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What have you done to strengthen the swing arm at the lower shock mount? It seems to me that that part of the swing arm is not designed for taking such a load.
Mak's step-by-step guide to building a not unique, but fun, cafe bike.
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Nothing yet. The arm is going to go through a lot of trauma before it’s all said and done. Without going into much detail...because i don’t know how i’ll do it yet...but at the end of this project there will be a 180mm tire on the back. Maybe a 170, but i’m shooting for a 180.
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Okay some more pictures...I've been asked a few times if I really know what I'm doing here...and the answer is "of course not!" But I thought I would make it a point to EXPLAIN why I went with this shock, in this location, at this angle,etc and so forth. Everyone who's gone and done something like this seems to want to keep all their math and details a secret which leads me to two conclusions:
1. They made it up to look the way they wanted because the bike was meant to be looked at, not used...a theory often supported by the ties on these things.
~or~
2. They don't want to give away their hard earned work.
Honestly I'm not offended by #2, and I don't care enough about #1 one to be concerned with it. I'm going to try and make it a part of this build to explain how I'm doing the single shock, how it's working, what should be done different, what changes I make, and so on.
So before I went to my pile of shocks I measured travel of the rear from my desired ride height up to the extreme of the swingarm could muster. At the brace in the arm there was just under 2.25" of swing...it was close to 54mm.
I've got a large collection of rear shocks and strokes anywhere between 40mm and 90mm. I wanted an eye-to-eye shock for ease of mounting...I don't want to have to press a bearing/bushing into the arm to make it work. That left me with the CBR954RR shock and a 2007 YZF-R6 shock. The R6 shock is sprung at 10.8kg/mm and has a 67mm stroke. The 954RR shock is spring at 14.8kg/mm and has a 57mm stroke.
I went with the 954 shock because it was almost exactly the right stroke and is already designed to work with a considerably heavier spring. What's more is that the linkage on the R6 is pretty long and the bike has a slightly shorter travel...which means the stroke on it is going to slower. The 954 shock was part of a short arm system that's already designed to be under high stress and moved rapidly (shorter stroke). It just made sense to me to use the 954 shock (from my collection of old used stock shocks). I'm sure there are better options out there.
Now as said earlier the spring is a bit soft, but there are plenty of options out there for replacement springs. I pulled the shock to maximum compression (minus maybe 2mm...the next tooth on the winch was hiting the bump stop).
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This gives me just over 7" total wheel travel in the back...which I believe should be sufficient...but it is still quite a bit shy of the mechanical limit of the arm. Means even if I completely bottom out the shock I'll still have a little room to keep things from breaking.
If my math is right I believe that what I need back there is a 16kg/mm spring. I'm going to wait until I have the tank and everything else in place and then measure for the appropriate spring.
1. They made it up to look the way they wanted because the bike was meant to be looked at, not used...a theory often supported by the ties on these things.
~or~
2. They don't want to give away their hard earned work.
Honestly I'm not offended by #2, and I don't care enough about #1 one to be concerned with it. I'm going to try and make it a part of this build to explain how I'm doing the single shock, how it's working, what should be done different, what changes I make, and so on.
So before I went to my pile of shocks I measured travel of the rear from my desired ride height up to the extreme of the swingarm could muster. At the brace in the arm there was just under 2.25" of swing...it was close to 54mm.
I've got a large collection of rear shocks and strokes anywhere between 40mm and 90mm. I wanted an eye-to-eye shock for ease of mounting...I don't want to have to press a bearing/bushing into the arm to make it work. That left me with the CBR954RR shock and a 2007 YZF-R6 shock. The R6 shock is sprung at 10.8kg/mm and has a 67mm stroke. The 954RR shock is spring at 14.8kg/mm and has a 57mm stroke.
I went with the 954 shock because it was almost exactly the right stroke and is already designed to work with a considerably heavier spring. What's more is that the linkage on the R6 is pretty long and the bike has a slightly shorter travel...which means the stroke on it is going to slower. The 954 shock was part of a short arm system that's already designed to be under high stress and moved rapidly (shorter stroke). It just made sense to me to use the 954 shock (from my collection of old used stock shocks). I'm sure there are better options out there.
Now as said earlier the spring is a bit soft, but there are plenty of options out there for replacement springs. I pulled the shock to maximum compression (minus maybe 2mm...the next tooth on the winch was hiting the bump stop).
This gives me just over 7" total wheel travel in the back...which I believe should be sufficient...but it is still quite a bit shy of the mechanical limit of the arm. Means even if I completely bottom out the shock I'll still have a little room to keep things from breaking.
If my math is right I believe that what I need back there is a 16kg/mm spring. I'm going to wait until I have the tank and everything else in place and then measure for the appropriate spring.
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221 Posts
Just to note, when I pulled the arm up to full compression there was no flex in it at all. I'm still bracing it, but it is pretty strong for what it is.
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221 Posts
eBay tank sits a little higher than I thought it would, but I think it looks okay. Will bring the seat down a little. Once I get the forks squared away I'll be able to adjust the rear mount to get the trail where I need it to be, then I can start sorting out mounts for the tank and seat.
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221 Posts
The forks are literally the easiest part. You take whatever front end you want and just swap bearings...or press the stem out and install your old stem and a bushing, though this part requires a machinst.
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130 Posts
But then the can of worms is open on wheel choice;
1) use modern front cast wheel that goes with those forks
2) adapt Comstar to fit modern forks
3) go Cognito moto custom spoke wheels (front & rear) $$$$$$$
I can't commit to which of those choices I will make.
I have been browsing for a set of forks to sit in my garage, until I decide...
1) use modern front cast wheel that goes with those forks
2) adapt Comstar to fit modern forks
3) go Cognito moto custom spoke wheels (front & rear) $$$$$$$
I can't commit to which of those choices I will make.
I have been browsing for a set of forks to sit in my garage, until I decide...
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221 Posts
The comstars do not clash terribly with the r6 wheel so that is a cheap, easy option.
My plan is to either adapt the 5.5” r6 wheel or to go laces front and back. One is hard but won’t cost a lot...the other is easy and costs appropriately
My plan is to either adapt the 5.5” r6 wheel or to go laces front and back. One is hard but won’t cost a lot...the other is easy and costs appropriately
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221 Posts
Got the R6 forks sorted out and set the bike at the rake/trail I'm wanting. Closer to the final stance. Need a stiffer string!
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221 Posts
I have a harder time with bars that keep my back upright...it's like my spine compresses with every bump. But my wrists are also getting weaker the older I get so clip ons are getting tougher and tougher. Honestly I'm getting to a point where I have more fun building them than riding them.
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221 Posts
Started on the subframe today. It's not pretty but when I do these projects I really like to reuse as much as I can. Would have been easier if I'd just bought a loop but this'll do the job.
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Also my new exhaust showed up today
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Also my new exhaust showed up today
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I am going to have to get my vision checked. i think i see too many runners on that one!
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221 Posts
You should take a look at how much a single 1.5” mandrel 90 costs on ebay, then look at how much a civic header (which has 8 of them) costs
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221 Posts
New headlight, some gussets under the subframe, and I started getting that Civic exhaust installed
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