bykemike 

I just bought a nice condition 1985 Trek 2000 frame from one of our members, nice frame, good deal , can't wait to build it up and ride it.

I've gone ahead and bought a nice Dura Ace 7400 box of brakes, shifters, crank etc but what I am having problems with is the seatpost bolt...any thoughts? Looks like it is about 40 mm long and maybe an M4 metric bolt.

I have a Trek dealer right near my shop and I took the frame there and all I got was shrugs, good luck, that kind of stuff.





Any thoughts most appreciated, better yet you may have one.

calamarichris

If you have an older hardware store near you, you might be surprised. Home Depot and Lowe's don't really carry such things, but I have an old Tru-Value Hardware Store, (which regrettably got acquired by Ace that still has a cornucopia of stainless steel gems that have saved my bacon more than once (twice in precisely the same spot on the frame). If your region has been Walmarted, you might have a drive a ways. Ye olde hardware stores rule.

bykemike 

I do have one of the older style Ace Hardware with a full isle of all kinds of things nuts and bolts.

I'll give it a try but I am really hoping for the right bolt, I'm hoping to get a nice period piece here.

SoCaled 

Without knowing specifically, I would get out the calipers and confirm size, head, shaft and length. Maybe use small hex key through the hole and mark it to get length? Matching the knurling, so it engages properly, seems like the hardest part. Quick search seem to show Campy and Miche with knurled post bolts, not sure what Trek used?

bulgie 

First, get yourself some measuring calipers. Dial, vernier, digital, whatever you like. Adequate plastic ones are like $8 or crappy steel ones start maybe $12 so there's no excuse for not having any!

Then measure the through hole, which is probably just over 6 mm, to allow an M6 SHCS (socket-head cap screw), but double check in case Trek pulled a sneaky one to make generic bolts not fit. It could be an M5 but unlikely, and definitely not M4, that wouldn't be nearly strong enough.

Measure the diameter of the counterbore, where the head of the bolt nestles in, should probably be a bit over 10 mm to allow that standard M6 SHCS. If those dimensions are right for a generic bolt (as I expect they are) then all you need is the length, which is measured on the 6 mm shaft part only, i.e. not including the head. M6 x 1 SHCS is common as dirt and just as cheap, get 'em anywhere.

Oh by the way just trying a generic M6 bolt in the hole is good enough, if you have one, to where you don't need to go buy calipers. But you should have calipers anyway!

Next you need the nut, which might be tricky. Getting the knurl to match the indentations in your frame is unlikely unless Trek is willing to help — or a BETTER Trek dealership than the one you went to. You may have to use a generic nut. A plain hex nut on the outside of the hole would work, but would look ugly. Try the nut that attaches caliper brakes to the fork crown or rear bridge, they are also M6 x 1 thread, and the diameter might just work as-is. Downside is no knurling, so you'll need to use two wrenches to tighten. If the brake nut almost fits but not quite, you can drill the frame to 8 mm easily enough, just use a 5/16" bit, close enough. The aluminum is soft and easy to drill. Oh wait, avast that, without a rigid setup, the drill might catch and wrench the drill out of your hands, and muck up the hole. I can do it but I've drilled probably 10,000 holes in my time, I can't assume you have the skill (no offense), so it's risky. Proceed if you trust yourself on this sort of hole-making. Safest is to find or make a nut that fits in the existing hole.

If Trek refuses to help you then shame on them, and never buy anything from them ever again. You gave them a very simple test and they failed.

Bianchigirll 

I'm willing to bet it's pretty much a standard M-6 Cap head bolt/screw but finding the knurled nut might be challenge. I'd take the frame and pic of what you need to the local ACE, True Value, Do it Best and start rummaging through their drawers.

bykemike 

I've got my share of calipers and assorted tools, I'm ok in that department. The M6 knurled cap head screw as depicted by Bianchigirll...I've got a bin with a number of them and they will not go into the hole at all, I have inserted an M5, Tight but it will go.

There has been a change however. I messaged the seller and he went looking and found the original bolt in his shop he meant to include it but forgot, Load off my mind. He is shipping it to me in the next couple of days.

Now lets hope it doesn't get lost in the UPS mess. :>)

I'm still going to look in Ace Hardware. BTW, our local Trek dealer has been in business 25 + and is sought after for his shop work and has a couple of good techs as well, Really now, how often have you seen a seat bolt clamping system that looks like this Trek 2000?

bulgie 

Yeah I was too harsh by half. That was a pretty tough test you gave them. I apologize for lashing out!

Sounds like a happy ending, great news. So did you say M5 was the final answer? I've found those to be borderline for this application, when there's only one bolt, though it depends on the lug design, tolerances and such. This Trek is well designed, by my old boss Tim Isaac I believe. Still, maybe it should be high strength bolts only, say class 10.9 or 12.9, not a hardware store stainless that's somewhere around half as strong. If you're getting the OEM part right from Trek then we can assume it's the correct strength of bolt the lug was designed for, but hardware store, not so much.

Always liked those bolts thru the seatstay tops, elegant. Like Bruce Gordon, or my old 1933 Excelsior. Looks organic, like it grew that way.

bykemike 

Oh, no problem at all, While I have a Trek guy to talk to...what is the rational for doing the seatbolt thru the seat stays like that? I think it is very cool looking but I haven't seen that design before. Maybe will now though, now that I'm aware

Bianchigirll 

It's a lot cleaner looking, probably less susceptible to breaking and maybe even cheaper. Since you don't actually have a lug with ears like a steel bike you need to extend the seattube above the joint and add on "ear" or a lug.

calamarichris

Just take the frame into Ace and you'll be able to tell immediately if it fits or not. It's not like they're going to charge you for the frame.
I did this with my 1986 Schwinn Peloton, (found exactly what I needed), and they didn't flinch at all.
Also the stainless steel was precisely the length and dimensions I needed. Stainless steel hardware that will outlive me by many decades.

oneclick 

Better to put the bolt in the drill in the vice and file the head to fit.

Always better to attempt modifications to the part you don't care about ruining.

(...and of course a drillbit doesn't give a 90 degree seat...)

bykemike 

An update.

I have the actual 1985 Trek 2000 seat bolt. Oh yee of little faith it measures as an M4.5 bolt with the trick little knurled nut, all chromed.

Here it is next to an M 6 bolt for comparison

I called the guy I bought the frame from and he sent it right away...great guy!

Piff 

Nothing like a happy ending

I guarentee you this thread will help someone out in the future. The number of times I've gone fishing on google for an esoteric answer and found it in some bikeforums thread, sometimes decades old now...

JohnDThompson 

The frame and fittings were designed by Tim Isaac, who used that type of binder on the custom frames he built before joining Trek.