Hey folks, I wanted to share my little DIY project to put power meters into some flat pedals. Across here, Reddit, and other places there have been a few discussions related to this, so I am obviously not the only weirdo who wants to rock the “kiddie pedals” with power meters.
The main concern that I had was that sticking the DUO-Shi meters into a non-approved pedal body would damage or otherwise compromise them, even if they were able to be physically fitted. These meters are one of the cheapest options out there, but even so they are by no means “cheap” parts!
Check out this little Instructable article that I wrote up to detail the project. IMO the end-result is that the DUO-Shi’s are installed in a way that is functionally identical, and structurally 95% the same as in any of the officially compatible pedal bodies.
Obviously, most people do not have access to a milling machine, so the “DIY” part is a little misleading. As noted in the article, it could be done with a hack saw and file, but really that is only a good idea if you are an experienced fabricator, and you know how to properly fixture things. Whatever the case, maybe it will inspire some other people to try things!
So far, I have a couple hundred miles on these and they are working out flawlessly. There seem to be several other Shimano pedal bodies that these would work in, either directly, or with modifications like those I made. Basically, if you look through the maintenance manuals for their pedals and see that the spindle assembly uses bearing balls and a sleeve like the ones in my article, then there is a good chance that the DUO-Shi’s will fit.
The main areas of concern with any non-official pedal bodies are around how far in the M15 threads start and end, and the depth at which the 13.83mm bore ends. If the threads start too far in, then excessive bending force will be placed on the DUO-Shis’ outer aluminum sleeve. If they end too soon, you cannot thread them in all the way. If the 13.83mm bore ends too soon, then the aluminum sleeve could bottom-out and cause all sorts of issues. And, if there is no 18.83mm bore then that is its own issue. If the bore is too small, then the sleeve will not go in at all. If it is larger, then there is a potential for premature failure of the sleeve at the end of the threads. The radial clearance between the sleeve and 13.83mm bore is 0.01mm (10µm!), and under pedaling loads there is probably more than enough flex in the assembly so that the sleeve will deflect and press against the bore, giving it support. If the bore is even slightly larger, then the end will just be floating and possibly deflect even more. This paragraph probably only makes sense if you read the Instructable entry.
Lastly, “Should I be worried about being able to easily step on the power meter body since I am not clipping in?” In short, no. I tend to ride in running shoes which have relatively soft soles. Clipless shoe bottoms are generally a lot harder and have plastic+metal bits. One could easily clonk the power meter body with a hurried attempt to get at the pedals, and if anything, the running shoes seem less hazardous. Thus far, I have not found myself stepping on the meters at all anyway. If anything, the approximately +15mm Z offset suits me better and I am enjoying an improvement in leg comfort when riding now!
(Though I’m in the UK and I assume you’re probably US?)
