THM Clavicula M3 -- Crank arm to spider engagement?

Discuss light weight issues concerning mountain bikes & parts.

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drasnian
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Joined: Sat Dec 16, 2017 2:41 am

by drasnian

Hi all.

I'm mulling over a new crankset for XC. Looking at the Clavicula M3, I can't work out how the drive side crank arm secures to the spider to drive the rings. The spider has depressions in it, and it looks like the 4 crank arm 'fingers' may just sit in their seats in the spider. Surely that is not all (?) If it is all, then am I correct in thinking that the only thing holding the drive side crank against the spider is the tensile load on the spindle supplied by the bearing preload on the non-drive side crank arm?

Surely not. Please tell me there is some sensible mechanism by which the crank can provide torque to the spider.

Cheers,
Simon

by Weenie


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Klaster1
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Location: Krasnoyarsk, Russia

by Klaster1

The image of a spider from THM website shows an interface very similar to Specialized and Lightning, I bet it's compatible.

UpFromOne
Posts: 701
Joined: Wed Apr 08, 2009 5:23 am
Location: Olympic Nat'l Park, WA

by UpFromOne

The M3 road and mtb versions are completely different. The splined mtb spider is secured with a lockring - it has nothing to do with bearing preload. But I don't know if the spider has the exact same pattern as Specialized/Lightning.

FWIW, I prefer the narrower Q factor of the road cranks on my XC bike, so I run a double chainring on M3 road cranks, with both being 5-bolt 58bcd, the same pattern as the road spider attachment. I use a standard granny for the inner, and a larger custom made 58bcd chainring as the outer. Both rings are secured into the arm with 14mm long titanium chainring bolts. 5mm spacers between the rings. Works very well, and a definite WW win.

drasnian
Posts: 2
Joined: Sat Dec 16, 2017 2:41 am

by drasnian

UpFromOne wrote:The splined mtb spider is secured with a lockring
Ah, so that circular metal piece on the base of the spindle (in the photos) is the lock ring? So it's just a case of take it off, chuck the spider on, then screw the lock ring back down against the spider (?)
UpFromOne wrote:FWIW, I prefer the narrower Q factor of the road cranks on my XC bike, so I run a double chainring on M3 road cranks, with both being 5-bolt 58bcd, the same pattern as the road spider attachment.
What's your XC bike? What Q-factor do the road cranks give you?

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wheelsONfire
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by wheelsONfire

Bikes:

Ax Lightness Vial EVO D
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by Weenie


UpFromOne
Posts: 701
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Location: Olympic Nat'l Park, WA

by UpFromOne

OP, yes, that is how it works.

M3 Road with a 22/36 on a climbing 29er hardtail:
Image

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