How to torque this down?
Moderator: robbosmans
This is the seatpost for my BMC TMR02. I’m using Romin Evo Pro saddle with carbon rails. Before it was the Romin Comp with Ti rails so I didn’t worry about tightening it down.
But with carbon rail, not sure how to go about it. The socket won’t fit through the hole in the saddle and not sure if there’s such a thing as side torque wrench?
Thoughts?
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But with carbon rail, not sure how to go about it. The socket won’t fit through the hole in the saddle and not sure if there’s such a thing as side torque wrench?
Thoughts?
Sent from my iPhone using Tapatalk
Does't look like a stock mount. It should be a hex head on the bottom, and nut on the top. Nut might be specific to that seatpost too. I'd contact BMC and figure it out. I bet you can easily source screws there.
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First before you start wrenching make sure that clamp is approved for those carbon rails. The alloy ones are round and the Specialized Carbon rails oval so you might end up crushing them if you use the wrong clamp. Just a thought....addictR1 wrote: ↑Tue Apr 03, 2018 7:45 amThis is the seatpost for my BMC TMR02. I’m using Romin Evo Pro saddle with carbon rails. Before it was the Romin Comp with Ti rails so I didn’t worry about tightening it down.
But with carbon rail, not sure how to go about it. The socket won’t fit through the hole in the saddle and not sure if there’s such a thing as side torque wrench?
Thoughts?
Sent from my iPhone using Tapatalk
there're images of the post that show the same bolt head, it's also in the bmc online manual, so it seems correct, for instance...
https://aerogeeks.files.wordpress.com/2 ... _02571.jpg
https://static.evanscycles.com/producti ... 8500-1.jpg
that clamp looks like it makes rail contact over a large area, that should give a wide safety margin, i would just gradually tighten it / test it until it's secure
https://aerogeeks.files.wordpress.com/2 ... _02571.jpg
https://static.evanscycles.com/producti ... 8500-1.jpg
that clamp looks like it makes rail contact over a large area, that should give a wide safety margin, i would just gradually tighten it / test it until it's secure
As mentioned, replace the bolt with on that has a Allen or Torx head.
You could also use a crows foot on the torque wrench.
You could also use a crows foot on the torque wrench.
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I would use a 1/4" drive low profile metric socket with 1/4" extension. Place the socket on the nut, insert the extension, then attached the torque wrench to the extension.
- Michael
"People should stop expecting normal from me... seriously, we all know it's never going to happen"
"People should stop expecting normal from me... seriously, we all know it's never going to happen"
thanks all for the response. the bolt is original from BMC and yes i agree it looks like a bodge! the rail fits and support the carbon rails, so should be ok there. i fitted over the carbon rails first and inspected before mounting and fitting it on.
KarlC, which kind of bolt did you get and where to get a light one from? Thanks!
KarlC, which kind of bolt did you get and where to get a light one from? Thanks!
what is the code on top of the bolt? it looks like it might be 12.9 which is a high-tensile steel, but the image isn't clear
whatever grade it is, presumably bmc's engineers decided that's what is needed, i.e. to take any off-axis forces from the saddle
if you replace the bolt, i'd use one of equivalent strength
whatever grade it is, presumably bmc's engineers decided that's what is needed, i.e. to take any off-axis forces from the saddle
if you replace the bolt, i'd use one of equivalent strength
Ok I’ve took some pics of the bolt for your references. Didn’t know about the number listed on the bolt till I saw Sungods post.
Not sure what the number represents but hopefully there’s a Ti lightweight version of this bolt I can use instead.
If you guys have a link on where to get it, that will be greatly appreciated
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Not sure what the number represents but hopefully there’s a Ti lightweight version of this bolt I can use instead.
If you guys have a link on where to get it, that will be greatly appreciated
Sent from my iPhone using Tapatalk
12.9 is a high strength steel bolt, ti bolts wont be as strong
what the numbers mean...
https://www.westfieldfasteners.co.uk/Re ... _Spec.html
assume that bmc's engineers chose 12.9 grade for a reason and forget about saving a few grams on a part that could cause a serious accident if it failed
from the image it looks like m4, get a 12.9 grade steel hex bolt, might be worth putting a washer under it as the head will be smaller than the standard bolt
https://www.westfieldfasteners.co.uk/Bo ... -12.9.html
best option is leave the current bolt as is and simply tighten until the saddle is secure, with that clamp design you have plenty of margin
what the numbers mean...
https://www.westfieldfasteners.co.uk/Re ... _Spec.html
assume that bmc's engineers chose 12.9 grade for a reason and forget about saving a few grams on a part that could cause a serious accident if it failed
from the image it looks like m4, get a 12.9 grade steel hex bolt, might be worth putting a washer under it as the head will be smaller than the standard bolt
https://www.westfieldfasteners.co.uk/Bo ... -12.9.html
best option is leave the current bolt as is and simply tighten until the saddle is secure, with that clamp design you have plenty of margin
M4? On a single bolt clamp?
M6 is more like it.
https://www.westfieldfasteners.co.uk/BZ ... ap_M6.html
Still, best to measure across the threads etc to check all the dimensions.
But my money is on a M6x40 being the best fit.
M6 is more like it.
https://www.westfieldfasteners.co.uk/BZ ... ap_M6.html
Still, best to measure across the threads etc to check all the dimensions.
But my money is on a M6x40 being the best fit.
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