Considering a homemade build

[nolipoli]

Apparently one doesn't want much more chain growth than around 20mm total otherwise you get big kickback in the pedals.

At the same time you do want enough anti-squat to avoid pedal-bob (but this changes depending on what gear you are in).

 

Leverage ration is pretty linear progressive, which means it will ramp up as it moves through its travel. This means I will be able to run it quite plush for small bump sensitivity without bottoming out too easily.

[Burner]

Those results look pretty good, I'm sure the bike will feel quite plush with enough response from the progressive rear end to make it fun. I'm still wrapping my head around anti-squat and gearing. Great job

[nolipoli]

Anti squat has a lot to do with where the chain runs relative to your pivot (or virtual centre). If your pivot is above this line it will resist squatting (pedal bob). There is a limit though, because it is also linked to your pedal feedback.

[Burner]

ok, ...did some reading up and its not too hard to resist squatting if you just place the linkages/pivots well... but in that lies the wizardry lol

 

So what your'e saying is the main pivot should be above the bb centre line (depending on the suspension system used)??

[nolipoli]

ok, ...did some reading up and its not too hard to resist squatting if you just place the linkages/pivots well... but in that lies the wizardry lol

 

So what your'e saying is the main pivot should be above the bb centre line (depending on the suspension system used)??

 

Well mine is basically a single pivot layout, so it is quite simple. If you draw the line that the top part of the chain would follow from front chainring to rear cog, the pivot should be above that line. Effectively this makes a triangular shape if you draw lines from chain contact points to the pivot point.

 

When you pedal, the tension force in the chain is going to try and change the shape of the triangle (shortening the chain section). This tries to pull the back wheel downwards towards the ground, creating the anti-squat.

 

As far as I know, when you are working with a more complex system, you work around the Instant Centre (Virtual Pivot Point), which might move around as the suspension compresses. Maybe my next bike will explore this a bit. In the meantime, I think I want to go simple first so I can understand easier.

[Burner]

Aaaaah ok....makes sense when you break it down like that. Hopefully by the end of the weekend I'll make some time to do a 3D scan of myself on a bike in a seating position I'm comfortable with. I'll use that data to manipulate the 3D model even further and check if my initial measurements and assumptions were on track

[nolipoli]

This thread has been a little quiet for a while, so I thought I would post something that Borriz just 3D printed for my project. 

It is the bottom shock mount that is needed to create a rigid joint between shock and seat stays, effectively making the McPherson strut.

 Thanks Borriz!

 

[Burner]

Nice work nolipoli!  Did you design the part and your friend print it?

 

I apologize for the quiet thread. I just relocated to Pretoria North and getting settled in. Hopefully I will get the 3D scan done soon, other than that, the design is carrying on slowly. I now have access to a big composite factory  , and some high tech tooling. Over the next few weeks I'll probably sort out my time management and fall back into the project, but for now I'm going to try out the Hakahana trails...I hear they're awesome

[Burner]

http://www.pinkbike.com/news/nicolai-mojo-geometron-first-ride-2015.html

This is the type of methodology I'm all for. Throw all the "limitions" and marketing mambo jumbo you read and do some real systematic testing. Don't worry what others think, create something insane

 

I've been riding an intense Uzzi this past weekend and I'm still left wondering if the coil sprung DHX 5.0 gives it the progressive feel or is it the VPP suspension system? 

 

Then, I measured the actual rear travel on a 2011 Trek fuel and it's about 140-144mm of rear travel. I dont know if I've mentioned it in my past  posts but anyone that rides with me knows that I always say the fuels feel way more than the 120-130mm.they claim.

 

I can't decide between the floating rear style suspension or the dw-link/VPP type. Both feel very good for ME and MY personal riding style. Something still needs to tip the scales in either direction for me......only more riding will tell

[nolipoli]

I wondered what you were up to...

 

Yeah, I designed that part - Borriz advertised some printing services on here so I figured I would give it a try, just for fun.

 

I have stalled a little right now - had to wait for ages for some laser cutting, and now waiting for some lathe time. Only then can I get the welding done.

I really need to get this project finished now.

[Burner]

I've relocated about 1700kms from my old home....so busy settling in and still travelling in-between. I think the stalling and little breaks actually give you time to reflect on your design/fabrication process and lets you make sense of it all before you carry on. I'm confident of my angles after reading the article on the Geometron. I went down to 64 deg head angle and was not sure if it will be practical, but I'll give it a go. I also found out about a chrome-moly  in Gauteng which is good....so I'm thinking of a carbon/composite front triangle and metal rear end.

[nolipoli]

I've relocated about 1700kms from my old home....so busy settling in and still travelling in-between. I think the stalling and little breaks actually give you time to reflect on your design/fabrication process and lets you make sense of it all before you carry on. I'm confident of my angles after reading the article on the Geometron. I went down to 64 deg head angle and was not sure if it will be practical, but I'll give it a go. I also found out about a chrome-moly  in Gauteng which is good....so I'm thinking of a carbon/composite front triangle and metal rear end.

Congrats on the move. 

 

I am trying to not reflect at the moment, because I really want to finish this bike and ride it a bit before I change anything else.

 

If I remember correctly, you are looking at quite long travel (150-160mm?), so a 64 degree HA should be awesome. 

 

If you are going to do it partly in Chromoly, you may want to bang out a test mule front triangle in Chromoly too, before committing to a your carbon. At least that way you'll be able to quickly assess your geometry. 

[Burner]

Congrats on the move. 

 

I am trying to not reflect at the moment, because I really want to finish this bike and ride it a bit before I change anything else.

 

If I remember correctly, you are looking at quite long travel (150-160mm?), so a 64 degree HA should be awesome. 

 

If you are going to do it partly in Chromoly, you may want to bang out a test mule front triangle in Chromoly too, before committing to a your carbon. At least that way you'll be able to quickly assess your geometry. 

Thanks

 

I'm with you on the 'getting it done' bit....or you'll end up confused like me.

 

Yes the bike I'm working on is a 150/160mm frame. Maybe I should make up a tester with chromoly in one go....I just need to settle on my design   Picking up my scanner again today and will hopefully scan in my seated position soon and post it up here. I'm sure there's a market for scanning in riders and doing a number of studies on seated, standing, climbing and descending positions for better riding. I'll get there one day...need to figure out how it's going to benefit me first, if any..

[Jimmy 2.0]

.

[Jimmy 2.0]

This thread has been a little quiet for a while, so I thought I would post something that Borriz just 3D printed for my project. 

It is the bottom shock mount that is needed to create a rigid joint between shock and seat stays, effectively making the McPherson strut.

 Thanks Borriz!

 

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IMG_3109.JPG

IMG_3110.JPG

IMG_3112.JPG

howzit guys been following this thread very closely any updates on how the builds are going? As well as pictures please????

[nolipoli]

Hey Jimmy, 

 

I don't know how Burner is doing, but I suspect his life got very busy after moving up to Gauteng.

 

Me...I have been battling to finish up some details before getting the bits to a friend of mine that is going to weld it up. Mostly it has been a lack of access to a lathe that has held me up.

I actually ended up giving a couple of the parts, main pivot bearing cups, that needed turning to an engineering shop around the corner from my office, and had them do it. Sadly I have noted that the one cup has been set up skew and I will now need to fix it before welding anyway. Can't trust anyone these days!