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

Discuss light weight issues concerning road bikes & parts.
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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:


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:

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.

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:

Seperated spindle:

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: ... ower-Meter

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


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


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.


Starting to look like the spindle length is pretty good!


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:

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

by Weenie

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