Instructables
Picture of SPD to flat pedals
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Hi

Before I went camping on the bike last time, I realised that I want to ride with my spd pedals and shoes. The problem I've seen was what about short trips to grocery, or for a coffee, or just simply to town for a meal or something. I know one option is to have a normal shoes in panniers/rucksack, or double sided pedals. Because I haven't had too much time to purchased them and also walking with spd shoes inside rucksack seems for me like pain in the butt, I've solved the problem in slightly different way.
I've made "platforms" out of 3mm aluminium, so I can attach them to existing spd pedals and ride wearing standard shoes or sandals. They are small and flat after removing from pedals and not taking too much space in the panniers.
All I needed was piece of aluminium, 3mm sheet in that example, couple stainless steel 3mm screws, and spd cleats/bolts. I needed also saw to cut the aluminium sheet to size a file, a piece of sandpaper, and tap 3mm/5mm to make threads in the platforms.
The platforms dimensions are roughly 90x60mm. Aluminium is very easy to cut and file, so no big deal, done in no time.
Next thing I've figured out position of the cleats (basically in the centre), made holes for cleats and threaded them with 5mm tap. Small hint. On the chart (http://www.carbidedepot.com/formulas-tap-metric.htm) you'll see that you'll need to use 4.2mm drill bit for M5 screw, but because the material is so thin is better to use slightly smaller drill bit. I've used 4mm and it was just perfect. 
Final step was make small holes for grip pins. They are basically 3mm stainless steel screws. I've used mine with slight countersink but I think better option will be with standard butt head. Hint again. First hole I've threaded, but I realised when I apply small amount of threadlocker on the screw, and force them to screw in, they making perfect thread without using tap. Time saving, and after the thread locker dry out, they are stays in place firmly. The screws from cleats poking just the same height as the other screws so that was fortunate, but if they don't you can cut them to a size. 
I've used the platforms couple of times and they're brilliant. I know people touring in standard shoes and platform/bmx pedals but I like the feeling of spd very much so I think that's not for me. The only problem I've found is that you need to learn how to rotate pedals. You'll need to do it in opposite direction than standard road pedals, backwards. First few times might be awkward but then you'll get used to.
The instructable is so simple that I think just set of pictures will be enough.
Keep'em rolling. Cheers.
Everybody makes fun of Crocs, but I love them when road cycling. I just wear the crocs for the short time I'm in the store or the bar, and put the cycling shoes back on when I leave. The crocs weigh little and don't press into my back from inside a backpack, and can be bungeed to outside of packs or even taped to the seatpost.
shootr2 years ago
No offense to Instuctables, but the search feature kinda blows - I swear I looked for this idea diligently before posting my almost exact copy for road pedals. Sorry I didn't see this, I really tried!
thewhite (author)  shootr2 years ago
Don't worry mate. I'm not that fussy. I think even better that you published it, because you increasing chances someone will find it, make it and ride.
Keep'em rolling!
If multiple people have the same idea for an Instructable, it just shows a need for a product to be born.
3366carlos1 year ago
i like it.
That's pretty cool. I bought some of the plastic ones once, and they lasted 1 ride. Do you have any problems with them clicking out of the pedals in casual use? (did you have to tighten the SPD mechanism?) I've heard of people making these out of plastic from cutting boards or wood, just for minimally used sneaker pedals. What do you mean about the pedal rotating backwards? Do you mean the weight makes them so the tail end rests downward when the shoes are not on them?
thewhite (author)  Yard Sale Dale1 year ago
No problems at all. I didn't tighten SPD. They works "straight from the box" ;-).
The only small problem I've got is exactly what you've described. Normally you don't bother rotating mtb spd pedals as they are identical both sides. Road pedals you need rotate forward, and those backwards. Of course you can make two pairs and stick to both sides. Cheers
rustytoy2 years ago
wow, this is one of those ideas that I say to myself... why didn't I think of this. Nice! now I can ride my road bike anytime.
kjones52 years ago
The use of grip tape like that of skateboarders is good alternative to screws to keep your shoes from sliding around. I agree with using aluminum for the platform; it's nice an easy to work with and strong enough for the task of putting on temporary platforms.
Congrats you're the 42nd entry in the bike contest (If you have no idea why thats important, read "The Hitchhikers Guide To The Galaxy". Nice work, my bike came with a pair of those but they were much flimsyer.
josefski2 years ago
Nice work! I like that you included the screws from the other side as traction. I'm going to try to figure out how to make this robust enough for mountain biking!
thewhite (author)  josefski2 years ago
I think is robust enough for any kind of cycling. You're applying pressure to 6x9cm piece of aluminium against pedal. What wrong might happen? Of course depend what kind of aluminium you are using. Mine was 60xx don't remember exactly. 3mm thick was very hard to bend in a vice.
The weakest point might be the length of the threads, but it can be 4mm thick plate, and 1mm extra will do the job even in extreme conditions. With steel you're adding weight and as Josefski mentioned need to be stainless. If you've ever worked with stainless "in the shed" you know how difficult it is.
Cheers
I think it's plenty robust enough to handle the pedal pressure. That's not the issue. Mountain bikers aren't any stronger than road bikers, after all. What damages pedals during mountain biking is getting whacked against rocks or dragged on the ground. Those would get pretty dinged up in short order going through a rock garden.

I'm always amazed when I see what a good fall can do to some of the most robust equipment!
use steel
It would have to be stainless. But the thing I like about aluminum is it's easier to work with. i don't have the right tools for working with steel and getting a decent looking result...
hmmmm... didnt think about that I think I'll make a set.
This is really cool! You have some great pictures, though it can be a bit hard to match them up with the text- any chance of a step-by-step?
thewhite (author)  SelkeyMoonbeam2 years ago
Hi. Ok I've updated the photos. Hope that will explain slightly the whole procedure, which in my opinion isn't too complicated. The thing which might be confusing are the pins, but once you'll see the final picture you'll know what I'm talking about.
Cheers
Thanks!