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BikeCad Pro and Bike Machinery Hydra


Hi everybody,

I have troubles setting the hydra with the "Bike Machinery X" and "Bike Machinery Y" values provided by BikeCad.

I am building a frame for myself, to get to know the hydra. BikeCad gives me a X value of 526 and a Y value of 276 for the head tube- bottom distance.

There seems to be a calculation step to use to be able to use these values to adjust the jig, but i do not get it.

The jig is third hand and I have no manual to refer to.

I set the head angles, bb drop, seat tube angle, chainstay length on the jig but it seems like a good idea to get the head tube on the right stop!

Any BikeCad/ hydra users willing to help?

Thank you in advance,



Hi Vincent,

Hi Vincent,

For future reference: Here's a copy-paste of my reply to the same question over at VS: velocipedesalon.com/forum/f10/bike-machinery-hydra-bikecad-pro-41889.html

First of all I'll refer to this thread on the framebuilders-email list from a few years back: search.bikelist.org/beta/View...aspx?id=445066. Then (referring to your posting on bikecad.ca) I'll explain the scales briefly. You have the Y scale at the bottom of the whole front center frame assembly. That's where you use the Y measurement from BikeCAD.

Then at the base-plate of the jig above the Y measurement you have the horizontal X measurement, but that's the front center X-measurement. In other words: the _horizontal_ X-measurement from the BB to the front hub. Thus you should use the data given from the "Front Center horizontal" measurement in BikeCAD - NOT the "Bike Machinery X" (unless this have been corrected recently - I will have to check the latest BikeCAD on my other computer later). Given that you've set up the front assembly of the Hydra correctly (ref. your bikecad.ca posting: the two scales at the far left top of the image). The fork measurements needs to be set with the correct rake of the fork you're going to use/make, as well as the correct length of the fork including the lower headset cup.

Here's a scan of the Hydra spec-sheet for dimensions: m.flickr.com/#/photos/planetjohnsen/8190109974/

Given that you have all of this done, it should give you a correct setup of the jig.

Did this make sense?


Truls Erik Johnsen
Johnsen Frameworks
Hølen, Norway
"There are some tools that you don't really own. You are just their temporary custodian on their voyage through time"


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