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M&M Mars and the Shimano connection...(6 posts)

M&M Mars and the Shimano connection...Ahimsa
Oct 11, 2001 5:45 PM
If you add caramel to a 3 Musketeers it becomes a Milky Way, add peanuts and it is a Snickers. Swap peanuts for almonds and you get a Mars bar.

Seems the same with Shimano road cranks...Sora plus one aluminum ring begats Tiagra. All aluminum rings + hollowtech becomes 105. Slighlty more hollow and you get infintum, ad nauseum.

My question: Does the idea of hollow crank arms concern anyone but me? Does the durability of a hollow aluminum crank sound dubious? No doubt ridden many miles by many of you; how have they held up? Any broken arms (crank or flesh) due to heavy use?
I am wary of less durable components, but my commuter needs a drivetrain update and Shimano looks like a good deal. It occurs to me that to alay my fears, I might wish to build up a Tiagra triple with Ultegra rings and hardware to get a non-hollow, all aluminum setup that weighs in around a mere 60 to 80 grams more than Ultegra triples. Is this do-able? Any tech flaws in this? Anyone wish to claim that my durability issues are ludicrous and sell me on the 105 hollows? I prefer tough parts with tried and true designs.

Speak up. Comments are appreciated.

re: M&M Mars and the Shimano connection...TJeanloz
Oct 12, 2001 7:30 AM
It is true that the cranks are hollow- but they are really durable. I have a Dura-Ace crank that was bent 90 degrees in a bike/auto mishap, no cracks, just a nice bend. Where most crankarms fail is right at the bb spindle. And in the case of Tiagra, you'd be using a UN52 (square taper) bottom bracket, which I think is probably more likely to cause failure than the splined type (pure speculation).

Historically, not being hollow hasn't kept crankarms from cracking- Shimano and Campy both have had recall issues with their lower-end solid cranksets (Alivio/Acera from Shimano and Mirage/Veloce from Campy).

Personally, I would be more confident in the higher-end 105 crankset's durability than the Tiagras. You also would use the 'better' (in my opinion) splined bottom bracket design. And you might find that buying a Tiagra crankset and putting Ultegra rings on could cost more than a whole Ultegra crankset.
Go hollow...Curtis
Oct 12, 2001 8:16 AM
...I've been running HollowTech cranks on my mountain bike for two years with no problems. I'm not a very good mountain biker, so I really bang the hell out of them (hit rocks, roots, trail markers, anything out there to hit).

I also agree with splined, cartridge-type bottom brackets. easy to install, last forever without real maintenance, strong connection...
re: Mars vs. Almond JoyChen2
Oct 12, 2001 10:47 AM
I think the differences in cranks goes beyond hollow vs. solid. I think the alloys are different (but I can't back it up with data). I do know that the upper-end cranks are less likely to corrode from sweat than the cheaper ones.
hollow is good, and no problems, aside from cost.jw25
Oct 12, 2001 12:01 PM
Put another way, would you rather ride a frame made of tubes, or of solid bars? More materials doesn't correlate to more strength, it's more dependent on where the materials are placed.
Aside from 1 story of cracking Dura-Ace arms (from a shop monkey, and not substantiated - "A friend saw..."), I've yet to see any problems from the hollow design. I use 2 sets of splined cranks on my mtb's, and while I don't notice more or less flex than square-taper BB's, the splines make replacing the cranks easier and more reliable (as does a torque wrench).
For the commuter, I'd look around for a deal on a 105 triple crank. All aluminum rings, splined BB, and less than upgrading Tiagra to alloy rings.
Then again, it's a commuter, so any decent triple would work (steel inner rings also last longer), and I've seen a few solid-arm designs that use a splined BB. FSA sells the Gossamer, and CODA made a triple - might be tough to find, though.
As always, my first choice would be Ebay and a bit of patience. Chances are something will pop up, and I've saved more money there...
Good luck
Good advice from all of you, thanks. I'll try the 105 triple. nmAhimsa
Oct 12, 2001 3:58 PM