THM Clavicula M3 -- Crank arm to spider engagement?

Discuss light weight issues concerning mountain bikes & parts.

Moderator: Moderator Team

Post Reply
drasnian
Posts: 2
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


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



User avatar
Klaster_1
Posts: 1390
Joined: Mon Aug 15, 2016 10:25 am
Location: Paphos, Cyprus

by Klaster_1

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

UpFromOne
Posts: 1186
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?

User avatar
wheelsONfire
Posts: 6299
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

Bikes:

Ax Lightness Vial EVO Race (2019.01.03)
Open *UP* (2016.04.14)
Paduano Racing Fidia (kind of shelved)


Ex bike; Vial EVO D, Vial EVO Ultra, Scott Foil, Paduano ti bike.

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



UpFromOne
Posts: 1186
Joined: Wed Apr 08, 2009 5:23 am
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

Post Reply