Non telescopic suspension forks.

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  • Non telescopic suspension forks.
  • Premier Icon zippykona
    Subscriber

    There seems to be bit of a craze developing for the above . There’s some on the front page.

    Are we at a position that motorbikes were in the late 80s  , where telescopic forks were rightly deemed to have been the wrong evolution of front suspension.

    Suspension dive when braking was seen as the most heinous crime going.

    A fortune was spent trying to make something different  but eventually everyone gave up as the wrong thing, for all its flaws is still a good thing.

    Premier Icon wwaswas
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    There’s a always a fringe of products moving to a different beat…

    amedias
    Member

    it’s like the 90s linkage heydays all over again…

    Girvin, Amp, Look, U.S.E SUB and at least one other name of which I can’t recall spring to mind.

    It’s an alternative, and they have as many positives and negatives as they always did, but mostly we ended up with telescopes because they were cheap, easily bolted into the front of almost any frame without issue and ‘good enough’.

    Some of the benefits of mechano forks could be achieved In other ways, eg I’d much rather see more modularisation and standardisation of telescopics to allow for replacing wear surfaces, steerer’s and springs/dampers more easily across models tbh. (Never going to happen of course…) But some of the attributes are more intrinsic and whether or not you value those (axle path, AD, geometry etc.) is a personal decision but the thing mostly holding them back is incompatibility with existing frames, you can bolt a (compromised) version to ‘most’ frames if you do it right but ultimately a decent linkage front end needs to be designed into the frame from the beginning and isn’t something you can just bolt on without having to give something else up in terms of its performance or design.

    I don’t think there is a “right” evolution, just the one that becomes commonplace, they all have their plus and minus points.   Personally I’m liking having the choice of different suspensions.

    Premier Icon jeffl
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    Those forks on the front page to look super funky though. I didn’t notice any mention of weight so assume they’re on a par with standard telescopic forks.

    Premier Icon vincienup
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    Lauf’s are particularly popular in some Fat circles,  although listening to some riders the fact that theyre ‘different’ may be a USP for some.

    It’s valid that not everyone wants the same from suspension though, and if buzz taming is all you want then most hydraulic forks are chronically over engineered.

    Premier Icon frogstomp
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    Those forks on the front page to look super funky though. I didn’t notice any mention of weight so assume they’re on a par with standard telescopic forks.

    I think they said they were similar weight to Fox 36s.

    Premier Icon nickc
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    The ones on the front page seems to have answers to many of the issues arising from traditional linkage forks. No brake dive, similar Geometry characteristics to tele forks, no servicing of complex and numerous bearings, and decent travel (160/170mm)…seems almost too good to be true. I could be persuaded I think, but a) they are still a premium over tele, and b) I don’t want to be their field testbed

    Are we at a position that motorbikes were in the late 80s  , where telescopic forks were rightly deemed to have been the wrong evolution of front suspension.

    Errrrr…..because Moto GP, Superbikes and MX and thetbast majority of road bikes have gone to linkage forks have they?

    Premier Icon vincienup
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    A fortune was spent trying to make something different  but eventually everyone gave up as the wrong thing, for all its flaws is still a good thing.

    Context is always important. 😉

    The linkage on the Motion E18 is designed so the axle path of the front wheel is vertical through the final 50% of travel, so retaining wheelbase and boosting stability in those sections of trail where you need it.

    So the fork won’t attenuate large hits properly, or hits when 50 prrcent of the travel has already been used.

    Design flaw being marketed as a positive. The human body is capable of adapting to low speed low frequency changes in balance, but not so capable of absorbing high frequency high speed bumps.

    First of all Motion isn’t using bearings, but instead, a composite bushing made from a material that was originally intended for use in deep sea machinery applications

    Bushings but no stiction lol? I call bullshit on that, frictiomless bushings would be a game changer for entire industries….  I imagine the engineer who owns Vorspring would agree as well.

    hols2
    Member

    I’m just amazed that there haven’t been long, tedious threads about this before.

    Premier Icon austen
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    With road (race) motorcycles the argument for telescopic forks is that the increased steering angle under braking is a big advantage at getting the things turned into corners.

    I’ve no idea how important this is off-road, but my memory from a brief spin on at Whyte PRST1 many years ago suggested that the front end felt a bit vague.  It definitely helped on steep downhills, but took a bit of adapting to.

    There were so many cool things about that bike!

    Premier Icon lovewookie
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    I had a USE SUB fork for a while. didn’t get on with the inconsistent damping from the Englund internals.

    However, the anti dive worked very very well, though you’d not notice, until you ride the same section on a normal fork and wonder where all the bumps came from. I mean, it didn’t totally revolutionise your riding, but it was like adding another 20mm travel to the front of your bike in the rough stuff.

    It also made me aware of my riding style, and how much I’d got used to leaning back and dabbing the rear brake to brush off speed, only lightly front braking to naturally combat fork dive. This meant that, in most situations, it kinda rode the same. When I started to push the fork a bit more, using the anti dive to my advantage, braking late and hard, the internals couldn’t cope.

    I kinda wish USE would remake it, but with proper internals.

    Premier Icon thisisnotaspoon
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    So the fork won’t attenuate large hits properly, or hits when 50 prrcent of the travel has already been used.

    That assumes that

    a) whatever head angle you’ve chosen exactly matches the vector of the forces from a given hit in the first place. One of the big drawbacks of telescopic forks is that at slack head angles the bushings bind because they’re not sliding in line with the applied force. Which is actually two problems in one, the bushings bind because they can’t deal with much load at all, and the fork is only moving in that direction because that’s the only way it can (head angles are chosen for completely different handling reasons, you wouldn’t spec a rigid fork with a different sagged head angle).

    b) that pretty much every FS bike has got it wrong too (most having slight chain growth in the first half to counter pedal bob, then the wheel actually moves forward (roughly constant chainstay length) to prevent too much pedal feedback on big hits.

    If telescopic suspension is so good, why did it die a death in the 50’s

    I’ve no idea how important this is off-road, but my memory from a brief spin on at Whyte PRST1 many years ago suggested that the front end felt a bit vague.  It definitely helped on steep downhills, but took a bit of adapting to.

    The argument in MX against them, is that you cannot get the same amount of travel out of them for a given A2C, negating the improved bump absorption under braking. (if we went to dual crowns for enduro, we could be running 190mm of travel for the same length 170mm single crown telescopic) Remember, on top of that you have to conaider the trade off between bump absorption on the straights and under braking, if you run less travel you may lose time on the straights.

    And so far, no one has produced a fork where the axle path is not compromised, it’s not too heavy, or lacks travel on the straights.

    a) whatever head angle you’ve chosen exactly matches the vector of the forces from a given hit in the first place. One of the big drawbacks of telescopic forks is that at slack head angles the bushings bind because they’re not sliding in line with the applied force. Which is actually two problems in one, the bushings bind because they can’t deal with much load at all, and the fork is only moving in that direction because that’s the only way it can (head angles are chosen for completely different handling reasons, you wouldn’t spec a rigid fork with a different sagged head angle).

    Although 63 to 66 does seem to give a good axle path, whilst non linear axle paths eg the one on the fork on singletracks homepage…are even harder to predict….in terms of balance. Fork offset can be used to adjust handling as well remember.

    Secondly, it’s not like bicycle linkage designs don’t have binding issues at the rear. What makes you think the front would not suffer similar issues to rear designs?

    b) that pretty much every FS bike has got it wrong too (most having slight chain growth in the first half to counter pedal bob, then the wheel actually moves forward (roughly constant chainstay length) to prevent too much pedal feedback on big hits.

    Which is why I bought a Commencal Supreme SX… that has about 45mm of rearward travel. A 170mm fork at 65 degrees has about 61mm using geometrycalc.

    I’ll add, the only time I feel bushing bind in forks is when I land to flat hard, bounce around in a carpark  with my head and chest way iver the front of my bars, or hit an object I really should have popped my front wheel over in the first place. Otherwise I never feel it. Under normal conditions, when descending I don’t feel it.

    Premier Icon thisisnotaspoon
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    Secondly, it’s not like bicycle linkage designs don’t have binding issues at the rear. What makes you think the front would not suffer similar issues to rear designs?

    Because bearings don’t bind anywhere near as much as telescopic bushings. When people talk about binding in rear suspension it’s usually in relation to badly designed systems from 15 years ago putting side loads on the shock.

    A 170mm fork at 65 degrees has about 61mm using geometrycalc.

    That’s 61mm less front center, probably just when you could really do with a bit more stability.

    And it’s not just axle path you have to consider, there’s the braking forces too. The SUB fork added a bit of offset through the travel, but more importantly balanced the brake forces.

    And I’m not convinced you actually want the wheel moving back that much at all to absorb bumps, look at a car’s suspension, it’s near vertical when viewed from the side, even on big Dakar cars and trucks.

    I’ll add, the only time I feel bushing bind in forks is when I land to flat hard, bounce around in a carpark  with my head and chest way iver the front of my bars, or hit an object I really should have popped my front wheel over in the first place. Otherwise I never feel it. Under normal conditions, when descending I don’t feel it.

    In the same way most people don’t notice until they try a lefty or headshock and see what roller bearings feel like compared to telescopic  bushings.

    Not sure you can compare to a 4 wheeled application, as steering and handling geometry becomes a lot more complicated. Besides, baja trucks look to have some rearward travel at the rear. They also have very very soft initial spring rates and huge amounts of travel and massive wheels and tyres to make up for it. All backed up by dual rate springs and ridiculously complicated external bypass shocks.

    My argument against the notion that vertical wheel travel is an improvement, is that humans are a lot more biomechically capable of dealing with changes in balance than they are at stabilizing high speed high frequency impacts.

    I’ve tried a lefty, I’m also good at spotting differences in how the front and rear is behaving and performing under use.

    With linkage designs surely you run the very real risk of transfering that bind to lateral binding, during cornering, where it actually matters?

    PrinceJohn
    Member

    That bike on the front page tho… it’s not a looker…

    In fact, I’m certain i read somewhere that trailing arms are used on Bajas partly because they do offer some rearward travel. They run positive caster at the front as well.

    Anyway, in 4 wheel applications it’s much more the cars job to deal with chassis balance. Humans can influence chassis balance to a much greater extent on two wheels, so you don’t have to make as many compromises in the name of handling stability. In fact, wiyh cars, the suspenaion has to do more if if  work in every situation.

    Premier Icon thisisnotaspoon
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    Not sure you can compare to a 4 wheeled application, as steering and handling geometry becomes a lot more complicated.

    Agreed, but the principal bit of absorbing a bump doesn’t really change.

    Besides, baja trucks look to have some rearward travel at the rear.

    At the rear. Most suspension designs with idler pulleys would replicate this, the nearer vertical path on most bikes is acknowledged as a compromise.

    They also have very very soft initial spring rates and huge amounts of travel and massive wheels and tyres to make up for it. All backed up by dual rate springs and ridiculously complicated external bypass shocks.

    I’m not sure what impact damping has on the discussion (and most bikes have external bypass shocks and big wheels there’s days too, not truck big, but rally car big anyway).

    My argument against the notion that vertical wheel travel is an improvement, is that humans are a lot more biomechically capable of dealing with changes in balance than they are at stabilizing high speed high frequency impacts.

    True, a rider could move their weight back as the suspension compresses, but why would you design a bike that meant they had to if given a clean slate? If you could build a bike with parallel (only you are talking about completely vertical paths) axle paths front and rear, and no brake dive would that be an improvement?

    <span style=”font-size: 0.8rem;”>With linkage designs surely you run the very real risk of transfering that bind to lateral binding, during cornering, where it actually matters?</span>

    Telescopic bushings bind under side loads, it doesn’t matter if they’re vertical, front in front of the side, the result is the same (actually worse from the side as you twist them as well as just applying a side load. It’s why Fox used to sell 40’s with so much bushing slack from new to keep them active when loaded.

    There are real downsides, like how to make linkage forks stiff, and light (lauf only manages one of those).  But telescopic forks are just a highly evolved compromise, it doesn’t mean they don’t have pretty substantial flaws.

    axle paths front and rear, and no brake dive would that be an improvement

    My point is, is no one has managed to produce a fork with the same amount of travel for the same a2c, with a good axle path that doesn’t dive. If someone makes one, I’ll be the first one jumping on the bandwagon.

    My point about bajas, is that they have a lot more travel, more complicated dampers and beefier tyres to make up for it. I don’t think we’ve managed to package a proper bypass damper into a pedal bike shock yet.

    The commencal is no harder to balance btw, it took lesslthan half a day for me to adjust to how the rear behaves. The difference in bump absorption vs my 2015 Reign could not be starker though, even when taking into account the extra travel.

    Point taken on binding.

    Premier Icon AlexSimon
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    My point is, is no one has managed to produce a fork with the same amount of travel for the same a2c, with a good axle path that doesn’t dive. If someone makes one, I’ll be the first one jumping on the bandwagon.

    Do we know the A-C of the Motion Ride forks?
    It looks as good as a normal enduro fork. It weighs the same as a normal enduro fork.

    I reckon it’s the closest thing we have to a good test bed.

    Andy @ Singletrack seemed to find them very interesting on the ride he did with them (or maybe it was Matthieu that was the attraction – not sure).

    Do we know the A-C of the Motion Ride forks?
    It looks as good as a normal enduro fork. It weighs the same as a normal enduro fork.

    I reckon it’s the closest thing we have to a good test bed.

    Andy @ Singletrack seemed to find them very interesting on the ride he did with them (or maybe it was Matthieu that was the attraction – not sure).

    A2C is 6mm higher than a Fox 36 at 170mm, whilst a Fox 40, with the crowns slammed can get 200mm of travel out of a A2C of 566.2mm.

    Whether that tiny damper with basic low speed rebound adjustment is any good or not remains to be seen as well. I also don’t believe a word they say about the bushings either.

    I’ll be waiting for long term user reviews, mag writers rave about new crap all the time – for whatever reason – they get bowled over by new features and then fail to appraise the entire package etc and  a few months later they quietly ditch the stuff.

    https://www.youtube.com/watch?v=HoHvnaqCGSw

    So when did this lubeless, bearingless, wearless, playless bushing revolution occur then STW? Sounds awesome!

    So what’s the life expectancy of the composite bushings, before the unservicable fork is toast, and what kind of friction co-efficient do they have and how do they degrade over time?

    You know, ask real questions please instead of helping to sell us snakeoil bullshit.

    Would these be Resin (PTFE) bushings by any chance?

    https://uk.misumi-ec.com/pdf/fa/2014/P1_0379-0380_F06_EN.pdf

    https://www.theguardian.com/politics/2018/apr/16/brexiters-tend-to-dislike-uncertainty-and-love-routine-study-says

    You have to admit, the “routine loving” turkeys voting for chaos is fairly amusing isn’t it? More evidence that this is going to backfire politically as well as economically, if we do a hard leave.

    Premier Icon oldnpastit
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    For me, raybanwomble’s post sums everything I think about telescopic forks.

    Do you not see any stupidity in – “what do we hate? Bushings! What do we want? Moar bushings!”?

    otsdr
    Member

    Would these be Resin (PTFE) bushings by any chance?

    Their website says something about fiberglass, probably more like https://www.ggbearings.com/en/products/filament-wound/gar-max

    I personally wouldn’t mind sending the fork back to them every 3 years or so for a full service; the bushings in regular telescopic forks are not user-replaceable either and no-one’s complaining.

    Premier Icon epicyclo
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    raybanwomble

    So when did this lubeless, bearingless, wearless, playless bushing revolution occur then STW? Sounds awesome!…

    It is. I’m looking forward to seeing the results after a muddy gritty UK season. 🙂

    I hope it’s true, but I am deeply suspicious of non serviceable products.

    But no brake dive, that bit is great.

    Their website says something about fiberglass, probably more like https://www.ggbearings.com/en/products/filament-wound/gar-max
    I personally wouldn’t mind sending the fork back to them every 3 years or so for a full service; the bushings in regular telescopic forks are not user-replaceable either and no-one’s complaining.

    So the maximum velocity looks to be no better than a standard bushing? We all know how much stiction bushings introduce into rear suspension systems – let alone systems where the constituent parts have such tight tolerances that you need a machine to press everything together.

    With telescopic bushings you can size them at home, with the know how and some basic equipment. Big **** off machine presses and jigs are not needed. Remember that damper will need servicing as well, so you won’t be sending it back once every three years – unless they will allow you to remove the damper and send that back.

    On the topic of dive, you can run 30mm more travel by running a dual crown – which will have the same Axle to Crown and make up for much of the bump absorption under brake dive and give you better shock absorption when off the brakes. Weight? The motionfork will get much heavier if you/they add a decent damper to it and dual crowns are getting lighter, MRP’s latest dual crown is as heavy as a coil single crown.

    How capable will that fork be of resisting the stresses of nose diving and banging through the travel as a result, if the latter part of it’s travel is vertical? The resultant forces won’t be annenuated and will instead travel into the fork or headtube, surely? Are current bikes designed to take that increased stress without the headtube ovalizing?

    …….

    …..sorry, stw’s video sent me into sceptic overdrive mode….I think my industry has done it to me.

    I also think it’s telling that in Vorsprungs video on telescopics vs linkage forks, he trashed the idea of using bushings.

    @raybanwomble What about the Specialized E150?

    Nice infomercial…..hardtail XC rider…..yup, his opinion is automatically invalid. Yes, anti-dive sounds great – now what about everything else. Adjusting sag using preload only sounds **** terrible.

    I’ll listen when the NSMB, Dirt and Enduromag riders get a hold on one.

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