Cross Bike Build

 

I have been working on my next bike build and it is nearly complete.  I just have some final touch up and details to add before sending it out for painting.  I will be placing the cable guides on next and a seat stay bridge.

 

Building bike frames gives you a whole different perspective on the bike industry.  It makes you evaluate how much you care about frame weight, ride quality, bike geometry, etc.  I had some fun on this frame adding in some interesting characteristics.  It is a bit of an experiment and I look forward to seeing how it rides. 

 

The first choice I made was to create a bike that was a mix between mountain bike and cross bike.  I used a much higher bottom bracket to create a lot of clearance for actual single track riding.  My current cross bike has a medium high BB and I pushed this one up a bit.  I had to sacrifice making it easier to mount/remount with a lower seat to create more clearance for pedals in the rocky trails around Boulder.  It is likely that I will also experience less ability to carve the corners with this change, but I shouldn’t ever hit pedals like I have in the past.  It will definitely feel like a taller bike.

 

In regards to stiffness/comfort, the plan was to have an uber stiff frame horizontally, but to make it pretty forgiving.  So I used some very light weight tubes for the seat stays and the seat tube.  I also used curved seat stays to help flex under load.  I will be adding an additional bridge between the seat stays to keep it stiff.  In contrast, I used a heavy duty bottom bracket and chain stays.  I sacrificed clearance on the chain stays to have a stiffer bottom bracket junction by using chain stays that are round and thick at the BB joint then oval for the tire clearance.  I can still run 35 mm tires, but there are only a couple of millimeters clear.   I had to do quite a bit of mod in the shop to get this to work right.

 

In the front end I designed a very tall head tube with some stiff tubing to create a 190 mm span that should keep my front end tracking very well.   Additionally, I created a more upright bike position.  Again, this is to find that in-between mountain and cross bike. 

 

In regards to weight, the frame is 4 lbs, which is actually quite light for this type of build.  I used mostly higher end Columbus Tubing (a mix of Life, Spirit, and Zona) and some basic lugs. 

 

I will be mounting all my cable guides along the top tube and not placing any bottle cages on the frame to keep it looking clean. 

 

I haven’t decided on the paint job yet, but I will be getting it powder coated.  So I will take any suggestions on color.

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