in gamma model: a set of two plates ("fork/frame upper connector gamma") 
1 variant, allowing for support heights from 36 to 44cm.

in alpha models: a tube ("fork/frame upper connector alfa")
available in 3 variants, allowing for support heights: 37-41cm/ 39-43cm / 41-45cm,

It comes in a shorter and a longer version, and each of those allows to set the frame in a lower or in a higher position
in relation to the ground.

When ordering, the upper and lower elements are pre-set to obtain optimal geometry at a given support height.

The lower element (responsible for calibrating the bicycle geometry) is the same for all models and is an H-shaped connector
("fork/frame lower connector "):

Support height changing

At any stage of the bike's use, the user can self-adjust the support height within the selected range.

Gamma model

One can self-set the support height every ~1cm within the range of 36-44 cm by choosing a different hole in the fork/frame upper connector gamma to fix the fork.

Alpha models

One can self-set the support height anywhere within the chosen range (37-41cm OR 39-43cm OR 41-45cm) by changing the protrusion of the tube from the fork in the fork/frame upper connector alfa.

If an alfa user needs to change the range of support height (f.e. he/she has the 37-41cm tube and now needs 42cm instead of 41cm support height), it’s enough to purchase a longer fork/frame upper connector alfa, and replace the 37-41cm tube with the 39-43cm or the 41-45cm tube.

Note however, that such situation is rather unusual. If one hesitates whether 41cm or 42cm is optimal, he/she would rather initially go for a 39-43cm tube (where „41-42” is in the middle of the range), or even for a 41-45cm tube (where there is a lot of space to go up from „41”). But still, if there is a mistake in the initial support height assessment, one can just get a longer fork/frame upper connector alfa and replace the old one with it.


Geometry adjusting

When the support height is changed, the geometry of the bike changes slightly as well.

I.e. decreasing the support height, rises the frame slightly; increasing the support height, lowers the frame slightly. If this effect becomes significant, the fork/frame lower connector setting should de changed in order to rise / lower the frame to the desired level. The fork/frame lower connector comes in two lengths, and each length offers two positions in which the frame can be placed in a relation to the ground.


  • the lower the support height, the longer the fork/frame lower connector position needs to be to keep the frame closer to the ground,
  • the higher the support height, the shorter the fork/frame lower connector position needs to be to keep the frame further from the ground.

With the support height specified in the order, the manufacturer selects the appropriate fork/frame lower connector setting. However, it is possible to self-change the fork/frame lower connector setting to the user's preferences (or significantly changed support height) at any stage of the bike's use either by choosing a different set of holes in the existing connector or by purchasing a different variant of the fork/frame lower connector, and replacing the old one with it.

1-2cm changes of support height, usually do not result with significant changes in bike’s geometry, and thus don’t create a need of
adjusting fork/frame lower connector settings. Such changes may result with a need to change the connector setting if the initial positioning was at the limit of its range.

The system of connecting the JetBike fork with frame is also the one responsible for support height adjustment.
It consists of an "upper" and a "lower" element.

The upper element (responsible for the support height) is:

Support height




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