[toodles]

Yeah yeah, DH forum etc. But fuck it. Half the threads here are discussing supercars or E-bikes so here's a rambling discourse of my experimenting with fork offsets. Not sure if any monkeys have played around with this at all - I don't know anything about vehicle handling and dynamics, just my observations.

Storytime - The characters

Anyway, I got a new Transition Patrol frame this year which is designed around a short offset fork under their SBG moniker. When I built the bike I used a standard Lyrik as thats what I had (27.5, 46mm offset) combined with a 50mm stem. Transition recommends and specs a 37mm offset fork and 40mm stem. After injuries forced me to cancel all my racing and holidaying plans for the year, I also went out and bought a Smuggler - their 29er trail bike thing with the same SBG design but using a 42mm offset 29er fork instead of a 51 or whatever 29er forks normally are.

A few rides in on the Smuggler and it was apparent that it turned like a mofo. Just tipped into any corner, no matter how steep and felt super composed and had this weird no micro-correction stability going on that was awesome.

The setting
I decided to try a short offset on the Patrol. Cue immediate shock when i find out a Lyrik CSU is like $500 AUD. Git farked. Gave up that idea until one came along at half price. CSU aquired, I waited till end of race season and installed it.

The plot.
Genuinely a different bike. In Pinkbikes review of the Sentinel they tried standard and reduced offset forks and were like "meh - not much difference". Maybe the 29ers are different but the 27.5 bike is a completely different animal with the reduced offset. It feels less slack just standing on the bike due to the shorter front center, but actually turns in slower than it used to. Cornering has oodles of front wheel traction, but a slight tendency to "tuck" on a few hard corners so far.. I dropped the stem length from 50mm to 40mm to see and ran it that way yesterday. Now its turning better than before, and has a weird calmed feel when tipping it into a steep corner. It feels like a much slacker bike but with good front end weighing if that makes sense.

The conflict
The only thing I'm not liking is the reduced hand foot distance. Not sure if I'll adapt to that with more riding time or if it'll drive me crazy/cost time on steep sections.

The resolution
Not sure. The turning is good, but the shortened hand-foot distance is an issue. I could try the 50mm stem again or just revert the bike back to the old CSU and stem. Or just adapt to it like a normal person.

 

[Happymtb.fr]

You should write more articles like this on the internet, dude!

Back on topic, I played with different offset too and found that the shorter offset was offering slightly more grip probably because of the shorter front centre. On overall, nothing really mind blowing from my point of view. FWIW
I swapped between Yaris on a 66° HA bike, same travel, same tweaked internals, just the offset going from 51 to 42 mms.

 

[Udi]

As above, you'd actually have to correct for the change in FC and WB to make these claims with accuracy.

A gain in front wheel traction (and feel, and weighting) would also come purely as a result of decreasing the horizontal distance between CoM and contact patch of front tire (even with offset left identical). I'm not saying some of what you feel may not have been as a result of reduced offset alone, but I do find most people making these kinds of comparisons don't isolate the effects (ever!), when ultimately small changes in WB and FC/RC ratio have substantial effects on traction and handling due to the effect on tire normal force and pitch angle.

If you still have an offset headset cup (not angled but purely translational), it'd be interesting to match bar height and wheelbase, then compare the impact of offset alone.

I think the industry likes to wank on about offset when really, old offsets were fine, new offsets were created as a solution to an imaginary problem, now old offsets are sold back to punters as an "improvement". It's the classic wallet-double-drainer move.

 

[Cerberus75]

I changed my fork offset from 51° to 41° at the same time I upsized my frame. My wheelbase grew 10mm from the results and i have better traction at the limit, and I dont have the wondering counter steering a longer offset causes. The longer offset cause understeer.

 

[kidwoo]

Dafuq you sitting around worrying about fork offsets for?



PEDAL!!!!!!!!!

 

[toodles]

If you still have an offset headset cup (not angled but purely translational), it'd be interesting to match bar height and wheelbase, then compare the impact of offset alone.

Dude. I totally forgot I still have an offset headset in the garage. That's an awesome idea. *edit* mine is External Cup top and Bottom. No good*

Obviously the front end traction increase is going to be due to the shortened FC. I don't think the offset could affect traction. The weirdest part is the change in "turn-in" or steering speed and the calmed cornering manners. Hopefully I've still got all the parts for the offset headset - if I do, that will be a really good option.

As an aside, just quietly - rather surprised by the difference in stiffness and vibration between the 40 and 50mm stems. They're both the same brand and model of stem but its palpable. Obviously the 50mm is a bit older but only talking months, and there could be some kind of tolerance issue or whatever but geez. The 40mm is downright punishing.

Dafuq you sitting around worrying about fork offsets for?
PEDAL!!!!!!!!!

The bushfires are indeed a fucked situation man. Even the minor ones are pretty insane to see, and when they get moving its nuts.

 

[toodles]

I think the industry likes to wank on about offset when really, old offsets were fine, new offsets were created as a solution to an imaginary problem, now old offsets are sold back to punters as an "improvement". It's the classic wallet-double-drainer move.

On that point, why the f*ck did they increase offset anyway when they went to the bigger wheels? Clearance maybe? It seems that across the board, most manufacturers are now speccing shorter offsets and increased reach on bikes so maybe its just a genuine geometry evolution but the old 29er offset was 51mm which is really nuts.

 

[kidwoo]

Apparently no one in stralia rode 2001 gary fisher 29ers with whatever fork offsets were back then. They did greater offsets on wagon wheels for a reason. They just went overboard. And it's more pronounced with bikes generally being able to go a hell of a lot faster now.

But long offsets absolutely do help slow speed steering. My biggest eureka was just from riding a 27.5 boxxer and 40 back to back. You don't need to normalize everything else on the bike to tell the difference. It's there.

Quit worrying about the minutia that doesn't matter and just switch shit around till you find a setup you like. And please just stay the hell away from those fires.

 

[Inclag]

Quit worrying about the minutia that doesn't matter and just switch shit around till you find a setup you like.

But that's not spirit of enduro now is it....

...This whole geometry thing seems to be getting a little out of hand with the absolutes that are being thrown around along with just the terrible 'review/first ride/marketing machine' articles led by PB, Vital, and 'woof' Enduro-mtb.

Folks might be surprised if they considered a 50 or 60mm stem on a long travel or downhill bike. Also for some reason nobody seems willing to call out that super steep seat angles suck for rolling jank. All that front end grip and ability to prevent loop outs comes at the expense of added front wheel pressure and awkwardness when riding more level raised saddle terrain.

Geometry comes with compromises.

 

[toodles]

Quit worrying about the minutia that doesn't matter and just switch shit around till you find a setup you like.

I guess the point I was making is that there's a definite difference. I'd obviously need to run offset headset or something to 100% prove that, but there's certainly something going on. I'm not surprised that some of the bigger teams are faffing about with offsets on DH bike where this sorta stuff would actually be most relevant.

For my personal stuff, I'll just opt for what gives me the best all-round bike for the racing\riding I wanna do in the next 12 months.

I could see Syndicate or whatever playing with this stuff when courses change speeds/steepness and cornering varies. It seems so far to make a definite change I think.

 

[kidwoo]

I guess the point I was making is that there's a definite difference.

Of course. I could move your brake lever 1.5mm and you'd notice it.

I'd obviously need to run offset headset or something to 100% prove that,

Not really but if you've got the parts and it would make you feel more comprehensive, go for it.

I've popped off for the last 4 years about 27.5 fork offsets being a little much, especially on dh forks. But on my trailbike that I climb on for hours...I deliberately used a 27.5 totally transition unacceptable long dong offset fork because it's better for an all around kind of thing. I also cut out the arch on a 180mm 26" fork to run on that same trailbike when it's in beat the shit out of things mode, partially because of ye ole shorty offset. Longer offsets help low speed handling, lower ones offer a little more stability and calm. That's all there is to it. You can ride either and will adapt to either just fine.

The +/-10mm reach thing is just farting around in la la land. Move your seat, cut your bars, put wider bars on, lower or raise your stem with an itty bitty spacer. The church of absolute reach is just fucking stupid IMO. There are so many other variables that matter just as much.

 

[toodles]

I've popped off for the last 4 years about 27.5 fork offsets being a little much, especially on dh forks. But on my trailbike that I climb on for hours...I deliberately used a 27.5 totally transition unacceptable long dong offset fork because it's better for an all around kind of thing. I also cut out the arch on a 180mm 26" fork to run on that same trailbike when it's in beat the shit out of things mode, partially because of ye ole shorty offset. Longer offsets help low speed handling, lower ones offer a little more stability and calm. That's all there is to it. You can ride either and will adapt to either just fine.

The +/-10mm reach thing is just farting around in la la land. Move your seat, cut your bars, put wider bars on, lower or raise your stem with an itty bitty spacer. The church of absolute reach is just fucking stupid IMO. There are so many other variables that matter just as much.

Yeah I agree its getting into the nitty gritty and silliness - I'm the first to admit that. I probably won't bother faffing around much more as the Patrol was getting the job done well enough in the non-SBG long offset guise anyway and the shortened hand-foot is bugging me more than the improvement in turning.

The main point behind all the waffling on was to share the fact, that despite all the changes people want us to care about (ermagherd cable-less remote activated droppers!!!11!!) there's actually relatively non-subtle difference to be made with this adjustment IMHO. Someone like @buckoW who has access to tinkering parts and lives somewhere where you could consistently and reliable do back to back testing could and probably is, benefitting from playing around and making a Frankenbike for MSA or Fort Bill kind of speed sections.

 

[Electric_City]

Whaaaa?

Monkeys telling you that some minute changes are irrelevant? Nothing to worry about? Don't mean much?

I must chop off my very own monkey hands and never visit here again.

 

[frorider]

Ian Alexander, the engr behind Whyte bikes, goes into some detail on his decision a few yrs back to go with reduced offset in this 2017 article: https://m.pinkbike.com/news/whyte-s-150-carbon-rs-review.html

From what I’ve seen, the rave reviews of the S150 in Yurp several yrs ago appeared to usher in this recent wave.

Another euromag reviewing the S150 tried std and reduced offset forks on the same bike & trails and preferred the reduced. hrug:

 

[kidwoo]

Monkeys telling you that some minute changes are irrelevant? Nothing to worry about? Don't mean much?

No one said that.

 

[jonKranked]

Apparently no one in stralia rode 2001 gary fisher 29ers with whatever fork offsets were back then.

i rode a GF 29'er around that time. might have been 2003? i proceeded to roll both tires right off the rims.

 

[englertracing]

Also for some reason nobody seems willing to call out that super steep seat angles suck for rolling jank. All that front end grip and ability to prevent loop outs comes at the expense of added front wheel pressure and awkwardness when riding more level raised saddle terrain.

Geometry comes with compromises.

"Rolling jank"
What is that?

As a dude who rides mx and super moto, where you gotta sit quite forward on the throttle.

I am a habitual forward seat slammer.....
I enjoy some front wheel weight...

But i also realized S,M,L, and XL should perhaps come with slacker seat angles for small and steeper for larges, as when you have 200mm of post out on an xl you end up right on top of the rear axle, where the midget riding the s with 100mm of post out is quite a bit forward in comparison

 

[Inclag]

"Rolling jank"
What is that?

As a dude who rides mx and super moto, where you gotta sit quite forward on the throttle.

I am a habitual forward seat slammer.....
I enjoy some front wheel weight...

But i also realized S,M,L, and XL should perhaps come with slacker seat angles for small and steeper for larges, as when you have 200mm of post out on an xl you end up right on top of the rear axle, where the midget riding the s with 100mm of post out is quite a bit forward in comparison

Technical trails that don't have any significantly sustained up or down components.

I totally get the whole grind up, up, up, and away to then hit some network of trails that are generally made to go down. In this instance, I understand and appreciate at 6'3" the steep seat angle since it biases more weight towards the FC.

However, for technical trails that don't have a significant bias towards up and downs, I find that it isn't reasonable to be adjusting the seat height every 10 seconds. So this shouldn't be a surprise to anyone, but a saddle position optimized to weight the front wheel more when the grade is angled up, feels too forward biased when the terrain is on average a level grade.

 

[S.K.C.]

Rumor was, Gee and Zee Fraunch were experimenting with custom fork offsets during the 2019 WC season, mainly with this:
https://www.mojo.co.uk/mojo-morc-crowns-3-c.asp

 

[kidwoo]

trails that don't have any significantly sustained up or down

I don't understand.

You mean like where I walk my dog?

 

[Udi]

The +/-10mm reach thing is just farting around in la la land. Move your seat, cut your bars, put wider bars on, lower or raise your stem with an itty bitty spacer. The church of absolute reach is just fucking stupid IMO. There are so many other variables that matter just as much.

Changing multiple variables at once (most of those unrelated to the issue) is a great way to see the results of nothing at all. The point with offset headset cup was little to do with reach, and everything to do with WB and FC as I originally said - because these numbers change the effect of the largest mass on the bike and its (most direct) distribution between the only two contact points with the ground.

If you're going to change fork offset via crown/lowers alone, the "results" you see come from a change in fork offset together with a change in WB and FC. If you want to explore the results of fork offset alone, you need to simultaneously reduce the impact on the other variables.

 

[Inclag]

I don't understand.

You mean like where I walk my dog?

Or riding your horse.

I'm talking about eastern Massachusetts. Hills, conservation lands, old money/wealth, equestrians, NEMBA...

We have to work with what we've got which is limited terrain, existing 'multi use' trails, and limited support for significant recreational initiatives.

Got to keep it glass half full.

 

[kidwoo]

Changing multiple variables at once (most of those unrelated to the issue) is a great way to see the results of nothing at all. The point with offset headset cup was little to do with reach, and everything to do with WB and FC as I originally said - because these numbers change the effect of the largest mass on the bike and its (most direct) distribution between the only two contact points with the ground.

If you're going to change fork offset via crown/lowers alone, the "results" you see come from a change in fork offset together with a change in WB and FC. If you want to explore the results of fork offset alone, you need to simultaneously reduce the impact on the other variables.

Subjective riding "shows" you nothing at all if you want to really get semantic. The bikes I've done this with, even with a 3mm-ish (or whatever it works out to) shorter wheelbase resulting from a shorter offset fork, your front wheel gets deflected less and feels more stable at mach stupid, and pushes a little more climbing slow. So a shorter wheelbase bike feeling like a more stable ride. That's enough for me and jives with everything else lars from transition was messing around with a few years ago.

Lengthening the wheelbase even more just goes farther than needed if it's a handling/steering answer you're after. Like I said, if you've got the parts, sure go for it. It's just not necessary IMO. And I never said you harped on reach, that was toodles talking about his hand position.

Until you start measuring forces, sitting on scales with each wheel, and establish repeatability in a real test, it's still subjective. Yes you can always minimize variables more. Make sure the pins on your pedals always sit in the same grooves on your shoes, and you've got the same thickness socks on. I'm just trying to get to "this is a bike I like riding better," not "this is objectively established data." Objectively established data made trust forks.

 

[Cerberus75]

Subjective riding "shows" you nothing at all if you want to really get semantic. The bikes I've done this with, even with a 3mm-ish (or whatever it works out to) shorter wheelbase resulting from a shorter offset fork, your front wheel gets deflected less and feels more stable at mach stupid, and pushes a little more climbing slow. So a shorter wheelbase bike feeling like a more stable ride. That's enough for me and jives with everything else lars from transition was messing around with a few years ago.

Lengthening the wheelbase even more just goes farther than needed if it's a handling/steering answer you're after. Like I said, if you've got the parts, sure go for it. It's just not necessary IMO. And I never said you harped on reach, that was toodles talking about his hand position.

And besides, until you start measuring forces, sitting on scales with each wheel, and repeatability in a real test, it's still subjective. Yes you can always minimize variables more. Make sure the pins on your pedals always sit in the same grooves on your shoes, and you've got the same thickness socks on.

This is my experience. I have a short wheelbase bike that is comfortable at higher speeds. And only a small compromise for slow tight stuff, but still better than a long bike.

 

[toodles]

Another spin yesterday afternoon. Went and did some higher speed sections and a few steeper lines. Stability and ability to hold a cross-camber line is definitely better with the shorter offset. It seems like the bike will "lock" onto the chosen line better than previously, even though the WB is smaller and I'd predicted it would be less stable.

I thought I was on really good runs (or it felt that way) but the highly scientific Strava results for those sections indicated a couple seconds slower than the times I got last week on my normal offset fork.

One noticeable thing - the reduced offset is frustrating on really tight sections, particularly through trees. Turning the bars to get around a corner feels like it does less now, which means you've either got to turn the bars more (which makes the front end push easier) or lean harder which isn't always possible depending on the trees or obstacles on the inside of the corner.

 

[kidwoo]

I thought I was on really good runs (or it felt that way) but the highly scientific Strava results for those sections indicated a couple seconds slower than the times I got last week on my normal offset fork.

Totally unscientific until we see soil moisture comparisons, your blood sugar levels, and how full the vape pen you had in your fanny pack was. Without equalizing these variables, you've proven nothing.


The rest of that sounds about right.

 

[toodles]

Totally unscientific until we see soil moisture comparisons, your blood sugar levels, and how full the vape pen you had in your fanny pack was. Without equalizing these variables, you've proven nothing.

None of this makes sense in Australia.
Soil Moisture at the moment? Does that scale go into the negative? Even after it flooded here a few years ago the ground was only described as "packed down" and "bordering on tacky".

BAC is more important than blood sugar around here, and I was in a rush to go get a pint so it must have been low.

Vaping is for e-bikers. Analogue riders roll their own. Duh.

 

[kidwoo]

analog riders

 

[William42]

What I'm hearing from this thread is that everybody should rush off to go by short offset forks and that lives are meaningless without them.

FWIW I've been riding a short offset fork for about a month now and it echoes most of the things said here. Although talk about fuckin variables out the wazoo, it's a new bike, it's a 29er (which I've never ridden really), and the last bike I seriously pushed and tried to shred on was a 26" bike. I skipped the entirety of 27.5.

But the steering feels sharper and more precise and less "give the handlebars a wave and you'll probably end up going the right direction eventually after lots of corrections that I remember from my v10, and before that session. Which took me by surprise, because I was expecting the 29ers to have a pretty vague "point it generally the way you want to go and make lots of micro adjustments to get there.

In reality, the new bike feels significantly more precise than my old DH bikes, while still feeling just as stable and controlled at speeds.

I wonder if I'm a sheeple just following the heard because people seem to like short offsets.

Fuck, I'm going to go have an existential crisis in the bong shed, I used to know what I wanted from bikes. Some analog rider hit me up.

 

[Udi]

Subjective riding "shows" you nothing at all if you want to really get semantic.

That was my point - this is an incredibly subjective comparison to begin with, and yet toodles is still harping on about the impact of his offset change even though he's changed WB/FC at the same time. He claims that some things should be the opposite bla bla but really it's just a flawed comparison - not having a go at him - but I've watched many people do the same in the past and it's pretty well useless.

The biggest factor with changing WB/FC simultaneously to offset is that a lot of people have bikes that are either a little too long or too short to begin with (or two bikes of different sizes), so the impact of this specific thing will favour different people depending on the bike they're riding. It's exactly why you might prefer a shorter offset on a DH bike and a little longer on a trailbike (ironically identical to what I'm running) - but it's NOT necessarily because of the offset itself.

I just think you either need to "shut up and ride your bike", or make nerdy subjective comparisons as close to objective as possible - otherwise you end up with the pinkbike.com news homepage.

 

[toodles]

That was my point - this is an incredibly subjective comparison to begin with, and yet toodles is still harping on about the impact of his offset change even though he's changed WB/FC at the same time. He claims that some things should be the opposite bla bla but really it's just a flawed comparison - not having a go at him - but I've watched many people do the same in the past and it's pretty well useless.

Dude I've literally listed every change I've made from stems and fork CSUs. I haven't attributed anything to the change in offset, just describing the changes I've noticed with the setup as a result of the wheelbase/offset and even the shorter stem, both with the stock parts and otherwise. This isn't a double-blind science experiment, I'm a bored guy with the parts in the garage to fuck around with.


If you flick back to my original post, you'll notice the bolded segment titles are actually the sections of a novel. Theres a reason they don't say Aim, Hypothesis, Method, Results, Summary instead.

 

[Flo33]

I'm a bored guy with the parts in the garage to fuck around with.

I envy you. Don't get kids - never ever!

I got a 650b 36 and a 26 one, each of them with their respective offsets. The difference in steering feel is very noticeable, but there is another variable coming into play here, different a2c and therefor different head angle - have fun... and yes, I do run an extra head tube spacer with the shorter 26 fork.

I ordered a 37 offset csu for the 650b one some time ago but never installed it. I do shut up and ride my bike atm. Maybe on a long and cold winter eve I'll install it and report back how the difference in offset, wb and fc/rc ratio totally changed my riding.

 

[Udi]

Dude I've literally listed every change I've made from stems and fork CSUs. I haven't attributed anything to the change in offset

Went and did some higher speed sections and a few steeper lines. Stability and ability to hold a cross-camber line is definitely better with the shorter offset. It seems like the bike will "lock" onto the chosen line better than previously

You're literally attributing your improvements to the change in offset here.
Transition increased the lengths of each size purposely to compensate for the shorter offset intended, so there's a good chance that the whole bike being shorter means it's just the correct size for you now and half the "benefits" are partially due to greater mass % over the front contact patch from the FC being reduced.

I really don't think this stuff is a huge deal, I just dislike the industry profiting from "new ideas" when it's just rehashed old stuff. At least you didn't also rave about longer offsets when they came out like @buckoW (who's firmly in denial about that fact now).

 

[johnbryanpeters]

I suggest dynamically variable offset, governed by lunar phase.

 

[Jeremy R]

Ridemonkey works like the opposite of a therapist.

Toodles: I changed this thing on my bike and it feels great and I am happy.

RM: You don’t even know what you are feeling assbag. You should feel sad and alone for not understanding why you are actually smiling.

 

[Happymtb.fr]

I suggest dynamically variable offset, governed by lunar phase.

Just trust the message

 

[jonKranked]

Ridemonkey works like the opposite of a therapist.

Toodles: I changed this thing on my bike and it feels great and I am happy.

RM: You don’t even know what you are feeling assbag. You should feel sad and alone for not understanding why you are actually smiling.

 

[djjohnr]

Interestingly the stated steering effects of shorter offset sound very similar to what you get when you increase bar width.

 

[Sandwich]

happy to hear of your experimentation. Keep posting with further thoughts. I tend to agree- the shorter the offset (within reason) tends to have beneficial results on handling, especially at speed. Slower, somewhat less so, but I'd rather have neutral, predictable handling that I have to wrestle than something that's razor sharp at slow speeds then dangerous at high.

I haven't experimented with different offsets on the same bike, but with each move to a shorter offset fork, I've noticed an improvement in desirable handling traits. Again, lots of things happening, but overall I wouldn't move in the opposite direction if I had the choice, regardless of other variables. I think those only enhance good steering feel.

 

[Udi]

RM: You don’t even know what you are feeling assbag. You should feel sad and alone for not understanding why you are actually smiling.

Nah that's me, no need to blame RM.
Someone's gotta do it, and it's sure as hell not gonna be the Transition fanclub.

In case it wasn't clear - I do (like everyone else) also think shorter offsets work better - but we already had shorter offsets before the industry decided they needed to be longer for whatever reason. Now we have shorter offsets (again) and it's sold back to people as a "feature", hooray.