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Discussion Starter · #1 ·
Anyone know what size these are or where to buy them? I lost two from my chainring, I don't want to buy a whole new chainring just for two little screws.
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That's a non serviceable part by Shimano's reckoning. If it's less than 2 years old, they'll probably warranty it.

That said, it's probably a 5mm thread and an 8mm shoulder. Custom hardware, so not really something you can walk into a store and buy.

What size chainring is it?
 

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That's a non serviceable part by Shimano's reckoning. If it's less than 2 years old, they'll probably warranty it.

That said, it's probably a 5mm thread and an 8mm shoulder. Custom hardware, so not really something you can walk into a store and buy.

What size chainring is it?
On my last ride I found one of the screws loose on my SLX cranks. I catched it before it fell to the ground. At home, I found 4 of the 8 bolts were totally loose. The cranks are 1.5 y/o and have around 5000km on them.

I understand that they're "not serviceable", but I found more people with this issue (including myself) and, in any case, its easier to tighten a bolt, than sending a cranks for replacement. I just tightened the bolts with thread lock and found nothing wrong.

What I don't get is:
  • Why the bolts are safety torx instead of standard torx.
  • Why use a direct mount chainring that also uses bolts to hold it to a spider. Isn't the idea behind direct mount avoiding the separate spider in the first place?
 

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Discussion Starter · #5 ·
That's a non serviceable part by Shimano's reckoning. If it's less than 2 years old, they'll probably warranty it.

That said, it's probably a 5mm thread and an 8mm shoulder. Custom hardware, so not really something you can walk into a store and buy.

What size chainring is it?
Thanks, it's a 30T.
 

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Discussion Starter · #6 ·
On my last ride I found one of the screws loose on my SLX cranks. I catched it before it fell to the ground. At home, I found 4 of the 8 bolts were totally loose. The cranks are 1.5 y/o and have around 5000km on them.

I understand that they're "not serviceable", but I found more people with this issue (including myself) and, in any case, its easier to tighten a bolt, than sending a cranks for replacement. I just tightened the bolts with thread lock and found nothing wrong.

What I don't get is:
  • Why the bolts are safety torx instead of standard torx.
  • Why use a direct mount chainring that also uses bolts to hold it to a spider. Isn't the idea behind direct mount avoiding the separate spider in the first place?
I agree, it's a little frustrating. I can't service the bolts, and to remove the spider I have to buy a special tool. Bikes....
 

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On my last ride I found one of the screws loose on my SLX cranks. I catched it before it fell to the ground. At home, I found 4 of the 8 bolts were totally loose. The cranks are 1.5 y/o and have around 5000km on them.

I understand that they're "not serviceable", but I found more people with this issue (including myself) and, in any case, its easier to tighten a bolt, than sending a cranks for replacement. I just tightened the bolts with thread lock and found nothing wrong.

What I don't get is:
  • Why the bolts are safety torx instead of standard torx.
  • Why use a direct mount chainring that also uses bolts to hold it to a spider. Isn't the idea behind direct mount avoiding the separate spider in the first place?
It's a bizarre choice, but I suspect it goes something like this: like the brake rotors/cassettes, there are undoubtedly shared parts between the different product levels/configurations. For whatever reason, Shimano decided that, in this specific case, screws were better served than rivets. Possibly because the factory they were working with didn't have the capacity to rivet them, or because screws were simply faster to assemble. Safety torx was probably used for the same reason security screws are everywhere else: not to keep people from disassembling it, but to send the message to leave it alone. My guess is that they were supposed to be installed with permanent thread fixative, or torqued to yield, staked, etc, and weren't.

As for the separate spider, well, Shimano is a manufacturing company, and outside of the super high-end stuff, where people wouldn't tolerate it, they were probably looking to reduce manufacturing costs (stamp a spider, stamp chainring, attach) versus more expensive processes like the XTR chainring. I suspect that there will be changes going forward, but who knows.
 

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It's a bizarre choice, but I suspect it goes something like this: like the brake rotors/cassettes, there are undoubtedly shared parts between the different product levels/configurations. For whatever reason, Shimano decided that, in this specific case, screws were better served than rivets. Possibly because the factory they were working with didn't have the capacity to rivet them, or because screws were simply faster to assemble. Safety torx was probably used for the same reason security screws are everywhere else: not to keep people from disassembling it, but to send the message to leave it alone. My guess is that they were supposed to be installed with permanent thread fixative, or torqued to yield, staked, etc, and weren't.

As for the separate spider, well, Shimano is a manufacturing company, and outside of the super high-end stuff, where people wouldn't tolerate it, they were probably looking to reduce manufacturing costs (stamp a spider, stamp chainring, attach) versus more expensive processes like the XTR chainring. I suspect that there will be changes going forward, but who knows.
I get that. What I don't get is why they go with the direct mount thing. They could have put a spider in the cranks and just bolted the chainring like it has always been done. It would also be easier to replace chainrings that way, as disassembly of the cranks wouldn't be required.
 

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Discussion Starter · #10 ·
It's a T15 safety torx. You can easily find it if you want.

The thing is: why the hell are this bolts for if this is direct mount?
Thanks, the tool side isn't the problem, was asking if anyone knew if these were available or the screw size/shoulder size. I'm measuring it and checking McMaster etc. now. It just seemed like it was a unique screw for this purpose so I am doubtful there are standard screws of this size. If I find some I'll post back.
 

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I get that. What I don't get is why they go with the direct mount thing. They could have put a spider in the cranks and just bolted the chainring like it has always been done. It would also be easier to replace chainrings that way, as disassembly of the cranks wouldn't be required.
Well, direct mount interfaces allow for smaller chainrings. And also the flexibility to attach a spider if you want to run multiple chainrings. SRAM started it a long time ago by just making their spiders bolt-on. Then aftermarket companies used that interface for DM rings. The rest is history. Now SRAM doesn't even offer spiders, but they kept the DM interface. RaceFace and Shimano offer both spiders and DM rings.

Since every company making cranksets has decided to use its own DM interface, the aftermarket companies like wolftooth and oneup got fed the f*** up with the sku spew, and decided to offer spiders for the different interfaces, that then allow you to bolt on the ring you want (size, round/oval, tooth profile). They use a smaller bcd on them so you can still run smaller rings (smaller than 28t is rare anymore).

Sounds to me like maybe you should buy a Wolftooth or OneUp spider with the ring you want, that's INTENDED to be bolted onto the spider without removing the crank and messing with the DM interface. Yes, they both do make them for Shimano cranks with their new DM interface.
 

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Yea, I got two of them. But I'm in NJ and you're probably in CA. McMaster-Carr has the metric screws, but they don't have the 5mm bushing. The screw size is 4mm x 0.70 thread size and it is probably 6mm long. The part number is 97763A815 and it is a normal Allen head without the security pin.
 

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Discussion Starter · #14 ·
Yea, I got two of them. But I'm in NJ and you're probably in CA. McMaster-Carr has the metric screws, but they don't have the 5mm bushing. The screw size is 4mm x 0.70 thread size and it is probably 6mm long. The part number is 97763A815 and it is a normal Allen head without the security pin.
Thanks! I'm actually in Austin, TX, but sorta the same situation. Checking McMaster as soon as I get home. I don't like to deal with LBS's for little things like this, but I think I'll stop by one or two and see if they have any used chainrings in the parts bin or dumpster. I hate to spend so much time on two little screws, but I hate to buy new parts when this chainring should work fine...
 
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