Custom Sizing Made Easy

Building frames for myself over the past few years, I’ve managed to get the correct size for myself by iteration.  However, you don’t have this luxury and need to get the correct size and geometry on the first attempt.  This causes a great deal of ‘brainpain’ for some of my customers!

Starling Cycles offers: head angle, reach, seat tube length and head tube length options.  I’ll discuss each of these in turn and try to make the job of picking your ideal geometry as easy as possible.

Head Angle

Current fashion is for slack head angles.  However, this is great if you’re a good rider and can control the bike, but the less able among us might appreciate something slightly steeper. 

With each model I will give my head angle recommendation based upon my riding experience of the bike.  For example, for the Swoop frame I recommend 64°.  For the Murmur, I suggest 65°. Some riders have gone as slack as 63°, this is great for strong dynamic and good riders.  But for myself, with my “fastest of the duffers” speed, the recommended angles feel better. 


Reach is the dimension from bottom bracket (your feet), to the top of the head tube (your hands -ish).  This is quite a hard thing to measure. However, measuring the length of the downtube of a bike is much easier, from BB centre to headtube/downtube centreline intersection.

I've worked out sizes that seem to suit most of my customers, from weeny 5'2" (157cm), upto giant 6'9" (206mm).  At 5'11" myself I ride frames with 480mm reach and recommend you use this as a baseline.  But note the maximum reach I can build due to available tubes is 535mm.

Seat Tube Length

Measure your existing seat position (from top of seatpost) at full extension.  Reduce this value by 350mm, i.e. the typical post extension from frame for a 150mm dropper.  Job done! 

Head Tube Length

By default, Swoop frames come with a 120mm headtube, Murmur with 110mm. 

If you like your bars high, or are tall, you may want to increase this.  Although, for aesthetics reasons, too long may make the frame look a bit gate like. 

If you like them low, you may want it shorter.  However, 110mm is the shortest I can comfortably go.