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  1. #1
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    Long, Slack, Steep gravel bike?

    Any gravel bikes out there with longer reach/shorter stem, slackish 70deg HTA, and steepish 75deg STA? I have my reasons, and no, I'm not planning on racing enduro on a gravel bike.

    I know some of the Salsa offerings are close to this - but what else?

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    Midnight Special comes close too at 73.5? Not sure of any others. I looked at the Gorilla Monsoon but no cigar.

    https://surlybikes.com/bikes/midnight_special
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    Quote Originally Posted by jcd46 View Post
    Midnight Special comes close too at 73.5? Not sure of any others. I looked at the Gorilla Monsoon but no cigar.

    https://surlybikes.com/bikes/midnight_special
    Really fun bike! Love mine!

  4. #4
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    Quote Originally Posted by smoothmoose View Post
    Any gravel bikes out there with longer reach/shorter stem, slackish 70deg HTA, and steepish 75deg STA? I have my reasons, and no, I'm not planning on racing enduro on a gravel bike.

    I know some of the Salsa offerings are close to this - but what else?
    I'm curious about your reasoning.

    Usually the mtb >74* seat angle is a consequence of preserving cockpit length and steering behavior, but pushing the front-center forward as far as possible. It's an acceptable compromise cuz it's not so bad on climbs. With a road/gravel bike you don't need to go to those extremes to get a sufficiently long FC for terrain where drop bars make sense.

    The short stem is also a bit strange; it's gonna speed up the steering sensitivity on roadie style corners for no apparent benefit. It might be really helpful to consider what front-center you want, and then go from there. FC can be sloppily approximated by subtracting chainstay length from wheelbase.


    The salsa bikes are designed around flared bars and unusually fat tires. IMO they are chasing a somewhat niche market, but one that's pretty cool.

    In general, what you're after doesn't tend to exist in a production design because those design features are at odds with one-another.

    It's common for road frame builders to compromise front/rear geometry to try to fit everyone on the ~same wheelbase (and small sizes have their geo determined to some extent by mitigating toe overlap), so you gotta say what size bike you're looking at.

    As a hobbyist framebuilder with an interest in gravel bikes, i've found that a 20mm change in front-center has a much more profound effect on gravel bikes than it does on mtbs. I find bikes with huge tire clearance and almost traditional roadie geo, like the midnight special, to be much more interesting than what you describe.

    Here's a cad image of my gravel bike. It's good for up to ~42c tires. Much beyond this bike i'd rather ride an XC bike- the balance between handling in a group and aero is outpaced by rolling smoothly through chop and a rearward weight distribution.
    Long, Slack, Steep gravel bike?-gravel-bike.jpg


    Again, not trying to start a debate, just offering some observations and interested where you're coming from. This category is still being explored and that's pretty fun.

    edit- lol what a bunch of cryptic nonsense. I'm super fascinated by this topic, but i don't want to dictate anything to anyone. I've spend hundreds of hours playing with cad and have built XL and XS gravel frames/forks to the best of my ability. I want to share what i've learned and learn from others.
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  5. #5
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    Whyte Friston. Short stem, wide handlebar, long top tube, 70 deg. head angle, 74 seat tube angle.

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    Genesis Fugio, Kona Sutra LTD, Libre.

    Not exactly what you're looking for, just some ideas. This kind of geometry is pretty rare but we are going to see more of these bikes in the future for sure.

    Quote Originally Posted by scottzg View Post
    I'm curious about your reasoning.
    I'm not the OP. You mentioned toe overlap, that's a big reason to me. It's SO annoying.

    My bike has a 565 top tube, 72 head angle, 73 seat angle, 50mm rake fork. Size 10.5 shoes.
    The toe overlap with 622-43c tyres is horrible. Now that it's winter I installed some fenders... and almost crashed the other day because of toe overlap. But it's still bad without fenders. When i'm climbing slowly on a technical offroad climb and make corrections my shoes hit the tyre all the time. Wheelies feel downright dangerous. When I stop at an intersection and make a tight turn slowly=toe overlap. Just some examples.
    I'm so jealous when I see any MTB and the giant space between the pedals and the tyre...

    I'm not an engineer or frame builder but I think this kind of geometry is pretty interesting. The Warbird V4 comes with 622-40 or 650-47 tyres, it has a 70.5 head angle, pretty long top tube, and shorter than usual stem.

    I don't want to have the "what's a gravel bike" discussion but now we are also seeing more and more drop bar bikes that can clear 650b MTB sized rubber. On one of those things I think i'd like a more MTB-ish geometry.

    Quote Originally Posted by justwan naride View Post
    Whyte Friston. Short stem, wide handlebar, long top tube, 70 deg. head angle, 74 seat tube angle.
    Holy crap, didn't even know this thing existed! Any info on tyre clearance?

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    Wikkit Qbomb or Turbo.

  8. #8
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    Quote Originally Posted by HollyBoni View Post
    Holy crap, didn't even know this thing existed! Any info on tyre clearance?
    No, but I suspect they use the same frame for the Glencoe, which is spec'ed with 27.5 "road plus" tyres. I've had good results asking them about such stuff on facebook though.

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    Quote Originally Posted by scottzg View Post
    I'm curious about your reasoning.

    Click image for larger version. 

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    Again, not trying to start a debate, just offering some observations and interested where you're coming from. This category is still being explored and that's pretty fun.
    OP - definitely no expert or frame builder. I'm 5'5" 165cm tall....so I think for "traditional" roadie sizing I'm a 52-53cm ish?

    70deg HTA / longer FC - exactly as you mentioned - alleviate toe overlap - and hopefully more stability on descents.

    Shorter stem/wider bars - is the assumption it will compensate to quicken up steering due to the slower slack HTA

    75deg STA - Compensation from riding large flat pedals on midfoot position - my foot shifts to the midfoot position by 3-4cm compared the traditional cliped postion. Based on my math on my inseam - I'll need to compensate 2-3 degs in steeper STA.

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    Quote Originally Posted by justwan naride View Post
    Whyte Friston. Short stem, wide handlebar, long top tube, 70 deg. head angle, 74 seat tube angle.
    Very cool. I'll add to my list to watch. But I'm state side and I think Whyte USA only carries the MTB range at this point.

  11. #11
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    Quote Originally Posted by smoothmoose View Post
    OP - definitely no expert or frame builder. I'm 5'5" 165cm tall....so I think for "traditional" roadie sizing I'm a 52-53cm ish?

    70deg HTA / longer FC - exactly as you mentioned - alleviate toe overlap - and hopefully more stability on descents.

    Shorter stem/wider bars - is the assumption it will compensate to quicken up steering due to the slower slack HTA

    75deg STA - Compensation from riding large flat pedals on midfoot position - my foot shifts to the midfoot position by 3-4cm compared the traditional cliped postion. Based on my math on my inseam - I'll need to compensate 2-3 degs in steeper STA.
    Makes sense to me!

    Personally, if i was 5'5 i wouldn't even consider a 700c gravel bike. Dedicated 650b all day long. At 5'5 your handling geo is largely dictated by fitting the rider around the wheels, with 650b there's more room to make the bike ride/handle awesome without needing 'enduro' geometry. I'm 6'3 and i get a touch of toe overlap on the bike above with 700x35c tires, and it's plenty stable for anything where a 35c tire is a great choice. Sorry to derail your thread.
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    Quote Originally Posted by justwan naride View Post
    Whyte Friston. Short stem, wide handlebar, long top tube, 70 deg. head angle, 74 seat tube angle.
    Quote Originally Posted by scottzg View Post
    Makes sense to me!

    Personally, if i was 5'5 i wouldn't even consider a 700c gravel bike. Dedicated 650b all day long. At 5'5 your handling geo is largely dictated by fitting the rider around the wheels, with 650b there's more room to make the bike ride/handle awesome without needing 'enduro' geometry. I'm 6'3 and i get a touch of toe overlap on the bike above with 700x35c tires, and it's plenty stable for anything where a 35c tire is a great choice. Sorry to derail your thread.
    Yes. I'm still trying to reconcile the MTB 29er hype vs. the gravel bike 650B hype. Nowadays even the extra-petite lady racers are riding 29er. While the obvious answer of going to 650B for gravel is larger tire clearance without needing to change frame clearances and geometry. But only down side I keep hearing about with 700C voluminous tires is toe overlap.

    So the inquisitive part of me keeps asking, why NOT adopt frame geometry to better work with larger 700C wheels. This approach seems to be working well on the MTB side with the recent proliferation of 29ers from XC to DH.

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    Quote Originally Posted by smoothmoose View Post
    Yes. I'm still trying to reconcile the MTB 29er hype vs. the gravel bike 650B hype. Nowadays even the extra-petite lady racers are riding 29er. While the obvious answer of going to 650B for gravel is larger tire clearance without needing to change frame clearances and geometry. But only down side I keep hearing about with 700C voluminous tires is toe overlap.

    So the inquisitive part of me keeps asking, why NOT adopt frame geometry to better work with larger 700C wheels. This approach seems to be working well on the MTB side with the recent proliferation of 29ers from XC to DH.
    Don't forget that gravel bikes use a narrower BB shell, and have clearance for larger chainrings. That makes squeezing a wide 622 tyre in the back much more difficult unless you go with super long chainstays.

    In the MTB world you have a wider BB shell to start with. Then you go boost with a boost offset chainring, and limit the chainring clearance to 32 or 34 with a 1X, and you forget about front derailleur compatibility. Easy!

    With 650b it's no big deal to make a gravel frame fit a 47-50, but even with 650b sometimes it's not easy to fit a tyre wider than that.
    The Gorilla Monsoon for example fits a 27.5x2.4, but it uses a 73mm BB shell, and the max chainring size for a 1x is 38T. Then you have things like the OPEN U.P. which uses a dropped chainstay.

  14. #14
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    Quote Originally Posted by smoothmoose View Post
    Yes. I'm still trying to reconcile the MTB 29er hype vs. the gravel bike 650B hype. Nowadays even the extra-petite lady racers are riding 29er. While the obvious answer of going to 650B for gravel is larger tire clearance without needing to change frame clearances and geometry. But only down side I keep hearing about with 700C voluminous tires is toe overlap.

    So the inquisitive part of me keeps asking, why NOT adopt frame geometry to better work with larger 700C wheels. This approach seems to be working well on the MTB side with the recent proliferation of 29ers from XC to DH.
    Bigger wheels on a MTB are problematic because they make the bike tall, whereas big wheels on a road bike are problematic because they make the bike long. With the mtb you can lower the handlebars and sorta solve the problem, but there's no way to shorten the front-center beyond ~620mm without some sort of compromise. Steering behavior, fit, toe overlap. 650b is another compromise to deal with the length.


    Check out this geo chart snippet from the surly midnight special. The wheelbase is almost the same for the first 5 sizes, and the 54 is larger than the 56. Surly is trying to fit a bunch of different size people around the same size bike.
    Long, Slack, Steep gravel bike?-midnightspecial.jpg
    (road bike geo charts that look like this one are pretty common)



    IMO
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    Quote Originally Posted by HollyBoni View Post
    Don't forget that gravel bikes use a narrower BB shell, and have clearance for larger chainrings. That makes squeezing a wide 622 tyre in the back much more difficult unless you go with super long chainstays.
    Acknowledged. However what other than reusing existing road/CX frame designs is preventing manufacturers to goto a larger BB shell? I also acknowledge design reuse is a serious consideration in any business that creates derivative or similar product. But it's a business driven decision rather than a design driven one.

    Quote Originally Posted by scottzg View Post
    Check out this geo chart snippet from the surly midnight special. The wheelbase is almost the same for the first 5 sizes, and the 54 is larger than the 56. Surly is trying to fit a bunch of different size people around the same size bike.
    Click image for larger version. 

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    (road bike geo charts that look like this one are pretty common)
    I get this conceptually - deliver the same vehicle with the same handling characteristics independent of driver size. Does this really work well in practice though? I understand with a road bike compared to MTB - you very very seldom move your body "around" the bike to create leverage like you would on MTB riding technical terrain. However on a gravel bike, maybe you do want to move around more - depending on how gnarly you want to get on it.

    I admit, I haven't been on dropbar bike for many many years - so I've pretty much "forgotten" how it "should" handle and feel. But I'm still wondering for gravel do we really need the "snappiness" and "sharp" handling feel people talk about? I don't need to dart between other riders for mass start or sprints like a road racer does - so is the longer/slacker handling really that bad? And to further to that, the same was said about MTB geo a few years ago as we got longer and slacker. Seems everyone is doing fine chucking through rock gardens and weaving tight singletracks with 65deg HTA bikes nowadays.

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    Quote Originally Posted by smoothmoose View Post
    Acknowledged. However what other than reusing existing road/CX frame designs is preventing manufacturers to goto a larger BB shell? I also acknowledge design reuse is a serious consideration in any business that creates derivative or similar product. But it's a business driven decision rather than a design driven one.
    Some people don't like the increased Q factor a 73mm BB gives you.

    Press fit gives you more freedom, but as soon as you hear press fit you think of creaking. There is T47 which is promising, but there aren't a lot of BBs for it yet. Hopefully some day that is going to be the new threaded standard. IMO the industry should have moved to it as soon as integrated cranksets came out.

    Bombtrack moved all their previously press fit steel bikes to T47 this year.

    The Hook EXT has 425mm chainstays and can clear a 27.5x2.1 with the help of T47 and a chainstay yoke and is compatible with road drivetrains.

    Hook EXT 2019 – Bombtrack

    More and more manufacturers are using the dropped chainstay design tho. Pretty neat idea.

    Personally I like a lazy, stable, go over everything bike better than a snappy road bike. Even when you just go to wider tyres the bike starts to feel so much more stable and confidence inspiring. After owning a gravel bike i'll never buy a skinny tire road bike again, even if for some reason i'd only want to ride on pavement. I'm not a professional racer, I don't need it, and it doesn't feel like my 43mm tyres hold me back on pavement.

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    Quote Originally Posted by HollyBoni View Post
    Some people don't like the increased Q factor a 73mm BB gives you.
    Sure - I get that some people care if their feet are clip-in and locked into the exact same position all the time. For me, once I set my feet free on flats a whole new world opened up.

    Personally I like a lazy, stable, go over everything bike better than a snappy road bike. Even when you just go to wider tyres the bike starts to feel so much more stable and confidence inspiring. After owning a gravel bike i'll never buy a skinny tire road bike again, even if for some reason i'd only want to ride on pavement. I'm not a professional racer, I don't need it, and it doesn't feel like my 43mm tyres hold me back on pavement.
    Exactly! That's what my gut is telling me as well. I took a gravel bike with more road like geo out for a test ride recently and didn't really like the "twitchy" feel of it. I was just hammering straight on the road...wasn't weaving my way between cars, a peloton, or mass start. Some people would call it "responsive" or "snappy", or maybe I've grown to MTB handling.

    Then I just watched Guy Kesteven's video review of the aforementioned Whyte Friston ripping through singletrack...and I'm thinking, this long slack gravel bike seems to handle just fine...

    https://youtu.be/mUNahi2IECk

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    Quote Originally Posted by smoothmoose View Post
    Acknowledged. However what other than reusing existing road/CX frame designs is preventing manufacturers to goto a larger BB shell? I also acknowledge design reuse is a serious consideration in any business that creates derivative or similar product. But it's a business driven decision rather than a design driven one.



    I get this conceptually - deliver the same vehicle with the same handling characteristics independent of driver size. Does this really work well in practice though? I understand with a road bike compared to MTB - you very very seldom move your body "around" the bike to create leverage like you would on MTB riding technical terrain. However on a gravel bike, maybe you do want to move around more - depending on how gnarly you want to get on it.

    I admit, I haven't been on dropbar bike for many many years - so I've pretty much "forgotten" how it "should" handle and feel. But I'm still wondering for gravel do we really need the "snappiness" and "sharp" handling feel people talk about? I don't need to dart between other riders for mass start or sprints like a road racer does - so is the longer/slacker handling really that bad? And to further to that, the same was said about MTB geo a few years ago as we got longer and slacker. Seems everyone is doing fine chucking through rock gardens and weaving tight singletracks with 65deg HTA bikes nowadays.
    I hate how surly scales up/down their sizes. I've had XL road bikes where they did it that way and they were super nervous to ride. Too sharp.

    Longer/slacker geo might be bad or good, but if you're 5'5 and riding 700c the wheel size is dictating a surprising amount of the fit and handling. It might not matter, but it might mean that the wheel size is keeping you from riding something really great. I don't know and it's a matter of taste.





    Larger BB shell means mountain cranks which means a wider Q factor and a different selection of gearing choices.
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  19. #19
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    Quote Originally Posted by smoothmoose View Post
    ...I don't need to dart between other riders for mass start or sprints like a road racer does - so is the longer/slacker handling really that bad?...
    I'll make a generalisation here. MTBs are designed for a market where downhill performance is more important than climbing performance. Long and slack favours that but the flop introduced does climbing no favours on steep stuff.

    A gravel bike is going to be ridden on tracks where steep DH type sections are less likely and so a geometry that does not impinge on climbing ability is better - after all on any given hill you spend a lot longer climbing the thing than on the descent. Steeper HAs mean a lot less flop. The nervousness of steep HAs on some road bikes is because they do not have a lot of trail - a bike with a steep HA and a decent amount of trail can be very stable.

    Toe overlap is more because of a short front centre than the HA, so long is a good way to avoid it, but that can be done within a given wheel base with slack or steep hAs.

    However humans are incredibly adaptable and are capable of riding bikes with completely "wrong" geometry in the "wrong" places. When discussing/arguing over the perfect HA and trail, always stop and think "Hang on, people can ride unicycles".
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    Quote Originally Posted by smoothmoose View Post
    Then I just watched Guy Kesteven's video review of the aforementioned Whyte Friston ripping through singletrack...and I'm thinking, this long slack gravel bike seems to handle just fine...

    https://youtu.be/mUNahi2IECk
    To be honest my steeper gravel bike easily handles terrain like that. A lot comes down to rider skill, but it's not that hard, you just grab the drops as hard as possible and go for it. This kind of terrain is only fun on a gravel bike for about 5 minutes tho. It can easily turn into torture when you try to push a gravel bike where you really should be on an MTB. Hours pass but you go nowhere and you get so sore and tired because of the bumpiness. Not to mention bottoming out the front tyre constantly if you have something like a 40-43. It's not fun.

    I'm on 43mm tyres and I feel like on an offroad descend what's holding me back is the tyre size and rigid fork by far, not the geometry. Sure, if I had 2.4s I think I might appreciate a longer and slacker bike, but really i'd go with geometry like that just to get rid of toe overlap in the first place.

    Tyre pressure is really important too, when I go down to 30-35psi the steering feels a lot slower and the bike feels more stable compared to when I go up to 40-45psi.

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    Thanks guys. All good points. I agree - don't really want a gravel bike to "rip" singletrack. Gravel is for gravel.

    Still being shorter toe overlap is an issue so yes, hoping a longer FC and slacker HTA will help. I still don't believe a 70deg HTA with the correct trail setup will too floppy. I'll just need to test ride more bikes to find what I like.

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    Use a 70.5* HT, 39mm offset Front Fork, or find something with between 75-80mm of trail. Look for a long front center and move away from short wheelbase - road-style designs. You will find something much more suited to gravel with the above spec.

    Also, regarding seat-tube angles, the difference between 73 and 75* is minimal. Depends on leg length, but at the contact point on the saddle you will need to calculate this. Draw it out. You can for instance push yourself forward on a ISM saddle by as much as 50mm over a conventional saddle and use a frame that is slack but compensated by the saddle.

    You have options.

    Eric
    If I don't make an attempt, how will I know if it will work?

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    Quote Originally Posted by Eric Malcolm View Post
    You have options.
    Such as...?

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    Maybe a Devinci Hatchet.

    STA = 73 to 76 depending on size
    HTA = 70 to 71.5 depending on size.

    It's long with a short stem.

    Looks the business too.

    DEVINCI


    -Tim-

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