# Synapse owners - how do you tighten your seatpost screw?



## ToiletSiphon (Jul 23, 2014)

With the Synapse unique seatpost screw placement, I haven't been able to find a torque wrench that would allow me to tighten the screw to the "correct" tension. So I take I wild guess and try not to overtighten it... which most of the time results in an under tightening and a saddle that won't keep its height.

Have any of you found a tool or a way to give it the correct tension all the time? And if I overtighten it, will I just break my seatpost or do I put my frame at risk?


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## GTR2ebike (Jun 30, 2011)

Park TW-5 works


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## ToiletSiphon (Jul 23, 2014)

The head of the tw-5 looks big.. It really fits between the screw and the seatpost?


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## Rogus (Nov 10, 2010)

View attachment 300240


There isn't much clearance. Have you used the Park TW-5 on one as it does look too big.


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## Lombard (May 8, 2014)

I have the same problem. My seatpost is slipping down. I do have the Park TW-5 but don't know what the torque should be. Is 5 n-m safe? I would be VERY careful as overtorquing could crack the frame resulting in a VERY unhappy Synapse owner. I haven't tried but it sure looks like the head of that torque wrench wouldn't fit in there.


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## Rogus (Nov 10, 2010)

Lombard said:


> I do have the Park TW-5 but don't know what the torque should be.
> 
> I haven't tried but it sure looks like the head of that torque wrench wouldn't fit in there.


Since you have one why don't you see if it fits and let us know. We'd appreciate it.


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## GTR2ebike (Jun 30, 2011)

It fits, the tip touches the post but it works fine.


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## Rogus (Nov 10, 2010)

Thanks for letting us know. Rep given.


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## ToiletSiphon (Jul 23, 2014)

GTR2ebike said:


> It fits, the tip touches the post but it works fine.


No risk of stripping the screw caused by an akward angle ?

There is a sticker on the seatpost that says the recommended tension is 6 n-m and the max is 8 n-m. I also had problems with my seatpost sliding down and my LBS put some kind of blue gel on the seatpost. Apparently this happens all the time with carbon posts and the gel is made by Park Tools especially for that purpose.

Would overtorking really crack the frame? I thought it would only crush the seatpost. I’m ready to save a few bucks and not buy a tool if only the post is at risk.


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## Lombard (May 8, 2014)

ToiletSiphon said:


> No risk of stripping the screw caused by an akward angle ?
> 
> There is a sticker on the seatpost that says the recommended tension is 6 n-m and the max is 8 n-m. I also had problems with my seatpost sliding down and my LBS put some kind of blue gel on the seatpost. Apparently this happens all the time with carbon posts and the gel is made by Park Tools especially for that purpose.
> 
> Would overtorking really crack the frame? I thought it would only crush the seatpost. I’m ready to save a few bucks and not buy a tool if only the post is at risk.


Could that blue gel be some kind of carbon friction paste?

Yes, you can absolutely crack the frame with too much torque! And I don't know which Synapse you have but my 2014 Synapse Carbon 5 105 has an aluminum seatpost. I believe the Synapse Carbon 3 Ultegra and above have a carbon seatpost, otherwise, they are all alumunum seatposts for 2014. Therefore, you will crack the frame before you will damage the seatpost - not nice!


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## ToiletSiphon (Jul 23, 2014)

I have the ultergra 2014, which has a carbon post, so I guess I am less at risk of breaking my frame before the post. But better be safe than sorry, I'm ordering a TW-5 this week.


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## ToiletSiphon (Jul 23, 2014)

Oh and to answer the other question, yes the blue gel was carbon friction paste. Seems to work well.

Do you know where I could get a good price on a TW-5, they are pretty pricey.


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## Lombard (May 8, 2014)

Rogus said:


> Since you have one why don't you see if it fits and let us know. We'd appreciate it.


OK, so last night, I tried to tighten with the Park TW-5 and it does fit - just barely. It says 5 n-m which to be safe, I am assuming is the maximum torque, not just a general guideline.

The trouble was, it WAS still at this maximum torque but the seatpost was still able to move inside the seat tube. So I loosened and removed the seatpost and guess what? There was grease all over the seatpost and inside the seat tube! No wonder it was slipping! So I figured, a little alcohol can clean that up. Got the seatpost clean but the inside, still gummy and greasy. Put it back and tightened to 5 n-m, still slips!

I'm going to resort to a trip to bike shop to see what they recommend as this is unacceptable. I'm not sure carbon paste would solve problem as my seatpost is aluminum so I'm dealing with aluminum against carbon.

Stay tuned.


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## Lombard (May 8, 2014)

ToiletSiphon said:


> Oh and to answer the other question, yes the blue gel was carbon friction paste. Seems to work well.
> 
> Do you know where I could get a good price on a TW-5, they are pretty pricey.


They are pricey but still cheaper than having to replace a cracked frame. I Googled it and couldn't find anything less than $100. It's still a valuable tool for general use on your bike for everything that tightens under 15 n-m. Howver, if you really think you will never use it again, a trip to the bike shop will be cheaper.


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## MMsRepBike (Apr 1, 2014)

You don't need a Park TW-5, any similar torque wrench will do. You just need one that will go from 3-15 Nm. That being said I do use the TW-5 at work and home but it works the same as others I've found.

As for the wrench fitting or not... You're supposed to use a knuckle on the torque wrench so that it doesn't rub against the post:









Like so. This thing will go between the wrench and the bit, giving you that angle you need.

Torque setting is 5-6 Nm, and the seatpost needs to have carbon paste on it.


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## Lombard (May 8, 2014)

MMsRepBike said:


> Torque setting is 5-6 Nm, and the seatpost needs to have carbon paste on it.


Will carbon paste work even if seatpost is aluminum?

Mine just says 5 N-m. Note that wrench has settings in increments of 0.2 N-m.


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## ToiletSiphon (Jul 23, 2014)

> OK, so last night, I tried to tighten with the Park TW-5 and it does fit - just barely. It says 5 n-m which to be safe, I am assuming is the maximum torque, not just a general guideline.




Where have you seen 5 n-m ? The sticker on my post says recommended 6 and max 8 n-m.


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## Lombard (May 8, 2014)

ToiletSiphon said:


> Where have you seen 5 n-m ? The sticker on my post says recommended 6 and max 8 n-m.[/COLOR]


Right under the rubber plug, it says 5 N-m. It's on the frame, not the seatpost. I have a 2014 Synapse Carbon 5 105. Yours could very well be different.


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## ToiletSiphon (Jul 23, 2014)

I found the manual on Cannondale website. They say to use 5 to 6 n-m tension.

It also says that carbon gel should be added when either or both the seat tube and/or seat post are made of carbon.


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## Hydrazine (Jun 11, 2014)

I have been using the Ritchey Torque Key. It is a little bit of a tight fit and there is no ratchet so you have to turn the bolt one facet and re-insert the tool but it is still easier to work with than the traditional torque wrench I have. The Ritchey key is also considerably cheaper at $15-$20 and it is small enough to carry with you on a training ride if you are fine tuning your position on the bike.


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## Lombard (May 8, 2014)

Update: I took the bike to the shop where I bought it. The skilled and reputable mechanic said the "grease" inside the seat tube was indeed carbon paste, but probably not enough. He put lots more carbon paste in there and tightened the seatpost back down. He admittedly torqued it over the 5 N-m spec in the seat tube telling me this was safe and he could feel when it was tight enough. No charge since I bought the bike there.

Needless to say, torquing over spec on a carbon frame is NOT something I would do myself. I will leave that to the mechanic's trained calibrated hands.

Rode 20 miles last night and seat did not slide down. Even tried to turn seat and it wouldn't budge. Problem appears to be fixed.


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