EMRG's 'Virtual Pivot Headset' Alters Fork Offset

Aug 24, 2022 at 8:56
by Seb Stott  

We've seen plenty of aftermarket headsets which alter the head angle or the reach, but this product from EMRG (pronounced “emerge”) aims to do something quite different.

Reach-adjust headsets move the headset bearings forwards or backwards within the head tube, therefore moving the steering assembly forwards or backwards with them; angle sets move one bearing forwards and one back inside the headtube, thereby changing the angle of the steering assembly. (The steering assembly is everything that rotates as you steer the handlebars: the front wheel, fork and cockpit). In either case, the steerer tube rotates concentrically about the steering axis, which is the line drawn through the centre of both bearings.

photo

By contrast, EMRG's "Virtual Pivot Headset" keeps the headset bearings in the normal place, but the steerer tube is mounted in a pair of eccentric races. That means the steering assembly is offset from the steering axis by 4 mm, and so it rotates about the steering axis which is no longer at the centre of the steerer tube. This effectively changes the offset of your fork by +/- 4mm. So if you had a 44 mm offset fork (the most common size these days), this headset would allow you to run either 40 mm or 48 mm of steering offset, by moving the front axle closer to the steering axis or further away from it.

Why would you want to do that? Well, a shorter fork offset results in more trail, which is the distance between the steering axis and the tire contact patch. More trail generally makes for heavier, slower steering, but the front wheel is less likely to be knocked off-line in technical terrain. Increasing the fork offset does the opposite, making for lighter but twitchier steering.

It's worth noting that in this case, because the whole settering assembly is moved forwards or backwards, changing the fork offset will also change the effective stem length by the same amount. Having done several back-to-back tests comparing 42 mm and 51 mm offset forks, I'd say that changing the effective stem length by 4 mm is probably more noticeable than changing the offset on a modern bike. Still, it's cool to see new ideas and new ways for racers, bike nerds and puzzlers to tweak their setup.

photo

The headset is compatible with 1-1/8" steerer tubes (DH forks) and tapered 1.5" to 1-1/8" steerers, as well as most head tube sizes. It costs €159.

For more information, check out EMRG.bike.


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90 Comments
  • 78 18
 This couldn't be more confusing.
  • 13 41
flag masonskis (Aug 24, 2022 at 9:50) (Below Threshold)
 I agree. Explain better. How is this not the same as reach adjust headset?
  • 30 4
 @masonskis: learn your language
  • 12 17
flag sanchofula (Aug 24, 2022 at 9:57) (Below Threshold)
 @masonskis: or is it the same?

I'm no math genius, but a headset offset is not the same as fork offset.

The only way it could be a virtual offset is if the cups move with the steerer, so that appears to be what they've done, kinda' complicated, easier to just to get a different fork.
  • 42 1
 @masonskis: reach adjust headset moves the headset bearings AND the steerer. This moves the steerer relative to the bearings, meaning the steerer no longer sits in the centre of the circle around which the headset rotates.
  • 10 2
 The difference is subtle (and probably irrelevant) but a reach adjust still has the steerer in the dead center of the circle your bars rotate around. With this thing, the center point is slightly offset from the center of the steerer, so when you turn the bars, it sorta "swings" around that point instead of the center of the steerer. But I agree, I don't really see how this is substantially different here on earth.
  • 20 2
 Ok cool, I get it now. I just slid some bearings onto a steerer, didn’t realize there’s wiggle room there. I’ll be sure to take some language lessons, thanks for the downvotes.
  • 5 0
 @nurseben: doesn't seem that complicated, it's like a normal headset install with like 1 extra step. And definitely cheaper than a new fork with a different offset. Changing offsets is just changing out the cups, right?

@gtill9000 idk, people were making a really big deal about fork offset a couple years ago. I don't think I'd buy one but it would be kinda cool to try out the offest thing without spending the money on a whole extra fork. Seems like you'd also want to swap stems to compensate for the the distance between bearing center and steer tube center though?
  • 6 0
 @nurseben: easier to get a different fork? Maybe (maybe not nowadays), but way more expensive. This is a solution to try a different offset _without_ needing a whole new fork, or least a set of a crowns or a CSU that needs to be installed which means dropping the legs and disassembling the air spring. Not easier than a headset install.

Headset offset, done this way, actually is the same as fork offset, with the exception that this also offsets the stem. Changing offset in most (all? Does anyone use different lowers for offsets?) forks is done with the crown, which moves the legs, lowers, and thus the axle closer or further from the steering axis. This moves the entire fork, including the steerer, relative to the steering axis. Same thing.
  • 1 0
 @gtill9000: the difference is that with this the axle location changes relative to the steering axis, where on a reach adjust that relationship doesn't change. If it's not substantial, then all the other fork offset differences are not substantial either.
  • 2 0
 @nurseben: where can you get a decent fork for 159 euros?
  • 6 1
 I’m sorry, but this is so last year. We’ve moved on to High Idlers
  • 1 0
 The offset of the fork determines the geometric trail, i.e how far is the contact patch behind the center of steering. This geometric trail is the thing that keeps the front wheel pointed straight, like a weather-vane effect, especially over rough due to the fact that contact patch moves forward if a tire has to roll over something. The lower the offset, the more you move the wheel back, reducing the wheelbase, but conversely the geometric trail gets bigger. This headset can be used to either increase or decrease geometric trail. The only difference to fork uppers is that it makes the stem length longer or shorter depending on how you mount it.
  • 1 0
 @Jake-Whitehouse: yea it makes it offset
  • 5 0
 Where do I thread my cables
  • 26 0
 When I read the company name it's always: Ermahgerd
  • 15 0
 So does this mean the steerer tube rotates eccentrically? If the steerer isn't centered in the bearings, doesn't that mean the steerer swings to the sides a bit as you steer?
  • 30 0
 yes, thats excatly what fork offset is
  • 12 3
 @mufa: True, but this also means you handlebars are swinging around eccentrically.
  • 21 0
 @toast2266: Well they're already mounted to the steerer eccentrically via the stem so it won't feel much different besides the stem effectively being longer/shorter by the offset.
  • 9 0
 @NickBosshard: Yeah, it makes sense. Just a little weird to wrap my brain around.
  • 6 0
 @NickBosshard: so say I've got a 44mm stem and a 44mm offset. The relationship between the handlebar position and the axle is effectively zero, right? So if I go down to a 40mm offset fork (switching out the fork, not using this headset), my stem is 4mm longer than the offset. If I use this headset to move down to a 40mm offset, then my stem is also effectively reduced to 40mm, and that relationship between the handle bar position and the axle stays at zero.

Do I understand that correctly?
  • 6 1
 @dreamlink87: yes.
  • 3 0
 @dreamlink87: The relationship between axle and hub doesn't have a lot of meaning, because the backsweep already places the grips behind the bar (and the axle, in your example)
  • 1 1
 @dreamlink87: almost. If you'd moved to a 40mm offset fork, then used this, it would be 36 or 44mm. This is instead of changing fork. It changes the stem by the same amount, so 0mm difference between bar and axle would stay 0mm different, just 4mm longer or shorter.
  • 1 1
 Yes, but it doesn't matter. Your bars are always swinging to the side. This will change your effective stem length however, by whatever the offset is. And though you will see the steering swinging, there is still a point on the stem that goes through the steering axis, so it won't be any different than a shorter stem.
  • 1 2
 @dreamlink87: No. your bars have sweep so your hands are closer to the center of the stem.

The stem stays the same, but the reach of the bike decreases by 4
  • 2 0
 @alexbn921: I think you’re confusing things.

Back sweep just makes effective stem length shorter (as the midpoint between your hands is closer to the axle than the stem’s length).

Nothing here changes the reach. The center of the frame’s headset mount is still the center of the rotating axle or axis or what you want to call it.
  • 1 0
 @DuRietz: it does change the effective reach (frame reach, plus stem, minus bar sweep, minus the effect of spacers under the stem and the head angle)

@alexbn921:.nope, effective stem length changes, and effective reach, too. But frame reach doesn't change: the steering axis remains where it was.
  • 12 0
 Reminder that Nico Vouilloz tested different offsets and said he couldn't tell the difference so long as it was in the mid 40ish range.
  • 2 0
 Many forks aren’t in the mid 40s range, especially the 51mm stuff commonly found on 29ers and the fox 40s that I believe are even higher.
  • 5 0
 I went from 51 to 44mm and can't tell much difference. It's very subtle.
  • 2 1
 I had a bike with 51 mm fork offset at the same time as I had a bike with 44 mm offset. I felt the difference, felt the 51 gave a lot more wheel flop when turning at slow speeds. I like the 44 mm offset more.

Now, this here EMRG 'fork offset altering headset' makes it possible to take an older 51 mm offset fork and decrease it to a 51-4=47 mm offset fork. This would make it better in my eyes. ...also decreasing whichever stem length used by 4 mm, for example 50 to 46 or 40 to 36 mm.

This here EMRG would also make it possible to decrease a 44 offset fork to a 40 mm offset fork. It could be interesting to try. At the same time, it would change stem length, so using a 50 stem it would become 46 mm.

Important though, is that this does not make it possible to change any other parameter at the same time, for example if wanting to slacken the head tube by 1 or 2°, normally done with an angle set.

Good to note as well, is that for a ZS44/56 bike frame, this here EMRG headset has external cups both top and bottom, changing things if currently able to use a headset with zero stack top and bottom.

--> Only a bike frame with ZS 56/56 coupled with a straight 1 1/8" fork steerer, typical that of a double-crown fork, would be able to use zero stack cups top and bottom. Transition frames, I believe, are ZS56/56 and could with a double-crown fork be used with this 'EMRG offset changing headset' without external cups, whatever this is worth.

---> And, a double-crown fork on a ZS44/56 bike with this EMRG would also retain a ZS internal cup on the bottom, but getting into the double-crown world has a whole other world of benefits and drawbacks...
  • 2 0
 Don't know if that is true. I feel like 4mm or more of offset change are very noticeable, you just get used to the steering very quickly....because you have to if you don't want to crash on every corner. I tested 46 and 50mm on my DH bike and prefered 50. On the Enduro I first had 51 and then something like 42 or 44, that was a big change. 56 to 50 on DH forks was also very different
  • 15 2
 Pat, I'd like to buy a vowel or two and send it to these guys.
  • 6 0
 Cnyn nds thm wrs
  • 12 1
 If I turn the eccentrics 90 degrees will that help me corner better?
  • 14 0
 Yes but only in the direction they are turned. So for Nascar style trails that only turn one direction this could be a game changer.
  • 6 0
 @notsosikmik: Also a game changer for riders with one arm shorter than the other.
  • 9 0
 You can turn the eccentric 90 degrees and re dish your front wheel to obtain a more balanced tension of the spokes. Probably the worst way to do it but it should work fine if the tire don't rub the fork. Also you would have the only bike in the world with that feature, for sure.
  • 10 0
 They should have made it cable routing compatible. Soon enough nobody will be able to use it.
  • 13 5
 Because 4mm does make a difference. At least thats what she said.
  • 2 0
 To the right or left or up or down? LOL
  • 1 0
 +/- 4mm converted to Imperial is 1 @mikelevy
  • 6 1
 Is my stem aligned with my upper offset cup aligned with my lower offset cup aligned with my wheel?
  • 6 0
 I could tackle the local blue trails so much better if I had this!
  • 3 1
 Pretty unique product and simple concept to change the fork offset. However, how much will 4-8mm offset feel compared to adjusting the head angle a degree or so with an angleset?
  • 2 0
 A lot, for some.
  • 1 0
 @DuRietz: How so? I definitely notice a degree change in head angle, but I don't think I could distinguish the difference in increasing head angle a degree compared to increasing the offset about the same amount. It basically is the same change by moving the front wheel up a few millimeters.
  • 1 0
 Would be cool to see a concentric offset bb for modern threaded bottom brackets if its possibly. That way you could simultaneously adjust chainstay length (longer) and reach shorter) or the option of a higher or lower bb for different applications. Megatower with cascade link has the ability to run a 230x65 shock. Would be 180mm, but at sag the bb is already so low with the stock 166mm travel setup. Is there any brand that does this?
  • 6 0
 Trick stuff makes one! And I think they’re easier to get than the brakes Smile
  • 1 0
 I have tested these offset kit. That was a bummer because of the stack height. Since the bearing needs to be offset it needs to be cups outside the head tube. If anyone are interested I have 2 kits laying around (1 for tapered and 1 for dc crown), just send me PM
  • 2 0
 Shame it’s an EC cup for 1.5 lower steerer. That’s going to put a lot of people of including me. I’d have tried it otherwise
  • 1 0
 I agree.
  • 1 0
 @JKL250 Technically, I guess it could be possible to make a combined ‘slackening (1 or 2°) and offset shortening headset’ that retains ZS in the bottom, as the slackening offset bearings in the bottom cup re-centers the fork in the middle of the frame. I would want such a headset.
  • 3 0
 So could I get a 27mm effective stem from this? What direction would I have to run it?
  • 1 5
flag justanotherusername (Aug 24, 2022 at 12:09) (Below Threshold)
 It doesn’t do a single thing to alter stem length.
  • 6 0
 @justanotherusername: yes it does. Changes effective stem length because the steerer is offset from the steering axis. So the steering axis will go through a point on the stem that is not the center of the steerer clamp, thus changing the effective length.
  • 2 0
 @justinfoil: ok I think I figured it out, if I wanted a shorter stem I would want to mount it with the steerer further towards the rider. And this would give an effectively shorter offset right? And larger trail number.
  • 4 0
 @justinfoil: Yes it does, of course it does, my mistake.
  • 1 0
 @plustiresaintdead: yes. Except if you wanted a shorter stem, you just get a shorter stem. You use this if you want to change effective fork offset, and then maybe a different stem if the effective stem length change doesn't work for you.
  • 4 0
 Get to the choppa!!
  • 4 0
 i like it
  • 3 0
 Seb, will you get to test their Senduro when it becomes available?
  • 1 0
 We need an actual ride-review of this. This looks like it would either feel fantastic or horrible depending on what you're trying to achieve.
  • 6 0
 Why would it feel either fantastic or horrible?

Most will use it to reduce offset, so from a 51mm 29er fork to 47mm - still more than the 44mm alternative fox offers for example.

It will be a subtle difference, no fantastic / horrible scenarios.
  • 3 0
 What's to ride test? It's just like fork offsets, and those have been ride tested before. They can help certain ride qualities, hinder others, just like everything.
  • 2 0
 Could this be combined with an angle adjust headset?
  • 2 0
 160 bucks to change fork offset by 4mm. LOL.
  • 5 0
 Less than a new CSU or set of dual crowns...
  • 2 0
 I understand what it does, I just don't understand why I would want that.
  • 1 0
 Best comment read to date. I’m crying!
  • 1 0
 Sone serious engineers in here. Not that I’m better, but I don’t tell people that I know the product better than its developers.
  • 2 0
 Works on ears too?
  • 1 0
 Will this offset the Lefty to the right?
  • 1 0
 I think most people don't notice different fork offsets anyway
  • 2 0
 *ERMEGERG Meme*
  • 5 4
 Wtf just take some riding lessons
  • 1 2
 This increases or decrease the distance between the steer tube and BB. By about oh 5 mm . Could I even feel that? I doubt it . changes reach not HT angle . Got it .
  • 1 1
 Fork offset is something different that's the angle of the stantions in relationship to the steering tube .
  • 3 0
 We simply do not measure angles in millimeters
  • 2 0
 @somebody-else: thanks for sharing ! Reach : mm.
Degrees Fahrenheit.
Got it .
  • 1 0
 I wonder if I can just machine my race to do this for any headset?
  • 1 0
 And what about getting a fork with the right offset?
  • 1 0
 Jeez. It’s too early for this!
  • 1 0
 What the hail
  • 1 3
 Just buy a shorter or longer stem. This will affect the steering and stability cheaper than buying a different offset fork.
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