Could the spindle of a pedal have just one set of bearings, not two?

Question

Pedals can be cleaned with a solvent and an air compressor without removing the races from the spindle.

How is that possible? It would seem that there must be a second set of bearings—one that's only accessible through complete disassembly.

The service instructions for PD-M520 and PD-M540 are down (at the moment?). These might have the answer.

Other References:

• The 20-Year History of the Shimano PD-M520
• Shimano PD-M520 pedals review
• How to service Shimano SPD pedals: walkthrough guide with video

What's the point?

1. It's nice to know how things work.
2. It's nice to know this can be done in 15 minutes.
3. It's good to know that someone else, if not oneself, can use old pedals. There's no need to throw them in landfill. Donate them.
4. It's a celebration of engineering for Shimano to give us the right-to-repair—even if not everyone will use it.
5. If in 20 years all bikes have electronic shifting, we will miss the days when Bowden cables were universal. Now is the time to demand that, at least, electric bike cables, connectors, and batteries, be standardized. This is, incidentally, not something that can be done in North America. The EU just required all mobile phones to use USB-C. If you're in the EU, lobby your representative for legislation to be applied 5 or 10 years down the road.

Answer 1

Okay, I probably could have given the drawing a bit more effort, but hopefully the idea is clear. Most SPD, SPD-SL, and their knockoffs use this bearing arrangement. You have two cup-and-cone bearings on the outboard side of the pedal, and a bushing on the inboard side. So yes, you have two bearings (possibly even three, depending on your definition of a bearing). However, there’s enough empty space in the system that you can indeed get solvent and compressed air through all the bearings just like shown in the linked video.

Re-lubrication is easy. The bearings are all lined up in a way that if you put grease inside the pedal body and then install the axle, the grease will be displaced by the axle and escape the pedal…going right through the bearings.

Also, do note that the ball bearings are hidden deep inside the pedal. It’s unlikely you’ll see any large contaminants there; mostly you’d just expect fine metal particles worn off the bearings. Those will easily be removed using a solvent bath.

(The axle does not actually have a thin section in the middle like I drew it as having. That’s just operator error. Same excuse for why I forgot to draw the threaded retainer which the bushing is encased by and connects the axle and body.)

Quick and easy SPD pedal service:

1: Remove axle using spline tool or open end wrench as appropriate. Careful of which way to turn the tool: it is different between the two sides.

2: Clean axle unit and pedal body.

3: Add grease to pedal body as deep down as possible.

4: Reinsert axle and tighten it in the direction indicated.

Answer 2

The pedal actually has two sets of bearings. If you look at the video slightly before the linked point, about 2:40, you'll see that there are bearings at both ends of the bushing. The Park Tools instructor thinks that sinking the whole assembly in solvent is enough to clean both bearings and filling the pedal body with grease and pushing in the bearing assembly is enough to get grease to both bearings.

I think there is a more general theme here: Read or watch the full instructions.

Answer 3

In the linked video, the shaft has a series of bearing inside it, which is not serviced in that video. The disassembled shaft (at 3:00 in) shows the inner bearing is a series of bushings.

I did not pick why the shaft was not disassembled and cleaned (sorry if it covered, can't be bothered listening to every microsecond of the video). Maybe its not something that is possible or not needed within the typical service life of a pedal. When installing the shaft in the pedal, the new grease is forced though the shaft and greases the shaft bushings (This is not made clear in the Park Video).

My guess is the tapered sections of the shaft are the bearing surface, and will eventually wear. The end nut and bearings are used for preload, and need adjustment as the shaft wears to take up the play. Pedaling forces do not actually get transmitted though the ball bearing set, they all get transmitted though the bushings.