Your weak point is that section in between the two mounting points. Simply changing the print orientation will improve the strength significantly and avoid snapping along those layer lines. You would want to print it standing up on its side instead. The weak point would then be the mounting holes but printing it with double layers and or using large metal washers should keep it from breaking along those layers lines. As for materials avoid pla and go with abs, asa, or carbon fiber nylon. I recommend you watch the 3D Printing Nerd's video on 3d printing bicycle parts. You can see why he chose the materials he tested. Another great channel with lots of material testing and info on improving strength is CNC Kitchen.

Very cool 😊I have 3D printed for some years now, also MC parts. It works great! Some of my learnings (also shared some on my YT channel): Use PTEG instead of PLA, it's more flexible = less brittle, tolerates better vibrations, it's UV tolerant (PLA will suffer in the sun) . Make sure print orientation is optimal, 3D prints are weakest along the layers. 100% infill is not always better, it's most often the shell that causes the strength, it's easier to bend a solid bar than a pipe. 3D prints are strong when compressed (and for that 100% infill is good), not as strong when pulled.

Nice bike sir. I would recommend two things for you. First stop using PLA and switch to something like petg, or maybe even one of the engineering materials like poly carbonate or nylon. The PLA will be strong but you will run into creep over time where the material looks like it’s dropping even if it’s not hot. Second suggestion would be to print that part sideways. Your part needs to be strong in the z and y axis but not so much the x. Turning it sideways will dramatically increase its useable strength. Im printing end user motorcycle parts already and while there is a learning curve it’s game changer. My product is an add on shock absorber for the front fork of basic bikes. It holds the entire weight of the bike and manages thousands of psi of pressure. The tech has really come far. 🎉

i would recommend tpu over pla as pla degrades with sun however a solid part should last longer though colour will fade, on a side note tpu can also handle petrol and would dampen vibration because bendy obviously you wouldn't use a very flexible filament

From someone who has printed tons of motorcycle parts. a speedo bracket exposed to sun printed in pla is not the best choice. nylon, asa, abs are definitely better choices. Nice video though

Walls/perimeters have more impact than infill to get stronger parts. You should try ASA or PCTG for better resistance. Also you probably don't need a 'carbon printer', just replace the nozzle with a harden one.

using more infill doesn't necessarily mean its stronger, adding more top and bottom layers and the number of walls will really bump up the strength. for the infill gyroidal is one of the strongest imo. also printing that part on its side edge will add more strength as it will eliminate the horizontal layer lines that are splitting in your break test. the model would fail with the material uninterrupted in tension instead of how strong the layer bonding is.

100% infill auf das ganze teil zu machen scheint mir nicht nötig, sinvoller wäre es an der besestigungsstelle noch 2-3 streben einzubringen, das würde an der stelle an der es bricht eine sehr bessere stabilität geben und es ist gleichzeitig besser ohne stützen zu drucken, spart material und ist stabiler. und für den aussenbereich und direktem sonnenlicht, eher was UV beständiges was auch hitzefester ist, ASA oder wenns auch teuerer sein darf PACF oder was ähnliches

mate more perimeters are better than the infill amount

Pla will warp eventually in the sun