Ass Saver - Bicycle Mudguard

by fgebhart, published

Ass Saver - Bicycle Mudguard by fgebhart Apr 23, 2017
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5372Views 963Downloads Found in Sport & Outdoors


Perfect application for owning a 3d printer:
Saw other cyclists having this hot mudguard on the back of their saddle. Looked it up and it costs about 10$. Since it is just a piece of plastic I asked myself - why not print my own version of it?

There you go! After some iterations I managed to find a design which fits just perfectly into the frame of the bottom side of the saddle. This design totally saves my ass on a rainy day! Since the dimensions of the bike saddles frame are standardized, this mudguard should fit to your bike as well.


Make sure to carefully slide the mudguard into the frame of your saddle. Check out the last picture in the gallery, which shows the bottom side. You will realize that you first need to clip both rods into the provided gaps and then slide the nose of the mudguard into the thin slit of saddle mount. Moving the whole mudguard a little to the front will slightly tilt it upwards, which makes your bike look really hot!

Have Fun saving your ass and share your makes, I would love to see other colors on other bikes!


There are two versions now:
bike_mudguard.stl -> is the original design with a total length of 279mm, which fits perfectly on the printerbed of the prusa i3 mk2 if you position it diagonal
mudguard_short -> is the new and shorter version for all smaller printbeds. With a total length of 250mm it is designed to fit to the print bed of the anet a8.

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The total length of the mudguard is 279mm and easily fits on the printbed of my prusa i3 mk2 if I rotate it by 45% to be diagonal.

The height of the flat part is 0.6mm which totally sufficient for this purpose. I printed the mudguard with a layerheight of 0.15mm so I ended up having 4 layers for the thing part.

Adjusting the infill will not make any difference since there is no big volume at all. Having 4 shell layers lead to a 100% solid part.

I was using PLA which performs very well. It is capable of holding off the water... for a couple of times now already. ABS or PETG might be more durable. Would be nice if somebody could give it a try!

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We successfully printed this diagonally in an anet a8. Our problem was that when trying to install it into the saddle it broke. It needs to be bent for installation. That's when it broke. Maybe we were not installing it properly?

Sorry for that. This happend to me with the previous versions of the modell. I already worked on improving the overstressed parts. For sure it needs to be bent for installation, but you should be able to find a way to slide the model into the rack of your saddle without overstressing it too much! Check out my description of the file, maybe it helps

How effective is this at actually blocking mud? most mud flaps I see are closer to the tire and it makes sense that they would be better at blocking more mud. While I haven't used a mud flap of this design, it seems like it would do nothing for your legs and only protects a small portion of your butt/back.

Sure the traditional solution works bette in terms of blocking mud and water. This mud guard performs like a compromise between blocking mud and causing not too much air resistance + additional weight. They are already commonly used by many cyclists, check it out with a web search for "bike ass saver". You also might wanna check out the reddit discussion about it: https://www.reddit.com/r/3Dprinting/comments/67371x/hot_bike_ass_saver_mudguard/

Thanks for the reply. Good discussions in that reddit post. Sounds like others had concerns similar to mine.

It makes sense that this is a good solution for some people. Getting an 'optimal' product often depends on what you define as optimal. I am the most casual of bikers, so what I personally see as sub-optimal is clearly optimal to another subset of bikers. Your arguments in favor of this make sense to me.

Again, thanks for the info. Happy printing

it doesn't fit into my anet a8

hey, i checked the build plate size of the anet a8 which is 220 times 220mm, right? This leads to a diagonal of 311mm, which should be fine, since the length of the mudguard is just 279mm. But maybe the shape of the part will overlap of your anet a8 bed, since the prusa i3 mk2 bed is 250x210mm. Did you try to scale the length of the part down to maybe 98%?
If it does not help I could just also create a smaller mudguard.

Thank you for your answer.
I checked and it only fits diagonally when scaled down to 94% but I haven't printed it yet because it don't knows if fits my bike. Do you think the proportions will stay the same at that size?

I just designed the mudguard to be shorter. With a length of 250mm it should fit to your anet a8 printerbed. Let me know if it fits :)

No don't scale it that much. I will provide a smaller version soon.