Aussomeman

Is it possible to drill out a 1" head tube to enable the use of a 1 1/8" headset and fork, or would the structural integrity of the frame be compromised? I'm looking at purchasing a rigid steel frame with a 1" head tube for a singlespeed project, and I'd like to be able to use the fork(s) I've already got (both are 1 1/8) with it. I could swear I read that this was possible online somewhere. I thought it was at Sheldon Brown's site, but I can't seem to find it again. Thanks in advance!

supcom

I doubt that the head tube thickness is much more than 1/16 inch to begin with. If you were to undergo the expense of having it milled out, it would surely be paper thin.

You could probably buy a new fork for the machining cost anyway.

sydney

It obviously depends on what the material is and how much you have to work with. 1" cups are 30.2mm and 11/8" are 34.0mm. It isn't a job for a hand drill but would need to be done by a qualified machinist.

ImprezaDrvr

I'm envisioning your fork splitting right through the front of the head tube when you're on the trail.

You can find 1" forks. Why not go rigid and not risk it? For that matter, if you look around a bit and have a fork that will let you swap crowns, you can probably get a 1" steerer on one of the forks you've got now.

yojimblab

Personally- I wouldn't recommend that for even my worst enemies. Weakening the front end of your bike can really cause damage. I'm talking about damage to your face. And your colar bones, hands, ribs, arms, etc.
If you come across a site that recommends a procedure for this- please post... My curiosity is piqued.

pnj

you can use a one inch frame with a 1 1/8 fork. it just takes some special care to do so. and you need to run loose ball bearings.......

CMcMahon

Do they still make the 1" to 1-1/8" headsets, though? I haven't seen one of those in a long time.

Retro Grouch 

I'm not at all surprised that you can't seem to find it again. I'm very surprised that you think you read somewhere that it would be possible. Ask yourself this question: Why would anybody design a bike with a head tube that had 1/16" more wall thickness than was necessary?

sydney

D'oh?? Try runing a 11/8" steerer through a 1" cup.

sydney

D'oh?? If you have a 11/8" traditional headtube there are reducers that allow the use of a 1" HS.A campy hiddenset can be configured to go smaller if you start with a 11/8"

sydney

I have a lightweight Foco HT that measues 32.6 OD. Not much left to work with when drilled to 34.0....lol

pnj

I know it's been done because in the bmx world, it took some time before all frames had 'oversized' headtubes. kids had old 1 inch frames but bought newwer 'oversized' (1 1/8) forks.

I don't know how they did it, I just know it involved using loose ball bearings. as in, no bearing retainer.

sydney

This isn't the BMX world, I just tied sticking a 11/8" steerer thru some 1" cups. It doesn't fly!!The steerer diameter is larger than the part of the cup that goes into the headtube for support of the baering cup. Has nothing to do with not running retainers.

CMcMahon

Hey, Sydney, no need to be a jackass. And by "1" to 1-1/8"" I meant putting a 1-1/8" steerer into a 1" headtube.

sydney

Double D'oh??

CMcMahon

Like PNJ said, it's been done before (and it's worked) with BMX bikes, so there's no "d'oh" involved.

Mr.Endo, Esq.

Sorry, but this is non-problem in search of a problem. Use the correct fork.

sydney

Yeah, there is a D'oh? Lemmie give you a clue. BMX 1" threaded HS used 32.7 cups and 11/8" threadless BMX HS used 33.0 cups. We aren't talking BMX here!! Obviously different size HT to start with, and little difference in cups. Not like trying to drill out a HT designed around 30.2 cups to accept a 34mm cup.

CMcMahon

Thanks for clarifying that this isn't about BMX, as if I didn't realize that before; I was simply stating that it worked for us.

sydney

whatever....

pnj

that's weird. I thought 1" was 1" an 1 1/8 was 1 1/8.

if bmx is different then how come I can use any 1 1/8 headset on my bmx frame, including those made for non-bmx frames?

sydney

Even 1" isn't 1" in road and mtb. Ever hear of JIS and ISO standards? That does not even begin to cover all the other nominal 1" stuff that was in common usage before the standards. Maybe BMX specs have changed. The first set of numbers was from the 98 QBP cataloge.The new QBP says 1" BMX uses 32.7 cups.Some junior and mini use 30.2 cups and 11/8" uses 34mm cups...............Again it involves the differences between BMX HT and standard road, and mtb. You want to try sticking an Approx 28.5mm OD steerer thru a 1" cup with a 26.5 ID, go ahead. Ill be glad to loan you a 5 pound hammmer.Try reaming a 1" HT to take a 11/8" cup, and in many cases you will have nothing left.

Aussomeman

thanks for all the replies, folks - didn't realize this would be such a hot topic. i kinda figured it wasn't too practical, but the situation is like this: i'm running my current mtb as a rigid singlespeed (with tensioner). it's an older aluminum frame with a 1 1/8" head tube, and i'm running a rigid threadless steel fork with it. i'm looking to pick up an old steel frame with horizontal drops so i can drop the tensioner and build the aluminum frame back up with some gears. i also just picked up a sweet old school white brothers fork with a 1 1/8" steerer that i'm planning to install on the aluminum frame, and the steel frame i'm looking at buying right now has a 1" head tube and no fork included. I was hoping perhaps i could just swap the fork from my current rig onto the steel frame, but if it's that sketchy, i'll probably just look for a 1" fork.

pnj

I don't care what the QBP catalog says. I know kids have done this.

king, fsa, dia-compe all make 1 1/8 headsets that fit both mtn. bike and bmx frames. the exact same headsets....same size head tubes, same size stear tubes. you know, that's why you can run a mtn. bike stem on a bmx fork.

why do you come across like an arse?

dooley

11/8" Aheadsets are all the same, BMX or MTB. 1" threaded are different, you have BMX threaded and at least 2 other types, as Sydney pointed out.
Maybe people are confusing running 1" forks in 11/8" frames, as that is a fairly common swap in the BMX world and can be done with off the shelf parts.