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Colnago C64 seatpost wedge bolt specs?

Posted: Sun Dec 16, 2018 3:36 am
by edwardk
Greetings all. Would anybody know the source of a replacement bolt for the Colnago C64 seatpost wedge, or alternatively its specifications? It's a Torx head, which is a great idea, but beyond that I don't know how to determine the precise thread. I am one of those odd folk who like to source a replacement for this sort of thing before there's a crisis, rather than on the first day of a vacation . . . .

Thanks very much.

Edward

Colnago C64 seatpost wedge bolt specs?

Posted: Sun Dec 16, 2018 3:36 am
by Weenie

Colnago C64 seatpost wedge bolt specs?

Posted: Sun Dec 16, 2018 6:15 am
by Calnago
@Edwardk: I don’t know the exact specs of that bolt but I’m sure if you just took it to a machine shop or somewhere they could quickly find you one.

But since the title of this thread will likely get owners of C64’s to have a peek, I have a question.
I’ve heard a couple people who have said they have to give the seat post a good whack to loosen it up first in order to remove and/or adjust. I’m not surprised by this as if there’s any slippage at all the seatpost will kind of just get wedged in tighter due to the nature of the design, but I suppose that’s a lot better than slipping further. But still, I’m thinking it if there was no slippage at all, then it would just stay put and not get wedged in, so that when you loosen the bolt, the seatpost is easily removed or adjusted without requiring any further “encouragement”. So what I’m thinking is that the seatpost bolt might simply not be torqued enough to begin with. I wish I had one of my own to test but I don’t, so I’m throwing this suggestion out to those of you who do. If I had one, I would apply a light film of grease on the portion of the wedge that contacts the frame insert (steel) that it slides up against (not the surface that touches the seatpost). And a film of grease on the bolt threads. I would use carbon paste on the section of the seatpost where it interfaces with the frame, but again, nothing on the roughened surface of the post that interfaces with the wedge. Then, torque it down to where you think it’s “guttentight” and keep note of the torque you used. Ride it for a week or so then loosen off the bolt to see if you have to “hit” upwards on the post to loosen it. If so, then I’m thinking I would increase the torque (without exceeding the max of 6Nm) a little bit and repeat until you find a torque that will hold the seatpost with no slippage and the resulting “wedged tight” scenario. It’s just a thought and I’m throwing it out here to C64 owners to also see what your experiences to date with the new seatpost design are. This applies to V2-R or V1-R owners as well. The steel insert in the frame looks hella strong so I really don’t think that part is at risk of breaking, but I could see how the seatpost wedging itself tight might be kind of annoying if you just want to do a simple adjustment. Post your experiences good or bad here please. Maybe you haven’t experienced any slippage at all?

Re: Colnago C64 seatpost wedge bolt specs?

Posted: Sun Dec 16, 2018 6:32 am
by edwardk
Calnago, thank you for your response. My experience is the same as this:

“I’ve heard a couple people who have said they have to give the seat post a good whack to loosen it up first in order to remove and/or adjust. “

Edward

Re: Colnago C64 seatpost wedge bolt specs?

Posted: Sun Dec 16, 2018 9:43 pm
by GothicCastle
Calnago wrote:
Sun Dec 16, 2018 6:15 am

I’ve heard a couple people who have said they have to give the seat post a good whack to loosen it up first in order to remove and/or adjust. I’m not surprised by this as if there’s any slippage at all the seatpost will kind of just get wedged in tighter due to the nature of the design...
I really don’t like these hidden clamps with wedges for this reason. They are a little annoying to work with and prone to creaking. They are also more sensitive to the post or (even worse) the seat tube being a bit out-of-spec. I certainly understand the clean aesthetic, but I’d prefer a design that clamps, rather than wedges.

Also agree that those are standard bolts. Just need to know the pitch and get something with the correct height.

Re: Colnago C64 seatpost wedge bolt specs?

Posted: Sun Dec 16, 2018 11:33 pm
by bikeboy1tr
I used the paste on mine and lubed it with Super Lube 31110 Multi-Purpose Aerosol with PTFE but when I was torquing the bolt I thought the 6 NM was a bit much considering its a wedge so I backed it off to about 5 and yes the calibration on the wrench is good. I have rode it a few times now and the post has not moved but I have not attempted to adjust the post yet on the V2R.

Re: Colnago C64 seatpost wedge bolt specs?

Posted: Wed Dec 19, 2018 1:19 am
by mag
I've done that "grease the wedge" thing a couple of days ago so I'll see if that makes any difference in regards to the easy seatpost removal/adjustment, however after looking at it thoroughly I don't believe it's going to help much (if at all).

I think the "problem" occurs in the contact between the wedge and the seatpost itself. There's some rougher and slightly gummy stuff on the front of the seatpost where it's supposed to come into the contact with the wedge. It's like some dried glue or something like that. The contact surface of the wedge has also some anti-slip treatment - here it loks like some micro porous stuff (maybe just a thin layer of some anti-slip paint). And I suspect that when the wedge is pushed against the seatpost it may become stuck to its surface and that's why you need to give it that whack in order to release it.

Colnago C64 seatpost wedge bolt specs?

Posted: Wed Dec 19, 2018 2:03 am
by Calnago
You don’t want to grease those “non skid” surfaces for sure, for the reasons you just mentioned. And the grease on the surfaces of the wedge and the steel insert in the frame is just to provide a smooth and easy surface for the wedge to slide on when you’re tightening or loosening it and to prevent it from becoming stuck from corrosion. But what makes the seatpost get stuck is a bit of post clamp “wedging” from the seatpost sliding down. That’s why I think you need enough torque to prevent any movement downwards by the seatpost. If the seatpost stays put from the first clamping, it can’t move down to get further wedged in. Make sense? If, on the other hand, the clamp was initially adjusted just a bit too loose and the seatpost was allowed to slip down even a little unnoticeable bit, it would just further wedge itself tighter. You may have thought the seatclamp was tight enough, but in fact the seatpost was able to move just enough to nicely wedge itself enough to make the removal “hit” necessary. That’s my theory at least.
But you may be right too @mag, that there could be some sticking between the roughened surfaces of the wedge and seatpost that takes a release “hit” to loosen up simply from being in contact under pressure. Anyway, I’m curious if any of this stuff makes a difference. It’s not a big deal I suppose, but not quite as easy as just loosening a round seat clamp and being able to slide or remove the seatpost effortlessly.

Re: Colnago C64 seatpost wedge bolt specs?

Posted: Wed Dec 19, 2018 1:40 pm
by wilwil
I tried greasing it as you said and it makes no difference. Once 'whacked' it moves very easily.

Re: Colnago C64 seatpost wedge bolt specs?

Posted: Wed Dec 19, 2018 3:42 pm
by Calnago
I may have confused things when I mentioned greasing the steel faces where the wedge slides on the steel frame insert. That was just an aside that I would do for any two metal services that require smooth sliding for adjustment. The main point I was trying to make was that maybe by increasing the pressure against the seatpost, it wouldn’t slide down even a fraction of a mm, and thus have no chance to get further wedged in. But if the “sticky” point is due to the two roughened surfaces mating as @mag was suggesting then that’s a different thing. In any case, it sounds like more of a minor annoyance than anything, correct? I don’t have one to experience just how hard a “hit” is necessary to loosen it up.

Re: Colnago C64 seatpost wedge bolt specs?

Posted: Wed Dec 19, 2018 4:10 pm
by edwardk
It’s a heel of the hand whack, not a take a mallet to your precious bike whack.

Edward

Re: Colnago C64 seatpost wedge bolt specs?

Posted: Thu Dec 20, 2018 9:33 pm
by bikeboy1tr
I undid my seatpost clamp today and the bolt was not very tight, certainly not as tight as I had originally torqued it. Anyway I loosened it a few turns and then whacked the head of the ratchet with the heel of my hand to break the clamping mech free which was easy enough. The post is was still pretty snug as I had to whack the underside of the seat with my hand to make it move and that was with the paste supplied. One thing for sure is this post will not gradually change its position from a loose clamp. I am okay with that though. So this would be the case with a bolt that is undertorqued and I am wondering if there is any difference with one that is properly torqued as Calnago mentions. I would imagine once this system is torqued you could remove the fastening bolt and the clamp would not come undone.

Colnago C64 seatpost wedge bolt specs?

Posted: Thu Dec 20, 2018 10:18 pm
by Calnago
@bikeboy1tr: No, you would never want to remove that bolt, but your experience demonstrates exactly what I'm trying to describe. If that bolt is at all loose, the seatpost will slide down a small bit and "wedge" itself in further, making it harder to remove when you do loosen the bolt as you now have to get it out of where it wedged itself as well. Of course, this is a better alternative than some designs where if it comes at all loose it will just slide all the way down. But I'm still wondering if you had that bolt properly tight in the first place (you said it was loose upon removal), so that the seatpost couldn't move even a fraction of a mm, then would it even have the opportunity to wedge itself in further? i don't know. Test it out.
I’m likening this process to the same principle behind stress relieving spokes in a wheel during building. If you don’t ensure the spokes are fully “unwound” and properly seated upon finalizing the build, then they will surely unwind and seat themselves during riding, and consequently lose tension and lead to all kinds of bad things down the road.

Re: Colnago C64 seatpost wedge bolt specs?

Posted: Thu Dec 20, 2018 11:27 pm
by bikeboy1tr
Yeah Calnago I did torque the bolt by hand but not with a proper wrench and I know by hand I was not at 6NM but I did tighten it more than what was required to loosen the bolt. I know you normally have stiction upon initial movement in the loosening process but there was very little of that. When I smacked the clamping mech I heard it pop so I know that was not holding the post and I was able to move the seatpost but it did take a bit of force. Least I know the mechanism is well lubed and I will torque the bolt when I get my proper post position. So now we just need to hear from someone who has properly torqued and ridden for over a week and see how they make out with the process.

Re: Colnago C64 seatpost wedge bolt specs?

Posted: Fri Dec 21, 2018 1:51 pm
by mag
I torque it to 5.4 Nm (90% of the 6 Nm maximum) using a good quality and recently calibrated Norbar torque screwdriver so it should be really close to those 5.4 Nm. I also used the Finish Line carbon paste on the rear of the seatpost to reduce the likelihood of its slippage. With that, it still becomes stuck and needs a bit of "help" from the bottom of the saddle. :-D

I may try going to full 6 Nm next time, but not anytime soon (ugly winter weather over here so I don't want to take this bike out + I want to try some of the grit-free carbon pastes such as the Motorex or Effetto Mariposa ones to avoid the seatpost paint scratches as it's white, and it's pretty difficult to source them in small quantities over here as I don't really need 100 g of that stuff - Motorex 5 g packaging is basically non-existent here, Effetto Mariposa is mostly sold as pack of 15x3 ml, but some shops seem to be able to sell just one 3 ml blister)

Re: Colnago C64 seatpost wedge bolt specs?

Posted: Fri Dec 21, 2018 1:51 pm
by Weenie

Re: Colnago C64 seatpost wedge bolt specs?

Posted: Fri Dec 21, 2018 4:44 pm
by Calnago
Thanks @mag. That’s a good amount of torque and you seem to have tried out everything I was curious about. I guess that’s just the way it is. I’d hate to be encouraging people to torque it much higher than you’ve done. And seems like it sticks for most, if not all, since no one has come forward and said “mine never needs help if I want to adjust it or remove it”.