Gravel bike geometry (poll)

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  • Gravel bike geometry (poll)
  • Premier Icon roverpig
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    Just out of interest, if you have one of these gravel/adventure type (road and off road) bikes does it have:

    A) race geometry; 72-73 degree HA
    B) touring geometry; 70-71 degree HA
    C) MTB geometry; <70 degree HA
    D) no idea I just ride it

    Thanks.

    Premier Icon Normal Man
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    Mine has A

    My previous one had B but although I can see how it would be preferred by many, it just was not right for me.

    D) – Thought it looked “right” in a picture, bought it, love it (72 now that I’ve checked)

    Premier Icon thisisnotaspoon
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    Had all three, not sure of your classifications.

    Prefer the CX race bike style of bike with 35-42c tyres and a ~71deg HA, certainly not setup for ‘touring’.

    The bikes with >72deg angles tend to be more allong the lines of winter road bikes (or audax / road based ITT).

    Mountain bikes with drop bars like the vagabond I had started to feel like the worst of all worlds. Neither as fast as a cx bike or as capable as an mtb (and tbh the high front end made it less capable than the cx bike in many ways as it robbed you of room to move arround).

    B, 70.5 (GT Grade)

    Bit slack for the road really, especially if you’re also riding a road bike. After a few sharp downhill bends I was off checking if the headset was too tight. Of course, soft 40mm tyres don’t help.

    Premier Icon BadlyWiredDog
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    D – it’s a cross bike with gravel-ish tyres on. It just works.

    The whole geometry obsession thing is starting to do my head in. When do you think we’ll reach the end of ‘long, low and slack’? When people are complaining that they can’t fit their bike in a garage without taking the wheels off? When people can physically no long coax their bike around a moderate switchback? When people need special, elongated forearm extensions to reach the handlebars? 🙂

    Premier Icon andytherocketeer
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    D

    as above. bar width is only one more than correct once you are resting your chin on the stem.

    angles will be one beyond right once the steerer tube snaps off due to being too close to horizontal.

    wheelbase only will be 1 too long once the frame needs to be articulating near the BB to be able to get around corners.

    and for gravel bikes, tyre width will only be right once it fully overtakes MTBs (it’s pretty much on a par with 1990’s ATBs right now so a bit more to go)

    😉

    Premier Icon thisisnotaspoon
    Subscriber

    The whole geometry obsession thing is starting to do my head in. When do you think we’ll reach the end of ‘long, low and slack’? When people are complaining that they can’t fit their bike in a garage without taking the wheels off? When people can physically no long coax their bike around a moderate switchback? When people need special, elongated forearm extensions to reach the handlebars?

    TBH I think we hit Peak-Reach years ago. I’ve (6ft) tried 500mm reach bikes, and while fast over rough stuff, they’re a bit of a one trick pony in that respect, climbing was just a case of winching over obstacles and letting the 150mm of travel deal with it, you couldn’t ‘ride’ it. My current bike is 467mm I think, and that feels on the short side of right (I’m at the tall end for the frame mind you). It’s long enough to be stable and ballance the chainstays, but not so long that I can’t hop the front end around a bit.

    I would love to experiment with a LLS gravel bike though, 50mm stem, 440mm compact drop bars set nice and low, 460mm reach (vs ~400 on a normal 56cm frame) and 68HA and a longer offset (or maybe not) fork. CX style geometry is fun, but it’s derived from a need to navigate artificial courses that just happens to be quick over long distances too, a gravel bike with the same mile munching position for speed, and geometry that favors rougher descents could be brilliant. Or shit.

    scotroutes
    Member

    D.

    I could probably look it up for you if it’s important though. Mine is definitely more tourer than CX, though I will admit to having been tempted by something more racey (as a +1 not as a replacement)

    Premier Icon roverpig
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    Thanks folks. I did swither about the word “touring” but wasn’t sure how else to describe the 70-71 degree range.

    Most gravel/adventure bikes I’ve looked at seem to fall in to one of two camps; either that 70-71 degree “relaxed road” or the 72-73 sometimes called “slightly slacker” in reviews but really just road race angles. There doesn’t seem to be much consensus though. Then you have the “monstercross” <70 options, but I’m not sure how popular they really are in practice.

    Of course I know you can’t define a bike by one number (or even a few) but HA does seem to work as a good proxy for how it was designed.

    Ha, I seem to have gotten obsessed with BB height for some reason, put off by 60mm BB drop a la CX bikes and would prefer 70mm drop for road and gravel stability at speed.

    Would be interested to do a blind test of the two and see if it made any difference!

    Premier Icon scaredypants
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    My “gravel” bike is a scandal (old) with a cx fork on it

    No idea on geometry but the HA may well be in the 80s, given the fork

    Premier Icon roverpig
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    I noticed the Fairlight Secan has a 77mm drop if you want to go really low 😀

    Premier Icon jameso
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    Race touring with some MTB attitude. 67mm trail. 🙂

    Premier Icon peajay
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    easily
    Member

    71.5 (which falls between your A and B)

    It’s a good all rounder. If it was a perfect world I’d maybe go a degree slacker, but i’m happy with it.

    Premier Icon UK-FLATLANDER
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    Not purchased one yet, but comparing geometry all the ones I have looked at are in your range B.

    fudge9202
    Member

    71.5 Salsa Vaya didn’t know before now but feels just right especially with 650b x 2.1 tyres and flared bars bombing down singletrack

    footflaps
    Member

    D – Specialized Diverge, no idea what any of the angles are and more importantly don’t care in the slightest.

    Far more important things are getting saddle and bar position right etc.

    Premier Icon roverpig
    Subscriber

    Look away now then. A Diverge is an A (72.5 degree HA for sizes 56 and 58 at least)

    Ooh and an 85mm BB drop. There’s one for you @13thfloormonk

    kerley
    Member

    Ha, I seem to have gotten obsessed with BB height for some reason, put off by 60mm BB drop a la CX bikes and would prefer 70mm drop for road and gravel stability at speed.

    Would be interested to do a blind test of the two and see if it made any difference!

    You probably would notice and a lot more than the difference between 71 and 72 head angle. I ride track bikes so have high BB and it is the one thing I would probably change as it feels like I am perched on the bike rather than sat in the bike.

    Premier Icon ta11pau1
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    D. Space chicken in XL. Short, goes like stink, gets scary off road at speed.

    Just ride it.

    Premier Icon simondbarnes
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    D. Same as all of my bikes.

    TiRed
    Member

    A) Charge Freezer

    Premier Icon roverpig
    Subscriber

    So, a few Ds, which is fair enough. You don’t have to geek-out over meaningless numbers and can just ride the damn thing 🙂

    For those who knew the angles there wasn’t much love for the monstercross (<70) idea but not much consensus on A vs B (race vs relaxed). I guess the comments kind of follow what you’d expect with a steeper HA feeling better on the road but “gets scary off road at speed” and the more relaxed HA feeling better off-road but “a bit slack for the road really” and feeling like “the headset was too tight” on sharp downhill bends.

    Doesn’t really help me as my current long-list has a mix of A and B but I guess it’s a case of “do you want a road bike that can handle the odd track or a bike for off-road tracks that will still be decent on road?”. Don’t know the answer to that one yet.

    kerley
    Member

    I guess the comments kind of follow what you’d expect with a steeper HA feeling better on the road but “gets scary off road at speed” and the more relaxed HA feeling better off-road but “a bit slack for the road really”

    I think you are overstating the differences. 1 or 2 degrees on a road bike style frame does not make the difference between scary at speed or too slack for the road.

    For me it is tyres that have that affect and where the compromise needs to be made on your preferences. I prefer a narrower tyre for all round riding (28c) while others prefer a wider tyre (47c). They feel very different and put 47c tyres on a bike with road bike geometry and it would be great on off road tracks

    Premier Icon roverpig
    Subscriber

    Fair point although I would have thought that two degrees is at least a difference you should be able to feel. So might prefer one over the other. But I take your point. Tyres do tend to trump everything else on a bike.

    Premier Icon jameso
    Subscriber

    Tyres do tend to trump everything else on a bike.

    Tyre size / OD, and width to some extent also
    Fork offset
    Stem lengths and your position on the bike
    – All things (among others) that affect front end handling in a similar way as HTA, by changing trail or handling feel. 2 bikes both with 72 deg HTA can feel very different to ride if the other aspects change, so it might be good to ride a load of bikes and start IDing the feel you like while ignoring the numbers (stated figures often aren’t that accurate anyway, not in terms of how fine-tuned the handling balance n a light road-ish bike can be). Once you know what handling feel / balance you like -ie a bit of ‘this’ and some of ‘that’, but not ‘that’- you can start to build a geometry spec that achieves that. It won’t be right first time but you’ll get there.
    TBH I think being able to ID, separate out or describe handling traits well is more important than the numbers if trying to understand or redesign bikes in this way.

    kerley
    Member

    Fair point although I would have thought that two degrees is at least a difference you should be able to feel. So might prefer one over the other.

    Direct back to back yes probably, after 10 minutes of riding the difference becomes largely irrelevant. A few years back I swapped a 30mm rake for a 43mm rake fork (all other factors staying the same. While I first noticed the difference in steering (a bit quicker/less stable due to less trail) but after a ride it just felt normal again and couldn’t really say if one was better than teh other, just slightly different.

    TBH I think being able to ID, separate out or describe handling traits well is more important than the numbers if trying to understand or redesign bikes in this way.

    Agree. As said above I would prefer a lower BB than I have but am happy with the 74 degree angles

    Premier Icon roverpig
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    I’ve always tended to build bikes (road and off-road) up from frames, so am used to the idea that you can tweak them to change the feel anyway and I agree that you tend to adapt. That’s part of the problem really. You do adapt and there isn’t a “right” geometry. They all have their pluses and minuses. I have two bikes at the moment (both with 700c/29″ wheels); a FlareMax with a 65.6 HA and my Principia road bike with a 73 HA. Jump from one to the other and it feels weird for a while, but you soon adapt and start to appreciate that both work well in their intended environment.

    The thing that strikes me though is that there is a pretty strong consensus on geometry for road and off-road. The numbers change a bit over time, but at any point everyone seems to agree what they should be. Pure road bikes are all around 73 degree HA. For a “trail” MTB they used to all be around 69 now they are all around 67. But for gravel/adventure there doesn’t seem to be that same consensus, with some sticking with a road-race geometry and some going slacker. That probably means that both work but I was wondering if we were moving towards some sort of consensus.

    Premier Icon jameso
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    wondering if we were moving towards some sort of consensus.

    fwiw/imo/ime etc … already there, there’s not a lot outside of the 71-72 HTA range and 45-5omm offset that’s been common for a decade or so on bikes like this. 71.5 HTA and 50mm offset, imo, makes for a bike that’s really good on road on 28mm tyres and stable off-road on 35-45mm tyres. The resulting trail figure, tyre OD range and weight distribution for a reasonable but not long stem all works out. The bikes that go to 69ish HTA are like the 63 HTA 29er hardtails – a bit more specialist, more extreme pros and cons, outlier geometry, marketing by geo numbers even, depends on your take on it. I expect MTBs still vary more than gravel bikes in geometry range.

    The general ride feel you get from that 71.5ish geo might be a bit of a handful on a steep or tricky off-road descents, but the solutions to that (situations normally making up a small part of the ride time on bikes like this) detract from the road bike handling – after all, why are you on a light bike with drop bars? – and put you on a course towards being either the Fargo style of all-terrain heavier-duty tourer, or a 29er XC bike. By that point you’re past it being what I’d call a good road bike though. And I just don’t think that more stability is a fix, the drop bars and the ride position that go with them don’t really allow you to get the best of that type of very capable off-road geo. There are exceptions but they are basically MTB 29er positions on very modified drop bar geometries anyway.

    fasthaggis
    Member

    The whole geometry obsession thing is starting to do my head in. When do you think we’ll reach the end of ‘long, low and slack’? When people are complaining that they can’t fit their bike in a garage without taking the wheels off? When people can physically no long coax their bike around a moderate switchback? When people need special, elongated forearm extensions to reach the handlebars? 🙂

    < extra smiley <

    D and everything that ^^ BWD said,in fact from now on BWD can be my geometry spokesperson

    Premier Icon thisisnotaspoon
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    Edit: just checked and my geared cx bike is actually 72.5 (caadx) and SSCX (plug) is 71.5 (with proportionally longer tt and shorter stem too). Never really noticed and just assumed any difference was due to weight.

    TBH you could do worse than look at the marketing for the bikes you like. Do they show rider doing the stuff that you want to do? Does it look like the designer developed it with you in mind?

    Im quite happy riding my caadx down descents its fundamentaly the wrong tool for. But that’s more than offset by the fact the descent in question is perhapse actually quite mediocre by mtb standards and a 2 hour ride from home so makes up part of a long mornings ride out to somewhere that id not otherwise bother riding (to far for an evening, too close to bother with a trip in the car).

    jonnyboi
    Member

    A) 72 deg.

    It’s a CX bike (Marin) bit I use it for endurance road, gravel and even a bit of xc.

    Premier Icon roverpig
    Subscriber

    TBH you could do worse than look at the marketing for the bikes you like.

    To be honest, this is pretty much where I’ve ended up with MTBs. Pouring over geometry charts can be fun, but fundamentally I don’t know what I’m talking about. So I pick a company I like and a designer I trust (based on reputation etc) and just see what bike in their range is designed for the type of riding I want to do. Even though the numbers often don’t make sense to me, they generally work.

    The problem with gravel is that I don’t know enough about the reputation of the companies involved, so want to fall back on the crutch of the geometry chart.

    So, case in point, Mason seem to get a lot of positive reviews, but the Bokeh looks pretty racy on paper. At the other end of the spectrum, Genesis is a company that I know and have tended to like their stuff over the years. I also quite like steel, so their Fugio 30 looks nice. But it’s pretty slack at 70.5

    Yes, I could try to get a demo, but as I said above tyres tend to trump everything so the test could just end up being a test of the tyres, which I’d change anyway.

    Mister P
    Member

    Head angle 70.5 and seat angle 73 according to the Saracen website –

    https://www.saracen.co.uk/bike/levarg-sl-2020

    What that means in the real world I don’t know, I just know I like riding it.

    Edit – same angles as the Fugio according to the Genesis website –

    https://www.genesisbikes.co.uk/bike/fugio-30-2020

    footflaps
    Member

    Look away now then. A Diverge is an A (72.5 degree HA for sizes 56 and 58 at least)

    Doesn’t actually mean anything to me, you could have come back and said 97 degree 😉

    Premier Icon roverpig
    Subscriber

    @MisterP Yes, I’d put the Levarg in a similar category to the Fugio. Both are a bit slacker at the front, shorter at the back and with a bit less BB drop than the more racy offerings. The Levarg takes the off road bias a bit further though with a longer reach and shorter stem. Good to hear that you are enjoying it though.

    longsider
    Member

    D. Space chicken in XL. Short, goes like stink, gets scary off road at speed.

    This made me smile, especially as I’m waiting on delivery of a Space Chicken.

    Linked to the thread, how does a slacker seat tube come into play with handling. Eg 72degree head tube paired with 72.5 seat tube on the space chicken. Most gravel bikes seem to be around 73 seat tube

    Premier Icon slowoldman
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    Look away now then. A Diverge is an A (72.5 degree HA for sizes 56 and 58 at least)

    71 on my 52cm Diverge. Though I was more interested in stack and reach. Being slow and old I wanted something less stretched out than my old racers had been.

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