Freeing stuck dub self-extracting bolt

Tech Tech Help
1

I’ve recently developed an “innovative” method for freeing these dub crankset bolts that tend to be very difficult to loosen and have been discussed at length (inner tube hacks, expensive ceramicspeed tool, etc). I haven’t seen it elsewhere so I’ll describe it here. Am I a genius? A crank? Am I putting unnecessary stress on my carbon frame? (Please tell me if I’m doing that.)

  1. Put the bike on the trainer.
  2. Put on bike shoes and clip in with both feet
  3. Put the drive side pedal at 9:00 and the non drive side at 3:00.
  4. Put a long wrench at 3:00 on the drive side.
  5. Push down with my left leg while pulling up on the wrench

Is this a bad idea?

2

If it works, it works.

Your method is actually pretty similar to how many mechanics approach this problem, but I think your approach adds a few unnecessary steps. You can achieve the same by resting the non-drive pedal on a block of wood or plastic step, hold the brake, and step on the wrench.

2 Likes
3

“Give me a lever long enough and a fulcrum on which to place it, and I shall move the world. ”

4 Likes
4

Impact gun?

1 Like
5

Thanks! This makes a lot of sense. I was trying to add more torque from the other side and your way seems like a much better solution that doesn’t require a trainer. Will do this next time, or get a trusted loved one to hold the bike while I’m clipped in :grimacing:

I was worried that the lever long enough to move the world might damage the dropouts or something…

6

Does anyone make a weighted 8mm hex socket? I find that often even with a more powerful impact wrench there isn’t enough momentum behind a typical 8mm socket to break the bolt loose and it just rattles away doing nothing.

7

Wood Clamp
Wood Clamp600×600 6.72 KB

You can thank me later.

1 Like
8

A relatively easy method is to:

  • remove the chain
  • left pedal forward
  • insert hex attached to long ‘breaker bar’ into dub crank bolt and place handle of the breaker bar on the ground towards the front
  • push down on left pedal with your foot

The longer breaker bar is key, but this method avoids having to pull hard etc. Very easy to exert high torque with low effort.

9

Another variation on the same theme:

  • Bike in workstand
  • Stool next to bike (seat height of stool around chain stay height)
  • Back pedal to rest pedal on stool
  • Long lever 8mm wrench into crank bolt to the left side (rear end) of the bike so that there is height above the pedal to push down on the wrench
  • Force wrench towards pedal

This has never failed me.