sean.hwy

My gravel bike and road bike both have 160 brakes. The are great on flats. I started doing hill on both bikes and now I am little concerned about when I need to upgrade the pads
and go to a larger rotor. The hills around here are long and steep ( at least by my standards ).

The bike with all its junk ( extra tube, water, tools, lights ), me with shoes and all my gear come in just under 200 lbs.

This is the one upgrade I want to do before I need it.

Amt0571

I don't think you'll need more than 160 brakes in a road or gravel bike. I live in an area with steep hills (I'm talking about 15% gradients, sometimes peaking around 20%) and running with 160 front and 140 back without issues with a similar weight to you. As long as your brakes are powerful enough to stop you and you don't drag the brakes like mad, you shouldn't have issues. I've done 30 minutes high speed descents non-stop with this bike without brake fading or any other issue.

I'm using Sram Rival HRDs, but I'm sure Shimano is as capable. You would probably be ok, albeit with a bit less power, with 140 / 140 rotors on a road bike. I have weak hands and I can definitely lift the rear wheel when braking from the tops, so no need for more power IMO.

I have also been riding a 160 front / 160 rear 26" mountain bike for ages without issues. My new 29er however has 180 / 160 rotors and I think the 180 front rotor is nice to compensate the bigger wheel diameter while keeping similar braking capability. In any case, in a mountain bike, the traction becomes a problem before the brake reaches its limit even with my current 2.35 tires.

I would only upgrade the brakes if:

a) They're not powerful enough (probably because of lever/caliper and not rotor diameter)
b) You experience brake fade regularly.
c) You notice a burning smell after descents (it happened once in 10 years with my old mtb).

sean.hwy

I have experienced zero brake fade. Both bikes have 700 wheels. Road bike has 28mm tires. Gravel bike has 38mm ( I think ).

I have no problems stopping currently on the hills I have been on. I am just getting started and plan to start doing a lot more hills. I like going up for the fitness part. Down hill not so much.


I just assumed the factory brakes of the 70th percentile people usage. Like when I used to track my car I had to upgrade to bigger rotors and calipers because the manufacture did not intend for you to track your car.

base2 

Have you ever wished you could stop sooner & more decisively? If yes, then a larger rotor would be able to have more leverage on the wheel. Stopping you sooner at the expense of some modulation & greater torque to the fork leg.

Have you ever experienced fade, funny smells, discoloration of the rotor? If yes, then you are already at or near the limit of your equipmant. A larger rotor affords a larger area & mass to sink heat energy into and more area to dissipate heat sooner. In short, a larger rotor has more capacity. At the expense of a few grams extra weight but would put you in a much safer operating range than you are currently.

If neither is something you've experienced then you are likely pretty ok with what you have.

FWIW: Organic pads fade sooner than sintered/metal. When the pad itself gets hot a layer of gas builds up & literally prevents good frictional contact between the pad & the rotor. This is the true cause of brake "fade" & why system heat capacity & smart braking technique (applying both front & rear on, off, pause, reapply versus front or rear with constant dragging) matters. One method allows for much greater heat dissipation opportunity than the other.

It's also worth noting that heat capacity aside, a rotors leverage is also effective in relation to wheel size. A larger rotor is more effective on a smaller wheel.

Inspect your rotors & see if there is evidence of overheating. If so, then it's a no-brainer.

base2 

Edit: Carp, I see you've already taken your car to the track & discovered all about it. Yes. You have the right idea.

fietsbob

you can loose traction and crash on gravel with what you have quite well ..

why not go big-time 210 front heat sink disk?? typical road is 140r/160f , try 180f & 160 retained on the back ..

metal sintered pads..

Elvo

Front gravel fork is probably not designed for 180mm rotors. Other options include using icetech rotors and sintered pads with cooling fins.

jp911

Plug for SwissStop RS pads. Having tried Shimano organic and metal, I much prefer the bite of these pads (gradual at first and then quite powerful) as well as how quiet they've been.

P.S. to the OP, I've got about 30lbs on you and 160mm rotors haven't been a problem, including some really steep (and long) single track

sean.hwy

Thanks. I will just swap out my pads and call it day then.

Where do you buy those pads?

fietsbob

I have 160 discs on 20" wheels they are .3 of the diameter, so I opted for TRP Hy Rd,
when original BB7 made me a Newtonian confirmation when the bike stopped but I stay in motion..

DrIsotope

Get the 180 for the front. It allows the F/R pads wear out at a virtually identical rate. At least it does for me... but I weigh 20lbs more than OP + bike when I get out of bed in the morning.

May as well go IceTech while you're at it. Easy to get 15,000+ miles out of a rotor.

jp911

I found them on Amazon, but Jenson has them as well.

fietsbob

Swiss Stop is carried by QBP, and most US bike shops have a QBP account.

Amt0571

180 front on a road bike is overkill. It's possible the fork can't handle it.

On a CX bike I also think it's overkill.

These are rotor sizes that shine on a mountain bike.

DrIsotope

I know, right? I'm often descending and thinking to myself, this bike has too much brake on it. I wish I had to work harder, and/or worry more about overheating it. If my fork couldn't handle it, I'm sure it would have mentioned it sometime in the last 20k miles or so.