Singlespeed Bike Build Project
SingleSpeed Biking

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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.

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.

The "Single Speed - One Is All You Need" cap installed and on display.

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.

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.

The rear triangle hinge is the center for the rotation that adjusts the chain tension.

The adjuster for the chain tension is on the bottom bracket. The two large bolts on the bottom hold the rear triangle in place.

The frame still looks pretty normal when viewed down the center.
The frame comes apart for traveling. Four bolts hold it together and double as the chain tensioner.
When bolted together the frame needs no other mechanism to adjust the chain tension.

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.

7 May 2003

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.

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.

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.
Seat stay hinge
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.
Frame from behind

It almost looks like it could be ridden. Almost. Kind of raw.

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.

The stay bracket came out weighing 113 grams. If it were a cast part it would probably weight half that but at 113 grams it beats an eccentric bottom bracket or is at least the same weight if the bolts and the brazed on nuts are included. It took a lot of hand filing to get the part to where it looked like I wanted it to.
Stay mount
The stay mount bolts on to the nuts that are brazed on to the bottom bracket. The stay mount is ready for the stays to be brazed on. It will look better once it's cleaned up but the parts fit.
Stay mount on bottom bracket
The stays are on the stay mount and ready for alignment.

A wheel was place in the dropouts and after a little tweeking the alignment is acceptable. There is a slight list to the right that will be fixed later by filing a few thousands of an inch of the dropouts.

Chain stays attached to mount

Current state of the frame

2 May 2003

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.

The triangle is together!

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.

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.


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...

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.