Wheel Sizes

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Here is a list of the rim sizes used up to now, together with a (fat) tire to give an idea of the size of the wheel. The typical WB and Trail are gleaned from the Python Projects Survey.

As you are going to have the wheel positioned between your legs it must not be to large so you can't reach the bottom bracket. For that you need to know your Inseam Length.

  minimum inseam for crank
  ERTRO Tire Width Wheel Diameter Typical Trail Typical WB 145mm 155mm 170mm
16" big apple 50 345 50mm 445mm -170mm 880mm N/A N/A N/A
20" big apple 50 406 50mm 506mm -140..-170mm 950..1200mm N/A N/A N/A
24" big apple 50 507 50mm 607mm -240mm 1140mm 79cm 80cm 81.5cm
26" big apple 50 559 50mm 659mm -250..-300mm 1070..1380mm 81.5cm 82.5cm 84cm
27" big apple 50 - 50mm - -270..-310mm 1200..1380mm  ?  ?  ?

Another point to remember is the BB-FWA distance. When this gets below 40cms you will get in trouble when using a derailler. The chainline gets so extreme that the chain tends to fall off. You could get around that problem by:

  • increasing the height of the BB, possibly increasing the seat height too, to have a comfortable seat-BB height difference (+15cm -> +25cm seems to be a good value).
  • taking smaller cranks
  • using smaller wheel sizes.