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I built my own frame at the United Bicycle Institute. It is be
a singlespeed with a unique chain tensioning system that allows for
vertical dropouts with disk brakes and also allows the frame to be taken
apart for traveling. The bike build project's progress is documented on
this page in reverse chronological order.
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20 June 2003
Finally all the parts are in. I picked up the rear cog from True
Precision and the bike is finally complete.
The tensioning system as seen from below. The rear triangle pivots
on the two bolts on under the seat and the two bolts on the bottom
bracket lock the triangle in position.
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The "Single Speed - One Is All You Need" cap installed and on display.
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14 May 2003
The frame is back from the powder coater. Now I can start putting
parts on it. It might take a little time to get them all.
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9 May 2003
It's ready for power coating! The frame has been sanded and is ready
for powder coating. There are some minor flaws that could either be
sanded out or filled but powder coating should fill them in.
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The frame still looks pretty normal when viewed down the center.
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The frame comes apart for traveling. Four bolts hold it together
and double as the chain tensioner.
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When bolted together the frame needs no other mechanism to adjust
the chain tension.
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8 May 2003
Not much to show today. Frame prep is complete and rough filing is
done. Sanding is all that's left. After sanding I'll post pictures of
the various details. The frame now weighs less than 4.6 pounds.
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7 May 2003
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Bridges are on and the bottle holder inserts are brazed in. No
other braze-ons were needed since there are no gears to change and
hydraulic brakes don't need guides or stops. Clean up has
started. At this rate the bike will be ready for powder coat by
the end of the week.
I've discovered that the inner corners are next to impossible
to file smooth so I bought a dremel and tomorrow the dremel tool
will be used to grind out the hard to reach places. Great care
will be taken to avoid grinding through a tube. That would be very
bad.
The weight before filing and cleanup is just under 4.7
pounds. With any luck cleanup will bring the weight down to 4.6
pounds. In any case the weight is on the lower side of the target
range.
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6 May 2003
The hinge works! All that's left to do is put in the bridges,
braze-ons, and clean it up. There is a lot of cleaning to do. Weight is
coming in as expected. The frame is 4.6 pounds now. The bridges and
braze-ons need to be added and lots of excess brass needs to be
removed. It may end up close to the current weight or it may bump up a
couple of onces. Either way it will easily be sub 5 pounds for a frame
that comes aparts for traveling and is set up as a singlespeed with
disk brakes.
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The seat stays were added to the chain stay and dropout
assembly. The hinge at the top of the seat stays works fine. There
is a little binding on the bottom bracket if the bolts are not
loosened enough. That will be taken care of with a little
filing.
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Seat stay hinge
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A view from behind. It looks pretty much like a normal bike but it
comes apart. Lots of tire clearance. I planned for at least a 2.5
inch tire and it looks like a 2.6 or maybe a 2.7 inch will fit.
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Frame from behind
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It almost looks like it could be ridden. Almost. Kind of raw.
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5 May 2003
I am so stoked. The frame is working out as planned. The stays went
on as designed and the stay mount slides for chain adjustment. The tire
and chain ring clearance are fine even with the short chain stays. It's
all falling into place.
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Current state of the frame
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2 May 2003
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The last two days have been great. Lots of hand fitting. All the
miters are complete and the main triangle of the frame brazed
together. It's a rush to know that you can really put together
your own frame. There will be a lot of clean up but all the
joints look pretty reasonable.
The fittings for the chain tensioning system are also on the
frame. The system will allow the frame to be taken apart for
placing in a suitcase and will also allow the chain tension to
be adjusted. The rear triangle pivots on a set of bolts where
the seat and top tube meet. The triangle is locked in place by
two bolts underneath the bottom bracket. The parts are being
made by hand as they are fitted to the frame. That makes them a
little heavy but with any luck the weight will drop as excess
metal is removed. The goal is to stay under the added weight of
an eccentric bottom bracket plus two S&S couplers. That adds
up to about 1.3 pounds. If the frame is between 4.5 and 5.0
pounds that would be excellent.
No more work over the weekend. Racing in the Spring Thaw on
Saturday.
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The triangle is together!
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30 April 2003
| Plan B is the one. It's definitely a novel way to
adjust the chain tension. More details as the parts are made.
The bike has been designed. The head tube is as long as I could
make it so that the bars will be up as high as possible without a
big stack of spacers on the headset. The top tube is somewhat
shorter than normal also. This brings the bars up and
back. Perfect for singlespeeding and standing. The rear wheel is
pulled in as tight as possible to keep it from spinning when
standing. Seat tube angle is 72°, head tube angle is
71°. This is about as singlespeed specific as it gets. |
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A sketch of the bike and the trick chain adjuster on the bottom bracket.
The first braze for the bike. It's the chain stay brazed to the modified dropouts. The derailer hanger has been ground off.
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24 April 2003
| The dropouts are ready, milled by Pierre Kamber
at Precision
Identity. Just in time for me to take to the bike school Sunday. I had
come up with a plan B just in case so I'll see what option makes
the most sense when I get to the school. Maybe both... |
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18 March 2003
There are some manufacturers that make bikes with horizontal dropouts
and disk brakes but no one seems to make the dropouts available to
other builders so I designed my own and am having it machined. I gave
Roland and Pierre Kamber at Precision Identity an
annotated drawing of the dropouts I wanted.
| Pierre created the CAD drawings from my
specification and the part is now ready for cutting on a CNC
machine. |
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