# '06 928L seatpost issue



## CalgaryDave (Jan 7, 2002)

I just took delivery of a used '06 928L and have a question for others who own the same model. The stock seatpost, an FSA SL-K 31.4mm, fits tight in the seat collar area but when inserted to ride height it can easily be rocked front to back. A lot! This indicates to me that the seat-tube has been reamed oversize. The amount of movement is enough to make me think a 31.6 would still have the same problem, noticeable but to a lesser degree, and the 31.4 is so snug on entry that I doubt a 31.6 would go in anyway. I measured the seatpost at a consistent 31.4mm over its length so that is not the problem. There is a crimp mark in the seatpost from the prior owner over-tightening it. I am unfamiliar with carbon seatposts but that sounds kinda scary if you ask me.

Any thoughts other than "you're facked matey!" I thought I would ask here, before contacting Bianchi, in case this is a known issue with a simple fix.


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## yancy0303 (Feb 13, 2008)

I sent you an email with a few things to check. let me know if they help.


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## I am Dirt (Jan 30, 2008)

Please post up what you find out on this. 

Thanks!

Pete


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## 1bianchi (Sep 25, 2006)

*31.4*

Hey, I hope someone had a good answer for you like maybe the seat collar was cracked. I have the exact bike as you, over a 1000 miles on it now, and I bought the laidback FSA 31.4 seatpost as was recommended and have had no problems. I do run into the problem though of knowing how much to tighten things on the bike. I don't have a torque wrench, but even if I did where do you find the correct torque to tighten it to anyway?


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## Microxot (Mar 3, 2008)

I was having a similar problem with my '08. Im a bit on the heavy side (280+change) and no matter how much I tightened the collar, when I went riding, the post kept sinking into the seat stay. The solution in my case was to add a washer between the bolt head and the collar. After that, my seat hasn't moved a mm in 400 miles!


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## California L33 (Jan 20, 2006)

Are you guys using carbon assembly paste? 

Torque specs should be available through Bianchi and your dealer.


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## alk3 (Sep 23, 2005)

Anyone know of the pros and cons of using shims and going with a smaller size seatpost?

I have the 05 version of the 928L and have been looking at changing out the the post from the FSA offset seatpost that came with the bike to a zero offset seatpost. It is so fun finding someone that makes a 31.4 post with zero offset.:mad2:


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## otoman (Mar 8, 2004)

I am going through the exact same problem with the seatpost issue. I just purchased a shim from e-bikestop (31.4 to 27.2mm) despite my LBS telling me it wasn't a good idea. They claim warranty issues.

My reasons for changing: I am 6'2" with a 37 inch inseam (very long legged for my height). When I bought my bike 2 years ago I was a lot less flexible so my seat was lower. Well that was fine then as the setback FSA post at that point still allowed a proper position of the knee over the pedal. As I have become more flexible, I have raised the saddle a bit at a time. Now I have to have my saddle all the way forward and my knee is still a little behind where it should be relative to the pedal spindle/foot position. SO that means I need a zero-setback post WHICH no one makes in a 31.4. Of course my LBS offered to order a custom T-cube for me 

3 solutions: 1)use the shim and a 27.2 0SB post
2) get a custom T-cube
3)go non-Bianchi in a frame that has at least a 73 degree seatpost angle (my 61cm 928L is 72.5)

Finally, I have been kicking around the idea of going up to a 180 crank, given my inseam length. That will not be possible with my current post but would be possible with a zero setback post.

That was probably more answer than you were looking for...


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## toyota (Sep 4, 2006)

otoman said:


> I am going through the exact same problem with the seatpost issue. I just purchased a shim from e-bikestop (31.4 to 27.2mm) despite my LBS telling me it wasn't a good idea. They claim warranty issues.
> 
> My reasons for changing: I am 6'2" with a 37 inch inseam (very long legged for my height). When I bought my bike 2 years ago I was a lot less flexible so my seat was lower. Well that was fine then as the setback FSA post at that point still allowed a proper position of the knee over the pedal. As I have become more flexible, I have raised the saddle a bit at a time. Now I have to have my saddle all the way forward and my knee is still a little behind where it should be relative to the pedal spindle/foot position. SO that means I need a zero-setback post WHICH no one makes in a 31.4. Of course my LBS offered to order a custom T-cube for me
> 
> ...


if you go with longer cranks you will lower your seat not raise it.


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## otoman (Mar 8, 2004)

Yep, your right. The issue is that I will also have to bring the saddle forward some more too, which I can't as it is already all the way forward...


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## Cogito (Nov 7, 2005)

California L33 said:


> Are you guys using carbon assembly paste?
> 
> Torque specs should be available through Bianchi and your dealer.


I agree on both points.
A torque wrench from Sears is a worthwhile investment if you swap bars and stems a few times. Seat post is less critical and the paste will stop all slippage with a snug turn of the hex wrench well below torque specs.


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## dave2pvd (Oct 15, 2007)

otoman said:


> Yep, your right. The issue is that I will also have to bring the saddle forward some more too, which I can't as it is already all the way forward...


How much? 2.5mm? Are you really able to get that accurate in measuring your knee's forward position?


Edit: WTF are you guys doing buying such expensive frames & components and not using a torque wrench??? How much is a 1/4" torque wrench? $60? Just sayin....


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## BikeGeek (Mar 19, 2005)

I was having a similar issue with sloppy seat post fit and slipping. I ended up bulking up the seat post to better match the seat tube by applying a few coats of automotive clear coat to the post. The clear coat in addition to the Tacx assembly paste solved the issue. In cases of being the original purchaser warranty replacement for poor manufacturing tolerances may also be an option.

Another option would be to buy one of the secondary clamps that attach to the seat post to keep it from slipping down. 

Do not use a seatpost shim unless it extends a few cm below the bottom of the top tube to seat tube junction otherwise you will be concentrating the stress in a small area and likely crack the seat tube above the top tube. Same stress issue as people running too little seatpost in a mountain bike with an extended seat tube.


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## otoman (Mar 8, 2004)

A little follow up:
I have been using a shim (31.4/27.2) with a zero offset Thomson post. Works great. Two other bike shops told me they were fine to use.

Dave2pvd: sorry didn't see your post. The seat would move forward almost 5mm to keep the same knee over pedal position. And yes, those kind of increments are easy to guage with a plumb bob and a level. Maybe not the 0.5 part of the 2.5mm you suggested but 2 mm is doable


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