Correct way to measure headtube?

[ilikebikes]

Whats the correct way to measure a headtube to find out what size fork I need? Should I measure from the inside? or from the outside? Ive got this old canti frame that someone tried to build up using Schwinn parts but the cups are wiggling around in the headtube? So Im guessing its 1 1/8th"? are there head cups that are smaller than 1"? Ill wait for your replies

 

[karfer67]

there are a few different sizes used in bikes. most modern frames use 1 1/8, most old road, mountian, bmx and most cruisers used 1". HOWEVER some used 1 1/4 and i believe there are two 1 1/8 sizes a standard and a bmx size. confused yet? anyways the best way is to get a high quality set of calapers and measure the ID or iner diamiter. also if you are trying to figure out the length don't forget to take the stack hight of the headset into acount before cutting and if it is threadless mock everything up then mark and cut the fork. no eyeballing alowed or you may be buying two forks

 

[62Higgins]

Karfer,

If I remember correctly, you and I both wound up using the 1 1/8" conversion inserts so we could use 1" forks and headsets on our Higgins frames.

Using the quality tools is always the right answer. In addition to that, I try to remove and keep every headset part of every donor bike I ever lay my hands on.

You never know what combination of parts is going to do the trick when your building rats.

Measure twice, cut once.

 

[karfer67]

yes your right my friend the higgins did use a 1 1/8 headset size so it proves to always measure. however my new bike the lucky 7 used a 1 1/4 headset so again just because a frame is new or old always measure.