Hub too wide? Seat post clamp? Builder too stoopid?

[aWolfDrawsNear]

Ran into a little snag today... My frame has what I assume to be an integrated seat post clamp:

And the Shimano Nexus 3 Hub I intend to use is slightly wider than the dropouts on my frame, so when I put the back wheel in, it spreads them out juuuuust enough that I can't get the seat post secured. I stripped and broke a couple of standard steel bolts by overtightening, but it's not enough to get the frame to squeeze the seat post. I've torqued down the shiny new grade-8 bolt pictured above, but the seat post is still slightly loose. What I'm wondering is if there's an easy way to make my hub a little narrower:

Are the nuts with the arrows pointing at them necessary? I think if they were gone, the hub would be a good fit and I wouldn't be "spreading" the back of my frame. I realize this is probably a super noob question, so be kind.

Or am I missing something? I have a hunch that maybe that hole through the frame is intended to mount something else to the bike (like a rear rack) and I'll actually need a different clamp to hold the seat post steady. When I found the frame, it was just a rusty frame with this 90 degree bent skinny-... seat post sticking out of it (no clamp), so I have no idea what should actually be there.

 

[Big Ape]

If you can flex the dropouts a little further than you need them, then when the wheel is tightened up, there should not be any stress in the seat clamp area. It also looks like you may be using 1/4" hardware, I would go up to 5/16" or possibly even 3/8" although that might require a flat area ground into the bolt so that the seat post will slide in past the bolt. That frame should have a 5/8" seat post, so yours looks correct.

 

[CrazyDave]

Firstly I would try tightening the seat post fully THEN installing the rear hub. If that fails, I would clean the seat post and the inside of the seat tube extremely well and try again. Very odd man. Very odd.

 

[Duchess]

Not only will tightening the seat clamp bolt first keep it from being too loose to tighten after, but it should make it easier for the rear triangle to keep its set once it's spread for the hub.

 

[Dr. Tankenstein]

I'm with Dave and Duchess, tighten seat first, then spread frame to fit hub.

That is the seat clamping mechanism, BTW. so your instincts are correct.
Before someone asks, can we see the whole frame? We love pics here...... [emoji16]


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[Toeslider]

If it's consistently that loose the way you are doing it, even with tightening it within an inch of its life, you might be able to get a shim in there. Try cutting a section of aluminum can out and forming it to the seat post. Put it half way into the hole, then insert the post if you can. That's the easiest way I know how to do it without slicing up your hands. If you can't fit something super thin like that in there, it ought to tighten up on its own.

 

[aWolfDrawsNear]

Thanks for the responses, guys. I did make sure I got the seat bolt very tight before squeezing the hub between the dropouts. Didn't make a difference. It's not greasy or oily in there, either. I like the thin aluminum can shim idea. I'll try that after work.

Tankenstein, here ya go:

Can't decide on what bars to get. I'm leaning toward getting something like Wald 867 bars and flipping 'em.

 

[Dr. Tankenstein]

Sweet ride dude! Yeah, try the shim thing, can't hurt right?

I like the idea of the classic Wald bars, up or down, they should look good.


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[Duchess]

I wonder, then, if you have a 3/4" for a frame that wants a 13/16" or a 13/16" instead of a 7/8". An aluminum can as a shim could probably make that difference.

 

[clamdigger]

Measure twice , shim once . May be ; http://www.porkchopbmx.com/Wald-905...-Bushing-Shim-13-16-to-7-8-WALD905BUSHING.htm

 

[GuitarlCarl]

You ride that bike in that seat position? There's custom solid seat posts over in the forsale section. Many sizes, many angles, might even fit better. Measure yours, add 1/16th...

Carl.

sent from my banana phone...

 

[The Black Monark]

Dunno if this will help but: Those Westfield frames take a special seat post bolt with a flat spot in the middle to clear the post.

 

[Big Ape]

Dunno if this will help but: Those Westfield frames take a special seat post bolt with a flat spot in the middle to clear the post.

I knew that I had seen that somewhere before.

 

[CrazyDave]

The position of that seat can't possibly help the problem, I hope ya get er sorted out man. Amazing the amount of knowledge around here...

 

[deorman]

It does look like there's an unnecessary nut over the brake arm. It also looks thinner than the on on the drive side, so maybe you could take it off and swap it with the one that's there now.

 

[deorman]

Also, is the seat stay bridge weld broken? I don't see how the seatpost clamp could be spreading other wise.

 

[aWolfDrawsNear]

A little beer can shim action and it's right as rain. Thanks guys.

Instead of grinding some threads off a standard 5/16" bolt, I just got grade-8 1/4" hardware. All is well.

 

[GuitarlCarl]

Yep grade 8, that's what I like to replace stuff with, especially seatpost bolts I know I'm gonna be cranking on...

Carl.