How can you tell what size of tube you have?

Not trying to be a smart aleck here, but ...measure it? That would work. It will either be 1" 25.4mm OR it will be 1 1/8" 25.575mm

Maybe I don't understand the question, or maybe???? I don't know it seems easy enough

I was just wondering if there was any other way to find the size with out measuring.

just meeeeeeeeeeeeeeeeasure it, dont make easy stuff hard

Measuring is probably the easiest way. Even a tape measure or ruler would be good enough to tell which you have. Most eveything built in the last 5-7 years will be 1 1/8" if its on a MTB. Road bikes still use both 1" and 1 1/8" so it hard to say about them. I believe most MTB's that used 1" will be a threaded type of headset and the 1 1/8" will be threadless. I am sure you will get more advice and expert opinions on here, I am just an amature, but I believe my info to be pretty accurate.

Good Luck

Call Miss Cleo!

There is no other way to be sure about your bike. You might get the info from the manufacturer's website or from some anonymous person on the internet who says they have the same bike or that they happen to know offhand.

I wouldn't spend $500 on a fork based on that.

So just measure it.

Midwestmntnbkr - 1 1/8" is 2.8575 cm, not 2.575 cm like you said. Not being a smart@ss, just pointing it out as it was probably a typo anyway .

You are 100% correct, I don't know whether it was a typo or just a case of hurried response. Glad to see someone is watching out for me!:thumbup:

ummm....
if you can't even measure the tube diameter, what the #&^#$ are you going to do when you need to cut the thing to size?? Do you have a headset press, etc.? Do you know about things such as trail and rake? Do you have a clue what you are getting into?

Im not cutting anything, or doing anything like that. I want to make sure that my freinds bike will work with my old forks.

D*Alex - take a chill pill, you'll live longer !

As for the headset press, nice to have but not absolutely essential. If you have a good quality G-clamp and two pieces of flat wood about 2" square to protect the ball races you can do it yourself, just be very careful to keep everything straight.

Btw, you are not measuring the fork steerer, you are measuring the internal diameter of the head tube of the frame. Even using a ruler, it should be pretty obvious because the difference between the two is over 4mm.

Btw Mk II, there is such a thing as 1 1/4" headtubes but they're rarer, they'd be 3.175 cm.

HTH .

This reminds me of the discussion about the way one takes a census of Wildebeests on the African plain. You fly over the herd in a light plane, count the legs, and divide by four.

Cheers...Gary

Hey Runge, when you measure the steer tube it may not be exactly 1 1/8 or 1. It'll be in the ballpark though, you'll know whether it is 1 1/8 or 1.

Okay, now I'm confused! (i'm trying to find out the same measurement on my bike.) now, do i need to measure the outside diameter of the steerer tube, the inside diameter of the of the headset cups, or the inside diameter of the head tube without headset cups? also, when i take off the nuts and washers and sundry off the top of the steerer tube(i'm using a threaded headset right now) should there be a lot of play in the fork?

[edit] after looking at it more closely, i get the distinct impression that the headset cups are extra thick or something so that a 1" threaded steerer tube can be used with a 1 1/8" headset, but that could be my inexperience talking.

Forget metal thickness etc, the measurement you want to know is the INternal width of the bare head tube with no cups or anything attached, just the raw frame .

woohoo! i bet it's 1 1/8" then. :thumbup:

I am selling some forks on ebay and people have asked me if it is a 1 1/8" at the top and 1 1/4" at the bottom??!!! Ive never heard of this kind of fork. Can anyone tell me what they are all about. I suspect I dont have this kind of fork

Thanks

A lot of bikes in the last couple of years have come with "tapered head tubes" that take forks like byrnsam described that are wider at the bottom of the steerer column than at the top. There are several variations on the tapered design, which is partly the reason why it is difficult to find an after-market fork for those frames. Looking at one of these forks when not in the frame, it is extremely obviously that the steerer tube changes diameter at some point.

The theory behind it is that having a wider lower headset bearing and steering column will make the front end of the bike stiffer. Apparently, the upper headset bearing and steering column isn't nearly as important, so they taper it down to the standard 1 1/8" which is then slightly lighter and makes it easy to find a stem that fits. It sounds nice, but I would never buy a frame like that due to the restriction of choice if you ever need/want to change your headset or fork (as your potential customers on eBay are no doubt discovering).

^I guess not everyone feels compelled to start a new thread for every topic.
I'd say byrnsam did well. Especially for a first post. Tied the new question into an appropriate thread.
Wrk101, you need to wrk on your welcoming skills.

Thanks Chris_W that's really useful information! And thanks Metzinger for sticking up for me!

Or an inappropriate thread. The next person to search for his particular problem won't be searching for "steer tube size" or anything like it. At any rate - the somewhat non-standard two bearing sizes are either going to be more popular or they will die the way of the dodo.

It doesn't matter at any rate, if those forks break it's a direct replacement from the person who made the bike anyways. Choices are much more limited than the standard 1 1/8 fork but people buying those high end bikes probably don't really care, or have enough money to not care.

^Kind of wasteful typing all that into an inappropriate thread.
You probably should have started a new one for that unsolicited rant.

It could have been titled; Why I hate tapered headtubes and the bourgeoisie.

Hi, I was trying to find the head tube measurement of a frame I want to get and saw this thread. Sheldon Brown has a quick trick to figure this out on threaded head tubes without taking anything apart or pulling out a ruler:

Put a quarter up to the quill; if it's diameter is a little larger than the quill it's 1", and if the quarter is a little smaller it's 1 1/8".

https://www.sheldonbrown.com/headsets.html

Sorry to keep posting in an old thread, but it may help people searching for an answer to the original question.

-g

^Welcome. Another excellent first post!
Many people around here could learn from you two.

Actualy this is a good example of how to join the forum
https://www.bikeforums.net/showthread...6-1973-Raleigh
oh darn, the "Why are people so mean" thread that followed got deleted