Broken seat post lugs

akbond1973

Hi all,
I am looking for some advice. When removing my seat post a few metal lugs fell out. It appears only one lug is left
attached to the bike which the seat post clamps onto. It is a Trek madone 4.5C . I was wondering if it is worthwhile
getting in touch with a frame builder to see if some welding might remedy this problem or any other suggestions ?



Many thanks for any help

Monty Dog

I would take it to a Trek dealer first - looks like a separate aluminium shim/sleeve that fits inside the frame.

andy_wrx

Is that one still in place actually attached to the bike, or is it just held in place by grime and a bit of corrosion ?

As Monty says, they look like loose shims which would just sit on that rim inside the frame

rolf_f

If they are meant to be loose, how is the seat clamp holding the post to the frame?

rake

it could be loose and hold the seat with a wedging action when clamped up, those shims may not be fully flat and clamping the top half may cause the bottom to splay out wedging into the frame. looks like it holds up on that ledge to stop the post slipping down. for a starter i suggest putting the seat back on whilst holding that loose shim in position, tighten the clamp back up and see if it holds. If it does i dont think youve got a problem really, just a slight inconvenience of it being loose when you take the post out.

NUAir

I had the exact same thing happen on my 4.5. Even the same three lugs broke off, with the same one standing.

Were you able to resolve this with Trek or are you still riding with the broken lugs? It seems like this could be a design flaw? My old Trek had a much stronger piece for the clamp and I never had anything like this happen.

NUAir

SO just heard back from Trek. Despite my bike being only 8 months old they will NOT cover it in their warranty.

A clear issue with the frame and they offer no solutions other than to buy a new bike.

Sorry Trek you have lost a loyal customers (my fifth Trek) business for life.

I would recommend that everyone on this forum check their Treks for the same problem as another Trek rider at my school is already seeing cracks in his seat post lugs after only 5 months.

F*^&ing ridiculous Trek!

yaya

I think this is where social media can be useful...

Post on Trek's Facebook Wall and they will HAVE to come up with a solution! Their frame have a lifetime warranty so if this is indeed a design flaw they should offer a fix or a replacement!

http://www.facebook.com/TrekBicycle

And on Twitter as well: https://twitter.com/#!/TrekBikes

Good luck!

mamba80

If you get no where with Trek...........
Is it possible to machine up a new piece and re bond it ?
http://www.carboncyclerepairs.co.uk/repairs3_19.html never used them so cant recommend but as its not a critical strength area of the frame, what can go wrong

NUAir

Thank you for the tips guys.

The Facebook tip seems to have paid off and I'm starting to get some reaction from Trek...

However, I have also been calling up authorized Trek dealers in the UK and yesterday I went 5 for 5. All five dealers said they have had recent issues with the seat post lugs on Madones and have been in communication with Trek.

It really is starting to sound like Trek is hiding a product recall and hoping people A) won't notice or they can put the blame on the rider for tightening the seat post clamp too hard and avoid any compensation or replacement (this seems to be the preferred method here in the UK).

NUAir

A bit of follow-up in case anyone is having a similar problem.

After posting on Facebook, Trek finally gave-in and provided me with a brand new frame at no extra charge. Just to keep myself out of trouble I made sure the dealer used a torque wrench to tighten the seat post to the exact specs given by Trek (I also ordered my own from Park Tools).

Three days later I noticed my seat post started sinking. I took it back to the dealer and they again tightened it to the specs given by Trek. The next day after 20 miles in the saddle I was sitting on the frame, the post completely sunk into the frame.

I have no idea what I am doing wrong and the dealer is also trying to figure it out with Trek, but it appears that maybe the only option is to over-tighten the seat-post clamp to ensure the seat stays up? Of course this means that you have a better chance of breaking off the seat post lugs...back to the initial problem.

Just to make sure I wasn't dealing with another problem bike, the dealer used a torque wrench on other Trek Madone's brought into the shop...guess what. Every single one (10 in total) were over-tightened according to Trek specs.

Has anyone actually been able to keep their seat post up without over tightening?

me-109

I went off Trek as a company when they took over Gary Fisher (about '92?) and failed to honour any of there warranty work. Since my Fisher frame was in for a warranty replacement at the time - and then the dealer went out of business - I lost all means of compensation. Bar-stewards! They'd it get away with it in the States.

sungod

NUAir wrote:

A bit of follow-up in case anyone is having a similar problem.

After posting on Facebook, Trek finally gave-in and provided me with a brand new frame at no extra charge. Just to keep myself out of trouble I made sure the dealer used a torque wrench to tighten the seat post to the exact specs given by Trek (I also ordered my own from Park Tools).

Three days later I noticed my seat post started sinking. I took it back to the dealer and they again tightened it to the specs given by Trek. The next day after 20 miles in the saddle I was sitting on the frame, the post completely sunk into the frame.

I have no idea what I am doing wrong and the dealer is also trying to figure it out with Trek, but it appears that maybe the only option is to over-tighten the seat-post clamp to ensure the seat stays up? Of course this means that you have a better chance of breaking off the seat post lugs...back to the initial problem.

Just to make sure I wasn't dealing with another problem bike, the dealer used a torque wrench on other Trek Madone's brought into the shop...guess what. Every single one (10 in total) were over-tightened according to Trek specs.

Has anyone actually been able to keep their seat post up without over tightening?

did they put any assembly paste on it?

i had a post that would not stay put at maximum rated torque, with assembly paste it's stable, no slipping after thousands of km

there seem to be two types, the clear, such as finish line's, which feels gritty (it's plastic 'grit', not abrasive/scratchy), and the pink, tacx and others, which is not noticeably gritty, you may need to try both to see which works best

desweller

Did your builder grease the clamp screw? That will have a substantial effect on the actual tensile load achieved for a given torque.

The quality of the screw in the clamp and the quality of the clamp band itself can also have an effect; more elastic or ductile materials will yield more for a given torque, reducing clamp load.

Mechanical torque wrenches are notoriously inaccurate anyway; you'll do well do get within 10% of your target torque 5 times in a row.

As far as the loosening test is concerned, crack-off torque values are usually much higher than the torque used to tighten the screw to begin with, particularly if the crack-off test is not done immediately following tightening. I wouldn't pay much attention to that.

The shims look like they are designed to lever into the seat tube against the seat pin; chances are it's quite difficult to get them to stay put. Does seem like an overly complicated design.