But where are your prin...
Nah, looks sick. Following with interest.
Nah, looks sick. Following with interest.
Full Suspension Mulligan
So about a year ago I built my first FS bike - and I spent most of my effort trying to figure out how to actually build it as well as create a leverage curve I wanted... I really didn't focus on the bike structure, I just took the bits of advice I could get from others who have made FS bikes and hoped for the best... And it failed as shown here.
So I decided I should try again - but this time focus more on creating a bike that theoretically should last longer... I don't know if it will ride as well or not, but that isn't so much my goal with this one.
For some background - I work as an engineer but what I do is very far away from structural metallics... However, software and access to knowledgeable/'much smarter than I' people is easy to come by (for me time is the toughest commodity)... So I spent some time with those people learning more about how to better evaluate what I'm doing - I am far from an expert and probably won't ever be one - but hopefully what I have started at least puts me on a better path.
This frame is a straight single pivot with a fully triangulated rear end - simple and easy. The front end uses a 44.5x0.95mm straight gauge tube for the main portion of the down tube (there is a 1.75x0.065” bottom section for where the pivot axle pierces), and 35mm ST and TT.
![Bicycle part Vehicle Triangle Automotive exterior Auto part]()
The rear end is a little more complicated but nothing crazy. The ‘yoke’ portion consists of 35mm tubing and some machined 17-4 to connect to the pivot (I like using stainless because I don't have to worry about rust/paint/etc. around the bearings - and Xometry Supplies sells it reasonably cheap). The bearings press into the machined plates and 15mm bolts connect it to the welded in axle through the DT. I used off-the-shelf chain and seat stays. I was never a huge fan of this particular design seeing similar things on production bikes - but it was enticing from its simplicity so I went with it.
![White Line Bicycle part Cylinder Auto part]()
Jigging the rear end was actually pretty simple, which was nice. I used 2 pieces of T-Slotted extrusions, some machined aluminum and some 3D printed parts... I bought a cheap ($250) FDM 3D printer for one of my kids - and despite being very spoiled with the printing available when I'm at work, I find this cheap printer still super useful and use it way more than expected for jigging... And I even think with a little patience, caution and extra fine-tuning, I could likely have swapped all of the machined aluminum parts for printed ones with little/no compromise.
![Automotive tire Bicycle fork Bicycle part Motor vehicle Rim]()
![Motor vehicle Wood Machine tool Gas Engineering]()
As of now I have the rear triangle and front triangle mostly done. I still need to put the pivot in the front triangle, add shock mounts and some other small details but it is getting there.
![Automotive tire Bumper Gas Wood Metal]()
Now with this particular design - if I am doing everything correctly - the downtube will actually be the weakest point when considering single event/heavy loading (i.e. the EFBE Tri Test max overload test). This is of course neglecting any fatigue, welding issues, or other f*ck ups that I may introduce. Anyway, under full compression the shock applies a pretty decent bending moment on the downtube - which at least in most available frames made this way - are reinforced/load distributed in some fashion or another.
Scouring the inter-webs at what others do at this location, I really only found 2 options: long shock mounts or sleeves. Because I am using basically a 1.75" DT, options for sleeving available to me would start with a 2" OD tube and some lathe work (I have a small sh*t lathe so that's not an easy option for me personally)... So I opted for long (~180mm) shock mounts with some aluminum adapter plates (yes I put my initials in the aluminum pieces).
![White Tool Automotive exterior Composite material Automotive design]()
A friend reviewing my design suggested 3D printing a shock mount instead. It's super interesting but I know nothing about metal printing so I was basically too intimidated to try... Though I am pretty stoked to see Natzoo's recent post about 3D printed parts and am hoping to learn more - potentially even trying this out in the not so distant future.
As for the rest of the bike - I hope to find time to complete it in the next week or two. Will post more when completed, but also will respond if questions/comments or useful criticism.
So I decided I should try again - but this time focus more on creating a bike that theoretically should last longer... I don't know if it will ride as well or not, but that isn't so much my goal with this one.
For some background - I work as an engineer but what I do is very far away from structural metallics... However, software and access to knowledgeable/'much smarter than I' people is easy to come by (for me time is the toughest commodity)... So I spent some time with those people learning more about how to better evaluate what I'm doing - I am far from an expert and probably won't ever be one - but hopefully what I have started at least puts me on a better path.
This frame is a straight single pivot with a fully triangulated rear end - simple and easy. The front end uses a 44.5x0.95mm straight gauge tube for the main portion of the down tube (there is a 1.75x0.065” bottom section for where the pivot axle pierces), and 35mm ST and TT.
The rear end is a little more complicated but nothing crazy. The ‘yoke’ portion consists of 35mm tubing and some machined 17-4 to connect to the pivot (I like using stainless because I don't have to worry about rust/paint/etc. around the bearings - and Xometry Supplies sells it reasonably cheap). The bearings press into the machined plates and 15mm bolts connect it to the welded in axle through the DT. I used off-the-shelf chain and seat stays. I was never a huge fan of this particular design seeing similar things on production bikes - but it was enticing from its simplicity so I went with it.
Jigging the rear end was actually pretty simple, which was nice. I used 2 pieces of T-Slotted extrusions, some machined aluminum and some 3D printed parts... I bought a cheap ($250) FDM 3D printer for one of my kids - and despite being very spoiled with the printing available when I'm at work, I find this cheap printer still super useful and use it way more than expected for jigging... And I even think with a little patience, caution and extra fine-tuning, I could likely have swapped all of the machined aluminum parts for printed ones with little/no compromise.
As of now I have the rear triangle and front triangle mostly done. I still need to put the pivot in the front triangle, add shock mounts and some other small details but it is getting there.
Now with this particular design - if I am doing everything correctly - the downtube will actually be the weakest point when considering single event/heavy loading (i.e. the EFBE Tri Test max overload test). This is of course neglecting any fatigue, welding issues, or other f*ck ups that I may introduce. Anyway, under full compression the shock applies a pretty decent bending moment on the downtube - which at least in most available frames made this way - are reinforced/load distributed in some fashion or another.
Scouring the inter-webs at what others do at this location, I really only found 2 options: long shock mounts or sleeves. Because I am using basically a 1.75" DT, options for sleeving available to me would start with a 2" OD tube and some lathe work (I have a small sh*t lathe so that's not an easy option for me personally)... So I opted for long (~180mm) shock mounts with some aluminum adapter plates (yes I put my initials in the aluminum pieces).
A friend reviewing my design suggested 3D printing a shock mount instead. It's super interesting but I know nothing about metal printing so I was basically too intimidated to try... Though I am pretty stoked to see Natzoo's recent post about 3D printed parts and am hoping to learn more - potentially even trying this out in the not so distant future.
As for the rest of the bike - I hope to find time to complete it in the next week or two. Will post more when completed, but also will respond if questions/comments or useful criticism.
1 - 20 of 32 Posts
I will play with things with the shock. I guess when I say mostly linear I mean not ridiculously regressive. Without spending too much time, and somewhat secondary to fitting the shock and not having to complicate things too much, I tried to pick a pivot point with minimal change in leverage ratio from start-to-finish. For reference, according to Linkage, this is what I end up with in that regard:
![Rectangle Slope Plot Line Font]()
So I do have a question for the more experienced/knowledgeable than I... With other people's similar frames to what I am building, I see various methods of bridging the upper portion of the rear triangle (and even some with no bridging). Space is tight for a full tube bridge, so I was considering something like shown below, machined from bar-stock.
![Wheel Tire Bicycle Bicycle wheel Bicycle wheel rim]()
![Cylinder Drawing Pipe Metal Tool]()
I have done this before and it works reasonably - the fact that I have done it and know it works is appealing.
But I have seen a few bikes that instead use a bolt on piece, like this picture of a Starling bike shown below. That is also tempting because it could be done with a few H20 bosses and a flat plate.
![Bicycle Bicycle tire Tire Automotive tire Bicycle frame]()
I feel like I have a reasonable understanding of what both options do for the most part - and feel like I would prefer to add one of them - but I don't know if one is better than the other. Does anybody have more insight about/experience with this?
I have done this before and it works reasonably - the fact that I have done it and know it works is appealing.
But I have seen a few bikes that instead use a bolt on piece, like this picture of a Starling bike shown below. That is also tempting because it could be done with a few H20 bosses and a flat plate.
I feel like I have a reasonable understanding of what both options do for the most part - and feel like I would prefer to add one of them - but I don't know if one is better than the other. Does anybody have more insight about/experience with this?
1 - 20 of 32 Posts
