The argument for wider tires

Those of you who have been riding road bikes for a while "know" that the fastest tires are 23c tires, filled to 110psi, right?  In fact, for time trials, you may even have used 20c tires filled to even higher pressures.     That was the way.

In theory, it is correct - but recent studies are increasingly showing that this is generally true only in ideal cases.   Tires filled to higher pressures are faster but only on really smooth surfaces, like indoor tracks.     Narrower tires are also more aero, but again, only in zero yaw (when the wind is coming head-on).   In the real world of imperfect roads and wind coming from various angles, this is no longer true.

Some of these conclusions fly against what many of us have "known" to be true for all these years.  In addition, there is a lot of misinterpreted versions of this info online as well.   This article is meant to be a primer to help you cut through the noise.    Resources for additional information are provided at the end of the article.


WIDER TIRES HAVE LOWER ROLLING RESISTANCE

When you sit on your bicycle, your tires deform, creating a contact patch that touches the road.     The area of this contact patch is such that it offsets the weight of the rider+bike.   When two tires are filled to the same pressure, the area of this contact patch is the same - after all, the contact patch is supporting the same force (weight of rider+bike) with the same pressure.

Tire Contact Surface (Source:  DT Swiss)

So what does this mean?  We know that Area = Length x Width - so for a wider tire, the length is going to be lower.

This, in turn, leads to lower tire sag and results in lower rolling resistance.     Obviously, this holds true to equal air pressures - ie, a 28mm tire will have lower RR than a 23mm tire at the same pressure.     Drop the pressure too much, and rolling resistance increases.

Here is an example of tire size, pressure and RR, as measured on a drum:

Source:   BicycleRollingResistance.com (Link at the end of the article)

As you can see - wider tires have lower rolling resistance.   But dropping the pressure does result in an increase in rolling resistance.   

However, keep in mind that this is based on a test done on drums.   When this experiment was replicated on various road conditions, it gave rise to the next point, namely...


LOWER PRESSURE IS FASTER ON IMPERFECT ROADS

I don't know where you live, but in most parts of India, you are not likely to have perfect tarmac.    And when the tarmac is imperfect, tires filled to high pressure will cause the bike and rider to bounce up and down - this doesn't have to be extreme:  even the force that causes small vibrations transmitted up your frame and body is energy that is coming from your pedaling.       Compounded over the course of a long ride, that's a fairly significant loss of energy.   

This loss of energy is referred to as impedance - you can think of this as the extra force when you get off smooth tarmac onto bumpy asphalt.    Then there is also casing losses - the loss of energy caused by your tire rubber compressing and expanding when your tires or wheel bounce - or even micro-bounce - over rough surfaces (which is not perfect in energy retention - some energy is transferred as heat)

Here is what the graph of total resistance (CRR + impedance + casing loss) looks like for different surfaces:

Source:  Silca (link at the bottom)

As you can see, as tire pressure increases, total resistance does reduce - up to a point, but after that, it rises up very significantly as well.    So in each case, there is a "sweet spot" which represents the ideal tire pressure - and in this case, for, say, rough asphalt, that is a fair bit lower than the 110-120psi that many people are used to.

Keep in mind that the efficiency losses are not symetrical - take a look at this chart, which shows a change in resistance when you change the tire pressure by 10psi over optimal:

Source:  Silca

As you can see, if you err on the side of too low pressure, there isnt a very significant change in wattage - 1-2W loss only with a 10psi reduction.   On the other hand, increasing the pressure beyond optimal results in a pretty significant increase in watts required. 

So if you aren't sure about what kind of roads you are going to encounter, it is better to be err on the side of lower pressure than higher.

The one downside to lower pressure used to be (and still is) the risk of pinch flats - go over a pothole at too high a speed and you flat your tire.       However, with the advent of tubeless technology, you are now able to get the benefits of riding at lower pressure without the risk of pinch flats.


WIDER IS AERO - KINDA

The early days of aero involved V-shaped airfoil shapes (NACA profiles), based on lessons in aerodynamics learned from planes.    But the thing is -  bicycles don't move at aeroplane speeds and without getting into the details of aerodynamics, they are more prone to facing apparent sidewinds (aka, wind coming from an angle or yaw).     This results in differential air pressures on either side of the airfoil shape - which is great on a plane (it lets it fly!), but is not so good on a wheel, as it results in sidewards force. 

Anyone who has ridden deep sections wheels on a windy day knows what that feels like - the wheel may be fast in no wind, but the moment there is a wind, it becomes a struggle to hold it steady, which defeats all the aero gains.

So the focus shifted from aerodynamics at 0 yaw to aerodynamics across a range of wind angles (0-15 or 0-20 degrees, typically).   This resulted in rim shape evolving from V-shaped to the more commonly-used U-shaped or toroidal shapes in vogue today.     The purpose of this was to improve the range of wind angles at which a wheel would provide an aerodynamic benefit.

(Note my use of the word "apparent wind angle" - that refers to the angle of wind as seen from the rider's perspective.   It depends on two things-  the actual speed and direction of the wind, and also the speed of the rider.   Faster riders generally see wind at a lower range of angles, whereas slower riders see wind at a larger of angles)

The advent of disc brakes - and the fact that it allowed manufacturers more freedom in rim shape - has changed the goals of wheel design these days.   Manufacturers are now increasingly thinking of overall speed - not just aerodynamic speed - and factoring in tire width and lower pressures into their wheel design.     After all, what is the point of building a wheel that is 2W faster with 23c tires, if you lose 10W in impedance losses in real world use? 

So yes, looking purely at aero, a narrow wheel with thin tires would indeed end up being faster in a wind tunnel.     But they would be very twitchy in crosswinds (poorer drag characteristics and also greater side force) and in addition, suffer from the increase in resistance described in the earlier sections. 

So optimizing speed basically involves balancing aerodynamic benefits (which depends on a rider's speed) vs impedancy/RR losses.   And this, in turn, depends on how a given wheel is designed.   For example, DT Swiss has the following recommendation for their wheels:

Roval also recommends using 26mm tires with their CLX64 wheels, even though the 24mm tires test a little faster in the wind tunnel.

So in practical terms - wider = better, although the exact point of "how wide is wide enough" depends on your speed and road conditions.

Do note, however -  in order to get the maximum aero efficiency out of your wheelset, the tire width should be no more than 95% of the width of the rim at the brake track.     This creates the most aerodynamic profile and results in improved aero gains across a range of yaw angles.   A tire that has a bulbous profile (much thicker than the rim) has a very heavy aero penalty.    Thanks to disc brakes, bikes can now take wider rims, which in turn allow wider tires.

And while on the subject of tire width:  even regular 23mm tires, when mounted on wider rims, will measure out wider as they get spread out more.      Eg, on my 21mm internal width rims, a pair of tires with a stated size of 24mm actually measures out to 28mm.     So don't go by the nominal size measured on the case - actually measure the tyres to see where you are ending up.


SUMMARY & PARTING THOUGHTS

So in summary, all this means that you need to find the right balance of tire width and pressure - and for a lot of people riding on less than perfect roads, that means wider tires/lower pressures.

A few guidelines to  consider:

• The ideal tire pressure depends on your weight and surface conditions
• The rougher the surface, the lower your ideal tire pressure
• It is better to err on the side of slightly lower pressure than slightly higher pressure
• If you are about maximizing aero, make sure that the outer width of your wheel, at around the brake track, is 105% of the measured width of the tire

At the time of writing this article, 28mm (measured width) is around the optimal width for  uncompromised speed on smooth tarmac, whereas 30-32mm would be the real-world "optimal" width that balances speed, comfort and efficiency.     Keep in mind these are just ballpark estimates, not hard-and-fast rules. 

There are tradeoffs, of course.    To get the benefit of these tire widths, you may need a disc frame - and the extra weight/maintenance issues that entails.     If you are running lower pressure, you may also need to run tubeless to minimize pinch flats - and that is a whole different can of worms.    And of course, if you live in a place with really smooth asphalt, you are good with thin tires pumped to high pressures.   Or if you don't deal with a lot of wind, you can go with narrower-profile aero wheels.

What is missing from all the analysis so far is the qualitative effect of being less fatigued on a  rider's ability to maintain power.      Does the fact that you havent gotten beaten up by the roads for the last 2-3 hours make you fresher and more able to maintain power?

Brands like HED, Zipp, Enve, Roval and more are all releasing wheels that measure 30mm or wider (outer diameter) with an inner diameter of 21-25mm makes it very clear that wide is here to stay.       While we can always debate the magnitude of the benefits, no company would deliberately release a product that was worse - there are too many independent tests being conducted these days to risk that.      So that fact that almost all the big brands have moved in this direction (HED has been banging the drum of wider rims for nearly a decade now!) supports this as well.

Personally, having ridden wider tires, I find the benefits to be very much worth it.     I do not notice any increase in required wattage in going from 23/25mm tires to 28mm, but i definitely find an increase in comfort.      

Hell, I have even started doing some group rides using Panaracer Gravelking 35mms, which measure a whopping 37mm on my wheels - I am sure it is a little slower than my normal race-oriented tires, but that difference is not as much as one might imagine.      For sure, on tarmac, they dont feel as fast - but  "feeling fast" and "being fast" are 2 different things:   the softer tires dont feel as fast because they deform around road imperfections, as opposed to bouncing on them - and that is the very same reason they actually are fast.     Certainly, the difference in power required to hold the same speed is lower than my ability to notice.    And if the road gets even slightly rough, there is a huge advantage. 

I am convinced enough to make 32mm my "normal" riding tire width, with 25-28mms reserved for races or fast group rides where I am barely hanging on for life.      In fact, I have just sold off my Cervelo R5 (one of the nicest bikes I have ridden) to get a Factor LS because I want to make 32-35mm tires my daily riding tires.

Note, of course - all this depends on the wider tire also being equally (or almost equally) fast-rolling.   That is not always the case.      In my experience, Panaracer Gravelking Slicks are very nice, fast wider slicks, as are Continental GP5000s.   Rene Herse also makes very fast wide tires (no personal experience, however).    So don't expect to put on touring/commuting tires with a lot of puncture protection and expect the same kind of speeds as a race-oriented thinner tire.

Questions?   Feel free to ask on our Facebook group, BikesZone Reborn.


FURTHER READING

Here are some links that do a very good job explaining the rationale.   Note that they are all manufacturer sites, but I have chosen them because they have made the science more accessible to laypeople.    You can dispute the magnitude of those numbers, but the science is solid.

BicycleRollingResistance - a review of CRR, tire width and pressure
Zipp and Total System Efficiency
DT Swiss on Endurance and balancing Aero vs Efficiency
Silca Blog on Rim and Tire Width - Effect on Aerodynamics
November Bicycles:  Wider is Better - Until It Isnt
Roval - Designing Aero Wheels Around Wider Tires
Slowtwitch article on Tire Pressure and Rolling Resistance
Silca Blog on Tire Rolling Resistance and Impedance
Active - Are Wide Wheels Faster
Enve - Real World Fast

Your first road bike should be a gravel bike with disc brakes

The typical progression for a new cyclist is as follows:

Stage 1 - he starts out thinking that he needs a mountain bike, because, you know, suspension, disc brakes, they look bad ass.    So he buys one, and rides it for a bit before realizing that it is utter rubbish, that the suspension does nothing more than absorb energy, the cheap disc brakes dont have a lot of stopping power and the entire bike is a pig and rides like one, too.

And thus enlightened, he moves on to to the next phase.   Or maybe he was warned off by a friend who knows bikes and avoided the entire mess that is Stage 1.    Or maybe he looks at road bikes, get scared off by the prices and decides to compromise.    Regardless, he is now in Stage 2 of his cycling journey:  he increases his budget and buys a hybrid.    This one is a bit better.    A higher budget means quality parts, the brakes actually work and while the bike may have suspension, it also works (hallelujah!).    The cyclist finally starts to understand the meaning of the phrase "you get what you pay for".   

For many cyclists, Phase 2 is sufficient.   If they just want to ride 15-20 min a day for exercise, or use the bike to run errands, or whatever, a hybrid is all the bike they need - and also the ideal bike for their requirements.    But other cyclists get hooked to the sport.    They actually enjoy the act of riding (as opposed to merely posting cycling memes online), and want to ride more - longer distances and faster.    And now they are ready to move on to Stage 3 - getting a road bike.

But stage 3 comes with some problems.   One is price.   Not much that can be done about that (see:  "you get what you pay for").   I suggest selling drugs or perhaps a kidney.     

The other is concern about  usability.  Maybe you have really broken roads where you are and are concerned about comfort.   Or maybe you want a bike you can ride on tarmac, and perhaps also take onto some light trails, or go exploring some country roads where you don't know what you might encounter.   And that has held you back.

Well, gravel bikes are the answer to all of that - read on to learn why.

DISC BRAKES SHALL SET YOU FREE

In the old days (read:  as late as 5 years ago), road bikes came with rim brakes.    They were fine as far as stopping power went, but they did limit the maximum rim and tire width that could fit in them.  Then carbon wheels started becoming popular - and it only took one ride in the rain on carbon wheels and rim brakes to realize that this was a really, really crappy idea:  braking was only notional at best.    And on long descents, the carbon rims would overhead, causing tubes to blow out.       Not fun.    But carbon was cool and carbon wheels were not going anywhere....  and thus were born disc brake road bikes.   

While rim brakes offer more than enough stopping power (under most circumstances - see exceptions above), disc brakes do a better job with modulating the power, allowing for precise braking.   And they work better in the rain and on long descents, especially with carbon rims.   This alone makes them a significant upgrade over rim brakes.

But perhaps even more importantly, by getting rid of a brake caliper, disc brakes allow a lot more flexibility in terms of rim widths and shapes.   And this is where things start to get interesting (more on this in a bit).

Most top-end bikes these days - be it from Specialized, Trek, Cervelo or Cannondale - are disc-only.   In the rare cases a rim-brake version is available, it is typically sold as "frameset only"

Yes, disc brakes are a little heavier (on average, about 200-300gm more) and a little more finicky to set up and maintain - especially hydraulics - but it is indicative of their benefits that the market has moved over almost overwhelmingly to disc brakes now.   Virtually all bikes being sold these days are disc brake models - and that is not just because the manufacturers are trying to shove them down our throats (contrary to popular opinion, marketing doesn't work that way).   Disc brake bikes are becoming more popular because most people who ride them realize how much nicer they are.

Now, to head off the inevitable - for those of you who already have rim brake bikes, this doesnt mean that your rim brake bike is going to assplode or that you have to go out and upgrade.   Of course not.   Or maybe you are a climber and prefer the lightest bike possible - in which case you still might want to look for rim brake bikes.   But for the vast majority of people looking for a new road bike, especially first-time buyers, disc brakes should definitely be on your radar. 

Note:  this holds true for any bike model from one of the reputed international brands, which will typically be fitted with Tiagra or higher and cost Rs 70,000 or more.   If you are getting an absolute budget model, with parts that are below Sora-level, then you might be better off with rim brakes because at that price range, you are not going to get decent disc brakes.

WIDE TIRES ARE BETTER EVERYWHERE (EXCEPT AROUND YOUR WAIST)

Not having the brake calipers limit the rim/tire size has freed up manufacturers to make the wheel rims wider, which in turn means that tires have a wider profile on the wheels,     Without getting into the physics of this too much, this results in a tire shape that allows for lower rolling resistance, greater comfort and also improved aerodynamics at yaw.     In other words, an improvement in every single area.

In those same "old days" of yore, roadies rode 23mm tires - or 25mm, if they felt like a comfort ride - filled to 90-110psi of pressure.    This was the generally accepted formula for speed.   But these tires were absolute nightmares on broken roads.   I remember doing the Tour of Nilgiris in 2010 and 2011, and each year, there would be one stage with a lot of broken, potholed roads and all of us on road bikes with 23mm or 25mm tires would be cursing the entire ride.

These days, that has changed.   28-30mm tire widths are the new standard for going fast - most modern wheels are optimized with such tires in mind.    Add in tubeless technology and these tires can be run at lower pressures - 65-75psi is common - without the risk of pinch flats.    That results in greater comfort (the tire acts as a shock absorber), lower rolling resistance and indeed, greater speed (the tire deforms around imperfections in the road, as opposed to bouncing up and down over it, reducing vibration loss).    

So there is no longer a compromise between speed and comfort - you get more speed AND more comfort when you go to wider tires.

And it does not stop at 28-30mm widths.   While this is the current sweet spot for maximum aerodynamic efficiency and speed on smooth roads, studies and empirical ride reports have shown that  going even wider with tires - 32mm width or larger - and running them tubeless at low pressures of 50-60 psi can have a massive improvement in comfort.       

And the interesting thing is:  while this increase in comfort comes with a tradeoff of reduced speed, that reduction is very, very minor.     You are looking at a few minutes over the course of a 2-3 hour ride only - insignificant unless you are racing.   In fact, on rough roads, the wider tires may be even faster.   Not only that, the increased comfort reduces fatigue, which can make you even faster.  

Yes, you read that correctly - 32mm wide tires at low pressures may actually be faster on rough surfaces like chipseal or rough concrete,     The bike ends up floating over road imperfections, road buzz is muted and your ride becomes super plush and comfortable.   

In fact, the most recent wheels released by  Zipp and Enve, at the time of writing this article, are optimized for use with 32mm tires!

  

So I will repeat it again - wider slick tires (30-32mm) give you much greater comfort and have a minimal effect on your speed.   If you are not racing, there is no reason for you to be riding anything narrower than a 30-32mm tire these days.     And if you are racing and are on smooth tarmac, you still shouldn't be on anything lower than 28mm.   

ENTER THE GRAVEL BIKE

By moving to wider tires at lower pressures - 30-32mm at 60-70psi, let's say - you have pretty much solved the question of comfort on tarmac and have gotten a plush, comfortable magic carpet ride.  Virtually all modern road bikes these days (ie, disc brake bikes) allow you to fit a 30mm tire.   A lot of endurance bikes and even some race bikes, like the above-mentioned Venge and R5, will actually fit up to 32mm tires.

So far so good.    But let's go back to my original question - what if you wanted to ride your bike on more than just tarmac, but also on trails, dirt roads and gravel paths?    Until recently, you had to pick one - the nature of the bicycle mean that you could either get a bike that was good on tarmac (rigid, fast, skinny tires) or you could get a bike that was good on trail (fat tires, suspension).   But now, that is no longer the case.

Imagine, if you will, a road bike that has the clearance to let you put on tires that go all the way to a massive 40-42mm (or even 2.1" MTB tires, in some cases) with a choice of treads - slick, semi-slick, light treads or heavy treads.       This could be that mythical single bike that lets you do EVERYTHING.

And the good news, freed from the restraints of rim brakes on road bikes, manufacturers have created such a bike - it is called a gravel bike.   

Gravel bikes are basically endurance bikes (as described in my Race vs Endurance bikes article) with clearance for very large tires and the geometry tweaked some more for off-road riding.     Some versions are tweaked very heavily, to be more off-road oriented.   Others are tweaked a little less, and are designed to mostly road bikes with some off-road capabilities.   It's a pretty wide spectrum and no matter how you prefer to split your priorities, there is a bike for you.

But regardless of which flavor you get, you get an immensely versatile machine.    Put on a pair of wheels with 30mm slicks and go out for a fast group ride with some friends.   Swap in wheels with 35-38mm light treads and go ride a mix of tarmac and forest trails.     Or put on 42mm knobbies and go entirely off-road.   The choice is yours.   And the bikes often come with more storage capabilities to support those epic rides.   And you get all of this without the weight, speed or riding position compromises of a hybrid or MTB.

Are there compromises over a pure road bike?   Of course there are.   Gravel bikes are designed to be a bit more robust - and so are a little heavier.    The greater stability for off-road use results in a bike that is not as agile as preferred by road racers.   Similarly, if your goal is to ride really technical off-road stuff, you would still be better off with a MTB with a good amount of suspension.    Special interests require specialized bikes.

But for the vast majority of people who just want to ride for fun, still care about going fast on tarmac without necessarily becoming hard-core racers, and who also want to go off the road a little without getting into super-technical stuff, the gravel bike is the perfect solution with very little in the way of compromises.

It truly is the "One Bike To Rule Them All".    

Questions?   Feel free to ask on BikesZone Reborn.  

Endurance vs race bikes - what road bike should you get?

Too often, I have seen people come on to a bike forum, looking for a road bike and just looking into size.    But what they don't realize is that not only does size depend on your particular body type, but the same size in 2 different bikes can result in 2 very different fits.

Most manufacturers generally have 2 separate line of road bikes - one is what they call their racing line, and the other is their endurance or sportive line.     In the Specialized world, the Venge and Tarmac are their race models, and the Roubaix their endurance model.   Trek has the Madone and Emonda as their race models, and the Domane as their endurance model.    Giant has the TCR and Defy.    And so on.

The differences between these models can be huge and it is worth learning a little bit about them before making a purchase decision.

Before you , continue with this article, I strongly recommend reading my article on Stack and Reach - Road Bike Sizing For Beginners Part 2

ENDURANCE vs RACE GEOMETRY FIT

Race bikes are the classic road bikes - designed to put the rider in a low, aero position for going fast, and with a geometry that favors quick handling and responsiveness.   Endurance bikes try to find a balance between comfort and speed - so they adopt a more upright riding position that more amateurs will find comfortable, especially for longer rides.   They typically also allow the use of thicker tires, for more comfort.

These were just generalizations, of course.    Depending on one's body type, a particular rider might be comfortable on a race geometry for long rides, and another rider might need an endurance geometry to get an aggressive fit.       So while many exceptions existed, broadly speaking, the bikes were designed accordingly.   

The endurance bikes would have the carbon tubes laid up with a greater emphasis on comfort, perhaps at the cost of a little weight, whereas race bikes would be designed to be as stiff and light as possible, with comfort a distant third in the priority list. 

Let's take a look at the geometries of 2 bikes that are the same size - the Tarmac 54 and the Roubaix 54:

If you were to go from a Tarmac to a Roubaix, the handlebars of the same sized bike would be a whopping 40mm taller (that's equivalent to 4 spacers under the bar) and 10mm closer to you (one stem size smaller).    That is an enormous difference!    In fact, this is a bigger difference compared to when you go from a size 54 Tarmac to a size 56 (comparable change in reach, but a smaller difference in stack).    

So if you get the two bikes to agree on the reach, the stack will be massively different.   If you get them to a comparable stack, the reach will be massively different.     In other words, these two bikes fit VERY differently - even for the same size.

And that is just the fit.

HANDLING

Look at the rest of the geometry - a slacker head tube angle on the Roubaix means that it is going to be slightly less responsive to steering input compared to the Tarmac.     For someone looking to get an agile bike for racing, this may not be optimal.   But for a beginner or someone looking for a more leisurely riding experience, the slightly greater stability of the Roubaix may indeed be preferable.    Or they may prefer a head tube angle that is as slack as 72 degrees, for even more stability.

Along with the stability, the Roubaix has a greater BB drop - this increases the feeling of sitting "between the wheels" as opposed to "on top of the bike", which also increases overall stability.     Lastly, the longer wheelbase and chainstay on the Roubaix also make the bike more planted on cornering.   Whether you prefer that or not is up to you.

To be honest, for a beginner, these geometry differences are not going to make a huge difference.  A Pro Tour cyclist rides the bike at the extreme edge of its capabilities, when it comes to cornering, sprinting or descending.    For someone like that, a few mm of BB drop, a small difference in head tube angle or chainstay/wheelbase length can make a huge difference.

For amateurs like you and me?   Very unlikely.    You are going to be riding well within the capabilities of these bikes, so to a large extent, these differences are mainly academic when it comes to performance.   But they do affect how the bike "feels" and that could be a difference maker.    

COMFORT

This is the part that is hard to quantify, but which is certainly very noticeable when you get on the bike.      Comfort comes from 2 things - riding position (which is dependent on fit) and bike characteristics.  

Race bikes are designed to go as fast as possible - so they emphasize stiffness and light weight.    Comfort is what it is.    Endurance bikes, on the other hand, make small tradeoffs in stiffness and weight in order to improve comfort drastically.     

This is especially true in the carbon shaping - by building in compliance in areas like seatstays and seatpost, endurance bikes are better able to absorb the impact of potholes and road imperfections, without transmitting them up your arms or spine.    The result - you are fresher after longer rides.

Admittedly, this is a bit of a generalization - of late, comfort is becoming a factor for race bikes as well, as manufacturers realize that a rider who is not battered by the roads at the end of the race is going to be able to pedal faster.   You can also mitigate comfort to a fair bit by using wider tires at lower pressures - and also by using carbon seatposts and carbon handlebars, which also soak up road buzz.    But obviously, having a bike whose characteristics suit your requirements to begin with is better than trying to fix things by changing other components.

SUMMARY

Dont focus on just a single number - size - when buying a road bike.   There is a lot more to road bike purchases, especially once you get to mid-end models or higher.   There is no single "correct" answer, either - it all depends on your fit, your preferred ride quality and also how sensitive you are to small differences.

Do your research first, try to do a test ride if you can and buy from a reputable seller who will give you honest advice.

PS - I havent even touched on gravel bikes yet - in fact, unless you are going to be racing, you should probably be looking at a gravel bike as your first (or only) road bike.

Questions?   Feel free to ask on BikesZone Reborn.