What screw? Dull man’s club post.

[SpokeyDokey]

Nice looking frame! 😁. Pretty sure they‘re all M5. 8mm seems about the right length. A stainless button head will be nice and aero. Cap head easier to get off if somehow it does ever get stuck in there. Maybe look for a security torx if you want to confound the bike shop mechanic (or the future you).

Does anyone (apart from maybe Pro's) factor in a screw head being aero, I wonder?

 

[BigSid]

I'd leave it because every 20 minute job is one broken bolt away from being a three day nightmare.

 

[Ming the Merciless]

Can't help with thread spec or length (the former probably common at M5 as most have stated, the latter will be relatively bike-specific I suspect). Only way to be sure is to pull it out and measure it!

I'd advise replacing with a stainless socket button cap - which will retain a similar low profile / aesthetic but with a nicer tool interface. I've replaced most of the standard fixings (for cable guide, guards, racks etc) on my bikes with these:

View attachment 761354

As @grldtnr suggests A4 is the more corrosion-resistant commercially available grade. I'd be cautious of sticking a tap up the hole - instead an old M5 bolt with a slot or three cut along its threads (like the flutes in a tap) will chase the crap out of the threads with less risk of damaging the existing threads.

GWR fasteners are my go-to for common metric bolts.

I'd probably fit the new one with anti-seize grease..

Those chainstays need work

 

[biggs682]

Just buy a new bike it will be less stressful in the end trust me

 

[fossyant]

Given the dirt within the cable guides, the OP hasn't looked under there for a long time. I'd get that out and replaced.

 

[Milzy]

Given the dirt within the cable guides, the OP hasn't looked under there for a long time. I'd get that out and replaced.

The cables were changed only about 6 months back too. Deffo be easy to fix.

 

[twentysix by twentyfive]

aesthetic

Yep - I'm always scrambling under folks' BBs to check the aesthetics

 

[Yellow Saddle]

This minor screw aero pan-head discussion is too important to die so quickly. Therefore, allow me to introduce you all the Engineer range of screw removing pliers from Japan. They come in various sizes and although there are other ways of removing screws with damaged heads, most involve drilling and considerable skill. These pliers should be the first port of call for most people and every toolbox should of course have one or more of these.
It is not as expensive as this other essential tool:
https://www.cyclechat.net/threads/downtube-thick.301242/post-7352836

and it is available from Amazon.

 

[Marchrider]

This minor screw aero pan-head discussion is too important to die so quickly. Therefore, allow me to introduce you all the Engineer range of screw removing pliers from Japan. They come in various sizes and although there are other ways of removing screws with damaged heads, most involve drilling and considerable skill. These pliers should be the first port of call for most people and every toolbox should of course have one or more of these.
It is not as expensive as this other essential tool:
https://www.cyclechat.net/threads/downtube-thick.301242/post-7352836

and it is available from Amazon.

View attachment 761605

I like the shadow it casts!

if it is made in Japan then it could be good quality, japan can make some very high quality steels
sometimes things look good then you find they are made out of cheese

 

[Profpointy]

I like the shadow it casts!

if it is made in Japan then it could be good quality, japan can make some very high quality steels
sometimes things look good then you find they are made out of cheese
View attachment 761612

As some wag pointed out "I like cheap drills as they are easier to straighten out if you bend them"

And an anecdote from my own experience. Back in day (45 years ago) I bought a comprehensive socket set by Kamassa in their distinctive green tin box. Despite being the cheapest on the market it was, to be fair, very good quality, everything worked, the sockets held up well, handles didn't bend and so on. Granted only amateur use, but I did do quite substantial jobs on my car. Anyhow the set got nicked from the boot, so I bought another identical set: total shyte, soft sockets, handles bent, ratchet broke etc. Gradually replaced the bits I used with proper Britool, which was top notch pro kit back then (sadly no longer), and many years later got a full Britool set second hand. It seems some of these brands just buy up from various far east suppliers with little or no regard to quality and slap their label on the tin. Draper were utterly shyte back then too, though I've heard it claimed they are OK now

Another aside, I have a couple of AF socket headed spanners which I used a lot on my Cortina, which didn't even have a makers name and were simply stamped "India", a nation which (back then at least) was not really associated with quality engineering, but they were superb and held up to a lot of (amateur) hard use.

I do somewhat get the impression that cheap tools can be fine, but I'm a bit of a brand snob these days, so am rather selective and very wary of buying off-brand, unless (a) precision doesn't matter much, (b) heavy use isn't relevant.

 

[wafter]

I like the shadow it casts!

if it is made in Japan then it could be good quality, japan can make some very high quality steels
sometimes things look good then you find they are made out of cheese
View attachment 761612

Clearly you've never had to drill a hole at 85 degrees to the drill's axis!