Sram Red BB386 Crankset with BB386 Bottom Bracket in BB386 Frame: Small Chainring touches Frame

Discuss light weight issues concerning road bikes & parts.
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jbattermann
Posts: 11
Joined: Mon Feb 20, 2017 10:47 pm

by jbattermann

Good evening,

I just got my new Red (eTap) Crankset which I ordered in the BB386 version (00.6118.446.002) because I have a BB386 Frameset (the new Lightweight Urgestalt Disc) and I also got a Kogel Bearings 30mm Bottom Bracket for BB386 Framesets.

So far so good - the Crankset does come with a wavy washer & a slightly thicker (maybe 3mm), black spacer on the non-drive side and an extra one of that 'thicker'/black spacer in the box (and also 2 or 3 of the very thin transparent washers).


Initially I just tried installing the crankset as is - meaning keeping that wavy washer + spacer on the non-drive side, stick it through the BB and place the drive side crank on, and tighten the bolt to the 54nm.

Now the thing is - one of the screw-heads of the smaller chainring rubs against the frame slightly, but noticeably.. which is obviously not a good thing ;)

I double-checked the Sram installation manual (https://sram-cdn-pull-zone-gsdesign.net ... ackets.pdf) but it unfortunately has no extra entry for the BB386 version I have.. so I was wondering what's wrong & what to do?

Intuitively I'd try either sticking the extra black spacer or 2-3 of the transparent washers on the drive side.. but is that the right thing to do? And if not.. what would be?

I also double-checked whether the BB shells are flush & properly pressed in (which they are), whether the chainring-bolt(s) are tight (which they are) and the entire crankset has no wiggly play when tightened - but is it ok / the right thing to do here to simply stick on the spacer/washer on the drive side to get enough distance between the bolt/screw-head and the frame?


Cheers and thanks for any advice!
-J

sp3000
Posts: 174
Joined: Thu Aug 21, 2014 7:12 am
Location: Sydney

by sp3000

How compressed was the wavy washer when done up? you can happily swap spacers around and use the 0.5mm clear spacers to pack out the drive side. I have the slighter thicker 3.2mm spacer and wavy on the ND side and the 2.5mm spacer plus 3 clear 0.5mm spacers on the Drive side. I also measured the crank arms to the center of the rear rim to make sure they were centered on the frame. Even if you can't get dead center to get clearance that's ok, you'll hardly notice.
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by Weenie


sp3000
Posts: 174
Joined: Thu Aug 21, 2014 7:12 am
Location: Sydney

by sp3000

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jbattermann
Posts: 11
Joined: Mon Feb 20, 2017 10:47 pm

by jbattermann

sp3000 wrote:How compressed was the wavy washer when done up? you can happily swap spacers around and use the 0.5mm clear spacers to pack out the drive side. I have the slighter thicker 3.2mm spacer and wavy on the ND side and the 2.5mm spacer plus 3 clear 0.5mm spacers on the Drive side. I also measured the crank arms to the center of the rear rim to make sure they were centered on the frame. Even if you can't get dead center to get clearance that's ok, you'll hardly notice.


Oh my - thanks @sp3000.. that Quarq guide looks like what I was thinking / hoping would be the right thing to do.. I'll give that a try and play with the spacers tomorrow until it (hopefully) fits well.

The wavy washer on the nds was not really compressed - at all.. that was weird for me, too. It was merely a bit squeezed.. but that's it.. you could still turn it quite easily on the axle, so I assume the axle itself hit the 'end' of the drive-side axle / thread.. even though I would/should have felt some horizontal play. But oh well.. I'll see tomorrow how it turns out.. but thanks once again!

sp3000
Posts: 174
Joined: Thu Aug 21, 2014 7:12 am
Location: Sydney

by sp3000

That all sounds good, you need to pack out the BB shell width to get the correct wavy washer pre-load. My first attempt (probably ok) was with 2x0.5mm spacers on the drive side but the compression was only about 50% of the wavy, it was such that if you pushed the crank arm into the bike (grab the ND chainstay and crank arm and squeeze) I could quite easily compress the wavy by hand, with one more spacer the wavy looks pretty flat but if I did the same test harder I could still get a slight compression extra, both had the crank spinning completely freely so I have stuck with the 3x0.5mm to get a bit more pre-load.

If you pack out the drive side with clear spacers you should take up the slack in the wavy and push the drive side out 1mm or so and you should be set. If you still need more on the drive side you can always swap over the thicker black spacers from drive to ND to get the 2.5mm on the ND and get a bit more movement to the drive side.

First thing is to get the spacers required for packing out for the pre-load correct, once you have that you can shuffle them side to side to get the crank position correct.

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KCookie
Posts: 896
Joined: Thu Feb 12, 2015 9:40 am
Location: Pom living in Australia

by KCookie

Hope your going to post a build thread of your Urgestalt disc once you've sorted out the crank.
Will be the first on this forum. Eager to see what parts will be used. I have an Urgestalt, not disc, only seen one other on here.


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by Weenie


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