PM me if you guys ever want to go and set up your own magazine, with blackjack and hookers

Dunno about blackjack and hookers but I’m in if there’s tea and shortbread. Performance Bikes magazine used to be ace BITD (80s into the early 90s) for technogeekery but then it went a bit shit (dunno if it’s any better now). Seemed people wanted to read/write about bolt on faux carbon fibrette headlight covers rather than how stuff works.

For me, axle paths make sense in the context of this video

and

Maybe we should badger Steve, to do us another vid!

Well precisely, so why, in the case of them steep bikes, didn’t anyone consider changing the stanchion angle separately from the angle of the whole thing? When people fuss about a degree of HA and 5mm of offset, it seems odd not to consider that as something to be tweaked. As many often say here, it might all have been marketing bs, but that just increases my puzzlement. If you can persuade people that offset is so important, surely you can persuade them to buy your forks with their new minus half a degree stanchions. You’ve made a sale and, who knows, the thing might even work better.

Isn’t that a really good way of making an angle adjust headset a lot more complicated? 😀 Angle adjust crowns! You better **** patent that quick before the guys at works components get any ideas!

Unless you mean, you’d keep the axle in the same place relative to the headtube? But adjust the stanchion angle?

I mean machine the crowns so the lowers are at a slight angle relative to the steerer. Currently all forks (so far as I am aware) are machined to be parallel. The effect would be that the fork offset varied over the travel.

@kayla1 performance bikes was at its best for me when the late John Robinson was there – I think when he died there was nobody to take on the mantle, though that may be unfair now as not read it for years (still have bikes just don’t read mags)…
I still have his book somewhere on four stroke tuning (late 80s) where you could code your own computer programme to model the effect of mods!!!

kayla1
The thing is though, a lot of the anti-dive things fitted to motorcycle forks were blanked off by riders who wanted the bike to dive on the way into corners.

It’s not necessarily a good thing per se. If it’s what the rider expects to happen that makes it good for that rider. It’s also the norm now, so doing something different feels strange.

It would be far better to have the full suspension travel available under braking, but then no dive would feel very strange to a rider who expects it. Bit like a drug, wean yourself off it gradually. 🙂

Clarification: I should have made it clear in my earlier post, the problem I mentioned with Vincent girder forks happened when they were topped out from hard acceleration, not during active suspension travel.

Greyspoke
Well precisely, so why, in the case of them steep bikes, didn’t anyone consider changing the stanchion angle separately from the angle of the whole thing?

It was done on some motorbikes. I fitted some forks and wheel I took off a mate’s drag bike to my wife’s bike and they had that feature. Can’t remember what they came from originally, possibly an early H1.

I think the more important issue with brake dive on a fork is the decrease in trail as the head angle steepens. That Trust fork decreases the offset as you go through the travel to make the trail more stable.

Greystoke – people have made mtb forks where the stanchions aren’t parallel to the steerer. The only one I’ve seen advertising it as a benefit were German-A:-

German Answer “Xcite Criterion” 29″er Fork:On Test/ Out Of The Box

For some reason it was also more prevalent on older forks – Pace RC36 Monobox, RST Mozo Pro (got them both in the attic and just checked), Scott Unishock. I think also the original Rock Shox.

And if you’re retro enough to recognise those forks, you’ll also know CP has been spouting opinion and proclaiming “problems” that only seem to trouble a tiny minority of mtbers for over 20 years 🙂

Santa Cruz has stated this as a reason for not going past 63.5 to 64.5 degree head angles in the past and that these numbers seemed to be the sweet spot.

Hmmm… The company who also lied about their rear axle paths for over a decade.

seems legit 😉

If you decrease the offset of the axle (by any significant amount) you need to move it below the leg or at least into a position where it interferes with the stanchion path. That adds complexity to the design* as well as reducing travel for a given a2c, which probably offsets the benefits gained… I would expect.

* EDIT: Complexity to the design for a fork that has adjusters etc. at the bottom of legs. If you’re making a simple sprung fork then the axle below is probably less complicated.

Why stick with exactly 0 degrees when you could experiment with a degree or so either way built into your crown forging(s)?

Many older/cheaper shorter travel mtb forks did use zero a small offset at the crown and stanchions angled forwards from the crown and zero offset at the dropouts.

As with Ben. The limitation with this dropout design is reduced bushing overlap and lack of rigitity. Especially with a longer travel fork

Interesting, thanks. Though possibly mainly about getting from the crown race to the axle in the easiest way.

more of a crude evolution from the original RS-1/Mag series of forks than anything else.
Those first forks weren’t a one piece casting though.

RS1 > Mag > Quadra > Indy/Jett

Other brands did similar. Budget brands still do.

And if you’re retro enough to recognise those forks, you’ll also know CP has been spouting opinion and proclaiming “problems” that only seem to trouble a tiny minority of mtbers for over 20 years 🙂

Ooh dont go being all pragmatical and that after three pages the tech heads were just getting going theorizing.

The video now having watched just looked awkward

epicyclo

It’s not necessarily a good thing per se.

I didn’t say it was a good thing, I said it can be a good thing. You copied and pasted my words but left the ‘it can be’ out 😉 When the forks are diving (on the brakes) I know the front’s not pushing!

Especially with a longer travel fork

oh yeah now we’re talking. These were actually quite stiff from memory. OTOH the steering was odd and they were really long (would post S8s but dont want to confuse things with them being USD)

These were actually quite stiff from memory.

No they weren’t. Eat more and stop shouldering your bike on the tricky bits! 😉

Your memory is also shit. It happens with childbirth so don’t worry about it.
They wouldn’t even stay aligned straight over a days DH riding with zero crashes. (I was 12 st back then and constantly had to straighten the things). the axle mounting design was seriously flawed, as was the arch connecting the two lower legs plus the slim crowns didn’t grip the stanchions or steerer well enough.
They weren’t actually overly long either, the slim flat lower crown and the fact they were only 6″ travel meant they weren’t actually hugely longer than anything Marzocchi did at the time.
The steering wasn’t actaully odd at all either. Fork offset varied quite a bit from fork to fork back then and stupid journalists who didn’t actually understand how axle offset works looked at them and said it was. Chinese whispers did the rest.
It was cool their damping ran on sewing machine oil though.

Apart from the forks, falling rate rear, sky high BB, brake jack, self increasing lever bite point Hopes, Chain jamming Mr Dirt, Gazzalodi plastic compound fatbike tyres and 50lb overall weight (mainly from that saddle) that thing still looks the absolute dream to ride down a hill on.

When the forks are diving (on the brakes) I know the front’s not pushing!

Stop pulling the levers then.

Rear brake squat is for real men, preserves the geometry under braking.

The steering wasn’t actaully odd at all either. Fork offset varied quite a bit from fork to fork back then and stupid journalists who didn’t actually understand how axle offset works looked at them and said it was. Chinese whispers did the rest.

Odd, as the set I had certainly left different to a normal offset. You had around 8lbs (or whatever it was) of fork sitting a lot further forward than usual, you could definitely feel it at lower speeds.

It was cool their damping ran on sewing machine oil though.

Automatic Transmission Fluid….. so probs the same stuff. The rebound adjuster was very effective, unfortunately it was also very easy to move and had no indexing!

Fore-aft stiffness was fine though I believe. You’re right about twisting though, and the axle system was basically non-existent (for those who weren’t lucky enough to have one – it was just a pinch bolt on each side, nothing actually tightening the legs up against the hub) which didn’t help!

Stop pulling the levers then.

I like my teeth, ta.

You had around 8lbs (or whatever it was) of fork sitting a lot 30mm further forward

Again;

you could definitely feel it at lower speeds.

HUX 2 FLTZ ?

I made a crude preload bar to fix the stupid axle design on mine.

kayla1
I didn’t say it was a good thing,…

Sorry, I didn’t mean to imply you said that. I recognise that the feel of fork dive is part of the sensory information used by riders, and that the feedback is important to them.

And that’s why switching to a fork that does not dive cause difficulty for some, because part of the expected feedback is no longer there. Moving to a non-diving suspension means that a considerable part of one’s riding instinct is redundant. Adaptation to no dive means going back to the beginning in that regard.

Since I raised my handlebars I don’t seem to care about brake dive!

You had around 8lbs (or whatever it was) of fork sitting a lot 30mm further forward

Not even sure what you’re saying here, 30mm is bloody miles in this context

Not pie related, floppy feeling steering in tight switchbacks and the likes is the memory I have (but not the same as the feeling when you first try and bike with a slack head angle)

Thanks for all the responses to my query, but most of the forks mentioned apart from the one of teh blue GT geex referrred to appear (from my image searches) to have stanchion and steerer tube parallel. They have axle in line with the stanchion, but that is a differnet thing.

floppy feeling steering in tight switchbacks and the likes is the memory I have (but not the same as the feeling when you first try a bike with a slack head angle)

Remind me what frame we’re remeniscing about?

Yeah. I don’t really have that memory at all. but there’s way more to steering handling than just what weight or how far forwards of the steering axis your fork lowers are. Remember I still favoured shorter frames back then too and have always been borderline mental about bar height preference to within micro spacer height.
Having said that I was also one of the only folk who never moaned about fork/bike weights back then and happily rode 8.5lb shiver and 9lb MonnyTs with all that weighty open oil bath goodness right at the very furthest forwards lowest point of the fork too. The MX6 was just under 7.5lb IIRC.
I do remember folk commenting about the crown offset of theirs in uplift trucks/queue chat but honestly thought most were just overthinking it since it definitely looked quirky compared to anything else out there.

I’d love to have an old 99′ DH ultimate back with Monnys (massive offset) to compare to something modern.

Greyspoke – ALL the forks I mentioned aren’t parallel (but the Pace and RST ones are only by a few degrees) . Did you actually read the German A fork link?

Got to agree that the Chris Porter video left me totally unconvinced by his words. It all felt a bit hippy/dippy and I think the contributions on this thread are far more informative so thanks to all the forum suspension geeks