Fork offset. 44mm vs 51mm and does it really matter.

[droo]

1 hour ago, Trashy said:

Sorry for jumping in here.

I've got a 2017 34 Performance Elite set at 130mm and I'd like to go 140 or 150.

 

Will it use the same cartridge as above?

Will it handle 150mm?

Rhythm is a different fork to the rest of them. Different spring lengths, volume spacers, topcap threads, lowers...

 

Post the ID code and I'll tell you what max travel is, although I doubt you'll want to go to 150 on that chassis unless you're a 50kg racing snake.

[Trashy]

9 minutes ago, droo said:

Rhythm is a different fork to the rest of them. Different spring lengths, volume spacers, topcap threads, lowers...

 

Post the ID code and I'll tell you what max travel is, although I doubt you'll want to go to 150 on that chassis unless you're a 50kg racing snake.

Thanks Droo.

Fork ID is C3C4.

I'm about 74kg and ride relatively smooth.

 

I'd be happy with 140mm, 150mm might change the Geo too much anyway.

[droo]

12 minutes ago, Trashy said:

Thanks Droo.

Fork ID is C3C4.

I'm about 74kg and ride relatively smooth.

 

I'd be happy with 140mm, 150mm might change the Geo too much anyway.

Seems like, because it's a 275, you can take that one to 160 if you're feeling brave and can find the right spring. I reckon at that travel it'll feel like cooked spaghetti though.

[Trashy]

10 minutes ago, droo said:

Seems like, because it's a 275, you can take that one to 160 if you're feeling brave and can find the right spring. I reckon at that travel it'll feel like cooked spaghetti though.

I definitely don't need 160mm!

 

Are you able to supply a 140 or 150mm?

[Steady Spin]

54 minutes ago, Trashy said:

Is this what you need?

https://bikehub.co.za/classifieds/item/mountain-bike-forks/496667/fox-34-150mm-air-shaft-27529-820-02-369

That's the one I think.

 

[droo]

5 minutes ago, Steady Spin said:

That's the one I think.

 

That is exactly the thing.

 

14 minutes ago, Trashy said:

I definitely don't need 160mm!

 

Are you able to supply a 140 or 150mm?

Will see if I can get, but pretty sure I can.

[Steady Spin]

5 hours ago, droo said:

That is exactly the thing.

 

Will see if I can get, but pretty sure I can.

Had a chat to the guy and unfortunately it is a used part. Would prefer a new unit with a warranty. 

Can you please have a look for me?

[eala]

On 2/1/2022 at 9:55 AM, Steady Spin said:

So... my fiance is upgrading from a Stumpjumper ST to a Forbidden Druid and I believe the Stumpy is a 51mm offset while the Druid is a 44mm. 

We are building the parts from the Stumpy across and my only concern is the fork now. Currently it is at 130mm and will be changed to 150mm which is what the frame needs. But now this offset thing. I understand it changes the handling but a lot of research suggests that it doesn't make that much of a difference. 

Anyone with real world experience? Will a 51mm offset fork ruin the experience on a frame designed for a 44mm fork?

I does make a difference ,but only noticeable in twisty single-track and especially on switchbacks .Longer offset is more turntable 

Edited February 3, 2022 by eala

[eala]

On 2/1/2022 at 11:26 AM, Grease_Monkey said:

Of course, your front wheel is further away from you. It's like riding a superbike vs riding a chopper (exaggerated example, but you get the idea). Short offset forks were introduced to counter the front wheel getting further and further in front of you with bikes becoming more and more slack...

No incorrect !.Offset has nothing to do with the length of the fork ,effects the trail /handling .AKA as the turnability of the front end .Similar length forks will turn differently with different offsets 

[Grease_Monkey]

Just now, eala said:

No incorrect !.Offset has nothing to do with the length of the fork ,effects the trail /handling .AKA as the turnability of the front end .Similar length forks will turn differently with different offsets 

Read my post again, I didn’t say fork offset has anything to do with length of the fork. A longer offset fork does mean your front wheel is further in front of you than a short offset though. 

[eala]

1 minute ago, Grease_Monkey said:

Read my post again, I didn’t say fork offset has anything to do with length of the fork. A longer offset fork does mean your front wheel is further in front of you than a short offset though. 

Not always .It is usually countered further up in the steerer of the fork ,so the overall position of the front axle does not change 

[Grease_Monkey]

1 minute ago, eala said:

Not always .It is usually countered further up in the steerer of the fork ,so the overall position of the front axle does not change 

Offset is made shorter / longer on the crown of the fork. Lowers are the same across different models of a fork (mostly). So a Fox 36 for example with a shorter offset will have the wheel closer to you than the same fork with a longer offset. 
 

Anyway, I’m out. Not gonna spend more time on this. 

[BaGearA]

6 minutes ago, eala said:

Not always .It is usually countered further up in the steerer of the fork ,so the overall position of the front axle does not change 

yes it does , if the offset is made at the crown or at the lowers the nett result is still the axle is further away(more/less OFFSET)

[droo]

15 hours ago, Steady Spin said:

Had a chat to the guy and unfortunately it is a used part. Would prefer a new unit with a warranty. 

Can you please have a look for me?

You'll only ever find used, the springs were only made for Specialized and will have come out of a fork supplied on one of their bikes.

[droo]

3 hours ago, eala said:

No incorrect !.Offset has nothing to do with the length of the fork ,effects the trail /handling .AKA as the turnability of the front end .Similar length forks will turn differently with different offsets 

  

On 2/1/2022 at 10:11 AM, 100Tours said:

diagram below helps understand. increasing the offset moves the tire patch forward, increases the wheelbase, and shortens trail. Not intuitive at all.

Increasing the fork length lifts the head tube (slacker angle), and increases trail again. 

Apparently the 'ideal' trail is something like 57mm

Edit - 150mm is a lot of travel. probably worth having a look at the geometry before you change the fork? Shorter travel will also reduce the trail.

If you end up with a number outside of 50mm-63mm you're probably too far off of reasonable numbers

 

3 hours ago, eala said:

Not always .It is usually countered further up in the steerer of the fork ,so the overall position of the front axle does not change 

Fork offset affects wheelbase. See above drawing.

[eala]

37 minutes ago, droo said:

  

 

Fork offset affects wheelbase. See above drawing.

 

37 minutes ago, droo said:

  

 

Fork offset affects wheelbase. See above drawing.

The offset effects the SIZE of the trail area and the virtual angle to the ground and that effects the turning acuteness .The wheelbase may extend slightly but that is not the reason for offset . Just like a smaller wheel will have a smaller trail size and therefore it will turn easier than a larger wheel .So to get a larger wheel to turn like a smaller wheel you have to get the trail area smaller and that is why offset was brought into production .Before 29 wheels all forks had the same offset 

Edited February 3, 2022 by eala