Hey there... I currently own a 1992 Trek 970 MTB. The bike is all original. I want to replace the current stem/handlebar setup to a nitto setup, possibly the Nitto Bosco Bullmoose bar, that will allow me to ride on a more upright position.

However, not knowing much about bikes I want to know if anybody can tell me how to properly measure the size of my current quill stem. I measured the diameter of the stem (Right before it goes into the tube) and it measures 1" or about 25mm. Is it safe to say that I have a 1" stem?

I hope my question makes sense... Thanks for your help.

This is a bit tricky because while it's reasonable to round off your measurement to 1 inch, it doesn't necessarily mean that you have a 1 inch stem.

Stem diameter is often stated according to the fork it fits. So your stem is made for a 1-1/8" fork. A stem for a 1" fork will usually measure 7/8".

So be clear and sure whether the stated dimension in the stem you're considering references the stem itself or te fork.


BTW - 1" stems like yours are relatively rare, so you have to be doubly sure when ordering.

Since he's talking about a bullmoose bar, he's obviously not talking about clamp size.

You can always pull the stem and see what size is marked on it. If you have access to a 32mm wrench see if it fits the lock nut.

Those Bosco bars look like they sweep back pretty good, so make sure you ca comfortably operate the shifters in that position

Neither am I.

This is a quill stem and in his words

.....I measured the diameter of the stem (Right before it goes into the tube) and it measures 1" or about 25mm....

I took that to mean that he's measuring the stem where it enters the fork (tube?), and posted accordingly.

I just want him to be sure that whatever he orders will fit his fork.

PLEASE NO.

Quill stems are removed by loosening the draw bolt at the top until it rises 1/8", they protecting it with a block of wood or similar and tapping it back down to free the wedge. Once the wedge is free, the stem is loose and can be worked out of the fork.

There's no reason to loosen the fork locknut and then have to readjust the headset.

To the OP.

I took a moment and searched out a photo of a bike like yours. (here).

It doesn't appear to have a 1-1/8" fork, but photos can be deceiving. So there may be a possibility that the stem has a step, measuring 1" where you measured it, and narrowing to 7/8" inside the fork.

To be sure, loosen and lift the stem as I described in the post immediately above, and check for a step, then measure the part that was inside the fork.

Just to clarify....... I do in fact know you do not need to loosen the lock nut on the headset to remove the stem. Perhaps my grammar could have been better but I simply suggesting the OP use a 32mm wrench as a "GO"/"NO GO" gauge for determining stem diameter.

That's an interesting point, and thank you for posting because i knew that you knew better and was wondering if you were losing it.

However, since the OP has a caliper, he doesn't need a wrench, he can simply measure the locknuts (convert to metric if necessary). 32mm means a 1" fork, and most likely a standard 7/8" stem diameter.

A 1-1/8" threaded fork would have a larger lock nut, most likely 36mm across the flats.

A friend called me once, asking this question about a bike she was considering buying at a yard sale. Not that the OP needs this method since he has a caliper...but the Saint Sheldon's "quarter method" worked for her. I'll post here in case it helps someone else out in a pinch, when they have no tools or way to measure, but might have some change in their pocket (or purse)!

Servicing Bicycle Headsets

Thank you all for your help... I ended up taking the quill stem out and there are no steps. I also saw that the stem is labeled 24.5, which I assume means 24.5 mm, which when converted equals 1". The new bars I'm getting are a 1 piece bar/stem setup... I will reach out to them on Monday to see what their specs are.

Thanks again!!!

If you cannot find bars and stem to meet your needs, you can make a shim allowing you to use a standard 7/8" stem.

Let's leave that as Plan B, but know that you still have options, and if necessary come back here and I'll lay out the plan for you.

Hey there... I'm back. Bad news... My new handlebars arrived, and they don't match my fork. I dropped the ball... I didn't understand your previous post about the correlation between stem/fork measurements. I do now though...

My current stem is 1"
My new setup is 7/8"

I know know that I should've referred to my stem as 1 1/8", not 1". 😕

Anyway, I'm ready for plan B. You mentioned making How I could make a shim and still be able to use the bars.

Thanks in advance...Hopefully you can guide me.

Happy to, but you'll have to do some sort of penance.

If there's a local co-op, head there and offer to help, but the real agenda is to get the raw material for the shim you need.

Find or beg a crashed 1" fork with bent blades and an OK steerer. Cut off a section 3-4" long (threads don't matter). Use a hacksaw to slot it lengthwise about half it's length. Slide it into your 1" ID fork, and you'll reduce it to take your 7/8" stem. Keep it oriented so the stem's expansion wedge is able to expand the slotted adapter and you're good to go.

You can do without slotting, by super gluing the reducer to the fork, but I prefer at least some expansion via the stem rather than rely on the glue. You can also do both if you;re a belt and suspenders guy.

BTW - it doesn't have to be a 1" fork steerer. Any tube with 1" OD and 7/8" ID will do, but I suggested a fork because that's an assured source.

I'm back. Just to let everybody know that I found a solution to my issue. My local bicycle co-op here in Orange County is temporarily closed, they're moving to a larger place and I was unable to find a used a 1" fork. However, I went online and I found a seat post stem reducer with the dimensions I was needing.

It arrived today and fits perfectly... Thank you all for your help. Especially FBinNY. Here are the pics.









This is the link to the item if anybody else needs it.

https://goo.gl/tjTlkX