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Bottom Bracket/Quarq help

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Bottom Bracket/Quarq help

Old 04-18-14, 10:59 AM
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Bottom Bracket/Quarq help

I've searched and talked to shop mechanics about this issue, and I've yet to find a definitive answer. I'll try to be concise.

The bike is a 2012 Pinarello Rokh with an Italian threaded bottom bracket shell currently using a SRAM Force crankset, and the bottom bracket is an aftermarket GXP bracket installed by my LBS last year. I'm unsure of the BB brand. I have a new Quarq Riken GXP power meter that I bought in December and installed on a different bike (my winter bike). I am now trying to move the Quarq to the Pinarello, and when just beginning to tighten it down, it preloads the bearings well before it's torqued. The crank won't even spin after just hand tightening the Quarq, and I haven't tried to torque it for fear of damaging something. I've taken it to two trusted bike shops and they both think the installed bottom bracket is slightly too long and that I need to replace the bottom bracket. So, I have special ordered a new bottom bracket because the GXP Italian threaded models are hard to find.

But, I'm trying to better understand what's going on here. Are some bottom brackets longer than others? I thought the SRAM compatible GXP BB's were all the same, but visually the cups on the aftermarket BB currently on the Pinarello appear to be slightly wider than those on other bikes I have (effectively making the BB longer). Are there different models of the BB cups? I've checked for spacers, etc. and there are none. It's just the BB installed on the Pinarello, no spacers.

Thanks for any insight you can provide. I think I have the problem solved, but I want to understand what has caused it.
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Old 04-18-14, 06:30 PM
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Italian bb shells are 70 mm wide and English bb shells are 68 mm wide. Could that be the problem?
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Old 04-18-14, 06:32 PM
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If the OP used the same spindle and spacers it sure would be. If there's a 2mm spacer he can remove, that should do the trick.
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Old 04-21-14, 08:53 PM
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Thanks for that suggestion. So, let me see if I understand. If my BB shell is 70mm, does that mean that when I order an Italian threaded BB, it will be a 70mm BB? And if so, does that mean that the Quarq won't fit it because it's a wider shell/BB?
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Old 04-21-14, 09:02 PM
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Originally Posted by DoubleTap View Post
Thanks for that suggestion. So, let me see if I understand. If my BB shell is 70mm, does that mean that when I order an Italian threaded BB, it will be a 70mm BB? And if so, does that mean that the Quarq won't fit it because it's a wider shell/BB?
Yes, Italian threaded BBs are generally set up for 70mm width BB shells. As for the Quarq, I can't help you.
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Old 04-22-14, 11:15 AM
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Thanks FB. I'm posting the answer here for reference in case it helps somebody else in the future. This is direct from Quarq support. The Quarq's are designed to work on Italian threaded BB's, but with very tight tolerances. If the 70mm BB is out of spec in the slightest, the Quarq will not work. So, they suggested having the BB shell refaced to assure that it is exactly 70mm, and then the Quarq should work just fine.

So, I'm off to the bike shop to see about having this done. I'm worried about it affecting the frame, so I'm going to get some second opinions before I jump right into having it done.
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Old 04-22-14, 11:26 AM
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Originally Posted by DoubleTap View Post
Thanks FB. I'm posting the answer here for reference in case it helps somebody else in the future. This is direct from Quarq support. The Quarq's are designed to work on Italian threaded BB's, but with very tight tolerances. If the 70mm BB is out of spec in the slightest, the Quarq will not work. So, they suggested having the BB shell refaced to assure that it is exactly 70mm, and then the Quarq should work just fine.

So, I'm off to the bike shop to see about having this done. I'm worried about it affecting the frame, so I'm going to get some second opinions before I jump right into having it done.
Rule No.1 of repair ----Don't fix what ain't broke.

I understand what Quarq is saying, but it's not on point. Nothing is ever spot on, so does Quarq prefer you err low or high?

In any case, before you remove any material from the faces, make sure there's material to remove. Specifically make sure your BB is not flat, square and over 70mm. If it's already right, removing material can only make it worse.

I'd start by measuring width, and if it's close to or under 70mm, color the faces with die-marker, or a dry marker, then do a super light skim pass to see if over 70% of the color comes off. If not, I'd face to the target width, and the uncut arc is less than 30%, whichever happened.
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Old 04-22-14, 12:38 PM
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Make sure that all of the spacers and seals from the old installation of the Quarq have been removed.
I've seen several posts where people have found the reason for similar problems is an old seal on the drive side that looks like it is part of the crank. Also some aftermarket GXP BBs use a sleeve on the non drive side to reduce the diameter of that bearing. Make sure it is still in place and didn't come out with the old crank.
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Old 04-22-14, 12:58 PM
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Originally Posted by FBinNY View Post
Rule No.1 of repair ----Don't fix what ain't broke.

I understand what Quarq is saying, but it's not on point. Nothing is ever spot on, so does Quarq prefer you err low or high?

In any case, before you remove any material from the faces, make sure there's material to remove. Specifically make sure your BB is not flat, square and over 70mm. If it's already right, removing material can only make it worse.

I'd start by measuring width, and if it's close to or under 70mm, color the faces with die-marker, or a dry marker, then do a super light skim pass to see if over 70% of the color comes off. If not, I'd face to the target width, and the uncut arc is less than 30%, whichever happened.
Thanks for this advice. It's mostly over my head, but is what I was thinking intuitively. I'm not just going to let somebody start carving on my Pinarello frame without more understanding of what's needed. Maybe the Quarq is just not meant for this bike and I'll have to use my Powertap on this bike. But, I called a shop here in Portland that specializes in carbon repair (Ruckus Composites), and they said they'd take a look and give me their opinion before they start working on it. They have an excellent reputation, so I'm going to take it to them for evaluation.
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Old 04-22-14, 01:00 PM
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Originally Posted by Slash5 View Post
Make sure that all of the spacers and seals from the old installation of the Quarq have been removed.
I've seen several posts where people have found the reason for similar problems is an old seal on the drive side that looks like it is part of the crank. Also some aftermarket GXP BBs use a sleeve on the non drive side to reduce the diameter of that bearing. Make sure it is still in place and didn't come out with the old crank.
Thanks for this suggestion. Both mechanics that I took it to previously thought this was the issue, but they ruled it out after inspecting it.
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