Fitting SRAM GXP (bsa)(not dub)(threaded) bottom bracket and crank. Inside chain ring rub against frame.

[sunchaser]

Hi guys,

I am building up road bike, and fitted a bottom bracket (threaded). That went very well, seeing this is part I dreaded of the build. However, when I fit in the crank, and completely tighten the crank arm on non-drive side, to make sure there is no play, the inside smaller chain ring(spindle) slightly rubs against the frame.

I assume I need to put in a spacer? Where do I put it:

- Bottom bracket?
- on Crank?

I used a mallet to make sure the crank is flush with bottom bracket. If I don't do this, there is definitely some play.

This is SRAM Red crank (10 speed) , still one of the older ones.

Please help.

[JA-Q001]

2 questions:

 

1. What BB did you use (be very specific)

2. Did you put any spacers between the BB and Frame on the NDS.

 

GXP only regulates the chainline with the NDS BB bearing, seeing as this is the one that gets "captured" by the crank and axle. 

If the blade is making contact with the frame, then something is taking up space on the NDS. No hammering is ever needed with these types of BBs.

[sunchaser]

Thanks for quick response.

1. The bottom bracket is SRAM GXP (english threaded, bsa), not the new dub ones.

2. No spacer on the BB.

There were two washer/spacers on Crank Arm (DS), but I removed it when took off my old frame. Not sure if need to put back, but it looked worn. Also not sure where to get it.

(bolts on crank which is slightly rubbing). 

 

Edited September 21, 2021 by sunchaser

[Carbon_Kooi]

As @JA-Q001 said, the setup is regulated by the NDS bearing and there should (in your build) be no spacers between the bearing cup and frame and there should never be any spacers between the bearing cup and crank arm. The dust seal does not count as a spacer.

GXP come in 73mm and 68mm (and I assume your SRAM Red crank would be for 68mm), is there any chance that your bike's BB Shell width is more than 68mm? This could lead to your chainrings being pulled closer to the chainstay as there is a little bit of space between the drive side cup and crank arm. If all this space is taken when the BB Shell is too wide or spacers were used the bearings will not be able to turn as you will crush them.

Can you maybe post some pictures?

Edited September 21, 2021 by Carbon_Kooi

[sunchaser]

Thanks Carbon_Kooi!

See attached pics 

Still some space (crank and frame) , but its not fully tightened??

 

[Carbon_Kooi]

I do not see any obvious issues with the installation, although it looks as if the NDS crank is almost in contact with the bearing? Would it be possible to measure the width of your BB Shell?

What frame is it?

[DieselnDust]

Isn't there supposed to be a spacer behind the drive side bb cup?

Is the wave washer fitted?

Edited September 21, 2021 by DieselnDust

[sunchaser]

Ok, yes @Carbon_Kooi,  I think that's my problem. I tightened both side against the bearing

I suppose its not to be against bearing?

But then there is very slight play, suppose this is normal.

Its one of the Chinese specials. (Bought it in June, when Rand run R13/USD)

 

Edited September 21, 2021 by sunchaser

[JA-Q001]

Actually no, I think your entire installation is correct, but I do however think that this frame is optimized for wider tyres.

That model SRAM RED crank was used in the time that 23mm tyres were fat and 25mm was huge. One thing that you could try, if you have to use this crank, is get a chainring bolt that sits flush with your blade.

Unfortunately with the advent of wider tyres, the chainline was widened in most groupsets, by about 2mm, in order to prevent this.

Once again, no spacers is needed between frame and BB, no spacers are needed on the crank axle. a wave washer can be used on the DS, but is not needed. The early SRAM RED cranks did have the NDS crank pull in right up to the BB.

Edited September 21, 2021 by JA-Q001

[sunchaser]

Correct @ JA-Q001, frame is made for wider tyres!!!

That's why, I could not understand why my old frame (23mm tyres) had so much space (from crank). All your points 100% match my crank. (extra washer on DS, pulls right up to BB)

Thanks so much, let see if I can get bolts that's flush with crank, or just check out another crank here. Not that much to spend.

Thank you.

Edited September 21, 2021 by sunchaser