ChromeSE5

I was rebuilding my bike up and found a crack and upon further inspection was something much worse. Human error > me.




I was thinking of just drilling straight through the side and putting an allan bolt. Another thought was to attach some type of clamp on the top from preventing from sliding down and a small screw or bolt in the back through the gap into the seatpost. It is going to be ugly but I am more worried about the frame integrity being compromised. Would an expanding seatpost work on carbon tubes? There was another thread on this but there wasn't a follow up and the guy hasn't been on since July. I had a campy chorus/record ergo 8 spd drivetrain on here but am thinking it might be best to just buy another frame and swap the components over. Oh well... any sugestions? Think if i polish the aluminum enough I can hang it on my wall?

blamp28

Trek will perform repairs like that. Contact them to get pricing. I think you are right to be concerned and would not ride that until a knowledgeable CF tech could recommend it.

phoebeisis

If trek wants a huge amount to repair it you might just set it up as a "your use only bike." I've found that lost of OEM maunfacturers will fix things like this, but their charge is so much-about what a good frame would cost used-that it is pointless.
I would find a way to use it, it the repair is too much.One thing that comes to mind is to smear the seatpost with adhesive-slow adhesive-and put it in at a height that you can use.You should put a dowel down the tube first-wood,PVC-whatever-for the seatpost to "sit" on.It will be sitting on the BB to some extent, but with luck,the adhesive will prevent the seat post from twisting,and the dowel will prevent it from shearing the epoxy by dropping downward.
Epoxy isn't very shear resistant-don't use it.An adhesive like liquid nails might work pretty well-but it takes maybe a week to really harden.
Yes,some folks might see this as dangerous.
I have a fairly high tolerance for risk,so .....
I would be extremely unhappy to just hang it up.It could be a fixed seat post beater-the lightest beater in the world maybe!
Luck,
Charlie
PS-The longer and deeper the seat post sits in the seat tube-the better.I would heavily score the seat post up first-maybe put some very shallow grooves in it with a grinder(give the adhesive something to grab.
If Trek will fix it for $50-well,that is the way to go of course.

MikeyLikesIt

A friend of mine had a frame just like yours. He cracked a tube and Trek replaced it at no charged. He told me that the frame had a lifetime guarantee...(although, they may not see this as a defect) Are you the original owner? I would check with Trek before doing anything else to it...

Mikey

submergedbiker

Look, you or someone has gotten some good use out of that frame...sometimes it just time to let go.

1. If you use some sort of adhesive you are just asking for it to let go at a bad time.
2. If you attempt to bolt it, you are asking for some minor imperfection in your drilling to cause a catastrophic failure at a bad time (you could also affect the CF/Al connection with the drilling).

I'm not sure she's wall art material, but that depends on your wall. Many a light bike have been put to pasture for less than what you have on your hands.

BTW, what were you doing to it anyway? There looks to be some deep scaring/gouging on the Al.

sb

DieselDan

You could cut and grind that down and install a collar and bolt. Take hearing and respiratory precautions when grinding aluminum.

HillRider

My first thought was to recommend you grind the broken side smooth and grind the other side off to match then add a seat post clamping collar. However on looking more closely, I don't think the seat tube sticks up above the top tube or seat stays far enough to clear the clamp.

I have to say anything you do now is going to be temporary and quite possibly failure prone. If Trek can't help you at reasonable cost, cut your losses and get a new frame.

phoebeisis

The seat post clamping was tightened too much,right?I'm guessing that is why it broke-aluminum isn't a bit forgiving like steel-not very elastic.
Try trek first.If the frame is worth-$150?? or so then maybe $50 shipping and $50 repair is OK.
If the trek repair is too costly,I would certainly give it a chance as a second string bike with the "fixed" seat post method I described.
If cost is no object-dump it,or hang it.
Liquid nails adhesive is very tough.It,and a dowel of some sort to prevent the seat post from dropping down the tube,should get you some more use.The dowel should be Liquid nailed also.Do it first,and then test the seat post length until you have it dead on.Leave as long a piece of seat post as possible.
Others have pointed out,don't try to fix it in place by drilling thru the frame.Aluminum is tricky enough with any extra holes.I would be tempted to put some short of shelf/stop on the seat post.It would sit on top of the seat tube,and give it a little support.
Liquid nails takes maybe a week to fully harden to full strength.
Luck,
Charlie
PS- If you have the time/interest,you might groove/notch the dowel so it fits the BB.Make sure you put liquid nail on the notch also.I'm assuming the BB has sealed bearings.Most of the support will be the side of the seat tube binding to the seat post, but there will be some force on the BB,and this will be transmitted to the BB frame.No big deal-when you stand up on the pedals,all the weight is supported there anyway.

ChromeSE5

Yeah, I screwed it up by tightening the seatpost clamp too tight over time. I know the frame isn't that expensive but the big thing about it is that it is my first road bike so there is a lot of sentimental value. I still have my other bike to ride so I am not SOL when it comes to riding. Thanks for the advice guys. I think I am going to sand down all the deep scratches and polish the crap out of the aluminum and keep it as a keep sake. I might even find old parts and use it for my trainer.

Trakhak

I agree with phoebeisis: if the seatpost is set at the correct height for you, why not glue the post in place? Bike companies are now cranking out extended-seat-mast frames with cut-it-and-ride-it technology; think of your Trek as a DIY version of that. And you could always epoxy an external collar to the bottom of the exposed portion of the seatpost, where you have electrical tape now, so that most of your weight is supported at the top of the seat lug.

ChromeSE5

Think it will support my weight of 190lbs?

phoebeisis

ChromeSE5,
The collar on the seat post wouldn't have to support all your weight.You would set it up as one more weight supporting/transferring.
The BB and BB shell would support "a lot" of the weight because the dowel-notched to match the BB-would be sitting on it(with an adhesive layer between to two),and the seat post would be sitting on the dowel.
The sides of the seat tube would be supporting a "lot" of the weight by having it transferred from the seat post -to the seat tube-via the adhesive.Heck,the Liquid nails is so strong,you might get away with not putting the dowel on the BB, but it could just shear the adhesive bond,so put the dowel in first.The dowel also will be "glued" to the sides of the seat tube.
To get a good fit-Don't cut your seat post-the longer the better.Put the dowel in first-notched if you are going to notch it-don't glue it yet.Put you seat post on,and check the height be riding (a little).Them remove the dowel-cut it-repeat until you have the height right.Take your time-if you cut the dowel too short,you have to start over(or just add a small length of dowel).
Once you have the right length-smear it with lots of liquid nails,and push it all the way down to the BB.Put it on the side for several days,and then recheck the ride comfort with the seat post in.Got it right-smear it with adhesive-stuff it in.If you want to collar it to sit on the seat tube lug, put the collar on before gluing the seat post in.A collar with an allen set screw would be nice. You could screw and glue it in place later.
It takes a week or so for the liquid nails to reach full strength.
Luck,
Charlie
PS-You could pull the BB first to notch the dowel to it-probably get away without doing it, but I would notch it..The more surface area touches,the less the(PVC-or wood) dowel will crush down.

ChromeSE5

ok i see what you are saying. The seatpost can't be supported by the BB because its an adjustable bottom bracket.

Mudu93

Any machinist worth his/her salt could fab a seatpost clamping collar for your particular application.

phoebeisis

No, I must have been unclear.
Yes,the BB will be supporting some of the weight.The dowel will be sitting on it just like this seat post is sitting on it.
If it is a typical sealed BB,then it is built tough-and won't have any problem supporting some of the weight.I think most of the weight is going to be transferred to the sides of the seat tube thru the seat post-via the glue.The dowel is there just to add more support so the seat post does shear the adhesive off and drop down.
If it is an old fashioned BB with an exposed spindle,then no you can't put the dowel on it.I would still give it a try-with the longest seatpost you have-and with a dowel, but not all the way down to the BB.
Luck,
Charlie

ChromeSE5

OOps sorry I meant that the axle for the BB is exposed so I can't rest the dowel on it.

phoebeisis

ChromeSE5,
I got it.Just use the dowel, but glue it to the side of the seat tube-just like the seat post will be glued.
The Liquid nails is very strong, but it is slow curing-be patient-7 days.The dowel should be as close in size to the seat tube seat post as possible.An old seat tube would work great, if you have one around.
Make sure you degrease it-and the inside of the seat tube-Simple green-lots of water.I would roughen and groove the dowel and the seat post before installing.
As Mudu93 pointed out a machinist could make a clamp for you-downside, if will have to be a buddy because they don't work cheap.It will have to be very narrow, of course.
I would be tempted-if trek wants too much to fix it-to try to adapt some other clamp as a seat post clamp.Since it wouldn't be as good as the OEM set up,I would still use the dowels etc.A clamp on seat post clamp of the right size would be first choice.You would have to remove what is left of the original clamping boss(threaded nub)
Luck,
Charlie

Booger1

Grind it smooth and get/make a clamp for it.

phoebeisis

Just a clamp won't be enough-it looks like there is only about 1/8- 3/32" of width to clamp on there.Make/adapt some sort of clamp, but it won't be enough by itself.
Glue-Liquid nail-and clamp it and it should hold.You could also built a shelf on the seat post so it couldn't slip thru, but like Booger1 said-more complicated is more complicated-a clamp and adhesive will work.Just the adhesive migh work-it might work OK with just a long roughened seat post if there is enough length to glue on.
If the seat post is long enough to glue 10"-I would just glue it in there.If it fails-drops down-you can take it out and use a clamp,and a lenght of dowel/seat post below the seat post.The more surface area glued-the better.Degrease and roughen it first.(simple green-water-file if that is what you have.If you have a grinder make some shallow grooves in the seat post-in a lot of directions-especially horizontal to ground-but all directions-not too deep-dont cut thru
Luck,
Charlie

wroomwroomoops

I see a different problem there: I am quite sure there is some amount of delamination below the clamp point, by looking at that picture. I def wouldn't ride that frame, and I'm light.

Thumpic

retire it..........clean it up.....hang it on the wall.......maybe suspend some cool pics of you on the bike from the top post........ lotsa possibilities for one-of-a-kind artsy fartsy stuff here...........

Zouf

The lugs on that bike are aluminium. You are looking at some gouging and scoring on an aluminium part, not carbon.

wroomwroomoops

In that case, I stand corrected.

wroomwroomoops

Oh, I would like to remind that the secret to strong and long-lasting gluing is thorough degreasing.

ultraman6970

This is what I would do...

Get that cold fusion aluminum rod thing and fill up the gap with it ( https://durafix.com/ ). The material wont breake EVER! Then as you thought,.. Drill 2 holes and put 2 allen bolts in there.

Solution 2, probably it will work even better because u'll get more surface to work with. Weld a little block of aluminum using the durafix thing, sand it to make it nice, drill 2 holes and put two allen bolts. Done!

Solution 3, use the durafix to weld the broken part back. 1 and 2 will work better anyways.
Since the lug is big enough u shouldnt have structural problems with the Durafix stuff. U'll save the frame that is the important part.

Just in case, the durafix wont work in the case of broken AL tubes ok? Probalby it will work a little bit but probably the tube will RIP somewhere else but not in the welded part. In this case it will work fine..

Just in case, the sistem with the 2 bolts works fine. Is an old idea that some companies used long time ago like for example Vitus and some TT aero bikes back in the day...well .. have fun