Hope BB Saga continues

Jaychale

Well, I think I'm admitting defeat on this one.The NDS bearing that was sent back was comparatively pretty rough to the one that was replaced. Gave it a good clean and new grease, which helped, but not entirely. Decided I could live with that, and went to install it.

I've been fighting with it and trying things all week now. The GXP spacers do not fit (Old BB was definitely GXP (http://www.chainreactioncycles.com/sram ... lsrc=aw.ds))

They catch on the spindle shoulder at the splines, have about the same OD.
But without them, I get either too much slop/wobble in the pedals, or bear up on the spider, and then doesn't spin freely.

I'm left to assume that this just isn't compatible, after trying every conceivable permutation of spacer/reducer combinations. Even tried my old crank to see if the Red could be different somehow, also with no joy.

I'm open to any suggestions, up to and including a brand that would fit, and an appropriate drink to cry into.

The Rookie

I'm not sure on your desscription, I am using a GXP crank with Shimano HT2 BB (so nominally the same dimensions as the Hope BB) and an adaptor (not Hope but the photos look the same) and it works fine.
The adaptor pushes into the NDS bearing from the outside with the larger outer diameter pushing up to the bearing, the crank axle then passes through from the drive side and bolts up.

Due to the way GXP does up you can test it through the NDS bearing off the bike as of course there is no bearing preload.

Should look something like this - Black Hope BB and silver adaptor according to the photo source.

keezx

The problem with these 22-24 mm adapters is that they have a collar which adds width to the LH bearing which not should happen.
I was also tempted to use a cheap Shimano BB with my S900 crank but decided not to because of the risk that the LH crank would not be 100% snug on the spindle and would be destroyed in no time.
IMO there should NEVER be any form of preload on GXP bearings, not necessary and plain harmful, when the LH crank is fitted properly, it was designed that way.
The only way a non GXP BB would fit properly is when the LH bearing + 2x collar is about the same width as a LH GXP bearing.
This is not impossible , but it has to be figured out properly.

hambini

As Keezx said, the left hand side often protrudes more and that will be the reason why you can't get it on. Also I'm never sure why SRAM decided to go for a 22mm bearing on the NDS. Seems illogical to me? I wonder if they did it to stop people using Shimano cranks.

If you get stuck, I can probably make you one that will fit.

keezx

The 22 mm makes perfectly sense for locating the spindle without spacers/preload on the bearings.
Well engineered.

The Rookie

Can only say that my GXP cranks and adaptor are working perfectly in my 68mm shell frame using a Shimano BB, there is a small visible gap on the driveside indicating no bearing preload as designed and it all measured up properly before I installed it.

The way my adaptor works (I can't speak for all) it doesn't affect the bearing preload at all as it spaces the NDS crank off the axle by the small amount (about 1.5mm) of the shoulder on it, the drive side crank and axle stays in the same place it would have been before relative to the bearings, all obvious when I was assembling it out of the frame as a trial.

Da_Reverend

Keezx wrote:

The problem with these 22-24 mm adapters is that they have a collar which adds width to the LH bearing which not should happen.
...
The only way a non GXP BB would fit properly is when the LH bearing + 2x collar is about the same width as a LH GXP bearing.
This is not impossible , but it has to be figured out properly.

My understanding is that the NDS ball bearing of a SRAM GXP bottom bracket is a non-standard 22/37 x 8 mm with an inner race that is 11,5 mm wide (so inner race is wider than outer race).

Any HTII compatible bottom bracket would normally have ball bearing with inner races and outer races equally 7 or 8 mm wide.

So to me it seems it could work if the width of the collar added to the width of the inner race make the 11,5 mm. I'd check that first.

(However, any plastic spindle sleeves like used on Shimano HT II bottom brackets may change the game. But I think Hope do not use plastic spindle sleeves, do they?)

Also, the question is whether the collar should be on the inside or outside.

keezx

Couple of good points...
As I mentioned , the set-up with the adapter has to be figured out properly.
As I see it now, the collar should be inside.

hambini

Whenever I have made these in the past for people, I have used a 69/22 bearing on the non drive side, No collar is required. It's not an easy bearing to obtain and only NTN and koyo make them.

The bearing is 9mm wide, not quite the 11mm but it has a very high dynamic load rating and no one has complained. It's commonly used in a pair as the front wheel bearing on Honda motorcycles.

keezx

Do these bearings fit in Shimano and/or SRAM LH cups?

hambini

Keezx wrote:

Do these bearings fit in Shimano and/or SRAM LH cups?

Shimano use 6mm wide bearings so the short answer is no. You'll have to machine a bit more out.

When I've made them in the past, I machined my own cup with the 1.37 x24tpi cup thread and then an external bearing carrier to hold the bearing.

The Rookie

Keezx wrote:

Couple of good points...
As I mentioned , the set-up with the adapter has to be figured out properly.
As I see it now, the collar should be inside.

Mine is outside, the photo above is outside, how sure are you it should be inside?

svetty

Doesn't the picture on the Hope website show two collar type adapters, one inserted from the inside and one from the outside of the inner race of the NDS cup:

http://www.hopetech.com/wp-content/uplo ... uvativ.pdf

keezx

Yes it does.
Stll could work if 2x collar+actual bearing is equal to GXP bearing.

paulbnix

I have been following this thread because I had a SRAM Force gpx crank to fit to my bike.

I bought the Hope and it's gpx adapter because the other gpx BBs seemed similar to the short lived mega exo bb that I had before.

Anyway I fitted it today and it's the freeest running bb I have had.