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BB90 to GXP Bottom Bracket
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So, I ended up getting a Trek SC that fits me instead of keeping the warranty replacement FeltDA that did not. Now I need to figure out the best way to get my Quarq Power Meter (that is GXP) to mate to my new frame which is BB90.

Thoughts?

Ryan
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Re: BB90 to GXP Bottom Bracket [ryans] [ In reply to ]
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Bontrager makes a GXP for a BB90 bottom bracket for your exact needs. Ceramic Speed and Kogel and probably others make it too. It is a 24mm bearing with a 22mm bearing. I ended up using a Bontrager one on my Quarq which is super nice since the smaller bearing is all one piece whereas the Kogel has a separate reducer. Any Trek shop will know exactly what you need and may even have them in stock.


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Re: BB90 to GXP Bottom Bracket [ryans] [ In reply to ]
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It is very easy change over. You basically just have to swap out the the non drive side bearing but the GXP goes together slightly differently than Shimano so you need the "wavy washer" thing to take up the slack so get the whole kit. Several companies offer the kit but here is the link to Quarq's kit.

https://www.quarq.com/product/trek-bb90-bb95-sram-gxp-bottom-bracket-bearing-kit
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Re: BB90 to GXP Bottom Bracket [ryans] [ In reply to ]
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I have a gxp quarq on my SC. My LbS did it no problem just used different bearings to convert it.
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Re: BB90 to GXP Bottom Bracket [ryans] [ In reply to ]
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Buy a bottom bracket.
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Re: BB90 to GXP Bottom Bracket [STP] [ In reply to ]
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STP wrote:
It is very easy change over. You basically just have to swap out the the non drive side bearing but the GXP goes together slightly differently than Shimano so you need the "wavy washer" thing to take up the slack so get the whole kit. Several companies offer the kit but here is the link to Quarq's kit.

https://www.quarq.com/product/trek-bb90-bb95-sram-gxp-bottom-bracket-bearing-kit

In that kit, what is the black ring/washer on the right of the pic for?
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Re: BB90 to GXP Bottom Bracket [ryans] [ In reply to ]
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ryans wrote:
So, I ended up getting a Trek SC that fits me instead of keeping the warranty replacement FeltDA that did not. Now I need to figure out the best way to get my Quarq Power Meter (that is GXP) to mate to my new frame which is BB90.

Thoughts?

You're going to want to get the GXP BB bearing kit from Trek. It is as easy as everyone above has stated, but the Trek kit comes with a proprietary NDS metal bearing cover that mates with the frame around the O.D. Any GXP bearing sets work and you may be able to buy the bearing cover by itself from Trek, but I'm sure procuring the whole BB kit is easier.
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Re: BB90 to GXP Bottom Bracket [jimatbeyond] [ In reply to ]
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That would be my preference. I found some for the BB30 to GXP conversion but nothing for the BB90 to GXP conversion. Hence the post.

Do you know of a brand that exists and works well?

Ryan
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Re: BB90 to GXP Bottom Bracket [ryans] [ In reply to ]
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ryans wrote:
That would be my preference. I found some for the BB30 to GXP conversion but nothing for the BB90 to GXP conversion. Hence the post.

Do you know of a brand that exists and works well?

You are misunderstanding how a BB90 bottom bracket is configured. There is no BB. You have a frame with pockets for two 37mm O.D. bearings. The bearings are pressed into the frame with a spindle shield in between. Boom BB90 bottom bracket. You can buy 37x7x24-22 GPX cartridge bearing sets from any company, but most of them won't be able to provide the proprietary metal bearing shield I mentioned above.

See page 39/41 of the Trek SC manual here for an exploded view and the metal seal: https://trek.scene7.com/...t_Service_Manual.pdf

So there is no "conversion". BB90 only reliably allows for cranksets with 24mm spindle diameters. To use the SRAM GPX crankset you use a special 22mm I.D. NDS bearing an the extended inner bearing race.
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Re: BB90 to GXP Bottom Bracket [ryans] [ In reply to ]
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Re: BB90 to GXP Bottom Bracket [SummitAK] [ In reply to ]
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SummitAK wrote:
ryans wrote:
That would be my preference. I found some for the BB30 to GXP conversion but nothing for the BB90 to GXP conversion. Hence the post.

Do you know of a brand that exists and works well?


You are misunderstanding how a BB90 bottom bracket is configured. There is no BB. You have a frame with pockets for two 37mm O.D. bearings. The bearings are pressed into the frame with a spindle shield in between. Boom BB90 bottom bracket. You can buy 37x7x24-22 GPX cartridge bearing sets from any company, but most of them won't be able to provide the proprietary metal bearing shield I mentioned above.

See page 39/41 of the Trek SC manual here for an exploded view and the metal seal: https://trek.scene7.com/...t_Service_Manual.pdf

So there is no "conversion". BB90 only reliably allows for cranksets with 24mm spindle diameters. To use the SRAM GPX crankset you use a special 22mm I.D. NDS bearing an the extended inner bearing race.

Sorry if a dumb question, but to use a GXP crank, do both bearings need to be 22mm ID, or just one?
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Re: BB90 to GXP Bottom Bracket [SBRcanuck] [ In reply to ]
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Further to my question... if you look at the attached pic of the GXP kit from trek, it looks like only the non-drive side is smaller. But:

1. Why does that non-drive side bearing have what looks like a sleeve attached to the inner side?? And is that proprietary from trek? Most bearings I see don't have that.

2. In this pic, I don't see the extra black spacer/washer that some other sets seem to be sold with?

Thx!

EDIT - OK, read on wheelsmith website, I see the sleeve is a pressed in reducer. So, is that only on the non-drive side, and the drive side still uses a 24?
Last edited by: SBRcanuck: Sep 15, 17 8:58
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Re: BB90 to GXP Bottom Bracket [SBRcanuck] [ In reply to ]
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SBRcanuck wrote:
Further to my question... if you look at the attached pic of the GXP kit from trek, it looks like only the non-drive side is smaller. But:

1. Why does that non-drive side bearing have what looks like a sleeve attached to the inner side?? And is that proprietary from trek? Most bearings I see don't have that.

2. In this pic, I don't see the extra black spacer/washer that some other sets seem to be sold with?

Thx!

EDIT - OK, read on wheelsmith website, I see the sleeve is a pressed in reducer. So, is that only on the non-drive side, and the drive side still uses a 24?

The SRAM GXP standard requires a 24mm I.D. bearing on the DS and a 22mm I.D. bearing on the NDS. The NDS has the inner race extended about 4mm to the inside. This extended race mates up with the step in GXP crank spindles where they are turned down from 24 to 22mm. This is how the crank spindle is locked in side to side. On Shimano cranks this lash is set with an adjuster. On the SRAM GXP a wave washer is used in conjunction with the stepped spindle.

Some bottom bracket sellers use two 24mm cartridge bearings and then provide a reducer/extender to use on the NDS side of the BB.

Not sure on the kit pieces or what is being sold for spacers. What you have in your graphic and what I posted from the manual earlier are what Trek provides. The metal seal works well for keeping grit out of the NDS side bearing and the BB area in general. BB90 lack of maintenance leads to the bearing seats wearing out in the frame. Trek stopped replacing frames for this and step one is an oversize O.D. bearing. Step 2 is send frame back to Trek for carbon work:(
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Re: BB90 to GXP Bottom Bracket [SummitAK] [ In reply to ]
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That is why I was hoping for a nice threaded converter like the Wheels Mfg one for BB30 to GXP.

Without that, what is the best maintenance plan for keeping my BB90 frame working for a long period of time without needing carbon work?

Ryan
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Re: BB90 to GXP Bottom Bracket [SummitAK] [ In reply to ]
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Thanks!

Yes, mine is one of the frames where the drive side no longer holds the bearing tight, so I use the oversized bearing.

Mine is a 2011 or 2012 frame. I love it other than the bottom bracket. Next bike I get, I would much rather not have a BB90...
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Re: BB90 to GXP Bottom Bracket [ryans] [ In reply to ]
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ryans wrote:
That is why I was hoping for a nice threaded converter like the Wheels Mfg one for BB30 to GXP.

Without that, what is the best maintenance plan for keeping my BB90 frame working for a long period of time without needing carbon work?

Grease is the best plan. Something with high adhesion properties. Trek recommends Rock n Roll Supercoat. This always worked well on my SC. If you can find Morgan Blue AquaProof it definitely works well for BB's. Pregrease the bearing pockets and seal the joint overlap in the spindle cover during install. If you ride a lot in wet weather then consider pulling the cranks and regularly regreasing. With GXP cranks it takes only a minute to pull the entire assembly.

I also recommend extra grease for the SC headset bearings, especially the top bearing.
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Re: BB90 to GXP Bottom Bracket [ryans] [ In reply to ]
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I picked up a used speed concept frameset a couple months back and have started to build it up. Is there an easy way to tell what if the bottom bracket is the native bb90 or already has the gxp conversion?

The non-drive side has silver plate over a black colored bearing that says Truvativ Sealex. The drive side bearing is blue and has Enduro MP243LLB. I attached a couple pics of that helps

Matt
Last edited by: Pun_Times: Nov 26, 17 8:07
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Re: BB90 to GXP Bottom Bracket [Pun_Times] [ In reply to ]
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If it is set up for a GXP crankset, the inside diameter of the non-drive side bearing will be 22mm.
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Re: BB90 to GXP Bottom Bracket [Pun_Times] [ In reply to ]
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Pun_Times wrote:
I picked up a used speed concept frameset a couple months back and have started to build it up. Is there an easy way to tell what if the bottom bracket is the native bb90 or already has the gxp conversion?

The non-drive side has silver plate over a black colored bearing that says Truvativ Sealex. The drive side bearing is blue and has Enduro MP243LLB. I attached a couple pics of that helps

22mm NDS bearing ID as Jim mentioned. But the other GXP indicator is that the NDS inner race extends beyond the bearing seal to the inside of the BB shell. Easy to check this on the installed bearing. This is 11mm race width vs standard baearing/race width of 7mm.
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Re: BB90 to GXP Bottom Bracket [ryans] [ In reply to ]
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check out Wheels MFG. They are my go to for all bottom brackets/parts:
http://wheelsmfg.com/bottom-brackets/bb90-95/bb90-95-parts.html


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Re: BB90 to GXP Bottom Bracket [SummitAK] [ In reply to ]
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Thanks guys. The other question I had is that the bottom bracket doesn't have a plastic shield - i.e. the plastic middle part that connects the two cups in a traditional shimano bottom bracket. this means the Di2 wires and junction b could potentially be directly touching resting against the crank axle and I wonder if that would be problematic with a spinning crank axle slowly wearing away the wires. Should I do something (and if so, what) to keep the wires from being able to touch the axle?

Matt
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Re: BB90 to GXP Bottom Bracket [Pun_Times] [ In reply to ]
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Wrap everything with several layers of electrical tape.
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Re: BB90 to GXP Bottom Bracket [ryans] [ In reply to ]
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You would just buy the bearings for a GXP setup... big detail is the non-driveside bearing. I like the angular bearings from Wheels Manufacturing... link to their BB90 page, pick one item from each box (1-5) appropriately for your GXP and you're good to go...

http://wheelsmfg.com/bottom-brackets/bb90-95/bb90-95-parts.html


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Re: BB90 to GXP Bottom Bracket [Pun_Times] [ In reply to ]
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Pun_Times wrote:
Thanks guys. The other question I had is that the bottom bracket doesn't have a plastic shield - i.e. the plastic middle part that connects the two cups in a traditional shimano bottom bracket. this means the Di2 wires and junction b could potentially be directly touching resting against the crank axle and I wonder if that would be problematic with a spinning crank axle slowly wearing away the wires. Should I do something (and if so, what) to keep the wires from being able to touch the axle?

You can pick up the spindle cover from a Trek dealer p/n 281823.
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