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Discussion Starter · #1 ·
I have a 2017 Specialized demo 8, full suspension downhill. Recently within the past week I have had a noisy bottom end (bottom bracket from what it sounded like). Every occasional pedal stroke it would crack, crack, crackidy crack. No hinder in performance. I recently bought a SRAMX01 crank, so I replaced the 2 pressfit bearings as well, cleaned everything, lubricated and all that. No cracks in the frame, nothing. This morning I rode it around and it still has that creaking/cracking sound. Not every pedal stroke, but every other one at least. I could check the rear drivetrain, but what would cause an aggressive crack sound like what I’m hearing other than a crank?
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I'm going to go with it being the pedals or possibly the seat.

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+1 on everything mentioned so far and also near enough anywhere else you can think of is a possibility.

Easy to fix, identifying the source correctly is usually the tricky bit. Sometimes it's the first thing you check, 😃sometimes the last. 😭
 

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I'm going to go with it being the pedals or possibly the seat.
I have had creaking sounds come from both those areas, but thought is was the BB at first.

OP, does the creaking sound still happen when you stand up and pedal? If not then it is probably the seat or coming from the seat post clamp area.
 

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My demo was creaking on hard pedal strokes. was coming from the handle bars or stem flexing. Also had a set of spec boom slang pedals that would creak on occasion from the needle bearing cage flexing
 

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Speaking from recent personal experience did you install the cranks yourself and if so did you use a torque wrench and torque to manufactureer spec? I had a creak coming from somewhere in the cockpit of my dirt jumper last week. Never did figure out exactly what it was, but disassembling and re-seating everything up front and then torqueing things down got rid of the issue. As for my cranks, well right now they are lock-tited up, still noisy, and awaiting a replacement arm. Mostly toast.

Lots of good advice here. It may be quicker to dissemble and reassemble strategically than to try to find the exact issue.
 

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Discussion Starter · #9 ·
So it was narrowed down to the bottom bracket. I have replaced the bearings twice, and put on the x01 crank arms every time, turns out the crank spindle is a tad bit shorter than the stock Sram Descendant. What’s up with that?
1935853
 

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Spindle looks too short. Not enough engagement on those splines. Might not solve your creaking problem, but I would get the right length before its too far gone to sell.
 

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So it was narrowed down to the bottom bracket. I have replaced the bearings twice, and put on the x01 crank arms every time, turns out the crank spindle is a tad bit shorter than the stock Sram Descendant. What’s up with that? View attachment 1935853
There are two types of BB30 MTB cranksets (BBs) - 73mm for "normal" MTBs and 83mm for downhill bikes... your bb is the 83mm one, therefore you also need a matching crankset with long spindle (link)
 
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