gravityhurts

Say - does anyone know where I could get a clamp-bolt for a Salsa 1"/26.0mm quill?

Kontact

The hardware store. Probably 5mm. Get the closest length in stainless.

gravityhurts

5mm?
Obliged to ya!

bboy314

Take the stem with you when you go to the store. There are a few possible sizes (but I agree 5mm is likely).

PromptCritical 

McMaster-Carr has a huge selection of bolts and more. Many of their bolts are passivated black, so they would look good. The per unit price of their bolts is astoundingly cheap. Next day delivery on weekdays (at least here in San Diego).

They also have sleeve nuts so you wouldn't have an ugly nut protruding from that slick stem.

Kontact

The stem is threaded.

PromptCritical 

Then one of the other options should be used. McMasterCarr will have infinitely more options than a local hardware store.

jamesdak 

Yep, like others said, local hardware store and take the stem with you. In my book better to go local where you can test fit bolts then risk an online purchase for what might be the right part.

Kontact

I'm sorry we don't seem to be communicating. The stem is threaded, so no backing nut or anything else with female thread is needed.

All the OP needs is one M5 socket head stainless screw in the appropriate length, which hardware stores will have a selection of. That will restore the stem to its original appearance:

birdly

As above, what you are looking for is called a socket head cap screw.

bboy314

A bike shop should also have these. Stainless 5mm bolts are a dollar where I work. If you go to a hardware store just make sure you get stainless and not galvanized, aluminum, etc.

Kontact

I find hardware stores much more organized and better labeled when it comes to screw types than the usual mixed up bins in bike shops.

bboy314

Every shop I’ve worked it has had easily accessible common sizes of 5 and 6mm bolts, since they’re needed so often. Now when you need an exact length 8mm bolt for your seatpost, or the random 7mm for a stem, that’s when the fun happens.

bulgie 

I'll be amazed and a bit disturbed if it turns out to be M5, that is inadequate for safety. Even M6 is inadequate as a single bolt with no redundancy, unless you use a high-strength bolt.

I know 4 people who've had a M6 stem bolt snap, and I'm one of them. I'm ashamed to admit, long ago I used a hardware store stainless bolt in a stem I made, and it broke. I wasn't riding it at the time, I just came to get my bike and found it broken, long ago but I think the bike probably fell over and landed on the handlebar.

Of the three others I know about (all friends or team mates of mine) who broke an M6 bolt, two rode it safely to a stop. You do still have steering and brakes, as long as you don't fall down immediately from having the bars rotate down suddnely. The last one crashed and broke her collar bone. But of course it could be much worse, like if there's a dump truck next to you when it happens.

Hardware store SS bolts are roughly half the strength of a good heat-treated alloy steel bolt, or less than half. A single high-strength bolt is not expensive nor hard to find, so there's no excuse for using one that's half as strong.

Metric bolt strength is given by the "class", where inch bolts in America use Grades. Class 8.8 would be an improvement over the weakest bolts, but you can do better. Class 10.9 or 12.9 give step(s) up in strength with no downside. For example here on McMaster, 20 mm long M6 in class 12.9 are $7.63 per pack of 50. No, you don't need 50 of them but they don't sell them in onesies — but would you seriously complain about spending $8 (plus shipping) to not crash and die? It works out to 15¢ per bolt. Sell some of the rest to your cycling buddies for a dollar each and recoup your investment several times over.

Note, I don't know if 20 mm is the correct lenght, just going from memory, from the Salsa stems I have held in my hand. It's in the ballpark, but measure.

I'm pretty sure Salsa didn't sell them with weak SS bolts, I'll bet you a dollar they used heat-treated alloy-steel bolts, class 10.9 at least.

PromptCritical 

Just trying to be helpful. Hardware stores with a good selection of metric bolts are scarce these days. Here in San Diego, there are good options. When I was living north of the SF Bay Area, not so much. The local hardware store had a marketing slogan of "If we don't have it, you don't need it". It was one of the town's jokes to come home and tell wifey, "Sorry, I guess we don't need it."

Camilo

There's at least three or four within 15 minutes of where I live in a small city of about 25,000 that have complete selection of metric and SAE fasteners of various materials, grades and types (button head, socket head, etc. etc). Tru Value, Ace, are two national chains that have this stuff pretty much everywhere I've traveled with the RV, needing things to repair the RV, truck or bikes. And, around here and probably everywhere else, are at least two other local, more commercial/industrial hardware stores. I've used Mcmaster Carr from time to time for obscure stuff, but not for routine metric and sae bolts, especially if I need to verify threading and diameter. All these places have boards where you can ascertain the size of bolt or nut you need.

PromptCritical 

Wow! That would be really nice.

PromptCritical 

Totally agree. I've had the torx head screws that come with 6-bolt discs strip, leaving one with a very annoying problem. Even though I have a mill, it means taking the rim off the hub to use it. I now use high quality stainless screws from either McMaster-Carr or Belmetric.

icemilkcoffee 

FWIW I have a 2-bolt face plate Salsa stem and I just measured the bolts at 6mm.

bulgie 

This requires more info. McMaster sells "high quality" 18/8 screws that are only 70 kpsi yield*, or about half the strength of class 10.9 (alloy-steel), less than half the strength of class 12.9. My conclusion is don't use 18/8 screws for a single-bolt style handlebar clamp, even if they're high quality.

*EDIT: oops, it's even worse than that. 70 kpsi isn't the yield strength, it's the utlimate tensile strength UTS), i.e. where they snap. They don't spec the yield, but it has to be substantially lower than that, maybe 50 kpsi. About 1/3 the strength of a Class 12.9

McM also sell SS screws made of A286 stainless that are good'n'strong, 120 kpsi yield, which puts them close to Class 12.9. I would have no qualms about using those. Don't think you can get them at Ace Hardware though!

Conclusion is, don't use any screws for something as safety-critical as a handlebar stem without looking at the strength spec. And get them from a trusted dealer who won't substitute cheaper/weaker ones.

Note, this becomes less critical for stems with redundancy, like 4-bolt faceplate style. On those, it's unlikely that all the screws will break at the same time.
But two-bolt faceplate stems (like Salsa made) do not have redundancy. If either bolt breaks, your handlebar can freely rotate, same as with a one-bolt style. For redundancy, you need two that are side-by-side. Sometimes found on 2-bolt non-faceplate stems (think Rene Herse), but nowadays found mostly on 4-bolt faceplates. Those often use M5 screws and they are very particular about the installation torque. They technically have redundancy to make the use of M5 screws adequate, but not as robust as a 4-bolt with M6 screws, which would be bomb-proof.

bulgie 

That's a good design but remember strength-wise, it's the same as a one-bolt resign. The 2 bolts are in series, not in parallel, so if either bolt breaks you're in trouble. Be sure to only use high-strength, Class 10.9 or better, not hardware-store SS, as my friend's broken collar bone will tell you.

gravityhurts

5mm - you were spot-on... thank you.
I visited my brother's place this weekend where he has a rather large spare parts bin(s). It took me all of 2 minutes to find the bolt - a 5mm hex bolt. If not for the extra length - it was a perfect match. It looked nearly identical to the bolt on his Salsa threadless 1"/26.0 stem.