Need an oddly-sized hex wrench
 

Hi. I recently got an old European road bike, and I need to adjust the handlebars, but I can't find a hex wrench that fits the socket. 6mm is too small, but 8mm is too large. 5/16" is too small, but 3/8" is too large. (At least, I think it was 3/8"; it mighta been mislabelled.) And my local hardware store sells nothing in between those sizes that I've mentioned.

Is there some funky hex size that's standard for bikes which I wouldn't find a small, poorly-organized hardware store? Or does anybody know where I could order a 7mm hex wrench for cheap?

Thanks.

Sears, Kragen, Auto Zone, Grainger, McMaster-Carr and maybe even Wally World ought to have a 7mm hex drive. 7mm is not odd. You might even get lucky at a local garage sale.

I ran into the same problem. Sears didn't have a 7 mm hex wrench except as one of eleven in a set (946814), so I wound up buying the set. I didn't have any luck at other retailers, either. Most of the sets skip from 6 mm to 8 mm.

Very strange.

for the most part a allen head thats going to use a 7mm key is going to be a 7mm bolt also. in europe that is a normal size here in the US it is an oddball size that no one in the US really stocks. While the rest of the world uses metric including bike manufactures the US is still using SAE for the most part.

6 mm is too small.
5/16" (7.93 mm) is too small.
8 mm is too large.
3/8" (9.53 mm) is too large.

I doubt there's a 7.97 mm hex available...

8mm = .31496
5/16 = .31250

Difference is less than .0025"!! It doesn't make sense that one is too big and one is too small.
Sounds like something other than an Allen head.

See? You guys shouldn't have invented that silly sizing system. You'd have well adjusted handlebars and a working Mars probe.

If you need a 7mm hex key, and have a hardware store near by, you may be able to get two 7mm nuts on a whatever sized bolt and use the appropriately sized socket/ratchet or wrench. That being said, what CdCf said.

11/32" ?

Off topic:

I couldn't agree with you more! When I was in grammar school (mid 70's), they started to teach us the metric system, then worked with it throughout high school and engineering school. The minute I graduated, and started working, American industry is all about to the English units of measurement. Do the English even use the English system of units anymore? I suspect even they went metric.

I think people in general still mostly use the old units, at least for bodyweight, height and probably also for distances. Most likely not in engineering and science, though.

And I've also come up with a fraction that should fit! 161/512 should do the trick!!! :D

I agree that this doesn't make sense. In most real world applications, 5/16" and 8 mm wrenches can be used interchangably. BTW, if a 5/16" is really too small, then a 7 mm will be even smaller so don't bother looking for one.

maybe what you need is a new 5/16 wrench.

Thinking about it a bit more, my guess is:
It's been "buggered" by using too large of a wrench. Try LIGHTLY tapping an 5/16" into the hex.
Else the OP has got his wrench sizes mixed up.

Could it be a Brit bike with the old Whitworth? size? It shouldn't matter though.

I found out that you need a 7mm hex to change the brakes on my friend's f***ing Jetta. You can get a Hex socket set at Wally World for around $8 that has a 7mm hex included.

You don't go to the pub and ask for "a litre of your finest draught!!", you ask for a pint.

I found the same. For some strange reason the hex socket sets I have don't include 7mm, so I had to buy the 7mm socket from AutoZone to replace my cars' brake pads.

True, but by law all foodstuff in shops is now sold in metric weight/measure and people use metric for personal height/weight. Temperatures changed to Celsius years ago but it was a long time before the weather forecast went solely metric. For years F and C were quoted until people got used to it.

I wish they would do the same here. They made talked the talk in the 70s but no one walked it. They do the dual labeling on foodstuffs here to, but everything is talked about in metric units. Except for scientists, soda bottles and some other things I can't think of.

Drug dealers in America talk in grams and kilo(grams).

It's quite likely that I wasn't actually using a 5/16" wrench -- the one hardware store in my neighborhood is really great at incorrectly stocking their stuff. And when you ask an employee a question -- any kind of question -- they look at you with utter pity for having been born so stupid.

Anyway, I've got a 7mm wrench on its way, so we'll see...

I should have scientists and medicos (doctors, nurses and their suppliers).

True story. When I was in college I took my VW bug to a one man repair place and the guy did not own 1 metric tool. He said you don't need them and he knew what American size would work on everything. Guy was amazing. Had a 30 foot long work bench and no tool box. All the tools were just piled up on the bench but when he needed a certain wrench or whatever he just knew where he put it down.

^ Good way to strip a few bolts.