What would be the best:to weld a bike frame to a trike chassis (same metal)orto build a new frame entirely (including the more complex bits such as the pedal axle and handlebar tube)?Any advise on welding the pedal axle hub thing from an old bike to a newly built frame?
If you are using an aluminum bike frame as a basis do NOT weld anything onto itIf you are using a steel frame then you MIGHT be able to convert itbut there is no way 3 adults will be able to ride itno more than 3 adults could ride the bike in its original formYou are trying to do something that takes some significant knowledge in engineering and some very fancy fabricating (machining) workI am a master builder, have built trikes before and it is definitely not for those who don't have an intimate understanding of making fabrications with thin walled tubing with a good dose of structural engineering whether it be through school or experienceIt is also important to get your terminology correctThe pedal axle is the bottom bracket (which comes in a variety of sizes that you'll have to determine) and the handlebar tube is either the fork steerer or the head tube (I can't decide which one you mean)There is also the seat tube (which has to be reamed for a particular size) as well as close attention paid to the head tube angle, the bottom bracket drop, and the chainline among dozens of other detailsAll the bits you need- including tubing- are generally available from various specialist shops onlineDo NOT use the pedal axle thing from an old bike for a new frameIf you want to look at a couple of custom trike frames, consider searching for Bob Jackson Cycles in Leeds England, and I think Mel Pinto Imports still has one lying around.
