a rear-wheel-based power meter, and see whether there's any difference in actual power transfer between square-taper and integrated/outboard.
More to the point, I'd assume that manufacturers have conducted these tests, and the fact that we haven't heard about them is probably evidence that they didn't show a meaningful difference. Much easier to claim "twice as stiff" than to talk about 0.004% increase in power transfer efficiency.

Stiffness differences can be calculated (e.g., concrete surface is 3x as hard as asphalt surface) but that doesn't mean those differences actually matter. For cycling, the meaningful questions for improvement with integrated BB/outboard bearings are
a) do they increase power transfer to the rear wheel
b) do they decrease chain rub
c) how does the durability compare

My sense is that differences will be marginal at best, and are most likely to matter for really powerful sprinters. Then again, Tom Boonen won the 2005 worlds on Campy square-taper while a majority of his competitors were on integrated BB. (Campy switched to an integrated system the next year)

Biggest practical knock on integrated BB systems is there's no mechanism for chainline adjustment. That said, integrated systems designed for road chainline should work fine with your road bike.

squirtdad

I don't see a cost benefit here minimal difference in performance for ..$100 for crank and BB, when you could do an upgrade to 10 speed tiagra for $400 with all new everything https://www.ribblecycles.co.uk/shima...uble-groupset/

pressed001

I must admit that I didn't think the ST vs. external bearing issue was such a hot debate. Found a great write-up here.

Also I must correct myself and say that I went from an ISIS BB to an external and noticed a night and day difference.

dedhed

I haven't found this to be the case. 20K+ miles on a 105 level HT II BB so far.

mtbikerinpa

From what I have observed owning and servicing a lot of both types, the 'shorter' life of the outboard depends on if the cartridges are properly greased from the get go. Sometimes a manufacturer, particularly an aftermarket can spec a generic bearing and not what grease is installed in said unit. That is clearly not as much the case with the older sealed cartridge bb assembly was not as dependent on pre-made cartridges therefore less variability. Every once in a while I have opened an external bb cartridge(and other places) and found a minimal amount of lubrication installed. As a response I have taken the policy to check when they are openable(of course) and supplement any periodic lacks.

raria

Actually it was a huge upgrade in stifness, shifting quality and general smoothness. I'm not sure if this is due to: i) Shimano vs FSA quality and/or ii) BB cartridge vs external bearings or iii) 2-piece vs 3-piece cranksets. I tend to think its all and soley i) casues the shifting improvement (the FD is the Shimano FD-3503 which matches the crankset).

Whilst I agree with you about the difference, I think that writeup is not appropriate for this discussion. They are referring to differences felt b/w external bearings in wider BB (i.e. PFBB86) standards and ST BB cartridges in 68mm. But I was referring to the same BB width but replacing the 3piece ST with an Hollow-tech style external bearing 2 piece crankset.

Wow that's a lot of insight. So the take away message is after-market BB can be problematic? What exactly is after-market vs not here: Chin Haur vs Shimano?