Are steep seat angles spoiling hardtails?

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  • Are steep seat angles spoiling hardtails?
  • markrh
    Member

    I’ve read a few posts on this forum and others about the unforgiving nature of hardtail bikes recently and I can’t help thinking when I look at a lot of modern hard tails that the current fashion for steep seat tubes and also to lesser extent, short chain stays is going to stuck a lot of compliance out of the frame and this is probably why a lot of people just can’t get on with them?

    Premier Icon hairyscary
    Subscriber

    The average age of the forum is about 50. We’re all knackered 😀

    kayla1
    Member

    No. It’s because people are soft and they can’t ride properly – HTH! 😉

    A bit more seriously, I think it’s just a bit of a shock moving over to a HT after a bit of time on a FS, even just a few weeks on a FS can have me thinking ‘hell’s teeth, this is rock hard!’ when I inevitably move back to a HT.

    qwerty
    Member

    Depends….

    on what you want from it, super steep seat angles will suit super steep climbing, but not so just riding along the undulations.

    Frame compliance is not just geometry angles and measurements, you also need to factor in material type (Ti, steel, aluminium, carbon, bamboo), tube diameter, thickness, butting etc

    So many variables.

    On frame geometry, I read somewhere: “if you improve one characteristic (by adjusting angles, measurements etc), you’ll make another worse. At the end of the day, it’s a compromise”.

    qwerty
    Member

    Oh, and define “steep” someone like Chris Porter may have a different idea on that than you or I.

    Premier Icon jameso
    Subscriber

    Yes.

    For me on my local terrain anyway, which I realise might count for nothing compared to the riding others do.
    But not for the compliance reasons. Steep (75-76 or more static) STAs are great for changing/correcting weight distribution for longer front-centre bikes and for better climbing, but combined with almost all posts being inline, they aren’t as good for longer, rolling terrain riding – and that’s where I really like hardtails. The weight-fwd over the BB + bar feeling simply isn’t as comfortable if you’re spending more time seated, can lead to back or shoulder tensions etc. I used to really like one of my old hardtails for it’s slacker ST and sat-on-back-wheel feel, it popped wheelies or could go light at the front or hop so naturally – was much more playful than a LLS HT. Had to climb steep stuff stood up but that’s OK imo.
    Hardtails are also great for just ragging around the local woods for a bit and tbh there I’d still prefer a slightly less long-slack set up, like ‘just slack enough’ big 4X bike rather than ‘how slack do we need to be to get noticed’ sort of FS-copy geometry.

    I do think 2 degrees on STA can change comfort for the high-posters, via seat post flex, but so does seat post spec and simply how much is exposed. I had a road-ish bike made a while back with a 71.5 STA to use with an inline post with the same ST size as normal, for that reason. Hard to say how much benefit there was but as one of those things that can add up with other factors it seemed to help.

    What jameso said!

    Premier Icon chakaping
    Subscriber

    I don’t think that many HTs have proper steep STAs yet, so I’m gonna say “not really”.

    If the reach extends at the same time, it all comes together anyway – only snag might be when the bike gets too long & slack to be as much fun on flat, twisty trails.

    hols2
    Member

    the current fashion for steep seat tubes and also to lesser extent, short chain stays is going to stuck a lot of compliance out of the frame

    Seat tubes are basically incompressible, and chain stays would have to bow out massively to give the compliance that a tyre does. IIRC a while back Brant explained that the compliance of a frame basically comes from flexing of the top tube. Seat angle won’t make any perceptible difference. A long, flexy seat post will, as will a fatter tyre run at lower pressure.

    It seems to get forgotten that hardtails get steeper once you’re on them whilst full-sus bikes get slacker, and even more so when pointed uphill.

    And on most hardtails the effective seat tube angle is much closer to or the same as the actual seat tube angle, so they don’t get slacker as you raise your seat as with pretty much all full-sus bikes.

    A 74 deg seat tube angle on a hardtail could feel as steep as 77 deg or more on a full-sus.

    Premier Icon BadlyWiredDog
    Subscriber

    For me on my local terrain anyway, which I realise might count for nothing compared to the riding others do.

    This. I think it depends a lot on how and where you ride. Most of my local Peak stuff seems to be either up or down, and relatively steeply at that. Statistically you probably spend more time climbing than descending. And when you’re descending, you’re out of the saddle anyway. And I like steep tech climbs.

    Personally I hate the nasty wandering, front end light, and oops, now it’s off the ground feel of slacker seat-tubed bikes on steep stuff, but as above, that’s me on my local terrain anyway, which I realise might count for nothing compared to the riding others do.

    Premier Icon brant
    Subscriber

    Bikes are becoming more extreme and many riders don’t ride terrain anywhere near tough enough for the new hardcore hardtails that riders think they need when in actual fact they’d be better off on some sort of flat bar gravel bike.

    Van Halen
    Member

    brant +1!

    most riders are massively overbiked (me included)

    i love a good HT though. my full suss barely gets ridden locally. I`ve not noticed a steeper seat tube being detrimenatal.

    my new longer framed HT is definitely less engaging to ride than my old one. it`d be great at BPW but for my local South Downs stuff a smaller frame is more fun as the trails are just too tame for a long stable bike.

    Blackflag
    Member

    Plus the aesthetics issue! A slack head tube and steep seat tube does not make for a pretty bike.

    Premier Icon Poopscoop
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    I only ride my ht in the winter but knew my back was going to suffer so fitted it with the cheap Suntour Thudbuster clone almost straight from the off.

    Im genuinely surprised at how much comfort it adds. Not bothered about the weight as it’s covered in mud anyway.

    Nothing to do with a steep seat angle but still…

    Premier Icon Bez
    Subscriber

    Bikes are becoming more extreme and many riders don’t ride terrain anywhere near tough enough for the new hardcore hardtails that riders think they need when in actual fact they’d be better off on some sort of flat bar gravel bike.

    🙂

    Controversial cycling opinions? Let’s hear ’em!

    the00
    Member

    Which bikes do you have in mind when you say this? I’ve not seen any hardtails with super steep seat angle.

    If you think about it, since wheel sizes increased, stays will have become longer anyhow; steepening the seat angle allows shorter stays, bringing back the glory days of fun, snappy and agile 26ers!!

    When it comes to compliance, ride feel can be engineered in; think back to the 456 Ti with the curved top tube, or Production Privee’s shaped stays…

    Whether or not that’s entirely necessary, given the additional flex likely to result from the increased reach and longer tubes of modern geometry, is another matter

    Premier Icon IdleJon
    Subscriber

    I’ve just ordered an Orbea Laufey – 65 HA, 75 SA 140 mm travel. My 90s Klein had a seat angle of 73.2 degrees. A 2020 Spesh Fuse is 74. A Cotic Soul is 73 degrees.

    philjunior
    Member

    Bikes are becoming more extreme and many riders don’t ride terrain anywhere near tough enough for the new hardcore hardtails that riders think they need when in actual fact they’d be better off on some sort of flat bar gravel bike.

    I remember when pretty much all bike were XC oriented. Even when sus forks were considered too heavy, so kind of agree here. Although I think some suspension is nice to have.

    Agree with much of the above. My Sherpa has a pretty slack seat angle by the current trend but the whole geometry of the bike seems to suit me fine. No issues on steep climbs, technique is more important.

    faustus
    Member

    I’ll be finding out soon, going to a LLS bike, 3 degrees more HA and 2.5 degrees steeper SA than I have currently. No idea how it’ll be but keeping an open mind. It’ll be mainly used on rolling terrain similar to that described by jameso.

    I quite like the idea of LL-NotTooSlack for a modern XC/bit of everything bike, much like the new whippet. Might cover more bases better for less steep terrain.

    Premier Icon Bez
    Subscriber

    I wonder whether a lot of it is just that people who’ve used full sus for ages have just got used to sitting down.

    The best solution is probably for them to go to a rigid singlespeed first, where you basically never sit down, and then dial themselves back to the luxurious plushness of a hardtail 😉

    hols2
    Member

    The best solution is probably for them to go to a rigid singlespeed first

    null

    Premier Icon BadlyWiredDog
    Subscriber

    Bikes are becoming more extreme and many riders don’t ride terrain anywhere near tough enough for the new hardcore hardtails that riders think they need when in actual fact they’d be better off on some sort of flat bar gravel bike.

    Hasn’t that always been the way though? I date it back to the Whyte 46 when the Peak was suddenly full of slightly overweight middle-aged men pushing up climbs and pottering downhill. The bikes have changed, but the basic pattern is still pretty much the same. A lot of it is undoubtedly attributable to seat-tube angles, but there’s possibly more to it than that.

    Premier Icon kayak23
    Subscriber

    Used to have a Charge Blender. An absolutely classic steel hardtail that was slightly spoiled by its slack sta. It was a pig to pedal around all day.

    My Production Privee is bang on. Like the Blender always could have been.

    I don’t think they spoil them at all. Always a balance.

    while parallel HT and ST looks nice on a XC focused bike – bi of roadie aesthetics there?

    Plus the aesthetics issue! A slack head tube and steep seat tube does not make for a pretty bike.

    counter argument – when the head angle is steeper than the set tube it looks like its been ridden into the wall and looks ridiculous.

    the00
    Member

    Another thing making a big difference is dropper posts. These tend to be a lot stiffer than a good lightweight rigid post.

    Premier Icon Trailrider Jim
    Subscriber

    the unforgiving nature of hardtail bikes recently

    Most trail hardtails are being specced with fatter tyres and wider rims these days, so not sure how relevant the recent feedback you’ve been hearing is. As for Brant’s comment re: riders being better off less biked, I don’t think this isn’t anywhere near the general case. A bigger bike may be OTT for the average trail centre, but a decent rider will get the speed out of one and have fun doing it.

    Another thing making a big difference is dropper posts. These tend to be a lot stiffer than a good lightweight rigid post.

    I’ve said that before – that a nice thompson is much more comfy than a dropper in the up position – and got roundly called an idiot. Good to find someone that agrees with me.

    Which kind of brings me to the next point. Back when all hardtails were steep xc machines, people rode them, and rode em on some challenging stuff. Then long and slack came, and people realised they were better for the steep chutes, for the high speed and so on.

    But that brought with it a reduction in the long distance XC ability. Those bikes still exist, and at pretty much every price point. For some people/ some rides, they’d be a good choice. From your bimblers to your South downs way in a dayers.

    Go over to the likes of a BFe, Zero, Crush; and you’ve given up that seated pedalling on flat terrain ability. If you like these sort of bikes – which I do now, I’ve fallen in love with the Zero29 – you need to stand up and crank those pedals hard. I’m riding for a fun time, not a long time.

    joemmo
    Member

    I’ve said that before – that a nice thompson is much more comfy than a dropper in the up position – and got roundly called an idiot. Good to find someone that agrees with me.

    how many mm are you imagining the rigid seatpost is compressing or flexing by?

    Premier Icon joebristol
    Subscriber

    I like my fairly LLS Enduro for certain trails, but on others a more moderately proportioned HT feels nicer.

    For example I’m going to Flyup 417 on Sunday. I’ve done it on FS and HT before – with the FS I enjoy the rockier reds more, on the HT the blues rock – just trying to corner harder and harder. For me and my riding I’m not sure a LLS HT would be as fun as a moderately modern one (Vitus Sentier 650b).

    how many mm are you imagining the rigid seatpost is compressing or flexing by?

    compressing – none

    Flexing –
    73 degree seat angle, 300mm long, 30.9 seat tube with 2mm wall thickness.

    Assuming a veritcal 90kg load thats 26.3kg perpendicular to seat tube.
    I get 1.8mm deflection.

    50% more for a 27.2mm with 2mm wall thickness

    hols2
    Member

    I get 1.8mm deflection.

    50% more for a 27.2mm with 2mm wall thickness

    That deflection is perpendicular to the seat tube? If so, the vertical deflection will be less than 1 mm, if I understand it correctly. Pretty small compared to the deflection in a tyre.

    That deflection is perpendicular to the seat tube? If so, the vertical deflection will be less than 1 mm, if I understand it correctly. Pretty small compared to the deflection in a tyre.

    well yes, but its still a few mm of “give” that will reduce the jolt to the gooch compared to a much stiffer dropper shaft.

    Premier Icon lovewookie
    Subscriber

    That deflection is perpendicular to the seat tube? If so, the vertical deflection will be less than 1 mm, if I understand it correctly. Pretty small compared to the deflection in a tyre.

    but we’re not talking about vertical deflection being the important part, perpendicular deflection (ala the same line of travel as something like a thudbuster) would be more relevent to comfort.

    Premier Icon lovewookie
    Subscriber

    that said, when riding, the load applied to a seatpost won’t be vertical either, the max load will likely be more complicated than that, if you imagine hitting a lump in the trail, there will be a vertical component against your butt, but also a horizontal component to get past the lump. How much of the latter will be determined by how much friction is applied to the saddle from the rider.

    markrh
    Member

    Heres another thought, could a dropper post have a some degree of travel engineered into it. Say 5mm of sag dropping another say for the sake of argument 20mm under full compression? And then have 100mm or whatever dropper capability. I know it probably sounds like the knackered dropper you chucked in the corner of the shed…but I think it sounds like hardtail seat post heaven.

    Van Halen
    Member

    if you need a suspension seatpost why not just buy a suspension frame as that sounds what you want.

    i recon a HT is for standing up on the rough bits.

    Premier Icon epicyclo
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    BadlyWiredDog
    …Personally I hate the nasty wandering, front end light, and oops, now it’s off the ground feel of slacker seat-tubed bikes on steep stuff, …

    That’s probably more to do with the larger amount of flop in you get with slack HAs (although seating position plays its part), and why the previous version of “modern trail geometry” of the 1920s fell out of favour.

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