PF30 BB with a DUB spindle?

[weiwentg]

By way of background, I have a Chris King PF30 BB for a 30mm spindle crank installed in my gravel bike.

On a long gravel ride the other day, I was on a bumpy climb, and I dropped my front chainring on a downshift. According to the guy from Quarq, the chain must have hit my DFour91 spider in just the wrong way - it really did kill the power meter spider. I believe he said it was a freak accident, but he had heard of this thing happening, so I don't know how unusual this is. Anyway, that Quarq had a 30mm spindle. They have ceased production of that model in favor of Quarqs with their DUB spindle, and I am getting one of those as my warranty replacement.

CK stopped making its PF30 BBs and their associated adapters some time ago, before DUB was launched. The CK rep I talked to said I could try their DUB fit kit for their T47 BBs. That has the 30mm to 28.99mm reducer I need, plus spacers to preload the BB properly. He could not guarantee that this would work. So, do people on the forum have any alternative adapter kits they can think of, or should the CK kit work? (It's their DUB Fit Kit B.)

As a side note, I got that DFour91 with aluminum crankarms from Competitive Cyclist. The crankarms themselves aren't compatible with the spider, so Quarq is sending me new arms. The aluminum Quarq arms worked but they looked pretty cheap, and I'm pretty sure Quarq is all carbon arms now, so I guess I get an upgrade. But if anyone needs a pair of 165mm aluminum Quarq arms with a 30mm spindle but no spider, feel free to PM me, they're yours for the cost of shipping.

[FlashUNC]

I would just got with the DUB BB from SRAM rather than hoping a converter kit from CK would work.

[Spdntrxi]

I use a CK thread fit 30 (English) with the dub fit kit.. no issues.

[John H.]

I don't see why the fit kit pieces for the T47 wouldn't fit. The bearings should have the same id and the fit kit is just a delrin tophat that reduces the diameter to DUB size.
And depending on your bb width you would have to use spacers anyhow.

[weiwentg]

Originally Posted by FlashUNC

I would just got with the DUB BB from SRAM rather than hoping a converter kit from CK would work.

I'm aware I can do that, and they're sending a PF30 DUB unit. However, I'd really rather use the very nice BB I have.

Originally Posted by Spdntrxi

I use a CK thread fit 30 (English) with the dub fit kit.. no issues.

This is an officially supported combo, though. There's no official CK solution for my combo (remember, their PF30 BB is long gone). As far as CK knows, the combo I propose should unofficially work, but they hadn't ever tried it.

[John H.]

I suggest trying the fit kit- It is the easiest and lest costly of all options. If that doesn't work, a new bb is cheaper than new crankarms.

Alternately you could track down a set of BB30 8 bolt crankarms if you really want to use the PF30 bb?

[weiwentg]

Originally Posted by John H.

I suggest trying the fit kit- It is the easiest and lest costly of all options. If that doesn't work, a new bb is cheaper than new crankarms.

Alternately you could track down a set of BB30 8 bolt crankarms if you really want to use the PF30 bb?

I was double checking my information with someone else at CK. In the process of the conversation, we realized that the CK PF 30 BB leaves a lot of exposed spindle - over 10mm on either side. The stock conversion kit does not actually have enough spacers. CK does sell additional delrin spacers, but they may introduce the possibility of creaking.

The CK PF30 BB sits flush with the exterior of the shell. In contrast, the SRAM DUB BB should protrude by about 10mm from each side of the shell. That BB also basically mounts the bearings externally to the shell, which spaces them more widely - I assume this should improve bearing life.

Anyway, does anyone have any impressions about the quality of SRAM's DUB BBs? I thought I had heard that SRAM's GXP or older press fit BBs weren't that good, but I can't recall where I heard that.

Anyway, the issue with tracking down the older crankarms appears to be as follows. While the mounting interface on the DFour DUB appears to be identical to the interface on the old arms, I think the DFour DUB spider is spaced so as to accommodate the BB cups protruding from the side of the BB shell. If I got a set of older arms, the DFour DUB would probably mount to the arms, but it might not be spaced correctly on the bike. The Quarq guys said that the old arms weren't compatible.

[Pinned]

I'd try the CK with extra spacers before putting a SRAM BB in.

[weiwentg]

Originally Posted by Pinned

I'd try the CK with extra spacers before putting a SRAM BB in.

It's a LOT of extra spacers - like 10mm on each side. I'm going to be spending $22 on the BB and then another $15 or so on the extra spacer kit. Plus it's not a guaranteed fit. Are their DUB BBs that bad, or are you basing this off their older BBs?

I mean, if their DUB BBs are really bad, then sure, I'll consider tracking down the spacer kits.

[FlashUNC]

Been using a DUB BB for over a year now with a bike that did the Roubaix sportive. No issues and spins just fine.

[KonaSS]

Just get the Sram Dub bottom bracket and have a solution that was engineered to work. While the CK may be better quality (an opinion that I might not share), you are asking for problems by using it in a configuration it wasn't designed for.

[joevers]

The sram GXP bottom brackets wore out really easily because of GXP issues. They are really sensitive to alignment, so frames with lower quality frame prep went through them really quickly, and even properly aligned they put a lot of stress on the NDS bearing. That is to say- I'd have no reservations about running a sram DUB bottom bracket