# Wouldn't disc brakes on road bikes (Tarmac, etc.) make every road bike a gravel bike?



## Guppie58 (Oct 24, 2006)

Bikes like the Roubaix and others that are geared toward the endurance or gravel markets all point to geometry as a selling feature for such bikes. More upright for the long haul. I always viewed the benefit more about tire clearance and slightly higher BB to get over obstacles (more so with CX bikes). Some of these bikes also have long reach brakes to allow for such tire clearance. 

I know people will say all road bikes can ride on gravel, which is true. But with disc brakes, these bikes can now handle more diverse gravel road conditions. The frame strength should be equal between the bikes, meaning the ability to take the pounding of dirt roads. I know Roubaix boasts a dampening system and some other bikes have similar features. 

However, with disc brakes, doesn't this pretty much qualify all road bikes as gravel grinders? Am I missing something.


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## wgscott (Jul 14, 2013)

Tires?


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## Trek_5200 (Apr 21, 2013)

gravel bikes will typically have tires that are 25 cm minimum, but more typically 28 or 32 cm. I'd say the tires matter more than the brakes.


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## ziscwg (Apr 19, 2010)

Trek_5200 said:


> gravel bikes will typically have tires that are 25 cm minimum, but more typically 28 or 32 cm. I'd say the tires matter more than the brakes.


This^^^^

Oh and wheels.....taking some of those low spoke count wheels around on the dirt will give them a nice shortened life. For me 24/28 wheels with nice 25 mm tires are the way to go. I am 175 lbs. You could probably get away with running 20/24 wheels, but you might have to spend a bit more time at the shop getting them trued.


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## ziscwg (Apr 19, 2010)

ziscwg said:


> This^^^^
> 
> Oh and wheels.....taking some of those low spoke count wheels around on the dirt will give them a nice shortened life. For me 24/28 wheels with nice 25 mm tires are the way to go. I am 175 lbs. You could probably get away with running 20/24 wheels, but you might have to spend a bit more time at the shop getting them trued.



Oh, and I've had zero problems stopping in the dirt. Even on steeper, looser sections my problem is keeping the wheels from skidding, not being able to stop them.


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## kiwisimon (Oct 30, 2002)

Tires and geometry. This is no gravel bike.


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## robt57 (Jul 23, 2011)

I guess my disc Roubaix with the 27mm Paves could be gravel worthy. But at 210lb I want to run tire bigger than the Roubaix will fit which is tight with anything near a 30mm tire. Plus I want a powder coated steel frame to bang rocks on myself. The canti TCX fits the 42C Speed rides and I tend to grab it. And it is nasty enough I could care less about banging rocks into any/every part of it.


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## Trek_5200 (Apr 21, 2013)

As far as geometry is concerned the gravel bike won't be as nimble as the race bike. It's built more for comfort and to handle those bad roads, but I think the author's point that a road bike with big tires and disc brakes could get the job done is more accurate than inaccurate.


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## ziscwg (Apr 19, 2010)

No.

I blast down gravel fire roads with my caliper brakes and 25mm tires.


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## SwiftSolo (Jun 7, 2008)

Not sure you can call any bike a "gravel bike" unless you can put 32mm's on it.

Also, those who ride on narrow tires (less than 40mm) in primarily dry conditions on dirt/gravel are likely the last people who need disc brakes.


Guppie58 said:


> Bikes like the Roubaix and others that are geared toward the endurance or gravel markets all point to geometry as a selling feature for such bikes. More upright for the long haul. I always viewed the benefit more about tire clearance and slightly higher BB to get over obstacles (more so with CX bikes). Some of these bikes also have long reach brakes to allow for such tire clearance.
> 
> I know people will say all road bikes can ride on gravel, which is true. But with disc brakes, these bikes can now handle more diverse gravel road conditions. The frame strength should be equal between the bikes, meaning the ability to take the pounding of dirt roads. I know Roubaix boasts a dampening system and some other bikes have similar features.
> 
> However, with disc brakes, doesn't this pretty much qualify all road bikes as gravel grinders? Am I missing something.


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## Trek_5200 (Apr 21, 2013)

Did I miss something gravel bike geometry will differ from road bike geometry. Longer chainstays, longer wheel base, more relaxed steering, lower bottom bracket, etc


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## davidka (Dec 12, 2001)

Disc brakes aren't a qualifier for gravel -y/n. They add weight and extra stopping power isn't useful on a slower surface with less traction where there is very little braking to do over the duration of the ride. 

Cx is a bit different in that there are several significant braking events per lap.


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## looigi (Nov 24, 2010)

Along with more tire clearance; longer seat stays and wheelbase, slacker head tube angle, greater trail.


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