[Closed] Gravel bike geometry (poll)

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)

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.

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? 🙂

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)

😉

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.

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)

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!

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

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

Race touring with some MTB attitude. 67mm trail. 🙂

B 70°

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.

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

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

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.

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

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.

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

Just ride it.

D. Same as all of my bikes.

A) Charge Freezer

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.

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

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.

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.

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

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.

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.

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

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).

A) 72 deg.

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

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.

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

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 😉

@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.

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

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.

This is a timely thread. I just looked at the 2020 Croix de fer and compared to the 2019 it is an inch lower in stack, an inch shorter wheelbase, it's gone from 71 HA to 72 and offset has gone from 50mm to 52. Trail is down 9mm to 60 and flop is down 3mm to 18, mechanical trail changed from 65mm to 57mm.
Not sure it's really a gravel bike anymore, seems like it's going towards the old school road, or newer CX bike.
This thread seems to confirm that.

^ looks same to me? Middle sizes are 71.5 HTA, as they always were. 50mm offset fork.

Not sure about the exact geo changes and it’s relevant to this thread that geo of the same bike can be quite different in different sizes, but they do seem to be positioning the CdF more as an endurance road bike with the Fugio now more obviously their gravel/adventure offering.

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

It would make no difference to me as I set my saddle in relation to the bottom bracket. A 1 degree change in seat tube would just mean I need either an inline seat post or a set back seat post to get my saddle in the right place.

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

With the shorter wheelbase and longer stem/bars you already have a lot of weight on the front wheel so the ~76 seat angle of modern mtbs is largely useless (and would probably push you too far forward). Contrary to many a rad skilz video on youtube, for sharp corners having your weight over the bb is better than over the bars.

It would make no difference to me as I set my saddle in relation to the bottom bracket.

Works to an extent and if you only have one bike and one position. But makes no allowance for a more aero position on a road bike, or a more relaxed position elsewhere. For example my road bike is setup with the classic "knee over pedal spindle" measurement, and it works. But if I get into a tuck my legs hit my ribs as the resulting hip angle is too tight. Moving the saddle forwards and up and adding 20mm to the stem would give a much better position for going fast.

My road and my gravel bikes (Cervelo and Scott) have a different head angles depending on the frame size. I'm not sure HA alone tells you much.

The thing with this geometry stuff (at least for me) is that it's fun to geek out over the numbers and try to understand how it all works, but then a bike pops up that pushes your buttons and it all goes out of the window.

Fifteen years ago now, I rode Etape du Tour, to commemorate turning 40 and to try to convince myself that I wasn't really getting old. There was a guy on our trip who had this lovely Kona road bike in a two-tone paint job. As a child of the 80s I thought this was the coolest thing ever. Now, I've just seen the 2019 Kona Libre in purple and I'm not sure I even care about the geometry any more 🙂

Have you ordered it yet?

This is a timely thread. I just looked at the 2020 Croix de fer and compared to the 2019 it is an inch lower in stack, an inch shorter wheelbase, it’s gone from 71 HA to 72 and offset has gone from 50mm to 52. Trail is down 9mm to 60 and flop is down 3mm to 18, mechanical trail changed from 65mm to 57mm.
Not sure it’s really a gravel bike anymore, seems like it’s going towards the old school road, or newer CX bike.

Where are you getting your numbers from? The frame hasn't changed.

I'm loving trying to get my head around this whole bike geometry. Through various searches I've just discovered that the 3T exploro in a large is pretty much identical to the large space chicken. The reviews on the way the exploro handles on road and off it seem my kind of ride. fast and fun. I love their mantra "Going nowhere..fast" Admittedly the two bikes won't ride the exact same due to all the aero work on the exploro but it gives me an idea what I'm about to thrash around on.

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

I owned a fugio, and now own a racier G2. The fugio was by far the more fun bike offroad, especially on twisty singletrack. You do notice the slack front end on the tarmac though. I changed wheelsets out to 700c and fitted 37mm tyres which helped the road feel, without sacrificing too much of the offroad fun factor.
If its any kind of a recommendation, I am thinking about going back to a fugio now that they have slimmed it down a little and have GRX. I just had more fun on it.

Fifteen years ago now, I rode Etape du Tour

Limoges > Saint-Flour ?
That was a long day 😉

lovely Kona road bike in a two-tone paint job

I bought one of those a while ago because :-
A)I wanted a Kona (actually a Dedacciai Scuro) road bike.
and
B) I am also a childish person of the 80s
Picked a size that usually fits me and built it up,never gave the geo a thought.
Still ride it a lot and it is indeed lovely.

Not sure I could ever love that Kona Libre though.

Admittedly the two bikes won’t ride the exact same due to all the aero work on the exploro but it gives me an idea what I’m about to thrash around on.

The aero is definitely a case of marketing over reality. I'm sure that quantitatively it's faster if you control the variables. But in the real world a skinsuit saves more seconds than a frame, several times over. No one wears a skinsuit. So it's fast, but only as fast as you can survive without any spares in your jersey pockets. Otherwise it's like the age old "you could save more weight/drag by having a poo".

My gravel bikes usually have something approximating a NACA aerofoil of mud and dirt on the back of the seatube anyway. How does that compare to a Kamm tail?

Limoges > Saint-Flour ?
That was a long day 😉

You're not kidding. I'm still getting over it 🙂 The climb up Puy Mary near the end still gives me nightmares.

Not sure I could ever love that Kona Libre though.

Each to their own 🙂

If its any kind of a recommendation, I am thinking about going back to a fugio"

Thanks, that is interesting to hear. Although I'm currently lusting over the purple Kona the Fugio still ticks a lot of boxes for me. I've always enjoyed steel bikes and the move to 725 plus that orange fade paint job works for me too.

Thanks, that is interesting to hear. Although I’m currently lusting over the purple Kona the Fugio still ticks a lot of boxes for me. I’ve always enjoyed steel bikes and the move to 725 plus that orange fade paint job works for me too.

Yep I`m very, very tempted. Like I say, they have sorted the bug bears I had with the original, better tyre clearance, slimmed it down a little. Unfortunately it still has the annoying allen bolt that you need to remove to get the rear wheel off, but that's not a game changer on its own. There are better value options out there, bombtrack hook ext, and the Norco Search XR which is insanely good value imho but I know the Fugio is going to ride well and fit me like a glove.

“you could save more weight/drag by having a poo”.

Drag..? Mind boggles / trying not to.

Where are you getting your numbers from? The frame hasn’t changed.

https://www.freewheel.co.uk/genesis-2020-croix-de-fer-frameset-vargn2006

Since it's Genesis' own site, I assumed they had it right.

^

Chainstay 405mm 407mm 407mm 410mm 410mm

No chance that's the CdF geo - someone's uploaded the road bike specs to the Freewheel site. Genesis site looks right. Madison own both companies but different staff etc.

Since it’s Genesis’ own site, I assumed they had it right.

Those numbers are different to the ones on https://www.genesisbikes.co.uk/bike/croix-de-fer-fs-2020

I shall go have a word with the Freewheel web gang now. Thanks for the heads up.

No chance that’s the CdF geo –

I did wonder. I assumed they had read the reviews that said it was comfortable and competent but not thrilling and decided to go for thrilling.
Would have made an interesting Gravel bike 😵

Also tell the freewheel gang the price is £299 for about the next hour or so..

I was told by someone who should know that all bike frame geometries are actually identical. They just change the numbers on the spec sheets and sit back laughing at bike testers and forum geeks as they adjust their perceptions to suit the numbers.

Bit like the Suzuki GSX-R1100 back in the day which had about 60 clicks of adjustment for every aspect of its suspension front and rear, of which, it transpired only around five made any real difference. Funny how none of the mags clocked that, probably because even the five that did owt were wrong anyway.

D

ooh, I looked it up
HA 70.5
SA 74
Reach 382
Stack 584

er, still D