Apologies if this is a bit of numpty question.
Been trying to get enough parts together for a BFEMax build, and I’ve noticed that Fox list 2 different offsets for 29er forks. Question is why ?
I’m guessing cotic will have designed the bike around a particular offset, would the average rider actually notice a difference with the wrong offset forks fitted ?
For some reason i’ve always had it in my head that 29ers should have 51mm, but i may have found some 44mm, Am i making an expensive mistake ?

Have a read of Cy’s thoughts on the Cotic site if you haven’t already

Shorter offset 29er forks are the hot ticket now, usually 42mm or 44mm rather than the old 51mm.

I have just swapped to a couple of them myself. One was pretty much like-for-like with the old 51mm Lyrik and I am a convert. Feels much calmer at speed and a bit more composed on steep, techy sections.

Having just read that link to Cy’s thoughts on it above, I’d say that’s the best explanation I’ve read so far… It’s very definitely personal preference. I note that some of the EWS guys have stuck with longer offset forks (along with smaller frame sizes, narrower bars, longer stems too in many cases), but these guys are incredibly talented riders that can ride around the limits of a bike and are looking to increase the agility of the bike at times. Not something most of us have to worry about!

From my own experience so far, I’m definitely a fan of the shorter offset forks. On a modern trail bike with a 1200mm+ wheelbase, 65deg HA etc. I find the increase in confidence in the front tyre and a little more stability when upright more than makes up for the slight decrease in agility.

However… On my XC bike which has a 69deg HA and 120mm up front and 100mm travel on the back, I’m grateful for the 51mm offset still as I want it to be a bit more agile and easier to flick into turns, I don’t require the same kind of outright stability as on a trail/enduro bike, and with the 69deg head angle I’m already closer to the front tyre and can get more weight on it to generate as much grip as I can from the less treaded tyres. So it’s definitely horses for courses…

What I haven’t yet decided (for myself, again this will be personal preference) is where I see the crossover in use/travel/geometry from the 51 to the 44/42 offset occurring. I have the ability to fit a -2deg Angleset in my XC bike so may try doing that to see how it behaves with the 51mm offset fork still, then possibly try and borrow/swap a 44mm of the same fork (Fox34 SC) to do a comparison. Having found in the past that a 160mm bike felt odd with a 51mm offset, and an XC bike with 70deg head angle and 90mm stem but with 46mm offset fork on it felt incredibly stable but not especially agile, my thoughts are that the crossover point is going to be somewhere around the 130-140ish travel with 66-67deg HA or thereabouts for my own personal preference… But these changes are small for certain, and I’ve had the chance to ride and own many different bikes in the last few years, and have ridden 29ers exclusively for 8 years or so now too. I still remember when it was only Trek that were using 51mm offset forks, everyone else was still on 44/46 for their 29er forks before the marketing guys stepped in and told us we all needed 51mm offset around 2015!!! 😂

The other thing I forgot to mention earlier that may have a bearing on your preference/choice… Reach.

If you’re sizing up on a bike and going deliberately short on the stem (like 40mm or shorter) then you’ll probably find the bike will feel better with the shorter offset fork, bringing the wheel just that bit closer and increasing the confidence in the front tyre.

The other way of looking at it is, if you are buying a new set of forks for a new frame that you’ve not ridden before, it won’t make any difference which you buy as it will just “be”.
It will only make a difference if you bought both and tried both. even then its mostly marketing or incremental gains that most riders would fail to notice any real benefit from.

buy whichever is cheapest, fit them and ride

I was surprised how much difference I could feel with the shorter offset, and I’m not usually a princess and the pea type about bike setup.

If you have a modern geometry bike and like to ride fast, it’s something I’d recommend – even if it cost a few quid more.

A slacker head angle slows down steering. Nowhere does Cy imply the opposite. Cy states that long wheelbase bikes may benefit from a shorter offset/increased trail figure. Now long wheelbase is partly due to a slacker head angle but more a result of long chainstays and long reach on his bikes; and he favours 35mm stems. Short stems speed up handling. Ask any roadie. I like short stems but on my Dog noticed very little difference changing from a 50 to 35, accepting that the bike felt far less nose heavy down steep hillsides, which was the change I was after. Brant has the offset on both the Dog and Scandel at 51. The Dog is longer than the Solaris, due to a slacker head angle.
I’m intrigued by what difference a shorter offset would make on an already slack hardtail. I had a Cannondale with integrated fork, and a Zinn. oh and an early Gary Fisher 29er. Those bikes had high trail figures and to a greater or lesser degree were trolley like uphill. I knew it was senseless but they gave the impression of labouring uphill, entirely due to the heavier steering. They weaved when climbing out of the saddle. And I spend far more time going up than down.