[Closed] Fork Offset and Trail...

I have a Transition Spur which also uses the 44mm offset. My mate's bike has the same head angle (66 degrees) but came with a 51mm offset fork. To me, his bike steers really slowly and vaguely, whereas my Spur is snappy, responsive and lively.

Same bar width (800mm) and rise across both bikes.

I'd stick with Transition's recommendation if you go for the Sentinel.

I have a Transition Spur which also uses the 44mm offset. My mate’s bike has the same head angle (66 degrees) but came with a 51mm offset fork. To me, his bike steers really slowly and vaguely, whereas my Spur is snappy, responsive and lively.

But thats the wrong way round isnt it? the longer offset fork should be making the steering feel lighter and more sensitive.

But thats the wrong way round isnt it? the longer offset fork should be making the steering feel lighter and more sensitive.

Agreed, all things being equal. Reducing trail should make the steering 'quicker'. However, it also increases wheelbase which increases the turning circle. devash doesn't mention other attributes that could cause the bikes to feel different, like wheelbase and chain stay length.

I stuck my old 51mm forks on my new frame that was designed for shorter and it's absolutely fine.

Less offset means more trail which means more "flop". The steering will feel quicker when pootling with more flop as leaning the bike over results in more steering being naturally applied (the other side of the coin is that slow hands off riding is trickier).

But at speed, more trail means it takes a bit more force to apply steering, because steering moves the front hub sideways more. Or something like that.

I would not think the small change in wheelbase would make much of a diff tbh.

My Revel Rascal was spec'd for 51mm offset and I had a 42mm Pike. So other way round but thought I'd share the response from Revel. I've ridden it about a 1000km on some pretty tight terrain and I can't say I've noticed. But it does have the steepest head angle of all my bikes anyway.

Worth giving transition a ping? I'm sure they'd give you some good advice.

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I think you'll still be just fine running that Pike with a 42mm offset, however you might notice some slowed steering response in tighter terrain. The 51mm offset fork is part of what gives the Rascal its snappy behavior.

How do you design a frame specific to fork trail? What are you going to change..the colour?

This old chestnut…
I’ve a 51 offset fork on a bike that usually comes specced with 42 offset. The geometry table says something along the lines of “designed for short offset fork, but will be fine with up to 51mm offset”
One day I will probably change the forks, and at that point I might get shorter offset to see if I can tell that difference, alongside the fact that the new fork would also of course be lighter stiffer and better damped…
I’m in no rush to find out though. I bet I can similarly change the feel of the front end with a longer stem instead

I reckon it'll be fine. A slack-ish MTB will work fine with a 42-51mm offset range, just think of it as fine tuning within the basic geometry the HTA creates. There's a fair bit of HTA variation as the suspension moves anyway.

Less offset means more trail which means more “flop”. The steering will feel quicker when pootling with more flop as leaning the bike over results in more steering being naturally applied

Maybe 'quicker' isn't the right term if we usually think of 'quick' as meaning 'light' or 'twitchy'. I know what you're saying though. More inclined to continue to turn in the direction you turn the bars or lean. The greater flop effect of longer trail steering creates a force in the steering, pulling the bars into the direction of the turn.

I'd say a longer offset fork makes a given HTA feel more quick/light/neutral steering feel at any speed and it's more noticeable at lower speeds. The combo of HTA and offset is really about getting trail and weight distribution right. No right answer to any of it really.

When I changed forks on my old Remedy that was designed for Trek's G2 or whatever it was forks, I was absolutely sure I could tell a difference. Then it turned out the forks were actually the same. With all the other differences between any 2 forks in terms of where they sit in the travel etc, it's kinda lost in the rounding and besides, who says the factory's idea of perfect setup is the same as yours?

Thanks for the input, i'm pretty much sold on the Jeht idea and the guys at Cotic have said its pretty much negligible too. Anyone care to confirm my original assertion though...

But… by my calculations the simple fact i will be running a slacker head angle means the “trail” will be noticeably increased from where i am today so the steering should already become slower and more solid than what i have now. So its gonna be either a fair bit better or much better is it not??

In short, I will have more trail and thus more solid steering than i do now? Correct??

Yes

Just had Covid thus only in the local park but I can't say I've noticed any difference BFEMAX

IME, putting a long offset fork(51mm) on a slacker bike (say less than 65 degree HA) doesnt make a significant difference. The shorter offset is better, but not drastically. You will get used to either and adjust accordingly.

However putting a short ofset fork on a steeper bike (eg 66 HA) makes it a bit tucky. Like the front wheel will jack-knife under you. The short offset brings the axle closer to the bike. And then the steeper head angle also bring it closer, so you are riding right over the front axle. I prefer a longer offset for a bike with 66+ HA.

In your case, I expect teh longer offset will be fine. But the shorter offset marginally better. But you might not even notice it.