Hondo6

I understand these brakes use a 3.5mm Allen wrench (hex key, if you prefer). I also understand that these specific wrenches were (a) nonstandard at time of the Delta brake's introduction, (b) were supplied with the brakes, and (c) were for a long time almost impossible to replace if lost.

Well, today apparently there are alternate sources for said wrench:

https://www.amazon.com/Eklind-18607-...dp/B07FP3QXH4/

Haven't ever used Eklind tools, so I can't comment on their quality. FWIW, the company website indicates their tools are US made and that the company has been around for over 100 years.

There are also some other 3.5mm Allen wrenches listed on eBay, with varying prices.

Disclaimer: I have no commercial interest in Eklind tools, Amazon, or eBay (other than having made purchases from the latter two). Just found this and decided it was worth posting the info here.

jamesdak 

Local hardware stores around here have them in the same area they keep all the various bins of other hardware (nuts and bolts section). 3.5 is just one of the many sizes easily available.

Hondo6

Thanks for the updated info. Not being a Campagnolo user and thus never having used Deltas, my lack of experience with those apparently led me astray.

What I'd read led me to believe the size (3.5mm Allen wrench) was quite uncommon, and it's certainly not one I've got in any metric Allen wrench set I own. Maybe it was just the "genuine Campagnolo" wrench that's difficult to source.

jamesdak 

Oh no worries. I saw all the same thing when I got my first bike with Delta's. Then I noticed my small town hardware store had them and later another Ace hardware store in town was checked and they had them too. I haven't checked our local Lowes or Home Depots.

'02 nrs

3.5mm = 9/64(3.57mm) and is easier to find.fits the Deltas very well.

Bianchigirll 

When I got a set of the brakes aroun '90, second hand, I went to Sears and got a craftsman

dddd

Be careful with that colored conversion chart, it has a mistake or two not to mention that you would strip a 1/8" socket with a 3mm hex key and the 1/8" key wouldn't even fit in a 3mm socket!

1simplexnut

Whoever made that chart up is seriously deluded .
Errors everywhere.

bulgie 

Can you show an example of an error?
Note, they aren't saying these are trouble-free, perfect fits, only that it'll go in and apply "some" torque before stripping. Seen that way, I'd call the chart somewhat useful.

They don't say to put a 1/8" key in a 3 mm socket, they say to put 1/8" into a 3.5 mm socket. Not great for torque, but it will fit in.

That's why there are two charts. The first one is for when you have fractional inch keys — what metric sockets do they fit.
The second is for when you have metric keys — what inch sockets do they fit.

With those assumptions, do you still find errors?

Note the only two-way compatibilities are 4 and 8 mm work with 5/32" and 5/16" respectively, in both directions (usually). They're close enough that the normal tolerance for socket-head bolts allows two-way compatibility. Everything else is somewhere between a kluge and a hail-mary. Note, when the fit is on the loose side, you can squeeze in some cut up bits of shim stock in a pinch.

1simplexnut

Hi biggest error (in my opinion) is even using the wrong tool for the job .
Why even do it and risk causing a bigger problem??
Right up there with using an adjustable spanner ( nutfecker ) instead of the correct ROE spanner .
I dont know what it is like on your side of the world , but metric (and imperial) sets are readily available from most decent engineering supply stores etc here .

That said , I see where it might be useful in an absolute desperation situation .
Thanks for sharing your opinion and assumptions about the chart . ( no I am not being sarcastic)

Apologies to OP for the derail !

bulgie 

If you have never once in your life been without the right tool, never had to make do, then you have led a charmed life.
I guess that was rhetorical, but it seems to me the answer is obvious: "because you need to get the job done, and time is short."
I don't know what an ROE spanner is, but it sounds like you don't know that a good quality adjustable, used correctly, is easier on delicate nuts, less likely to do damage than the "correct size" open-end wrench. For example, a Campy Super Record headset, with it's soft alloy nut, the best tool is not the Campy open-end wrench, it is a good quality adjustable, adjusted down snug so it has less freeplay than the "correct" wrench. (Well, the BEST tool is a Knipex pliers-wrench, which is guaranteed to do less damage than the open-end wrench.) A box-end wrench can be better still, but often won't go on, like on a headset with the stem installed.
So if you were doing a roadside repair and didn't have the right allen key, you would stop what you're doing, hitch-hike to the store for the right tool, and hope you can hitch-hike back to the car before dark? Rather than use a mis-matched but workable kluge? That's an uncommon level of commitment, I gotta say! Impractical, but kudos for sticking to your principles.

Please don't mis-characterize my position as "feel free to use inch keys in metric sockets and vice-versa, works great!" No one is saying that. I'm just saying the chart isn't useless, it has some limited use. The maker is not "seriously deluded" and there aren't "errors everywhere". As long as you take it in the spirit in which it is offered, a set of kluges for when you don't have the correct allen key, then I believe it is factually correct in every detail. Those are the closest matches you can make when you don't have the right keys. And a bit of shim stock and some scissors can usually make it fit actually rather well.

jamesdak 

Well.....this is a different take on a Delta brake thread. Normally they just turn into fights over whether they work or not. This is a welcome new twist, LOL!

'02 nrs

per the chart authors;

The Ultimate Guide to Allen Wrench Conversions

Sometimes—you just have to improvise when you’re on the job. So we decided to make that a little bit easier for you. If you ever need to lookup an Allen wrench conversion, keep our guide handy so you can reference it when out in the field. We’ve provided the best substitute for popular hex sizes from both Imperial & Metric measurement systems. But to ensure that you don’t damage your tools or your hardware, take a look at our instructions below for tips & recommendations.

Imperial to Metric for Allen Keys

On the left-hand side, we have our SAE to metric conversion guide for hex keys that provides the best substitute SAE Allen wrench for each given metric size. As you’ll notice, there isn’t always a perfect substitute. For instance, Metric size 9 mm doesn’t have an imperial counterpart. In a case like this, you’re only option is to just upgrade to a separate metric hex key set. With more and more hardware being produced internationally, both SAE and metric hex key sets will have a place in your tool set.

Metric to Imperial for Allen Keys

Moving over to the right-hand side, we’ve provided the metric to SAE guide for Allen wrench conversions. Similar to the metric hex keys, the SAE hex wrenches don’t always have a perfect substitute as seen for SAE size 3/16″. Thus, we recommend that those with only a metric Allen wrench set add a separate SAE hex key set to their stable.

Substituting Uncommon Hex Sizes

Lastly, there’s one other added benefit to having both SAE & metric hex keys. In the United States, larger metric half sizes like 6.5 mm aren’t standard in most hex key sets. However, the 1/4″ SAE hex wrench will likely work in place of a 6.5 mm wrench. In scenarios like these, use the chart to estimate the correct alternative. You can test different sizes till you find the best match. We do recommend starting slowly to ensure that you don’t damage the hardware.
Pro Tips:

• 3/8″ can be used as a substitute for hex size 9.5 mm as well as 10 mm
• 1/16″ works in place of hex size 1.5 mm, which isn’t included in most sets

When you reference the hex key conversion chart above, do be aware that using a smaller size bit will increase your vulnerability for stripping the hardware. In some cases, you may want to try using a size larger than the one recommended in the chart to see if it fits. Also, we will caution you that smaller screw sizes are more prone to stripping. Thus, be careful when substituting sizes with precision hardware. Lastly, do remember that not every Allen wrench size has a perfect counterpart. That’s it when it comes to comparing metric & standard Allen wrench sizes. Good luck! https://handtoolessentials.com/blog/...-allen-wrench/

dddd

For what it is, the chart's ok I guess, just that it seems like it perhaps validates optimistic assumptions of how much torque can really be applied, leading to the dreaded stripped-out socket heads.

My first glance at the chart showed asymmetrical interchangeability between 2mm, 5/64" and 3/32, while I have always been able to just use 5/64 and 2mm interchangeably.

I do find that as wrench sizes get larger, that new metric/SAE possibilities arise, I've used a 1-1/16" wrench on a 27mm motorcycle axle nut and 15/16" interchanges reversibly with 24mm.

Also I've used a 12-point, 1-1/2" socket on an octagonal 38mm Stronglight fixed bb cup to good effect!