If I convert vertical dropouts (as on picture) to horizontal dropouts as on youtube video by cutting and welding:.
Will there be any challenges with the V-brakes ? If axle hole more or less will stay on same place, there shouldn't be any problem ?
Bicycles Stack Exchange is a question and answer site for people who build and repair bicycles, people who train cycling, or commute on bicycles. It only takes a minute to sign up.Sign up to join this community
V-brake calipers have a radial (with respect to the wheel) adjustment range, so they can accommodate the wheel axle moving fore or aft a little.
What you need to do is make sure that the placement of the new dropouts does not place the wheel axle such that the brake track on the rim is outside the range of caliper adjustment.
You could do this with a simple cardboard template that marks the axle to brake track distance.
The "horizontal" dropouts that are usually used with rim brakes are not completely horizontal but slanted so that adjusting chain tension moves the rim along tangent where the brake pads make contact with rim. In the video preview picture, the front-facing dropout is aligned like this. With this kind of dropouts, there is no problem with fixed gear, but with totally horizontal track-style dropouts you will have to adjust the brakes every time you adjust chain tension.