#%%##&$ sun tour barcon recessed hex bolts-5mm??
 

I just recently acquired a '93 burley tandem and wanted to switch handlebars but I cannot get the recessed nuts off. help!!

They loosen the opposite way.

to remove them the hollow bolt faces inward , so yes to loosen it you turn the 6mm allen CW.

the bolt through the lever itself is yes a 5mm one, the Nut is custom made by sun tour for themselves

thinner thickness , bigger hex , then there is a screw slot locknut on the outside you tighten against the nut, beneath it.

the 2 of them work together to set and maintain the retro friction.

I have a screwdriver with a notch in the center to get the domed nut tight.


someone posted a exploded diagram of them earlier this Year..

The Suntour bar end shifters is made up of 2 parts. There is the shifter unit and there is the mounting unit that secures to the internal diameter of the handlebar.

1. Remove the cables from the derailleurs. Next remove the shifter unit from the mounting unit, this is done by using a flat head screwdriver. Put down any washers that you remove in the sequence so that you do not mess up the installation.

2. Once the shifter unit is removed, you should be able to access the allen key bolt that secures it to the handlebars. Loosen but do not remove it completely. There is an expander wedge that grips the internal surface of the handlebars. Once it is loosen use a small hammer to tap the allen bolt to loosen its grip. You should be able to remove it once the wedge is not expanded.

3. To install it back on the bike do the opposite steps that you removed it.

In case you didn't grasp this from the prior posts. The 6mm bolt that holds them in is basically a countersink screw, which expands the collets as it's tightened. However you're working it from the opposite end from normal, so to push the head deeper into the bar and loosen the collet, you turn the screw to the right.

I got frustrated and went to dinner. The shifter part is off. It's the mounting part that I can't get off. The first response indicated that it's reverse threaded. Is that true? I don't want to torque on it the wrong way.

ok. I will try that. Thanks!

No. it's a RH thread, but look at the picture in my prior post. You turn it to the right so it goes deeper into the bar, which means the taper is moving away from the expanding segments.

BTW- both units have the same RH thread and work the same way.

I got the bolts off, thanks!!

However, my elation was short lived. I didn't realize that the Nitto Technomic that I bought was 7/8ths and the tandem uses a 1" threaded stem. D'oh!! :cry:

Surely someone makes a spacer for these situations...I hope.

Well there are a lot of stems too fit your purpose as well as threaded 1inch too threadless type stem adapters that will allow you to run a tone off bars stems properly matched.

Don't confuse yourself here- it sounds like the stem on the tandem is for a 1 1/8" threaded headset, while the Nitto stem you bought is for a 1" threaded headset.

I measured the original stem with my caliper measuring thingy and it's exactly 1" whereas the Nitto is exactly 7/8ths.

Try shopping for a 7/8" headset and report back to me.

The Nitto is for a 1" steerer and the stock stem is for a 1 1/8", no matter what the calipers say. It's critical to know the proper terminology if you're going to shop online for bike parts.

It's a question of semantics. The OP is measuring the stem diameters, which equal the steerer IDs, while IthaDan is trying to explain the standard nomenclature for quill stems is by the OD of the steerer they fit. ia, a stem which measures 7/8" is called a 1" stem because it's for a 1" threaded fork. The OP needs a 1-1/8" stem (measures 1") for his tandem fork.

I don't know that anybody sells the adapter the OP needs, but it would have to be a 1" OD x 7/8" ID tube long enough to reach from the top of the headset to the bottom of the stem where the expansion happens. It would have to be split at the bottom so it could expand as the stem bolt is tightened.

The OP can go to the hardware store and see if he can find something with the right ID & OD, then fabricate the shim with a hacksaw. Otherwise hus best bet would be to return this stem and shop for a 1-1/8" stem.

Yes, I agree that it would be better to return the Nitto and get something else.

I disagree that using the headset size to define the stem size is universally used. Perhaps in bike industry internal terminology. However, I can post a dozen links if so desired that state the outside diameter for the actual stem itself.

FWIW, the headset top nut is exactly 1 1/8ths, I went back and measured that too just for kicks. In the future, I will seek exact clarification on whether sellers are referring to the headset size or the stem diameter.

I have quite a few Nitto stems kicking around. I guess I just got lucky up until now and I never had to actually think about fitment sizes. So I learned something in that regard.

While I agree that quill diameter is prevalent to clarify 22.2 vs 22.0 quill sizes, I'd be willing to wager a non trivial amount of money that were you to Google "1" quill stem" that 99 out of 100 results would be a stem with either a 22.0 or a 22.2 quill diameter.

At the end of the day I was just trying to help the OP clarify his search keywords so he doesn't male the same mistake twice.

Edit: oh, you ARE the OP. whatever, good luck.

Don't you love it when folks come for help, then decide they know more than the folks trying to help them?

As the OP said, it might be industry nomenclature that refers to stems by what they fit, but in the end isn't that what counts?

Sometimes they do...it depends who's answering the question.