Early this spring, I ended up tearing my Supraspinatus and Infraspinatus muscles in my right shoulder (those are two rotator cuff muscles for the uninitiated). But just before all that unfolded, I had JUST finished up the latest Snakedriver prototype. Despite the injury, I soldiered on and sent the prototype out to Cerakote. I even managed to miter, weld, face, chase and ream 3 titanium singlespeeds with two torn rotators before I knew they were torn. Go figure! I had injured my right shoulder about 2 years ago, but had since fully recovered after going through PT for several months. I had a false sense of security this time since pain and mobility were so much better. But once I got the MRI diagnosis, and by that time all the pain/inflammation were gone… It was really apparent mechanically my right shoulder just did not work as intended. So here I am, in a pillow sling for the next 6 weeks for an unexpected pause. Surgery went incredibly smoothly. Sleep is really good and I’m pretty much pain free only 1 week in. I’m staying positive and spirits are high. But that prototype Snakedriver? Well I wrapped that up JUST before surgery… and its sitting down in the basement Bike Dojo. Waiting. It’s a heck of a motivator to recovery and get back on the bike.
I spent the winter making updates and tuning construction methodology for the last little pieces of the puzzle that were nagging loose ends. I’ll detail those below. (What’s even more comical is I detailed a lot of these changes back in May when the prototype had just been back from Cerakote and was finally assembled… Sorta forgot about that! I guess I was more stressed and distracted than I thought.) There were 4 primary loose ends that needed further refinement:
1. The rockers width and its compatibility with worst case scenario air shocks.
2. The rocker / seat stay tip junction had a tad bit of unresolved tolerance stack.
3. The hardware deployed for that same rocker / seat stay tip junction.
4. The lower shock pivot fabrication approach with a bent down tube at this location had inconsistent results due to the variability of those 853 DT’s springback.
Problem number one was relatively easy to resolve. Getting my hands on shock models? That proved a tad difficult, but I reverse engineered a Fox air shock and scored the correct RockShox file from my Sram OEM contact. Once I had those two STEP files, narrowing up the profile for shorter riders and maximizing compatibility was straight forward. After resolving this, I am going to refine the rocker one last time with a revised center profile for ease of manufacturing, and with the use of extended race bearings, eliminate a set of spacers for the main rocker pivot and make those seat stay bearing bores more robust. Everything worked to plan, but like most projects… there’s things you don’t see till you get the part in hand and fiddle with a few full scale assemblies. But that will do it. Here’s a few shots of that new rocker.
Lets not forget an official parts count shot… Who doesn’t appreciate all the necessary hardware all laid out? I don’t think there’s anything finer albeit perhaps a close second would be a good old fashioned exploded view drawing (of which once all this is finalized, you can be your buttons I’ll be making!)
Another angle so you can see the bearings…
There’s a pair of bearings missing from the above photo for the main pivot for reference sake. Enduro MAX BOSL 6900 and 6901 deployed throughout the Snakedriver for those wondering.
Next up is the rocker seat stay time configuration. I deciphered where a bit of “wiggle” was coming from and it was the thread tolerance on the hardware I was using. I have two solutions going currently that both serve well. This iteration involved a custom M10 bolt while the other is a stock M10 shoulder bolt modified in-house to accept an M5 bolt and washer. This iteration uses the M10 custom bolt but I’ll be moving to an extended race bearing in this interface along with both the main pivot and rocker pivots eliminating 4 washers and the need to have a stepped interface at the rocker / seat stay tip. The whole assembly will just be more robust. Just need to put this through its paces before I know which configuration to go with be it custom bolts or an in-house modified solution. Here’s a look at that setup.
Problem 3 involves much of the above of problem 2. Here’s that one bolt solution:
And here’s two shots of that second option using an M10 shoulder bolt that’s modified in house. This one is a tad cleaner in the sense that I’m not tapping the printed part post print. I simply plunge through the part with a TiALN coated HSS 4 fluted end mill. It’s pretty straight forward work which I kinda like. But we’ll see how this newish option holds up over some trail time beating. I know I have this one in my back pocket and whats interesting is the other option can be converted to this option at a later date with some care…
Ok.. now for problem number 4: The lower shock mount. This seems pretty straight forward but it was a nagging one to solve as I had several ideas about how to go about this. The origin of the problem stems from the fact I was bending a Reynolds 853 down tube and those suckers are stiff as all get out. That resulted in mixed spring back rates so the bends weren’t consistent and THAT would throw off where the water jet cut lower shock mounts sat in space. SO each one had to be hand mitered and fitted. Ok for prototypes, but if its a production environment? Forget it… So I arrived at ditching the bent tube, leaning on a printed part that is consistent each and every time and a laser cut lower shock mount that once mitered, snaps right into place. A 1 hour finicky job turned into a quick and painless one thanks to lots of front end design time and simple tooling.
Here’s the seat tube assembly with that printed part mentioned above that lends a consistent placement for the DT:
This part will see further refinement to pull material out of it and make it more compact:
And the refined lower shock mount. This may eventually get a flip chip to make room for the stock configuration of the shock that seems to be how companies offer it which is 185×55 vs 185×50.
Notice the stock shock bolt hardware. Easily acquired at a local hardware store or via McMaster Carr. Those were the 4 main hurdles to jump but there were additional details that I was still mulling over and that centered around tucking the rear brake caliper inside the rear flex pivot assembly and what standard to use. I had a few ideas, some proprietary but I settled on good old ISO so customers can source stock adapters for 160 or 180mm rotors (200 fit but thats overkill IMO for this use case…). Here’s a few shots of how that all came together:
Last but not least was the dropper port configuration. I had been using a Salsa port grommet but that configuration and orientation was a bit nitpicky. I ended up going with a refined port with integrated internal routing designed into the printed lower main pivot part. You can see that here:
The smoother path it created here:
And what the inside looks like before its all assembled here:
So there you have it. A lot of thought, design, methodology assessment and refinement went into all of this one. Although I have to wait, I’m looking forward to earning this one once I get the green light from my surgical team and physical therapist. Plus there’s two suspension setups I need to test. First is Fox (as pictured) and well… the second? I’ll leave that for later. Here’s a few more shots for you all. If you want to see the full build set, head on over to Flickr. In the meantime, burn some turns and put in some miles for me this summer will ya?
Post Script: I should also mention that along with those 4 big revisions, there’s a slew of refinements in this next iteration. Although I’ve been making refinements all along the way since first building V4, which you can see in detail here, every single part of this bike that make up V4.2 has undergone a complete redesign from the ground up. Some parts, its incredibly obvious where as others are more subtle. Take the dropouts for example. Both the left and right sides underwent a lot of refinement:
Both are internally reinforced and the overall size has been reduced. I’m going to further refine both of these to be a tad smaller, shaving weight and added cost while retaining strength and durability and layering on a tad more clearance for the ISO mount and how that gets welded in place.
The swing arms yoke also saw a lot of refinement. Externally the shape and transitions were refined while the inside was heavily updated. The internal structure has a lot of relief to reduce weight while retaining strength and stiffness. I’m going to move away from the keyed pivot axle so the left and right use large M12 flat head screws for ease of post print machining and maintenance/upkeep along with common sourced parts. Lastly I’ll also move over to extended race bearings in this location to eliminate two 2mm in-house turned shims. No more shims on any of the connections.
The main rocker pivot assembly was completely redesigned to use a mix of waterjet cut parts that are post machined with an in-house turned center hub. This really freed up a lot of weight and allowed the part to be easily manufacturable at the fraction of the cost of the printed part.
One last revision that doesn’t seem that consequential but is rather important are the number of cable carriers on the down tube. I originally had the water bottle mounts which and 4 cable carriers but updated this to the bottle mount being a Salsa anything mount that allows the rider to shift where the bottle is but have 5 cable carriers total (and a rider could potentially add the two under the bottle mount for added security). The run between the one closest to the head tube and the next mount was pretty long. Adding that 3rd bottle mount to become an anything mount configuration shortened the run, allowed the cables to be overall neater and held more securely. I’m still using shrink tubing to organize the runs but that takes some planning and this just allows a rider to run things without that added fuss.
Snakedriver Updates
Early this spring, I ended up tearing my Supraspinatus and Infraspinatus muscles in my right shoulder (those are two rotator cuff muscles for the uninitiated). But just before all that unfolded, I had JUST finished up the latest Snakedriver prototype. Despite the injury, I soldiered on and sent the prototype out to Cerakote. I even managed to miter, weld, face, chase and ream 3 titanium singlespeeds with two torn rotators before I knew they were torn. Go figure! I had injured my right shoulder about 2 years ago, but had since fully recovered after going through PT for several months. I had a false sense of security this time since pain and mobility were so much better. But once I got the MRI diagnosis, and by that time all the pain/inflammation were gone… It was really apparent mechanically my right shoulder just did not work as intended. So here I am, in a pillow sling for the next 6 weeks for an unexpected pause. Surgery went incredibly smoothly. Sleep is really good and I’m pretty much pain free only 1 week in. I’m staying positive and spirits are high. But that prototype Snakedriver? Well I wrapped that up JUST before surgery… and its sitting down in the basement Bike Dojo. Waiting. It’s a heck of a motivator to recovery and get back on the bike.
I spent the winter making updates and tuning construction methodology for the last little pieces of the puzzle that were nagging loose ends. I’ll detail those below. (What’s even more comical is I detailed a lot of these changes back in May when the prototype had just been back from Cerakote and was finally assembled… Sorta forgot about that! I guess I was more stressed and distracted than I thought.) There were 4 primary loose ends that needed further refinement:
1. The rockers width and its compatibility with worst case scenario air shocks.
2. The rocker / seat stay tip junction had a tad bit of unresolved tolerance stack.
3. The hardware deployed for that same rocker / seat stay tip junction.
4. The lower shock pivot fabrication approach with a bent down tube at this location had inconsistent results due to the variability of those 853 DT’s springback.
Problem number one was relatively easy to resolve. Getting my hands on shock models? That proved a tad difficult, but I reverse engineered a Fox air shock and scored the correct RockShox file from my Sram OEM contact. Once I had those two STEP files, narrowing up the profile for shorter riders and maximizing compatibility was straight forward. After resolving this, I am going to refine the rocker one last time with a revised center profile for ease of manufacturing, and with the use of extended race bearings, eliminate a set of spacers for the main rocker pivot and make those seat stay bearing bores more robust. Everything worked to plan, but like most projects… there’s things you don’t see till you get the part in hand and fiddle with a few full scale assemblies. But that will do it. Here’s a few shots of that new rocker.
Lets not forget an official parts count shot… Who doesn’t appreciate all the necessary hardware all laid out? I don’t think there’s anything finer albeit perhaps a close second would be a good old fashioned exploded view drawing (of which once all this is finalized, you can be your buttons I’ll be making!)
Another angle so you can see the bearings…
There’s a pair of bearings missing from the above photo for the main pivot for reference sake. Enduro MAX BOSL 6900 and 6901 deployed throughout the Snakedriver for those wondering.
Next up is the rocker seat stay time configuration. I deciphered where a bit of “wiggle” was coming from and it was the thread tolerance on the hardware I was using. I have two solutions going currently that both serve well. This iteration involved a custom M10 bolt while the other is a stock M10 shoulder bolt modified in-house to accept an M5 bolt and washer. This iteration uses the M10 custom bolt but I’ll be moving to an extended race bearing in this interface along with both the main pivot and rocker pivots eliminating 4 washers and the need to have a stepped interface at the rocker / seat stay tip. The whole assembly will just be more robust. Just need to put this through its paces before I know which configuration to go with be it custom bolts or an in-house modified solution. Here’s a look at that setup.
Problem 3 involves much of the above of problem 2. Here’s that one bolt solution:
And here’s two shots of that second option using an M10 shoulder bolt that’s modified in house. This one is a tad cleaner in the sense that I’m not tapping the printed part post print. I simply plunge through the part with a TiALN coated HSS 4 fluted end mill. It’s pretty straight forward work which I kinda like. But we’ll see how this newish option holds up over some trail time beating. I know I have this one in my back pocket and whats interesting is the other option can be converted to this option at a later date with some care…
Ok.. now for problem number 4: The lower shock mount. This seems pretty straight forward but it was a nagging one to solve as I had several ideas about how to go about this. The origin of the problem stems from the fact I was bending a Reynolds 853 down tube and those suckers are stiff as all get out. That resulted in mixed spring back rates so the bends weren’t consistent and THAT would throw off where the water jet cut lower shock mounts sat in space. SO each one had to be hand mitered and fitted. Ok for prototypes, but if its a production environment? Forget it… So I arrived at ditching the bent tube, leaning on a printed part that is consistent each and every time and a laser cut lower shock mount that once mitered, snaps right into place. A 1 hour finicky job turned into a quick and painless one thanks to lots of front end design time and simple tooling.
Here’s the seat tube assembly with that printed part mentioned above that lends a consistent placement for the DT:
This part will see further refinement to pull material out of it and make it more compact:
And the refined lower shock mount. This may eventually get a flip chip to make room for the stock configuration of the shock that seems to be how companies offer it which is 185×55 vs 185×50.
Notice the stock shock bolt hardware. Easily acquired at a local hardware store or via McMaster Carr. Those were the 4 main hurdles to jump but there were additional details that I was still mulling over and that centered around tucking the rear brake caliper inside the rear flex pivot assembly and what standard to use. I had a few ideas, some proprietary but I settled on good old ISO so customers can source stock adapters for 160 or 180mm rotors (200 fit but thats overkill IMO for this use case…). Here’s a few shots of how that all came together:
Last but not least was the dropper port configuration. I had been using a Salsa port grommet but that configuration and orientation was a bit nitpicky. I ended up going with a refined port with integrated internal routing designed into the printed lower main pivot part. You can see that here:
The smoother path it created here:
And what the inside looks like before its all assembled here:
So there you have it. A lot of thought, design, methodology assessment and refinement went into all of this one. Although I have to wait, I’m looking forward to earning this one once I get the green light from my surgical team and physical therapist. Plus there’s two suspension setups I need to test. First is Fox (as pictured) and well… the second? I’ll leave that for later. Here’s a few more shots for you all. If you want to see the full build set, head on over to Flickr. In the meantime, burn some turns and put in some miles for me this summer will ya?
Post Script: I should also mention that along with those 4 big revisions, there’s a slew of refinements in this next iteration. Although I’ve been making refinements all along the way since first building V4, which you can see in detail here, every single part of this bike that make up V4.2 has undergone a complete redesign from the ground up. Some parts, its incredibly obvious where as others are more subtle. Take the dropouts for example. Both the left and right sides underwent a lot of refinement:
Both are internally reinforced and the overall size has been reduced. I’m going to further refine both of these to be a tad smaller, shaving weight and added cost while retaining strength and durability and layering on a tad more clearance for the ISO mount and how that gets welded in place.
The swing arms yoke also saw a lot of refinement. Externally the shape and transitions were refined while the inside was heavily updated. The internal structure has a lot of relief to reduce weight while retaining strength and stiffness. I’m going to move away from the keyed pivot axle so the left and right use large M12 flat head screws for ease of post print machining and maintenance/upkeep along with common sourced parts. Lastly I’ll also move over to extended race bearings in this location to eliminate two 2mm in-house turned shims. No more shims on any of the connections.
The main rocker pivot assembly was completely redesigned to use a mix of waterjet cut parts that are post machined with an in-house turned center hub. This really freed up a lot of weight and allowed the part to be easily manufacturable at the fraction of the cost of the printed part.
One last revision that doesn’t seem that consequential but is rather important are the number of cable carriers on the down tube. I originally had the water bottle mounts which and 4 cable carriers but updated this to the bottle mount being a Salsa anything mount that allows the rider to shift where the bottle is but have 5 cable carriers total (and a rider could potentially add the two under the bottle mount for added security). The run between the one closest to the head tube and the next mount was pretty long. Adding that 3rd bottle mount to become an anything mount configuration shortened the run, allowed the cables to be overall neater and held more securely. I’m still using shrink tubing to organize the runs but that takes some planning and this just allows a rider to run things without that added fuss.
Adding that 5th carrier just makes everything so much more secure. I run the setup with all 5 cable carriers for the record. And the frame will ship with all 5. All of this is to say a lot of thought, design and lessons have been applied to this build. Here’s that build album again for everyone who wants to dive in deeper to all the details that went into this next prototype.