[William42]

With a lot of bike geo nerds here, I was thinking about the spillover effect that downhill bikes are having on mountain bikes, and wondering if that's going to eventually transfer over to road bikes. Figured I'd post this in the DH forum in part because everybody who's given this some thought hangs out here, and partially because DH geometry seems to be gaining traction among the lesser people (roadies, who think 140mm stems are awesome and the shortest MTB stem you should consider is 120mm)

Used to be trail bikes and enduro bikes were setup to have 69 degree HA's, long 110m stems and 14+ inch BB's. If they do it on road bikes, they should do it on mountain bikes. I remember when I was working at a bike shop a decade ago, we legit had large stock bikes coming in with 71 degree head angles and 120mm stems with 5 inches of travel. They road like garbage too (hello Gary Fisher).

Seems like it took awhile for people to realize road bike geometry sucks. But companies have finally caught on, and now we're seeing trail bikes with 65-66 degree HA's, lower BB's, longer front centers, and 50-60mm stems seem pretty standard. The bikes handle way better in pretty much all situations. The wheelbases have gone up, the sizes have gotten bigger for people the same height, and the good riders no longer have to buy bikes 2 sizes up from what they should be on to find something equipped to go fast.

So the question I have is, as this better geo trend of wider bars, shorter stems, longer front centers, slacker head angles, lower BB's trickles into trail and XC bikes, think there's any chance of that moving over to road bikes? It seems like it wouldn't be crazy hard to design a road bike with the correct amount of drop for an aero position while not giving it dogshit geo with a 140mm stem so that you can size down on the bike.

Do all roadies just suck at figuring out handling, or do they know something I don't? Cause I know for sure I feel way more comfortable with the handling of a modern mountain bike at high speeds and low speeds, and I'd be interested to ride a road bike with a long wheelbase, low front end, shorter stem, and slacker HA than is considered normal. I'd be pumped as shit to ride a road bike with DH geometry sitting on a 64-65 degree HA, long wheel base, shorter stem etc.

Anybody thought of this? Am I the idiot? Should I stop talking about road bikes?

 

[jonKranked]

i suspect no. i think a lot of it has to do with different intended purposes of the bikes. ergonomics / fitment and aerodynamics are far more important design criteria on road bikes than mtb. climbing is also WAY more important, and they don't need to be as good at technical handling. trail / enduro bikes can technically climb, but they don't need to be as proficient at it; and the low / slack trend indicates that most mtb'ers with these kinds of bikes are fine with that tradeoff.

 

[Lelandjt]

I like 100mm stems on my road bikes because they don't handle like tillers. I'm lucky to have legs long enough that I can ride a frame with a long enough reach for that to work without concerns about seat tube length or stand over. My road bike is a 61cm Fuji Transonic. Aero everything and 14.3lbs. My travel bike is a 61cm Scandium frame that's 17lb with aero nothing. It's amazing how much of a difference I can feel between them on steep climbs or when cruising above 23mph.

I'm actually a fan of narrow bars for aero so I'll never be going wide bar for handling. Currently on 40cm Easton EC90 Aero because they don't make a 38. The travel bike has a 45cm bar. I don't really notice a handling difference but I can feel my arms and chest catching the wind.

I'd like to try a 71° head angle but I'm not sure it would be better. My handling limitation is my 23mm tires but those are staying cuz they're so fast everywhere besides the corners.

 

[Nick]

The bars on my road bike are much wider than my old road bike, so that's one thing that seems to be carrying over. I don't like them, and will swap sooner or later.

Also, what they said re: intended purpose/use.

 

[iRider]

Why don't you want the right tool for the job anymore? With every change in geometry you make some things better and others worse, so it is a tradeoff. Road bike geos had way longer to evolve than those of MTBs and are more meant to put you in the biomechanical best position for power output and aerodynamics then anything else. As on a road bike you don't ascent or descent slopes as steep as on MTBs, a more balanced geometry is used. Recently Cannondale and Canyon started playing with long TTs and shorter stems for their cross bikes which makes sense in this application.
In addition, road bikes are offered in 20 different sizes of each high-end frame (or close to that), which allows you to up- or downsize if you really feel to change it up.

 

[canadmos]

I've got a 60 or 70mm stem on my "road" bike, which has a 70.5 degree head angle. Its pretty sweet.

 

[jonKranked]

I like 100mm stems on my road bikes. I'm lucky to have legs long enough that I can ride a frame with a long enough reach for that to work without concerns about seat tube length or stand over. My road bike is a 61cm Fuji Transonic. Aero everything and 14.3lbs. My travel bike is a 61cm Scandium frame that's 17lb with aero nothing. It's amazing how much of a difference I can feel between them on steep climbs or when cruising above 23mph.

I'm actually a fan of narrow bars for aero so I'll never be going wide bar for handling. Currently on 40cm Easton EC90 Aero because they don't make a 38. The travel bike has a 45cm bar. I don't really notice a handling difference but I can feel my arms and chest catching the wind.

I'd like to try a 71° head angle but I'm not sure it would be better. My handling limitation is my 23mm tires but those are staying cuz they're so fast everywhere besides the corners.

this reminded me of something.... longer stems make steering handling more stable (or sluggish if you want to describe it that way), but bear in mind a lot of road riders are typically going on 30 - 40 mile rides or longer. this increased stability also helps fight off fatigue towards the end of the ride; short stems with slack head tube and road bars (ie not that wide, the widest stock road bars i've come across are 460mm wide) and that's a recipe for speed wobbles.

 

[norbar]

i suspect no. i think a lot of it has to do with different intended purposes of the bikes. ergonomics / fitment and aerodynamics are far more important design criteria on road bikes than mtb. climbing is also WAY more important, and they don't need to be as good at technical handling. trail / enduro bikes can technically climb, but they don't need to be as proficient at it; and the low / slack trend indicates that most mtb'ers with these kinds of bikes are fine with that tradeoff.

For road racing or triathlon yeah but what about commuters?

 

[jonKranked]

For road racing or triathlon yeah but what about commuters?

hipsters on fixies and e-bikes

 

[William42]

Am I missing something? People keep bringing up positioning - I don't see any reason positioning has to change even in the slightest - picture the rider floating in the air and just changing the shape of the bike under them to accommodate adjusting the geometry. You're aero positioning and biomechanics shouldn't change even in the slightest. I'm picturing the same seat tilt degrees, drop between saddle and bars, same reach, just moving the front end of the bike further forward, lengthening the wheelbase, and shortening the stem to accommodate.

As far as HA, it definitely makes the front end wander more on a MTB, but I'm wondering how much that's exaggerated by rocks, roots, dips and bumps pushing the front wheel around and the steering being quicker. It can take a second to adjust your steering, especially since you essentially have to move the entire bike around. On a road bike on pavement, would that really be noticable?

 

[HAB]

Some random thoughts in no particular order. I've fully embraced the modern mountain bike geo thing, but I actually think road bikes are much better optimized.

• I don't want wider bars on my road bike. In fact, I've swapped for narrower on my last couple, and this is coming from someone with 800mm bars on all my MTBs. I'm much more comfortable with 40cm road bars than 42 or 44s.
• Seat tube angles could be a touch steeper, but the UCI rule that the tip of the saddle has to be behind the BB centerline is probably holding things up there a bit. As per usual the UCI can go fuck itself.
• From trying things on mountain bikes, I kinda think you need to go all in on the long and slack geo thing, or it doesn't work. If you put a big reach and slack HTA on a bike with short stays, for example, the weight balance between the wheels gets off and it doesn't handle great. I'd be curious to try a road bike with all that going on, but I think that all the changes you'd need to make to design a road bike for a longer reach, shorter stem, and slacker HTA (I.e. correspondingly longer stays, steeper STA, maybe less fork offset and a shorter HT) add up to some weird compromises that aren't great on a road bike.

 

[Wuffles]

There are two problems with geometry changes in road biking:

1) The UCI's rulebook on bike design for road bikes is like 200 pages long and has heaps of geometry restrictions (like seat tubes can be no steeper than 73 degrees or something), and they have to "certify" (for ca$h money$ of course) frames for racing. Unfortunately, all of the bikes sold to the lycra crowd take their cues from racing bikes, so you'll never see a big departure from the UCI restrictions. Contrast this with the UCI's mtb design rule book, which is two points: must be a bicycle (two wheels, powered by pedaling), and no metal studs on tires. That's it- no other restrictions.

2) Road bikes are not designed with handling as a primary design consideration. The most important thing for roadies is comfort and efficiency, they don't really care if low speed handling sucks, or they get unstable over bumpy surfaces because they'll spend very little time doing that. Again, contrast it with mtb where handling is pretty much the first and foremost thing that matters.

Now I agree it would be nice if road bikes handled better, but I just can't bring myself to care that much.

 

[shirk007]

Everyone loves to hate on PVD but he's playing with all this stuff on a gravel road bike.

https://www.peterverdone.com/2018-pvd-bird-of-prey/

Anyone listen to Lance's podcast The Move during the tour? Him and George Hincapie were doing some mtb ride the other day and George has finally seen the light and has a dropper post...he was wonder how much better the big road descents would be with a dropper post.

I think we'll see this kind of geometry progression pushed from the gravel road bike / grinduro side of things. Maybe in 20 years the roadies will see the light.

 

[Gary]

Seems like it took awhile for people to realize road bike geometry sucks.

Eh? No it doesn't. not for riding on roads.

Do all roadies just suck at figuring out handling, or do they know something I don't?

Eh? No. but you sound like an idiot.

I'd be interested to ride a road bike with a long wheelbase, low front end, shorter stem, and slacker HA than is considered normal. I'd be pumped as shit to ride a road bike with DH geometry sitting on a 64-65 degree HA, long wheel base, shorter stem etc.

Am I the idiot?

Yes.
Suspicion confirmed!

I've ridden roughly the same roadbike geometry all my adult life. From my first handbuilt steel Flying Scot to my current Giant TCR carbon. I've always preferred a slightly smaller frame than most shops would have me on and I've generally always ridden a 100mm(ish) stem. Stability at speed is not and never has been a problem. Pretty much every road ride I ever do includes a section of road ridden at 40mph+ a fair few 50mph+ and the roads round here are unclassified farm roads (ie. shitty condition)
Handling is good. a bike like you suggest would be utterly shit.

Gravel bike merchants are just punting the new purple.

 

[Gary]

On a road bike on pavement, would that really be noticable?

Massively.

Spend some time on a decent race geometry roadbike. learn to wheelie it one handed, learn to corner it right on the edge of traction and learn to bunnyhop potholes and cattle grids at 45mph.

 

[bagtagley]

Everyone loves to hate on PVD but he's playing with all this stuff on a gravel road bike.

https://www.peterverdone.com/2018-pvd-bird-of-prey/

He's pulled back from the extremes of his previous "all road" bike. Boner stem notwithstanding, I like that thing.

 

[Electric_City]

I understand your point but it's not even the same sport really.

Your comparing - Superbike to motocross or soccer players to football players.

Road bikes have developed over a century to make the fastest and most efficient human powered machine. They've been designed to get as much power from your muscles to the cranks, through the chain and gears and to the tire to asphalt. Stiffer, more efficient and more aerodynamic is key.

Slack mountain bikes are a new concept. They work, but shouldn't be compared to road in any way. We're dealing with suspension first off and that alone is a completely different machine. Especially since you're taking that power created by our legs and now you're dealing with rocks and roots countering your power plus a ton more (such as balancing with your knees, slow pedaling, techy terrain, tight turns...). Not mentioning the handling NEEDS to be different. Front and rear wheels encountering different rocks, holes, roots- uphill and down- at the same time. It just creates a whole different game.

I understand your idea of floating body position, but I never rode in my saddle per-se on my mountain bike like I would on a road bike.

I think if I built a road bike personally, I'd probably put a dropper on it though. Lol!

You'll never see F1 cars with a lift kit and a low engine (think bb). @Tantrum Cycles

 

[shirk007]

Road bikes have developed over a century to make the fastest and most efficient human powered machine. They've been designed to get as much power from your muscles to the cranks, through the chain and gears and to the tire to asphalt. Stiffer, more efficient and more aerodynamic is key.

Road bikes have been stagnant for decades. The CONI manual was and still held up as the end word on bike fit and geometry. Go look at the number of unique designs that have been tossed out by the UCI that Greame Obree developed. Regardless if you want to you can make massive changes to the geometry of the bike and hold the rider in exact same relation to the contact points (pedals, seat, bars) and still get the same efficiencies from the engine.

Thinking that because the Pro's do it then it must be right is kinda garbage. They ride what their sponsor produces. Their sponsors are mass market builders that build to suit what they think they can sell to the average Joe. Look back at Ryder Hesjedal riding a smaller frame size due to the shorter headtube just so he could get the saddle to bar drop he wanted and needing to use a massive 140cm stem to get the bar to saddle dimension.

 

[Electric_City]

I HIGHLY doubt that the best bike companies in the world can't change basic geometry on their frames. I'm also fairly certain that each pro ride would be fit and measured by standards that make them as fast as possible.

They're sponsored because they're the best. So yes, they're getting paid to represent the bicycle company! Their sponsor doesn't say "Hmm. Well this is all I have. Good luck in the tour!". Lol!

I guess I should ask Gwin what the best road geometry is for me!

 

[rideit]

I run an 80mm stem on my med. road bike, seems to help 'feel' more like my mt. bike.

 

[Gary]

Go look at the number of unique designs that have been tossed out by the UCI that Greame Obree developed

seriously?
You're using Obree as an example in a thread about road bike handling? Greame himself is the first to admit a lot of his concepts in search of time trial records were incredibly poor handling and took time to learn to ride safely nevermind handle well.
He didn't ever win anything based on handling skills. infact he was well known locally for crashing out of road and mtb (XC) races all by himself.

 

[shirk007]

seriously?
You're using Obree as an example in a thread about road bike handling? Greame himself is the first to admit a lot of his concepts in search of time trial records were incredibly poor handling and took time to learn to ride safely nevermind handle well.
He didn't ever win anything based on handling skills. infact he was well known locally for crashing out of road and mtb (XC) races all by himself.

Where did I say we should be looking to Greame for handling?

 

[Sandwich]

yeah...no. design a mountain bike for climbing and it's not going to be dramatically different than a road bike in many aspects. You're going to want a longer stem, a shorter front center to get your weight over the front wheel, a steep seat angle to keep you in position, and an aggressively steep HA to keep the front end from wandering. Road bikes are designed for climbing, among other things, because that's where you spend the majority of time.

MTB have gotten on board with the whole "slacker is better" thing because it enhances downhill performance, and many people are willing to pay going up in order to enjoy going down even faster. If you look at XC bikes, they still haven't gone much past 69* head angles, because any slacker isn't really better for true cross country, and two seconds on the DH is more than made up for by not fighting a wandering front end on the way up. You and I don't really care about that, because you can push an additional 5mph through the corners with 800mm bars vs 720s, but an XC rider might want better aerodynamics or other such nonsense.

This is kind of the same point I made in the super slack HA thread, but I can't imagine going slacker out here on the east coast- the price you pay would not make up for the six seconds of downhill you get as a reward for that huge climb.

 

[Gary]

This thread is a fucking car crash.
Is there really nothing left in DH to discuss?

 

[Wuffles]

Eh? No it doesn't. not for riding on roads.

Eh? No. but you sound like an idiot.



Yes.
Suspicion confirmed!

I've ridden roughly the same roadbike geometry all my adult life. From my first handbuilt steel Flying Scot to my current Giant TCR carbon. I've always preferred a slightly smaller frame than most shops would have me on and I've generally always ridden a 100mm(ish) stem. Stability at speed is not and never has been a problem. Pretty much every road ride I ever do includes a section of road ridden at 40mph+ a fair few 50mph+ and the roads round here are unclassified farm roads (ie. shitty condition)
Handling is good. a bike like you suggest would be utterly shit.

Gravel bike merchants are just punting the new purple.

Road bikes have developed over a century to make the fastest and most efficient human powered machine. They've been designed to get as much power from your muscles to the cranks, through the chain and gears and to the tire to asphalt. Stiffer, more efficient and more aerodynamic is key.

@Tantrum Cycles

If this we're true, tri bikes would be all over the place, and TT bikes would be allowed in events other than TTs. But they're not- they're banned from the pro peleton because UCI reasons. The standard road race bike is demonstrably not as fast and efficient as it could be, which is why team tactics and racing dynamics have evolved to be the way they are. Handling is merely okay. Sure, you can do some macho shit with it, but you could do some macho shit on a rigid Mongoose in the 90's, and no one is arguing those are the pinnacle of mtb design.

The UCI racing rules have been a drag on road bike design for something like half a century, and even the big boys admit it.

https://newatlas.com/fuci-specialized/39154/

Yes, it's a stupid concept bike, and includes a motor because ebikes, but look at the geo- way longer than any road bike, and slacker than a DH rig.

 

[jstuhlman]

tl; dr. road bikes...lol

 

[chris_f]

So this is Roadmonkey now?

 

[gemini2k]

I think the biggest question I face for my road/CX bike right now is dropper or no dropper?

 

[djjohnr]

I think a road bike tuned for DH handling would be a ton of fun if you lived somewhere with a lot of vertical descent on tap. It wouldn't need to replace a typical road bike for typical road rides. It could just be for you know...DH. During my short stint with road bikes the most fun I had was racing cars down Mt Tam. Now is there a viable market for such contraptions...probably not.

 

[iRider]

I don't get it. Everybody that has ridden an old school XC hardtail knows about those sketchy moments on the descents which are nearly not existent on a modern geometry bike (or at way higher speeds). So far I have never felt uncomfortable even going Mach chicken on a road bike with its steep-ish geometry. In contrast, an on paper slacker gravel/cross frame feels less comfortable at high speeds because it reacts too slow to correct lines and feels like a handful around fast switchbacks.
Only thing really scary is a soft fork that starts flexing or vibrating when you hit the brakes.

 

[KenW449]

You'll never see F1 cars with a lift kit and a low engine (think bb).

Who wants to build a Ridemonkey racecar?

old school XC hardtail knows about those sketchy moments on the descents which are nearly not existent on a modern geometry bike

New XC bikes too. When i did the Pivot demo, their XC bike, (Mach 429?), had me all kinda of nervous riding the tech here, but the trail and All mountain bikes were just fine. Im sure it was much worse when you older monkies started out. We kids get all the new toys.

 

[Tantrum Cycles]

So this is Roadmonkey now?

as long as it's DH road.......none of that XC or Enduro road crap please

 

[rideit]

Im sure it was much worse when you older monkies started out. We kids get all the new toys.

You cannot even imagine how we all didn't die.

 

[mykel]

Who wants to build a Ridemonkey racecar?


New XC bikes too. When i did the Pivot demo, their XC bike, (Mach 429?), had me all kinda of nervous riding the tech here, but the trail and All mountain bikes were just fine. Im sure it was much worse when you older monkies started out. We kids get all the new toys.

Yup, you fuckers are spoiled. You can go to any bike store and buy a killer ride. Back in the day you built your ride from whatever you could beg, borrow or steal from the roadies, beach cruisers, the banana seat crowd or (I kid you not) local blacksmith/metalworking handyman. (welding broken frames and adding gussets etc )

 

[Jm_]

Can I get the 58 seconds back that I spent on this thread?

 

[mykel]

Can I get the 58 seconds back that I spent on this thread?

No.

 

[William42]

Seems like the post title was pretty clear, so I guess just leave if you don't give a shit about bike geometry for other types of bikes. Don't let the door hit you on the way out.

Anyway, I don't wheelie my road bike Gary, because its 13 pounds and the idea of snapping my carbon steer tube when I come down from doing a wheelie sounds both avoidable and stupid. I have done 59mph (thats 94kph in your old world units) through corners though, and I probably have a bigger penis than you, so maybe we can end the dick swinging cause I don't really give a shit if you have a chip on your shoulder.

At any rate, dick swinging and Gary taking things personally aside, "Pro's do it" doesn't really hold water either if you think about it. And honestly, neither does "Bike companies can do whatever they want" - the UCI has pretty severe limits on what bike geometry can exist, and the entire point of having professional teams is to sell bikes. Why make a specialty professional bike and then tell the public they can't have it, and what they really need is this other bike. They're in it to sell bikes, and there is probably about 0% chance of the geometry we're talking about making it to a mass market as anything other than a niche custom build for people not out to race.

Have you ever talked to a professional road rider? They don't know shit about bike handling or geometry, and literally their only criteria for whether or not a bike has good geometry is how aero it is, and whether or not its stiff. Seems like it'd be possible to design a bike with fast aero geometry (or hell, make it an endurance bike ala the Trek Domane) that also didn't have to have a 120-140mm stem to be "fast." Just talk to them about which bikes handle well, and they have no idea why some handle better than others. I don't think they're pouring a ton of time effort or attention into this.

So reasons why this geometry isn't done aside, I honestly haven't given this a ton of thought other than noticing that a larger frame with a shorter stem feels a billion times more comfortable and handles way better than a smaller frame with a longer stem, and wondered how far you could push that idea. Biomechanically, you should be able to achieve any desired fit position with this geometry. The main difference would be that instead of trying to balance the bike evenly by putting a bunch of weight out in front of the front wheel, you're just centering the weight more in the middle of the bike to balance it. Then you can have a slacker head angle so it doesn't feel sketchy on descents, and more precise steering that comes with a shorter stem.

Is wheel deflection really a big problem on climbs where you are? Maybe the roads I climb on on my road bike are better paved or something, but I've never noticed wheel deflection and the wheel pushing sideways to be remotely a problem, and can't imagine that a slacker head angle would compromise that all that much.

I'm just spitballing here. Maybe I'll talk to my buddy and we can build a steel frame up for me to dick around on and let yall know how it goes.

 

[Gary]

I do ride multiple bike styles. BMX, 4X/DJ hardtails, DJ FS, Enduro FS, DH and road etc. and most certainly do care somewhat about their individual geometries'. I wheelie all of them at times, mainly just because I can. And FWIW placing the front wheel back down from a wheelie on any bike creates lot less stress on the steerer than riding over rough ground or braking.

Anyway, I don't wheelie my road bike Gary, because its 13 pounds and the idea of snapping my carbon steer tube when I come down from doing a wheelie sounds both avoidable and stupid. I have done 59mph (thats 94kph in your old world units) through corners though, and I probably have a bigger penis than you, so maybe we can end the dick swinging cause I don't really give a shit if you have a chip on your shoulder.

Do I have this correct? You corner the same 13lb carbon road bike at 59mph on the open road that you're scared will shear its carbon steerer tube if you place the front wheel gently back down from a wheelie?

 

[KenW449]

neither does "Bike companies can do whatever they want" - the UCI has pretty severe limits on what bike geometry can exist

No, it just dictates what can race. BTW, who says only UCI can put together races? Why cant some other organization say, "Fuck you, we are doing this race. Bring whatever bike you please but no motors." If people quit giving them money, they will be forced to change their rules.

Anyway, I don't wheelie my road bike Gary, because its 13 pounds and the idea of snapping my carbon steer tube when I come down from doing a wheelie sounds both avoidable and stupid.

Buying a bike so fragile you're afraid ending a wheelie will break it is also avoidable and stupid.

 

[Gary]

No, it just dictates what can race.

Yeah. I've no idea where William gets his misinformation from.
The UCI has no jurisdiction what so ever to dictate what manufacurers roadbike designs can or can't be.
If you look at Giant. Possibly the largest seller of roadbikes in the world. Thier top selling roadbike isn't actually a race bike. It's the Defy. Most of the technology used in their race bikes is utilised but the frame geometry is purposely designed with a shorter reach and taller head tube for fuller figured men who can't reach down low enough to ride a TCR or Propel (Their actual race roadbikes).