I am getting a custom frame made and it is driving me crazy thinking about it.
I have been riding a lot of rigid as the frame is supposed to be a technical rigid ride anywhere bike. I have realized that the lack of suspension limits my riding very little. I can't climb stuff that is as steep and rough. I can't bomb down stuff as fast and thoughtlessly. I can't do big drops. I get tired out after a couple hours. Who cares. It is fun.
Here is my proposed geo for the upcoming rigid:
Based on a 475mm, 45mm offset A-C fork:
Chainstays- I will likely run 16.72" based on what my current 33X21 gearing allows.
HTA: 70 degrees.
Front Center: 25.75"
BB Drop: 70mm (~11.75")
ESTA: 73 at my saddle height of 31.5" above the BB
WB will end up at 42.25" with this set up. TT will probably be in the ~22.75" range (steep STA remember), and Reach will be ~16.5" I would consider extending the reach 1/2" which would also extend the TT 1/2", but no further. Also might consider going a touch slacker.
Random thoughts.
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3 comments:
I'd be a little tentative about running a bottom bracket that low, especially with all the rocks where you are. The BB drop on my Niner is 60mm, and I'd say it's at least a cm too low. With the big wheels, you can afford to be up higher and still be below the hubs--why wouldn't you to avoid having to ratchet the pedals?
That is a really good point, and I have agonized a bit over BB height, especially given that this is a technical terrain bike.
I have ridden 11.5" on my EBB bike and it rides okay and I can time pedal strokes, but I really bash the bash ring a lot. With the EBB up it is 11.9 and that is nicer.
My current rigid set up is 11.75" and I seem to have no particular difficulty with it, but a do ratchet a lot. If I were sporting small gears instead of SS, it would be different since I would try to pedal through those tough sections instead of ratcheting it as I need to do on the SS to keep in the powerband.
Essentially I want it as low as possible in case I ever want to use a big long fork on this bike. I don't want it jacked too much into the air.
If I was 100% committed to full rigid on this bike, I would probably raise it to 12"(60mm drop or so), and I may still do that.
One other consideration: this particular custom allows an extremely short chainstay. As that big wheel moves closer to the BB, the BB has less exposure and time to hit those rocks as you go over them since the rear wheel comes in fast. I think this allows one to get away with a lower BB. Longer chainstays need higher BBs to avoid high centering (a tandem is an extreme example of this)
I am open to input that challenges me on this design, so keep it coming. If I can defend it, then I know I have it nailed:)
This bike seems insanely short given my height, but I appreciate the "instability" of a short wheelbase and what it allows me to do. I have bikes at least this short in the "reach" measurement (horizontal from BB to HT) and I fit them fine while standing.
cool who makey? hope you enjoy it!
was that first vid the spot where you took a call on our last ride?
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