23/09/2019 - Fork Offset - Does It Matter?

Fork Offset - Does It Matter?

HELM29 forks with 51mm offset aboard a Cotic RocketMAX

Cy explains his views on forks offsets after much testing....

Given some of the chatter that other brands have been pushing recently I've had quite a few emails asking about what fork offset works best and what my thoughts are.

My take on fork offsets is that it's a personal preference, and the marketing budgets of other brands are making it a bigger thing that it actually is.

I have tried the RocketMAX with all the available 29er offsets: 42mm (short, on Lyrics), 44mm (short offset HELM), 46mm (X Fusion McQueen) and 51mm (regular Cane Creek HELM29 and X Fusion Trace 36) and they all handle great. Slightly differently, but good.

With my preferred bar width of 770mm across the grips I do prefer the slightly shorter offset, although I'll be honest I couldn't tell the difference between 42mm, 44mm and 46mm. I have to use 785mm bars to get a similarly calm feel on the 51mm offset as it's more lively around the straight ahead position. The slightly more linear rate of response of the shorter offset works a little better with the narrower bar width.

The Differences

Here are the main differences in handling of the different fork offsets based on running them on a MAX/29er Longshot Geometry Cotic:

Regular / 51mm

51mm offset reduces the trail which makes the handling quicker and lighter around the straight ahead. This makes the bike feel nice and easy and responsive flicking between shallow turns, like down a flow trail. On modern, long geometry bikes with slack head angles, what happens after this as you initiate a tighter turn is the main difference in handling between regular and short offset forks. The longer offset is light around the straight ahead, but as you initiate a turn and lean some angle into the bike, there's a feeling of 'dropping' into the lean. Some people have been known to call this 'wheel flop', but I don't like think of it like that. Long bikes need angle on them to turn, so what you get is quite a noticeable 'drop' into the lean, which is then really secure and stable once you're there, but takes a bit more effort to pick back up out of the turn. This is what I mean by rate-of-change of response. With 51mm offset the steering response is light and easy with the bike upright, then it changes quickly to solid and stable, but the transition happens quite quickly so you have to commit to getting the bike into the turn to make the most of it.

Short / 42 or 44mm

Short offset increases the trail, which makes the handling slower and more stable, which gives a slightly heavier feel around the straight ahead. The key difference between short and regular offset is the more pronounced 'drop' into the lean angle when you initiate a tighter turn isn't there like it is with 51mm offset. The rate of response of the steering is more linear, there's less difference in the steering feel between around the straight ahead and having dropped into a turn. Although the shorter offset is not quite as secure feeling once you've dropped it into the lean angle, it's also easier to pull the bike back upright again. The short offset also shortens the wheelbase and front centre slightly, which makes it a little bit easier to weight the front wheel.

Remember, this is real Princess-and-the-pea stuff. It's my job to be sensitive to these things. I'd be very surprised if anyone getting any of the Cotic 29ers was anything other than really stoked on the handling so long as they had a fork they liked, set up nicely, it will be all good.

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