Is it possible to fit a 130-140mm travel fork to a 120mm travel bike without it effecting the geometry or handling.

yes but its unlikely

You need to knwo the A- C measure

Axle to crown – where wheel goes to where the fork goes in the frame

Despite the difference in travel sometimes the a-c is pretty similar

I have gone 20 mm over on some bikes and its not totally daft but YYMV

Its geometry will change by an amount you’ll almost certainly not notice. Its handling difference you may notice or you may well not. Many of us here do exactly what you are suggesting as a preference. The trade off dipie to a very slight loss of manoeuvrability is compensated for by a bit more travel when we need it

I am average mincer and I have switchable 120-150 dual travel fork and sometimes I forget which setting its in, I think if yI did a “blind” test I couldn’t tell.

It will effect it but not that much. If its an older frame with a steeper head angle it may improve handling to some extent. I think all my bikes have longer forks that they were originally designed for. If you really want to keep the current geometry with additional travel then that’s what travel adjustable forks do.

tends to be much more noticeable when climbing steep stuff IME

It won’t mean you leave you dad behind on the downhills though sonny :o)

I’ve recently changed my trek fuel from 120mm to 130mm. I can highly recommend it. Obviously it slackened the front up slightly (a good thing) and raised the BB slightly (a bad thing). To be honest, I haven’t noticed any difference in handling. The extra front travel gives me more confidence on bigger jumps/drops and the front feels way stiffer (but I also went from 32mm stanchions to 34mm).

It depends on the bike really. What frame is it?

It will certainly change the geometry but whether you feel the difference and whether its for the better or not depends on how sensitive you are to geom changes and the frames current geom.

For example jambalaya says he doesn’t feel mush difference between 120mm and 150mm where as on an old bike I used to have with 120mm to 150mm U turn Revelation forks I could feel a big difference between the two extremes, It was noticeable straight away which setting I had the fork on.

An extra 20mm on fork travel is towards the upper limit of whats sensible. You’ll slacken the head angle by around 1 degree and raise the BB by a bit too.

The bike I’m wanting to change the travel on is the Norco fluid 7.2

I’m not familiar with the Norco Fluid range but a quick look at the geo charts shows it has steep seat angle and reviews state it has balanced handling.

I’m really not frame design expert just someone who thinks they might understand some of the very basic points. I don’t think you’ll ruin the bike’s handling by moving to 140mm but you will bias it a bit more towards descending. I think the steep seat angle will still allow it to climb fine.

this is all speculation from someone who is really not an expert!!