Any updates?
Homemade Split Pivot Gearbox DH Bike
- Thread starter TrueScotsman
- Start date
Sorry, just been so busy with work I haven't had time to do much more:-(
I been taking over the family business so my time has been spent elsewhere. At the moment I am getting ready for a trade-stand at the Fort William WC. Once the next couple of weeks are over I should be able to give it some more attention.
I will hopefully update then.
I been taking over the family business so my time has been spent elsewhere. At the moment I am getting ready for a trade-stand at the Fort William WC. Once the next couple of weeks are over I should be able to give it some more attention.
I will hopefully update then.
Right, sorry for the lack of updates/progress.
As I have said before, work commitments have been hectic lately.
Also, and this is a main contributor to my lack of any progress, I have figured out that my super, great, revolutionary idea to get 100% anti-squat is in fact.......BOGUS! Yup, the main idea that the bike design was conceived on, doesn't actually work. Graphically, on paper the idea is sound but I built a quick prototype of the actual set-up and found it to be no better than a standard g-boxx set-up.
This discovery has drained me of enthusiasm for continuing. I have, however, eventually decided that to abandon further work on the project would be a waste of time/effort/learning experiences, so the build is BACK ON!
I will outline the flawed logic/design in further posts.
Sorry to all those that have been waiting for progress updates. All notices of encouragement gratefully received!
As I have said before, work commitments have been hectic lately.
Also, and this is a main contributor to my lack of any progress, I have figured out that my super, great, revolutionary idea to get 100% anti-squat is in fact.......BOGUS! Yup, the main idea that the bike design was conceived on, doesn't actually work. Graphically, on paper the idea is sound but I built a quick prototype of the actual set-up and found it to be no better than a standard g-boxx set-up.
This discovery has drained me of enthusiasm for continuing. I have, however, eventually decided that to abandon further work on the project would be a waste of time/effort/learning experiences, so the build is BACK ON!
I will outline the flawed logic/design in further posts.
Sorry to all those that have been waiting for progress updates. All notices of encouragement gratefully received!
weld MOAR!!!!!!!!!!111111111oen
What was your idea?Right, sorry for the lack of updates/progress.
As I have said before, work commitments have been hectic lately.
Also, and this is a main contributor to my lack of any progress, I have figured out that my super, great, revolutionary idea to get 100% anti-squat is in fact.......BOGUS! Yup, the main idea that the bike design was conceived on, doesn't actually work. Graphically, on paper the idea is sound but I built a quick prototype of the actual set-up and found it to be no better than a standard g-boxx set-up.
This discovery has drained me of enthusiasm for continuing. I have, however, eventually decided that to abandon further work on the project would be a waste of time/effort/learning experiences, so the build is BACK ON!
I will outline the flawed logic/design in further posts.
Sorry to all those that have been waiting for progress updates. All notices of encouragement gratefully received!
LOL! not quite, but now you come to mention it!.......
Nah, the simple idea was to route the chain over an idler based ON the swingarm. According to the Tony Foale book (version1) the anti-squat line is the line from the rear tyre contact point to the intersection of the swingarm force line and the force line of the chain from front chainring to idler. Suffice to say that this is NOT the case if the front chainring is concentric on the swingarm. Follow me? For more info see the "Anti-Squat and idlers" thread. see here-
http://www.ridemonkey.com/forums/showthread.php?t=228831&highlight=anti-squat+idlers
I'll post up some pics of what i mean.
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here's a pic of what i mean;
Just make up an acronym for your failed idea, say it works and sell it any way. That's what any good bike maker would do.
I would buy one
ha ha! How about "Anti-Squat System With Idler Pulley Equilibrium"
+rep too funny
I think an ASSWIPE would improve my riding.
Anyway, here's some more photos of my failed idea (i have to remember that the system will still be OK just not as good as i hoped!).
This is the drive-side g-boxx mount;
As you can see the idler was to mount onto a vertical slot so I could use it to to adjust chain tension also (using a BMX chain-tug). Anyway, I thought it was quite clever!!
Here's a shot of both the g-boxx mounts in place;
I've some other photos of stuff (including the rough test piece that dashed my dreams!). I'll post them up over the next few days.
This is the drive-side g-boxx mount;
As you can see the idler was to mount onto a vertical slot so I could use it to to adjust chain tension also (using a BMX chain-tug). Anyway, I thought it was quite clever!!
Here's a shot of both the g-boxx mounts in place;
I've some other photos of stuff (including the rough test piece that dashed my dreams!). I'll post them up over the next few days.
Did you not perform any proper calculations on the suspension kinematics prior to starting manufacturing?! It's a shame that you have realized this midway through. You should at least finish the bike though.
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Still be okay for adjustable BB height.
I want to make a G-Box bike with a high virtual pivot bike with a vertical Marin type rear link with chain going up over link, and a front Marin type link.
I want to make a G-Box bike with a high virtual pivot bike with a vertical Marin type rear link with chain going up over link, and a front Marin type link.
As far as I am aware there are two ways to perform "proper" calculations- mathematically and graphically. As I am a more graphically-inclined person I used the "standard" Tony Foale method as outlined in his "Motorcycle Handling and Chassis Design" book. It includes a section on swingarm-mounted idlers and states that it is the force line from front sprocket to idler that is important.- (my mistake for not checking the latest, version2 of the book, apparently this chapter has been ammended!)
Another way is to put the design into a program like Linkage. Problem is that this program has been shown to have erors in the Anti-Squat calculations in the past- hence my "Anti-Squat and Idlers" thread here on RM- http://www.ridemonkey.com/forums/showthread.php?t=228831 well worth a read to understand the complexities.
It is very easy now to look back and say "what a dumbass!" at my mistake but everything looks easy in hindsight. What can you do but live and learn!
Last year I did some calculation and developed an Hydrid Method, half math and half graphical (Linkage). Link Link. I can do the numbers for your model if you want but it's going to be almost the same as if you don't have any Idler.
On the bright side, it's a clean design and you can use the Split pivot on the rear, even if it was a single pivot it would be a very clean solution without slider dropouts on the rear.
On the bright side, it's a clean design and you can use the Split pivot on the rear, even if it was a single pivot it would be a very clean solution without slider dropouts on the rear.
cheers V-Rock- i'll have a look at that. Now where's Google Translate!
*edit- just looked at Vrocks website- holy $*** ! He has been busy analysing all different types of suspension systems and even anti-dive forks- good work fella! I recommend taking a look!
*edit- just looked at Vrocks website- holy $*** ! He has been busy analysing all different types of suspension systems and even anti-dive forks- good work fella! I recommend taking a look!
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Anyway, I'll leave the theory to the "Anti-Squat and Idlers" thread, here's some moar pics of the build;
Cutting the heavy steel plate to form the jig table;
Welding on tabs to hold it in the (large) lathe;
Halfway through turning the jig table on the lathe to form a completely flat surface;
Cutting the heavy steel plate to form the jig table;
Welding on tabs to hold it in the (large) lathe;
Halfway through turning the jig table on the lathe to form a completely flat surface;
i envisioned you to be a younger bloke...Cutting the heavy steel plate to form the jig table;
Ha ha- that's my Dad!!!!
-he is doing most of the heavy duty work- he's better on the tools than I am. BTW I'm 32 and not quite as grey haired!
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Gutted for you that you're ideas haven't quite panned out, all the best lessons are learned from mistakes tho, sure you're next attempt will be even better again!
The bike will still seriously rock tho as it hasn't got a dumb arse shifter hanging off the back!
Keep the pics coming.
The bike will still seriously rock tho as it hasn't got a dumb arse shifter hanging off the back!
Keep the pics coming.
Wanted to bring this back up from the dead... anyone know what happened to this awesome project?