Thank you for giving some visuals, one thing you could test is if the XTR assembly will fit onto the PD-EH500 spindle. If this was to work you would be removing the Favero bearing/sleeve and threads from the spindle and sliding the XTR in place but only if the spindle would be able to accept the bearing itself.
Thank you again for the pictures!
Is anyone keeping a list/spreadsheet of compatible pedals, ideally with columns for price, caveats, special instructions, degree of difficulty, etc? Seems like a lot of people would benefit. Surely it would be pretty easy to make a Google Sheet along those lines, to be filled with crowd-sourced content…?
What is the cheapest way for someone in the UK to do the (non-Shi) Assioma hack? All the pedals mentioned here seem to be £100+
No go. XTR pedal body ID is about the same as the spacer and threaded portions of the EH500 spindle. The last couple gens of XT and XTR look similarly “svelte”.
Vintage pedal test, this one is +5mm vs stock. The SPD M737s are beasts but it’s nuts that they could be a body that works with the Shi Duos.
Anyone in the UK got a link for a 9mm socket that fits in the pedal body?
I use a Stahlwille 40D series socket. Bought it from RS but they’re out of stock until mid-December. This item from FFX looks like the same one and its available.
According ro the RS catalogue the OD of the socket is 12.8mm.
RS link (no stock but more info!) https://uk.rs-online.com/web/p/sockets/7370167/
FFX link Stahlwille STW40D9 Bi Hexagon Socket 1/4 Inch Drive 9mm
Hope tis helps
David
This thread is fascinating and all, but looking at prices online, if the assiomas are around £350 and you still need pedals to convert to, plus the time to modify it yourself, why not just buy the garmin xc100 for £550? (or less if you can find a discount?)
Because they are £200 more expensive 
You do have a good point though, I’m only going down the hack route because I have an old pair of Favero’s that need new pedal bodies anyway - and I love a project.
Hi,
I used some M19 pedals I bought second hand from ebay (struggled to find any other compatible ones in UK).
I am having an issue where there is a bit of a gap between the spindle/power meter and the pedal body. You don’t seem to have the same gap? I worry about the weather/dust proofness with my gap.
Also, tried them out on my turbo and they have quite a power discrepancy.
Photo attached
Hi Sweetspot
It looks like you have kept the bearing on the pod side of the axle?
I kept the pedal body completely as was with bearing on outside and plastic bushing on inside with lip seal then slid the Assioma axle in.
Chris
I really want to try that.
Thanks for reply
I had left the Wellgo bearing on but that’s how it looked.
I tried again using the silver bearing from the Assioma spindle. It looked a lot better / weatherproof but I’ve converted them back to stock now. The second hand wellgo pedals are not clipping in or out well so I’m trying to get better pedal bodies or a new road bike 
Thanks for this
In the end I had ordered a draper one from
Draper 82143 1/4" Square Drive Socket, 9 mm Size https://smile.amazon.co.uk/dp/B078BL19B8/ref=cm_sw_r_cp_api_glt_fabc_X51RY0E5Z88FY739M2F0
Which fits well. Cheaper once delivery taken into account.
I had some Garmin XC and sold them because they literally made me cry… They were so bulky and heavy I couldnt handle it.
The accuracy and readings was fine, but by doing this I now have a set of power pedals that are lighter than XTR pedals with great engagement and are not a brick.
Thats my $.02
What body did you end up using?
I ended up using the M-Force 8 in Chromoly spindle. This is the same one Shane used and honestly I think with my SPD cleats still on my shoes they feel better with engagement then my XTR pedals did. They seem more “crisp” and exact to me.
I used the “look” pedal bodies from the Assioma to make a nice set of road pedals for one of my other bikes.
Assioma DUO-Shi conversion. The additional width / Q Factor isn’t bothering me and I’m enjoying having Shimano SPD pedal bodies (M520). The add’l width improves shoe clearance from the pods.
Power comparison with P2M vs these in DCRainmaker’s tool = excellent alignment.
Super good job!
Shimano PD M520 and assioma duo Shi?
You had to change something, or you managed to fit them perfectly?
It’s a spot on match. I’d earlier spent a fair amount of time digging through the Shimano pedal exploded views, part numbers and what was sold as a replacement / cross-compatible.
If you read back up in the thread or search some of my other posts, you’ll get a quick overview of other options, etc.
