ISCG Tab Standards and Files

The Standard:

The current and most common ISCG standard is ISCG05

Source: http://www.iscg.org/
iscg-05_standard.pdf (34.7 KB)

CAD Files

BSA (1.5in) FILE: ISCG05 TAB 1p5.dxf (3.6 KB)

T47 (2in) FILE: ISCG05 TAB T47.dxf (3.6 KB)

Laser Cutting Suggestions:

  • I reccomend .25thk 4130 steel
  • Laser cutting is the cheapest method but leaves some slag and hardens the steel
  • It may be difficult to tap the M6 treads due to the heat affected zone!
    • Send cut send can tap holes for you, but it adds ~$2/hole
    • water jet does not harden the material

Another way to avoid tapping the steel is to braze on M6 bosses. I can provide this CAD too, but I don’t want someone to accidentally download the wrong file!

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A couple other laser cutting suggestions that would make tapping the hole’s easier (if you’re going to tap the holes yourself to save $6 per part)

  • have the hole locations marked with the laser so that you can center punch, drill and tap
  • have pilot holes laser cut to the minimum diameter for the material so that you can drill and tap

Engin makes a pretty neat locating tool to set the tab in the right position for welding

Engin ISCG-05 locator tool

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Just keep in mind that Engin’s tool is designed for a 92mm bb shell with internal bearings. You can’t use that on a 74mm shell without modifications.

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Right on! This seems like the kind of part where having the right tool is just as important as having the part itself.

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I didn’t realize anyone was still running these. Are they for bash only now, or are people still running chainguides on them?

-Walt

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I use then for a bash guard

Haven’t you heard? Bash guards are like a spoiler for your car :rofl:

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Better than a broken chain

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Confused by this analogy, even in street car applications various aero modifications can make a substantial grip improvement… sure there will always be people putting out there putting tacky non functional spoilers on their cars, but that doesn’t necessarily mean that all aftermarket aero is non functional.

Just because a bash guard doesn’t suit the riding that you do doesn’t mean its not still a widely used, functional component. Could be some internet sarcasm’s misunderstanding here.

It was a joke, hence the emoji and the GIF.

I design ISCG tabs and we include it as an option for that exact reason you stated!

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I saw the internet sarcasm :fearful:
Where I ride there are a lot of tree and rock over so I like having a bash guard. Plus it give you a .0000001 watt advantage.

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My bad! Glad to see there’s inclusivity for the folks riding rocks here haha

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This is my favorite use of bash guards:

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Yeah that’s what I kind of do …… not

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I had an ISCG mounted bash on a DH bike back in the day and I kept damaging the shell/frame from impacts so switched to a crank mounted bash.

But it’s good to know it still exists.

-Walt

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I know quite a few people that use them for small upper chain guides.

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One way to tackle the fixture dilemma would be to purchase and ISCG05 adapter, bolt it on the tab with spacers of the needed thickness to achieve the correct positioning along to the BB shell, put in in place with a BB cup, tack it on, take the picture and BB cup off, and finish the weld or braze.

Something like this, for example. Mrpbike.com – ISCG-05 Adapter

The Engin cycles tool works, you just have to mill the mount face for your desired spacing. You could make a simple adapter for use on BSA bb shells

You could also very easily design a tool to have made by send cut send when you order your tabs to get you to the free shipping dollar amount.

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At least hobby builder purposes, I can recommend just printing out a 100% scale drawing from CAD, and transferring hole locations with a centerpunch. There is in my experience plenty of tolerance for less than exact hole positions.
In that same mindset, here are some things I do that are different than OP. Mounting the cut pieces (I plasma mine) in a vice is challenging to avoid deforming, so I tend to just drill them clamped to the drill press table and tap with my hand held drill. I use 3/16 mild steel with less material “around the bb” and position them flush with the face of my BSA BB shell. Since any ground-hitting forces are primarily directly into the bottom two mounts, I place two ~1/2 stitch welds near them, and only a small weld around the end of the piece at the top.

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Daniel, thank-you for sharing the ISCG mount resources, particularly the standard drawing! I hope to add an ISCG mount to a frame and may use the drawings.

Is anyone aware of a supplier for steel ISCG mounts or a source for waterjet cutting them (I can re-drill and tap the holes)?

FWIW, Paragon offers titanium mounts if anyone is looking for them.

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