Why is front and rear travel usually the same?

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  • Why is front and rear travel usually the same?
  • Premier Icon roverpig
    Subscriber

    I’m wondering why, for full sus bikes, the front and rear travel tend to be the same. You can get a hardtail with a nice long trail fork and no rear suspension, but as soon as you decide that you want a bit more give at the back it seems as though it has to be the same as the front.

    If you are looking for a bit more forgiveness and traction at the back without losing too much in pedalling efficiency, wouldn’t you be better off with less travel at the rear than the front?

    joolsburger
    Member

    It’s to do with jommertry. 150mm bike with 100mm forks would be all wrong angles wise.

    Premier Icon roverpig
    Subscriber

    I was thinking of shorter travel at the back, but either way it should be easy enough for a designer to get the angles they want with different travel. They manage OK with 150mm at the front and zero at the back (hardtail), so why not 150mm front with 100mm rear. A bit more comfort and better traction over rough ground, but not as inefficient as 150mm rear travel. It just seems a bit limiting on the designers to always keep front and rear travel the same.

    Premier Icon mikewsmith
    Subscriber

    150mm bike with 100mm forks would be all wrong angles wise.

    Not if you sorted the angles…

    Generally (BS Time) the amount of front travel for what someone wants equals the amount of rear needed to cope with skill and ambition.

    slowrider
    Member

    There’s a few shorter travel bikes that will take longer forks. My banshee rampant being one, but Santa cruz’s shorter bikes, yeti asr5, cotic, transition, without thinking too hard.

    Plenty of mid travel bikes don’t give up pedalling efficiency either

    Premier Icon ahwiles
    Subscriber

    i had a cotic hemlock, my favourite setup was: 120 at the back, 160 at the front.

    it was chuffing ace.

    Dales_rider
    Member

    They are not all the same front and rear. I have a 140 120-150

    ndthornton
    Member

    It’s to do with jommertry. 150mm bike with 100mm forks would be all wrong angles wise.

    You can build a bike with any angles you like regardless of travel
    Clearly you wouldnt want 150 back 100 front but……

    150 front 100 back – I would ride that bike – I can see many advantages

    julianwilson
    Member

    iirc quite a few downhill bikes came with with 20-30mm less at the front than at the back. The original santa cruz v10 springs to mind.

    Mrs J has a cove hooker with 100mm at the back and 150m at the front, iirc it was designed around a 140mm fork.

    Premier Icon roverpig
    Subscriber

    OK, you can buy a frame and put what you want on it (or change your forks), but I can’t think of many bikes where the recommended fork length isn’t pretty damn close to the rear travel.

    ndthornton
    Member

    I love the spelling of “Jommetry” 🙂

    Premier Icon andytherocketeer
    Subscriber

    suspect that most bikes are slightly asymmetric

    is 120mm front, 100mm rear (a) front pretty damn close to the rear travel, or (b) 20% more than the rear travel? (esp. when the 100mm rear might well be 105mm, eg Turner flux etc.)

    also quoted travel is probably rounded up or down a bit (more likely at the rear?). Seen all kinds of quoted travel like 125mm, 127mm, 130mm and 5inch, all of which may well be basically the same thing.

    Premier Icon mikewsmith
    Subscriber

    Plenty of dh bikes 20mm longer at the back.

    There is also about 30mm to play with on 150mm forks between brands and headsets these days.

    r17anm
    Member

    Im pretty sure ragleys full suss bikes are gonna be more travel up front than at the rear
    Thats if they are still making em though

    Premier Icon aracer
    Subscriber

    Mine isn’t. I have 90 back, 100 front. Or sometimes 70 back, 100 front. Or occasionally 70 back, 0 front 😉

    Premier Icon Northwind
    Subscriber

    More in the front than the back makes sense to me, I’m another 160/120 Hemlock and it works superbly, very balanced. The 2 ends do a different job so no reason not to really. But it does seem to confuse people- I think part of the reason it’s not more common is that people just expect it to be the same and think anything else is weird.

    After all, my hardtail has 140mm more travel in the front than the back and that works fine- my legs still have more travel than my forks.

    I think with more rear travel, you sometimes end up with a big bike, with all the strength and packaging of the longer travel, plus extra bits and bobs to make it pedal well, which can mean it doesn’t soak hits as well as it might- you end up with the pedalling character of a shorter travel bike but also the suspension performance of a shorter travel bike too, and extra weight and cost for all the linkages and such. And at that point why not just be a shorter travel bike?

    legend
    Member

    julianwilson – Member

    iirc quite a few downhill bikes came with with 20-30mm less at the front than at the back. The original santa cruz v10 springs to mind.

    probably best to ignore that one for the sake of this thread. V-10s are designed to have a log more sag (40%) than other bikes, so they effectively settle into the same position as an 8″ bike but with a load more negative travel

    grum
    Member

    My GF has a Hemlock. What would I need to make it 120mm travel? It’s 160 at the mo with 140mm forks.

    nickhead
    Member

    Nothing wrong with mismatching travel, within certain ranges and as long as the geometry is designed around it.

    My Foxy XR has an extra 20mm up front over the standard 140mm Foxy, to match its more aggressive nature.

    I think with the linkages and tuning you can apply to the rear (more so than the front), these days you can achieve an almost bottomless travel feel from relatively little, but things are a bit more limited with the forks

    Premier Icon Northwind
    Subscriber

    grum – Member

    My GF has a Hemlock. What would I need to make it 120mm travel? It’s 160 at the mo with 140mm forks.

    All you need is the rocker… Cotic still have them in stock I think but they’re not cheap.

    I have a spare 120mm rocker- I’d need it back after but you’d be welcome to a loan to try it out and see if it’s worth the expense. IMO it’s a better bike at 120mm but not everyone agrees.

    joao3v16
    Member

    I’ve always suspected that bikes with less travel at the rear than the front might actually be ‘better’ generally … although this is based on nothing more than a hunch 😀 … and could also be complete cobblers …

    deviant
    Member

    The 2011 Saracen Ariel 3 came with 150mm forks and 140mm rear travel, one version of the Kona Tanuki comes with 140mm on a 130mm back end too.
    Plenty of bikes around like this, i believe the theory is they pedal better as they’re not wallowing around in as much rear suspension.

    Ive go one of those tanuki’s with 140mm fox up front and 130mm out back, but tbh would consider that to be as near as makes no difference the same…

    I do get the idea of a big fork short travel frame though, in many ways I think it would be better to have a 160mm-120mm adjustable rear with a 160 fork than a 160mm frame with an adjustable fork…

    Premier Icon ads678
    Subscriber

    My old shape Five has 130mm rear end and i run it with 140mm forks up front. it’s rated to run at 120-150mm but i’ve not tried it at 150mm, don’t think it would go uphill very well.

    Didn’t the Orange blood only have about 120mm out back?

    I’m going to join in with the Hemlock loving, by far the best bike I’ve ever ridden. SO much fun with 120 rear / 160 front. I’d quite like to try the longer rockers, but I like the… I dunno, is tautness a word one could use to describe the rear end?

    I also used to have a Giant VT which had about 150mm at the back, and was designed for (I think) 90-120mm on the front. I ran it with 130mm Revs. It was ok, I guess.

    Ooh the Blur 4X is another one, 115mm out back and ran nicely with 140 at the front. And the Genesis Grapil does it too doesn’t it?

    I suspect the real reason is more to do with marketing – a 6″ bike fits better into a niche than a 4″/6″ bike.

    andymc06
    Member

    I have upgraded my 2011 Trance X3 from 125mm front to 140mm. Giant did this anyway on their top of the range Trance. It still pedals well with 125 at the back but it is even better on the downs and through the rough stuff.

    mildred
    Member

    … although this is based on nothing more than a hunch … and could also be complete cobblers …

    Well this is STW so your hunch is pretty much as valid as most of the geometry or bike design ‘knowledge/opinion’ normally spouted on here. The difference with your hunch is that your not furiously smashing the keyboard trying to maintain or present your ‘knowledge/opinion’ as fact.

    Anyway, to the OP – if you look around there are loads of bikes with less or more at the rear than front. My Nicolai has 4 travel settings and can be set anywhere between 140mm – 227mm depending in what shock you use. You wouldn’t expect me to swap forks every time I changed rear travel, would you?

    It’s currently set at 140mm rear and 160mm front. It feels very different if I set the rear to say 180mm, as I’d run a bit more sag, it would feel a bit less ‘poppy’ and. The shock would have a bit more work to do damping wise. It’s not better or worse per se, just different for a different application. I also had an Orange Blood that was 127mm rear and 140mm or 160mm front. Both felt great but different.

    carlosg
    Member

    I run my DH bike with 7″ up front and 8″ at the back and it rides lovely, suspect that 8″ forks up front would make it feel quite bargelike and slower turning.

    Premier Icon boriselbrus
    Subscriber

    The Klein Mantra was the bonkers one when out came to mismatched travel – originally designed to have 160mm at the back and a rigid front.
    I think the theory was that with the pivot so far forward, the bike sort of hinged in the middle.

    Premier Icon tmb467
    Subscriber

    I’ve got 160mm at the front / 140mm at the rear on my 06 enduro

    I’m not dead yet

    Premier Icon dirtyboy
    Subscriber

    Blur4x had 115mm rear and upto 160mm front, loved mine with 140 pikes. Best bike I’ve had apart from the maintenance required

    joolsburger
    Member

    Lots of bikes have short travelish back ends and longer forks. I have 130mm forks so that’s what’s on my 145mm bike but they are 500mm axle to crown which is the similar to most 140mm ones. Can’t say I’ve noticed a problem.

    maxtorque
    Member

    Generally speaking even with matched amounts of travel a bike will use it in very different ways depending on the terrain. Most people will have a fork running a bit softer spring rate than the rear shock, and generally slightly more of the riders weight will be acting on the rear suspension than the front (especially when travelling fast over rough terrain etc). For normal forward velocity based perturbation / deflection, by the time the rear wheel has got to the obsticle the bike will already be being accelerated upwards by the front fork input for example so signifcantly reducing the effective rear loading.

    Of course, if you regularly huck off stuff to flat, and land entirely on the back wheel, then the rear suspension gets more of a work out, and chances are this is when you actually need the full rear travel.

    MoseyMTB
    Member

    I’m about to put 140mm forks on my trance x.

    All I’ve heard is good things. Plus they are U-Turn so I can run at 120mm if I hate it.

    Premier Icon tomtomthepipersson
    Subscriber

    I’ve got 150mm on the front of my Trance at the moment. I was intending to reduce it a little but will probably never get round to it.

    gmex619
    Member

    legend – Member

    julianwilson – Member

    iirc quite a few downhill bikes came with with 20-30mm less at the front than at the back. The original santa cruz v10 springs to mind.

    probably best to ignore that one for the sake of this thread. V-10s are designed to have a log more sag (40%) than other bikes, so they effectively settle into the same position as an 8″ bike but with a load more negative travel

    Wrong, well only slightly. The V10 is meant to have 30%-35% Sag depending on if your riding or “hucking”

    Also the travel difference is more than 20-30mm on it. The V10 has a quoted “254mm/10″” rear travel. As opposed too the forks SC specced and built it too “200mm/8″”

    I have ridden/owned quite a few bikes and I do agree that something like 160 100 would be great too ride. If the geometry is right for it.

    avdave2
    Member

    I expect a lot has to do with the marketing men rather than the designers.

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