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Spicer Cycles

FRAME FITTING INFORMATION 


Ordering a custom frameMost of the frames we make are some version of a track or fixed gear frame.  The below information and form is based on this assumption, you are ordering a track type frame.  Many of the concepts can apply to road frames but contact us if you are interested in some other style of frame.  Please provide what information you can in the form to help us get closer to your perfect fitting frame.  For some of our thoughts on getting us the specs. please read this on frame fitting information.The form follows the discussion about frame fit.After building frames for 40 years I try to keep it simple.  Assuming a frame has a level top tube I like to focus on standover (ground to top of top tube).  Once you throw your leg over frame, and it fits we are off to a good start.  Many people often first tell me seat tube size center to center, or center to top, or no designation at all how it is measured.  That is fine, but if you are comparing a road frame, the road BB is likely lower than your track frame, so the standover will be off, and higher on a track frame. The track BB is taller and we start measuring at a taller spot in the air. So take that variable out and work on standover. Here is a link about standover and how to calculate, find what you are comfortable standing over with your feet apart like standing over a bike.After the top tube is seat at your standover, if the top tube is level, the seat and head tube lengths almost just fall into place. I leave enough room to weld above top tube and have a seat collar.  What length the seat tube ends up does not really matter.  Let us know if you want an abnormal amount of head tube sticking out above the top tube.  I discuss compact frames or sloping top tube frames later.The next thing is top tube length. You can tell me how tall you are, your inseam, and do a fitting using online tools.  Many times people send me measurements of their body, and I try to plug into fittings and see what pops out.  Not always a comfortable feeling. After realizing that 9 out of 10 customs have a bike, many times a track frame, that is often the best thing to compare.  If it feels too long we can shorten it and to short we can lengthen it. I often ask for any links or know specs of your current bike so I can compare.  We can work on top tube, but give me what you think it should be.  If a level top tube measure head tube to center of seat tube, measure along center line of top tube.  If it slopes a little ignore slope and measure level to ground to get me the effective top tube.Toe overlap.  Some people do not care if your toe hits the tire when you are going supper slow and balancing bike etc and turn wheel.To others, that is the only concern. The shorter the top tube, the more likely to have toe overlap.  The remedy involves seat tube angle, head tube angle, fork rake and height, and tire size. When the head angle is steeper wheel gets close to feet.  As seat tube is steeper it makes BB farther back.  That is why small frames often have slow head angles and fairly steep seat angles.  Fork offset/rake and tire sizes affect clearance.  I have a spread sheet that calculates if a certain shoe size will clear a selected angles (head and seat) and fork with all the variables plugged in, but people ride with their feet different on the pedal, so it is not a precise science.  So be clear as the importance of toe overlap avoidance. Your ideal angles may get trumped by your desire to not have toe overlap.How tall the BB is off the ground is important on fixed gear as your feet keep moving and pedals can be down when turning.  It seems that a 280 tall bb is common.  If you have a 700 x 23 tire that is about 335 mm radius, to get the BB at 280 tall we can have a BB drop below axle line of 55 mm (335-280= 55 mm).  If you get a tracklocross and tell me you will only use a 340 mm tire we can do 60 drop and have the 280 clearance.  But if you put on smaller tires you will be below 280.   Chainstay length:  I normally make the rear ends as short as I can and have tire close to seat tube when all the way forward in the dropouts. If you are going big on the tires I often have to go longer for ring clearance (to bend stays around tire and try to clear chainring).  Chainring size can be limited by tire width and big tire often makes rear end longer and decreases diameter of ring use.My default is 120 track spacing, 68 bb, 29.8 seat collar, and 27.2 seat post.     

Ordering a custom frame

Most of the frames we make are some version of a track or fixed gear frame.  The below information and form is based on this assumption, you are ordering a track type frame.  Many of the concepts can apply to road frames but contact us if you are interested in some other style of frame.  Please provide what information you can in the form to help us get closer to your perfect fitting frame.  For some of our thoughts on getting us the specs. please read this on frame fitting information.

The form follows the discussion about frame fit.

After building frames for 40 years I try to keep it simple.  Assuming a frame has a level top tube I like to focus on standover (ground to top of top tube).  Once you throw your leg over frame, and it fits we are off to a good start.  Many people often first tell me seat tube size center to center, or center to top, or no designation at all how it is measured.  That is fine, but if you are comparing a road frame, the road BB is likely lower than your track frame, so the standover will be off, and higher on a track frame. The track BB is taller and we start measuring at a taller spot in the air. So take that variable out and work on standover. Here is a link about standover and how to calculate, find what you are comfortable standing over with your feet apart like standing over a bike.

After the top tube is seat at your standover, if the top tube is level, the seat and head tube lengths almost just fall into place. I leave enough room to weld above top tube and have a seat collar.  What length the seat tube ends up does not really matter.  Let us know if you want an abnormal amount of head tube sticking out above the top tube.  I discuss compact frames or sloping top tube frames later.

The next thing is top tube length. You can tell me how tall you are, your inseam, and do a fitting using online tools.  Many times people send me measurements of their body, and I try to plug into fittings and see what pops out.  Not always a comfortable feeling. After realizing that 9 out of 10 customs have a bike, many times a track frame, that is often the best thing to compare.  If it feels too long we can shorten it and to short we can lengthen it. I often ask for any links or know specs of your current bike so I can compare.  We can work on top tube, but give me what you think it should be.  If a level top tube measure head tube to center of seat tube, measure along center line of top tube.  If it slopes a little ignore slope and measure level to ground to get me the effective top tube.

Toe overlap.  Some people do not care if your toe hits the tire when you are going supper slow and balancing bike etc and turn wheel.
To others, that is the only concern. The shorter the top tube, the more likely to have toe overlap.  The remedy involves seat tube angle, head tube angle, fork rake and height, and tire size. When the head angle is steeper wheel gets close to feet.  As seat tube is steeper it makes BB farther back.  That is why small frames often have slow head angles and fairly steep seat angles.  Fork offset/rake and tire sizes affect clearance.  I have a spread sheet that calculates if a certain shoe size will clear a selected angles (head and seat) and fork with all the variables plugged in, but people ride with their feet different on the pedal, so it is not a precise science.  So be clear as the importance of toe overlap avoidance. Your ideal angles may get trumped by your desire to not have toe overlap.

How tall the BB is off the ground is important on fixed gear as your feet keep moving and pedals can be down when turning.  It seems that a 280 tall bb is common.  If you have a 700 x 23 tire that is about 335 mm radius, to get the BB at 280 tall we can have a BB drop below axle line of 55 mm (335-280= 55 mm).  If you get a tracklocross and tell me you will only use a 340 mm tire we can do 60 drop and have the 280 clearance.  But if you put on smaller tires you will be below 280.   

Chainstay length:  I normally make the rear ends as short as I can and have tire close to seat tube when all the way forward in the dropouts. If you are going big on the tires I often have to go longer for ring clearance (to bend stays around tire and try to clear chainring).  Chainring size can be limited by tire width and big tire often makes rear end longer and decreases diameter of ring use.

My default is 120 track spacing, 68 bb, 29.8 seat collar, and 27.2 seat post.  



 
 

 








 
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