ISCG-05 adapter question

tonyride

Don't piss off the red guy
One of my bikes doesn't have the ISCG-05 mount so I'm looking to get an adapter (MRP) so I can mount a bash guard. I have bash guards on my other bikes and seeing how scraped up they are a bash guard is definitely needed. So this bike has the SRAM DUB threaded BB setup for 1x boost. I understand the adapter needs to go between the bearing cup and the body of the frame on the drive side. NOT between the cup and the crank arm. But as it sits now there is no spacer between the cup and the frame but there appears to be a spacer between the cup and the crank arm. So how do I do this? Do I disassemble the BB, put the adapter between the cup and the frame, remove the spacer between the cup and the crank arm to maintain chain ring alignment assuming the thickness of the adapter plate is the same as the spacer I removed? Is it OK to have the cup further out from the frame than before given the adapter is now in between?
 

serviceguy

Well-Known Member
You need to remove the drive side of the bb and replace the spacer with the adapter. I used the same adapter on 3 different frames. Make sure of the exact width of your frame bb shell, it’s either 68mm (1 spacer on each side and the adapter not touching the frame) or 73mm (no spacer, the adapter between bb and the frame).
 

tonyride

Don't piss off the red guy
You need to remove the drive side of the bb and replace the spacer with the adapter. I used the same adapter on 3 different frames. Make sure of the exact width of your frame bb shell, it’s either 68mm (1 spacer on each side and the adapter not touching the frame) or 73mm (no spacer, the adapter between bb and the frame).
I'll have to do some measuring. Just by looking without taking anything apart it looks like there is no spacer between the drive side shell and the frame so there's no spacer to replace.
 

serviceguy

Well-Known Member
I'll have to do some measuring. Just by looking without taking anything apart it looks like there is no spacer between the drive side shell and the frame so there's no spacer to replace.
I am not familiar with the SRAM DUB system. I was referring to the Shimano/RF/Hope etc. standard. for DUB the following chart should work, you most likely should use the configuration highlighted in red (I took the picture it from the Worldwide Cyclery website tutorial section that describe a case similar to yours How To: Installing Sram Eagle DUB Crankset and Bottom Bracket). The same should be for a 30mm spindle.

So, if you currently don't have any spacer between the BB and the frame you should remove the crank, remove the 4.5mm crank spacer and drive side BB cup, add your adapter (the cupped side goes on the frame side), reinstall the BB cup, add a 2mm spacer and install the crank back on.
dubBB.JPG

The BBframe shell size can be easily determined using the brand/model/year of the bike.
 
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tonyride

Don't piss off the red guy
Damn. I think I'm beat. Here's what it looks like and there's no spacer for the adapter to replace.
IMG_20200505_111429186_HDR.jpg
 

serviceguy

Well-Known Member
Is there a spacer between the BB cup and the crank? When you're rested go back and read my post, all the info should be already there. If you want more elaborated detail go the link I provided where there should also be a video of the installation.

If you do have a 4.5mm spacer between the crank and the BB (which seems to be the case from your picture), you will be removing the 4.5mm spacer, add the adapter between the frame and the BB and replace the 4.5, spacer with a 2mm spacer to compensate the difference.

or see a LBS before dong any damage...
 

Patrick

Overthinking the draft from the basement already
Staff member
or see a LBS before dong any damage...

that's how i got mine - park across three parking spots, with cars in them, in fire lane, blocking exit.
bother wrench guy while eating lunch, insist it get done for race the next day.

ah, the good ole days.
 

tonyride

Don't piss off the red guy
Is there a spacer between the BB cup and the crank? When you're rested go back and read my post, all the info should be already there. If you want more elaborated detail go the link I provided where there should also be a video of the installation.

If you do have a 4.5mm spacer between the crank and the BB (which seems to be the case from your picture), you will be removing the 4.5mm spacer, add the adapter between the frame and the BB and replace the 4.5, spacer with a 2mm spacer to compensate the difference.

or see a LBS before dong any damage...
So it sounds like the adapter is 2.5mm thick. Cool.
 

tonyride

Don't piss off the red guy
Wow, another example of ever changing "standards" that drive DYI'ers crazy. So I've been emailing and chatting on the phone with tech reps at MRP who makes the ISCG-05 adapter I want to get. I tried to explain over the phone that there isn't a spacer between the drive side BB cup and the frame but there is one between the BB cup and the chain ring. Since that adapter is designed to replace a 2.5mm spacer that's normally there he was a bit confused until I sent him that picture above of my BB. He did some investigating and replied with the following below:

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Tony,

I just finished doing some digging into this, and found it’s the new system for DUB BSA bottom brackets, and under the radar change that would only be noticed if you work in a shop or have swap from the old to new in more recent times. But, as luck would have it, I had to idea to check my new bike that came yesterday to see if I could compare the old and new system in person, and sure enough. My bike from last year uses the older BB style for DUB, and my new bike uses the Dub BB that you also have, so I was able to experiment with chain line and modifications.

Here's what I found:

That spacer on the outside of the BB cup you have is 4.5mm and a specific bearing seat, the old style was just a plastic cover that was flat with a 2.5mm spacer, and what appears to be a slightly wider BB cup. So to find a way to make an ISCG-05 adapter work with the new bottom bracket, I removed the 4.5mm spacer and tried both a single 2.5mm spacer behind the BB(which did not pick up enough space for the crank to cinch down without play) and 5mm total of spacers (which amazingly resulted in too much drag when tightened enough to remove play) .

I’m getting the sense that this new style does not play well with our ISCG adapters either. The only other approach I can think of is finding a 2mm spacer to pair with a 2.5mm spacer, but I don’t see that as a guaranteed method for success since the 4.5mm also has a unqiue bearing race to it.
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I think the unique bearing race is the problem. I think I'm going to take it apart so I can see what is so unique about it. Fun stuff.
 

mattybfat

The Opinion Police
Team MTBNJ Halter's
My new bike came spec with a removable ISCG-05 on a dub setup. I doubt this helps but this is how it looks
20200509_121558.jpg
 
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tonyride

Don't piss off the red guy
My new bike came spec with a removable ISG-05 on a dub setup. I doubt this helps but this is how it looks
View attachment 128274
Yes, this actually does help because this confirms where the adapter goes. I just took the drive side crank arm off to get a better look and the outboard spacer on mine is 4.5mm. Do you know the thickness of the washer? Is it 2.0mm? Does the side facing the BB cup look like this with a lip around the outer part of the ring?
IMG_20200509_122040534.jpg
IMG_20200509_122040534.jpg
 
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