Sram Red BB30 chainset (integral spider) fitted to BBRight....

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pavlo
Posts: 10
Joined: Tue May 09, 2017 11:47 pm

by pavlo

I should have perhaps put this into the introduction/gallery forum by means of an intro but this has some useful tech info.

If you just want straight to the jam, I've fitted a Sram RED BB30 chainset with integral spider onto my S5 with BBRight:

Image

This is how, and why I did it:

I've been road riding for a few years now, starting on a used ebay purchase, then to a very nice Canyon Ultimate CF SLX 8.0 for proper rides and a cut price GT Grade alloy for commuting. But I wanted to try an aero bike so set about buying up parts on ebay, and settled on building up a Sram based bike due to the weight savings and to just be a bit different to my other shimano equipped bikes.

I must admit at this point the very nice looking frame actually is a Chinese copy, it's worked out for me having built the entire bike for for around $2000, but feel free to debate Chinese frames over in one of the many other threads! I was initially looking at a number of generic frames but I just couldn't pass up the distinctive shape of the S5 and naively thought that bb30 = bb386+adaptor or something and that it would work nicely with the used BB30 Sram Red chainset :lol: :oops: :roll:

So upon actually seeing the frame and looking at proper diagrams I realised what the crack was with BB30/PF30 vs BB386 vs BBRight. I realised it *could* work with a longer spindle, and that there are left hand crank arms available, such as the Stages Carbon. I looked at a number of options and new spares were pricey, and I wasn't sure on the fitment q/factor etc. I spent *much* time looking at left crank arms and replacement spindles and trying to imagine what might work.

But this doesn't work:
Image

I settle on a used Left hand S952 crankarm from US Ebay (I'm in UK) for just $50 delivered.This comes pre-assembled onto a BB386 spindle for use with a matching RH crank arm and spider.
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Now of course these arms come "permanently" fitted the spindle with a screw that typically says "Do not remove" but phew, lucky me, mine didn't come with the warning :D So I set about undoing the screw which is fitted with a medium threadlock, and then uses a 2 leg puller to seperate the two. To mount the pulley safely I used a flanged M6 nut with 10mm hex popped into the hex of the main fixing screw that was mostly screwed into the spindle, but backed off 2 turns, this gives the puller somethign to push against and the flanged nut prevented damage to the fixing screw.

Removed screw:
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Seperated spindle:
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The arm on it's own is 158g but I don't seem to have a pic.

After getting an arm and a spindle to use for measuring I was looking at finalising the right spindle and spacers. With the extra 11mm on the non-drive side compared to PF30, I figured I needed a spindle that was 11mm longer than the BB30 one, right? Hmm well it doesn't work out like that due to the slightly odd way in which the q-factor stacks up. The BB386 spindle is 118.75mm and stages offer a 100.75 spindle for their Sram LH arm, which would give a 111.75mm spindle. But BBRight is effectively a BB90 non drive side with BB30 (68mm) drive side so a 79mm shell width, or BB386 (86.5mm) less 7.5mm again pointing to around a 111mm spindle.

But I know it would be wrong, and putting the S953 arm on the Red chainset gave a huge q-factor of 158mm, compared to 145mm, this was a much better measure and gives a hopeful spindle length of 118.75-13mm or 105.75mm. Where the hell do you get a spindle of that length? Well it turns out Cannondale use a 104mm spindle and latterly a 109mm spindle on there BB30A cranks. But I found after a lot of searching though spindles from FSA, Stages (older images have lengths on) and Cannondale I was all set on a 109mm spindle when I found a 106mm spindle sold to go with Hollowtech2 crank and Stages crankarm, sold here:

http://www.cannondale-parts.de/Spindle- ... ower-Meter

Bingo! Disappointingly it's not as hollowed out as the Sram spindle but the weight gain is only 10g.

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You can start to see how this all fits with the two arms assembled on the same side:

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Check of Q factor, subract 3mm due to pedal mounting face being recessed back from carbon, I made it 146mm compared to 145 of the proper Sram Red BB30.

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Starting to look like the spindle length is pretty good!

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Spacing wise I ended up with 2mm alloy spacer on the nondrive side, and a wavey washer on the drive side and had a nice free running crank with no play.

I have individual weights for the overall setups:

Custom setup:
----------------
355.6g Sram Red BB30 RH Chainset 52/36t 172.5mm
158.0g Sram S952 LH crank arm 172.5mm
98.3g 106mm BB30 Spindle
13.3g LH arm retaining screw (DO not remove!!!)
2.0g Wavey washer
2.0g 2mm Alloy washer
---------------------------------------------------------
629.2g Total

Sram Red BB30 setup:
----------------
355.6g Sram Red BB30 RH Chainset 52/36t 172.5mm
180.9g Sram Red LH crank arm 172.5mm
6.2g Sram threaded preload adjuster
4.7g 5mm Alloy washer
---------------------------------------------------------
547.4g Total

Flickr album with various pics of setup here:
https://flic.kr/s/aHskV7yArj

Subtract 24g using Sram Red 50/34t chainrings
Subtract 45g using Praxis Buzz 50/34t chainrings

by Weenie


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