What happens if you do this (fork offset)

Ok

So Transition frames are had for a really reasonable cost. But they are built around a reduced offset fork…

What would the effect of putting a 51mm offset fork (already owned) on one be?

I’m looking at the sentinel. It’s made around a 160mm fork with reduced offset. Considering maybe running the current forks at 150mm (51mm offset fork).

I’m a pretty average mtb rider really so would I even notice I’m not on a reduced offset fork?

It’ll speed the steering up a bit and make it a bit harder to weight the front wheel – swap the stem for one 10mm longer and that’ll balance things out. But you might not even notice!

No! I couldn’t tell when I swapped from one to the other.

The big issue is that you’ll know- if you didn’t, you probably wouldn’t notice but when you do, all bets are off 😉

My understanding is that a higher offset will make the front wheel a bit flip-floppy. Kind of like a supermarket trolley castor. Speeds up the steering and makes it feel a bit more twitchy. Current trend for reduced offset (<40mm) helps make bikes feel more stable going downhill at the expense of being very slow to turn on tight and twisty stuff.

Wouldn’t more floppy floppy be less twitchy at speed?

you’ll not notice, compared to the variation as the fork compresses

Wouldn’t more floppy floppy be less twitchy at speed?

Think of trying to push a supermarket trolley which has the wheels forward of the steering pivot.

“My understanding is that a higher offset will make the front wheel a bit flip-floppy.”

No, it’s the opposite.

At low speed the shorter offset fork turns more quickly because the head tube drops more as you turn the bars. At high speed it turns more slowly because of the increased castor effect from the increased trail. And vice versa for longer offset.

After yet another F1-style pit stop at Mojo, it was back up the hill with a medium offset of 44mm – the same as a standard 650b fork from Fox. As you might expect, the handling was somewhere in-between the standard and super-short offsets used previously – not as calm and lazy as the 37mm, not as twitchy as the 51mm. After another trial run to get a feel for the 44mm offset fork, the stopwatch was applied once more.

Shorter offset also reduces the ‘floppy’ feeling that can occur when tackling tight corners, where the wheel can feel like it wants to tuck under.

From here: https://www.bikeradar.com/mtb/gear/article/pushing-the-limits-of-fork-offset-an-experiment-45343/

It’s just one tiny variable amongst a load of other variables you will be getting into on the new frame.

I bet you could provoke far, far more difference in feel by messing about with different length stems and bars.

I wouldn’t give it a seconds thought personally mate.👍

Fork offset is just the new “long, low and slack” as I think people are bored of hearing that phrase now.lol

Different example as on track bike but I swapped a 30mm offset fork for a 45m offset fork.
Trail was decreased and steering felt lighter/less stable for the first few minutes. After that I didn’t notice it and it made no real difference to actual riding (other than removing toe overlap)

Cheers folks.

Can’t believe how cheap these are in aluminium form? What’s the catch…. weight?

Interview with the guy from Pole bikes said in blind testing they couldn’t tell the difference.

I’d like to see a bunch of bike journos do the same & see if they could quantify the hype in some way.

“Interview with the guy from Pole bikes said in blind testing they couldn’t tell the difference.”

Not very sensitive testers?

I know there’s more to bicycle steering than the trail figure, but on the Sentinel which has a 64 degree head angle, a 42mm offset fork gives you 136mm of trail. To get the same amount of trail with a 51mm offset fork you’d have to reduce the head angle to 62.7 deg.

http://www.kreuzotter.de/english/elenk.htm

Can anyone show me a diagram that clearly shows why reduced offset increases trail please?, my head says it should be the other way around…. which means I have a misconception of what trail is!

first hit in google for ‘bicycle trail measurement’

EDIT – or the one above with more words

There was a thread on here about it.

Interview with the guy from Pole bikes said in blind testing they couldn’t tell the difference.

Probably ‘cos their heads hurt too much after crashing from trying to ride a bike blindfolded 🙂

TBF Pole bikes don’t need blindfolds their heads are stuck so firmly up their own arseholes

Seems mtb HA can be seen to be vital ie +/- 1 deg is a potential deal breaker to some while offset effect is often dismissed, yet makes similar levels of difference. Only been an option on mtbs in recent years granted, but on drop bar bikes the effect/use offset has been understood and valued for a long time – easier to adjust a steel fork of course and you feel differences a lot easier on a rigid bike.

You probably won’t be able to tell any difference. I couldn’t when I swapped between a 51 & 44 fork.

What you probably will notice is the super low BB is another bit lower with a fork too short for the bike.

Can’t believe how cheap these are in aluminium form? What’s the catch…. weight?

They are heavy, but not outrageously so, given their intended use. Catches> Limited tyre clearance, sh*t paint quality, rubbish bearings & a rear shock that is a bit of a pain to find a balance with & they only really make sense when you are absolutely hauling on it.

Only been an option on mtbs in recent years granted

It’s been an option since the beginning of mtb. It’s only recently certain companies realised how easily marketable it is an angle to get a fool to part with their money twice for the same thing.

Thanks folks. Lots of really useful responses.

Think this is the first time I’ve posted a question and not got half the responses full of sarcastic dribble!

The fork I have is a top end Lyric and I can swap the air shaft out to different lengths.

I’ve gone part time so £3k carbon frames are out these days, trying to find something to have as my one “do everything except xc” bike.

Really want it to be 29, long and slack. But not too fussed on travel if it’s light. But big travel and heavy isn’t really an option.

Anything else I should look at?

If you can find a 2017 Smuggler frame the Large weighs 7.3lb 2018/19 8.8lb for medium. But run better with 140mm forks, very capable bike.

Really want it to be 29, long and slack. But not too fussed on travel if it’s light. But big travel and heavy isn’t really an option.

I guess the obvious question is what do you define as long, slack & light?

As always there are plenty of owners of bikes on here that seem to defy the laws of gravity which doesn’t help when trying to potentially pick something new…

470 reach+ on a frame with a sub 460mm seat tube. Slack 66 or less.

Travel & weight aspirations?

Not that fuased about travel. 125-160 as I can change the travel of my Lyrics. Sounds vague I know but will have trade offs depending on whether I’m hauling it around the peak district or using a ski lift.

I can get a Sentinal for a touch over a grand new with warranty. Maybe I should lose 2kg and then it’ll be light?

To be honest if it wasn’t the fork Ofsett being marketed so much eaving a doubt over if it will ride funny I’d just buy it.

Shameless plug I am selling some 2019 performance 36’s with 44 offset which will get round the issue. Pm me if of interest.

Weight is a consideration for sure, but people do place a lot of emphasis on it, possibly even too much, unless you’re racing XC. When you take into account the entire ‘system’ weight of the bike, rider & associated paraphernalia, 1-2kg on the bike is going to make little to no difference.

I have an 11.8kg Fuel 9.9 EX, 140/130mm travel 29er, which is just over 66 degrees in the low setting & ~465mm reach, it’s a very lively, playful bike which I have in the past built up heavier & raced enduro’s on & even the odd regional DH.

I also have a 15.2kg coil sprung 160/160 29er, 64 degree HA, 500mm reach. I could maybe save 500g. If I ride it on local stuff, it feels massive, sluggish, heavy & dead – but it’s my race bike. it’s built to go fast & be taken abroad to ride & race which it’s perfect for.

When I get back on the Fuel after riding the Raaw, it feels scary light, twitchy & deflects off everything & when I swap back, the other bike feels just like the above. It doesn’t take long to adapt to either & I find my riding gravitates to the bike i’m on at the time. The thing I do find with the big bike is, you really do have to ride it hard for it to make sense & to do that, you need the terrain for it to work. I found the same with my Sentinel, as does one of the guys I ride with who has a carbon one.

Wonder how the Stooge Mk4 will feel.
That will be running 80mm offset rigids with 66′ headangle.
Look forward to trying it!

Hob nob. I’m not so sure. Think of how heavy a camelbak feels with 2litres. You know about it when you put it on.

If you strap that to the frame then you’ve got that permanently on the frame.

It’s been an option since the beginning of mtb.

Well yes, when forks were rigid. Since sus came out there wasn’t the option. RE marketing, maybe, companies can only market meaningless guff for so long though.

Hob nob. I’m not so sure. Think of how heavy a camelbak feels with 2litres. You know about it when you put it on.

If you strap that to the frame then you’ve got that permanently on the frame.

Absolutely you can feel the difference, i’ve got just over 3kg between my two bikes, it’s certainly noticeable (although less so when on the bike). Then it become geometry & suspension that make a bigger difference IMO.

But, much like I don’t want to ride my big bike around my local spots, I equally don’t want to take my Fuel out to race the EWS’s i’ve entered this year, nor do I want to take it to Whistler, because I want to keep it (and myself) in one piece!

The weight is the price I pay for increased durability & performance (in that area). You can’t have it all, so it comes down to where you are prepared to compromise.

Although the new Scott Ransom 900 gets close I think 🙂

Well yes, when forks were rigid

Nope.

Go measure the offset of the varoius suspension fork manufacturers throughout the entire history of mtb suspension forkage too.
not all brands used the same offset. infact look at DH forks and you’ll see offset between manufacturers/model year varied wildly

Go measure the offset of the varoius suspension fork manufacturers throughout the entire history of mtb suspension forkage too.

Oh no doubt, and there’s never been a standard offset of any sort. I meant only fairly recently would you have the same sus fork with a choice of offsets, lower leg castings in different offsets. I guess you could have varied fork brand to get that change but it wasn’t much of a like for like swap.

geex

Member

It’s been an option since the beginning of mtb. It’s only recently certain companies realised how easily marketable it is an angle to get a fool to part with their money twice for the same thing.

Absolutely.👍

I guess you could have varied fork brand to get that change but it wasn’t much of a like for like swap.

The only mtb riders I knew who actually cared about the offset difference were geeky downhillers like me interested in playing with geometry. All most punters cared about was what brand, colour and weight the fork was when infact many of the less popular cheaper forks (often with different offset) were actually more advanced and better performing than those more popular more expensive brands full of plastic shite to control damping and spring rates.

Why look for like for like when you could have had something that actually worked?