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I just purchased a new FSA Tempo Adventure JIS crankset - 46/30 to replace the FSA Vero Compact 50/34 JIS crankset on my 2018 Cannondale Synapse Sora 9 speed as I need lower gearing.

Both are shown as FSA "Road" and should be compatible. But they are not...

On the Vero, the interface to the BB sits slightly above the plane of the inner chain ring. On the Tempo, the interface to the BB sits a few mm below the plane of the inner chain ring.

Net result is that the chain rings of the Tempo are closer in to the frame, and actually touch the chain stay so cannot be fitted.

Does anyone know if there is a way to to overcome this problem?

Maybe there is there a replacement BB that would compensate for the movement of the Tempo cranks closer in to the frame?

FSA Vero

FSA Tempo

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    FSA has all kinds of weird bottom brackets. They're a true pain in the ass. Shimano has what? All of two types of bottom brackets? Probably ALL of Shimano's Hollowtech-II cranksets are ALL compatible with EVERY Hollowtech-II bottom bracket. FSA pulls crap like using 24.07 mm spindles so their cranksets aren't compatible with anything but some FSA bottom bracket. That uses really cheap bearings that wear out in six months. Nevermind the fact that FSA chainrings shift like the south end of a northbound bull that's been dead for two months.
    – Andrew Henle
    Commented Apr 16, 2021 at 20:57
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    I had to check, and BB-UN300s are still made with 4 different spindle lengths. IIRC there used to be even more choice when square taper was standard.
    – ojs
    Commented Apr 16, 2021 at 23:18
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    @AndrewHenle Hollowtech II cranksets and bottom brackets are not 100% interchangeable. Crank axle lengths vary (mtb vs road, different types of mtb/hybrid) and the threaded road bb cups for 68 mm BSA frames are actually 1mm thicker on each side than the cups for BSA threaded frames with mtb cranks, because the road cranks are also compatible with 70 mm Italian frames and bb cups. So even ignoring the spacers and seal tube, the road outboard bb bearings are different from the mtb bb bearings and should not be treated as interchangeable.
    – Pisco
    Commented Apr 17, 2021 at 0:27
  • @Pisco True, which is why I said "probably" - I was posting off-the-cuff because I've dealt with FSA's bottom bracket shenanigans for a while. But if you stick within road or MTB, you're fine. With FSA you have to look up what the phase of the moon was when you bought your crankset. And all bets are off if there was a grunion run when your FSA crankset was manufactured.
    – Andrew Henle
    Commented Apr 17, 2021 at 11:38
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    I'm not sure if it's unclear from photo or looking up specs, but to me the question seems to be about square taper cranksets.
    – ojs
    Commented Apr 17, 2021 at 12:14

2 Answers 2

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First, just that both say "FSA Road" doesn't mean that they are compatible.

The answer is to look up the documentation for the crankset. It's the first Google hit if you search with the name and then look for bottom bracket. It says 118mm (which is unusually long) and JIS. You need a bottom bracket with axle like this.

Edit: Looking at the bottom photo, it looks like the crank has originally been designed to be used to be used with triple chainrings and has been converted to supercompact double by just leaving out the largest ring. 118mm spindle is in the normal range for triples.

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  • Are you sure that this is correctly assembled? The gap between the bid ring and the crank looks very wide. Please post a 45° from above picture.
    – Carel
    Commented Apr 16, 2021 at 21:15
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    @Carel I think your comment was meant for the question, not my answer but since you're here, the two cranksets are designed for different bottom bracket spindles.
    – ojs
    Commented Apr 16, 2021 at 23:56
  • Yes, it went in the wrong place, but what bothered me, was the rather big gap between the chain catching pin and the crank, invisible now with the different picture. It made no sense because the chain would fall into the gap.
    – Carel
    Commented Apr 17, 2021 at 10:26
  • FSA is not exactly known for well designed products or quality manufacturing.
    – ojs
    Commented Apr 17, 2021 at 10:56
  • Well, now that I look at the photo again, the distance between big ring and the crank arm is unusually large, the big ring is mounted on inside of the spider and mounting studs for small ring are kind of unusual too. I think the crank arm has been originally intended to be used with triple rings but now that triples are out of style, FSA is selling them as doubles with outer chainring left out. Or that FSA needed to come up with subcompact crank quickly and decided to reuse the design and tooling for triple crank instead of investing in new product.
    – ojs
    Commented Apr 17, 2021 at 18:28
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Many thanks for the advice everybody, especially @ojs

I'll need to get a BB with a longer axle.

According to FSA tech support, the Vero uses a 110.5 axle length for a 44mm chainline, and the Tempo requires a 118 axle length for a 44mm chainline.

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  • Thanks. If it worked for you, please mark the answer as accepted one. "Thank you" replies are usually deleted.
    – ojs
    Commented Apr 19, 2021 at 14:44

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