I just bought my son a Trek Roscoe 8. It comes with 180 F/160 R. I have an extra 180mm Ice Tech rotor laying around, and was going to get another one to upgrade him to 180 F/R. At about 140 lbs with Shimano M315 brakes, would it make an appreciable difference to make it worth it to buy a new rotor and adapter and upgrade him?
At what point are upgraded rotors worth it?
askibum02
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I just bought my son a Trek Roscoe 8. It comes with 180 F/160 R. I have an extra 180mm Ice Tech rotor laying around, and was going to get another one to upgrade him to 180 F/R. At about 140 lbs with Shimano M315 brakes, would it make an appreciable difference to make it worth it to buy a new rotor and adapter and upgrade him?
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Won't make much difference IMHO. Many much heavier riders are fine on 180/160.
Personally I don't want my rear rotor as large as my front rotor because equal size rotors makes it easy to skid the rear wheel. Braking dynamics cause our weight to shift onto the front wheel so that's the wheel that does the lion's share of the stopping. The front-biased weight shift also lightens the rear wheel making it easier to skid the rear. I prefer to run a smaller rotor on the rear so that the pull on my brake levers feel as close to similar as possible.
If your son really needs more braking power (I wonder if he does at his weight), I'd recommend a larger front rotor before a larger rear one. You'd do him the greatest favor by going to a 200 or 203mm rotor on the front wheel.
My personal choice for rotors is 203F/180R but I weigh about 220# kitted up including hydration pack. I imagine at 140#, 180F/160R rotors would be adequate.
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Not sure bigger rotor stops you better unless you use your brakes a lot. I may be incorrect but my experiences has been larger rotors dissipate heat faster so fade may be less but I almost never experience fade, even on my smallest rotor. When I was riding the Alps, I smoked rim brakes a lot trying to stay in control on huge downhill runs. Have not run those brakes in years.
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If he is having trouble slowing down or stopping then sure. I had a SS with 160/160 and felt under powered on stops so I went to 180in front and could tell the difference on the first ride. Biffer rotors make difference
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I don't agree with that. I decide whether or not the wheel gets locked up, not the brakes. I pull the brake lever until the desired effect occurs, whatever the size of the rotor.
A lot of bikes are sold with the same size of rotor on both wheels, the world does not end.
bikes are equipped based on marketing.... so what the manufacturer equips the bike with may not be the best. Cars and motorbikes have stronger front brakes and doing the same on a bicycle will help to inherently brake harder on front.
sure, with ideal humans it wouldn't matter since you just could brake less on the rear, but in many situations humans are not perfect.
My fatbike came with 180/180 and my hybrid came with 160/160. no rhyme and reason. i ended up installing the fatbike rear 180mm on my hybrid front and now both bikes are 180f/160r. Really like it and would equip any other bike with a front bias as well.
To each their own, I'not saying anyone has to follow my plan.
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Our brains like to pull evenly on both levers. I like to have a smaller rotor in the rear to keep the finger pressure the same at threshold.
For the most part a 203mm will not stop you any faster than a 160. You just don't have to pull as hard with a bigger rotor. For scrubbing speed on steep hills or repeated stops larger rotors will preform more consistently and have a higher thermal load.
I find that I have a natural leaver pull where I have the best feel and modulation. A 203/180 combo works the best for me. 195lb and very steep terrain.
For the most part a 203mm will not stop you any faster than a 160. You just don't have to pull as hard with a bigger rotor. For scrubbing speed on steep hills or repeated stops larger rotors will preform more consistently and have a higher thermal load.
I find that I have a natural leaver pull where I have the best feel and modulation. A 203/180 combo works the best for me. 195lb and very steep terrain.
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I'm going to disagree with that, the first part, and then partially the 2nd part.
For the first part, your brain adapts, it's likely no problem at all pulling harder on one and softer and the other. We can do things like look through up-side-down goggles and our brain will eventually flip it to look "correct", in general ,we are highly adaptable. If the modulation is crappy, this can be a bit more of a problem, but as long as there's some modulation, and the rear brake by nature is usually more sluggish anyway, it's not really an issue.
On the 2nd point, yes, I have smaller rotors on 2 of my bikes, BUT, you tend to drag the rear brake a lot more for control, not the tire, but the brake, so it tends to get used more. On cars, you'll see some with smaller rear rotors, although I've had some high performance cars recently that had even larger rotors in the rear, although the brake was smaller. I'd reckon that what you really want is the same size rotor and a smaller brake caliper, like if you are running a 2-piston saint up front, then an XT in the rear, with the same size rotor. There's a good discussion on this on Ridemonkey. Now, if you are ok changing out pads, possibly more frequently, then disregard, and remember I run smaller in the rear on two of my bikes, so I'm by no means telling anyone to run out and go put a larger rotor on the rear.
I have noticed that the ice-tech stuff works pretty well. On steep descents where I used to bake 6" disc brakes, with the finned ice-tech rotors I've been able to ride my XC race bike during multi-thousand foot descents with nary a fade issue, and I distinctly remember having fade issues on these descents. I remember I had some issues on some super steep DH stuff on my bigger bike and switched that out to ice-techs too last year, and again, big improvement for heat-resistance for me. Seems to really work. It's only one component of braking obviously, so it doesn't mean it'll be an end-all solution to braking, but it works.
Bigger riders riding steep stuff with heavy or large (29) rims/tires need a lot of brake.
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I can only assume my brain is better than yours as this really isn't a problem for me ;0) My car has different pedals that I push with my left and right feet and I have no problem putting different amounts of pressure on those either. Maybe it's an American thing, you all drive automatics don't you?
I also got myself a Roscoe 8 about a month ago. I weigh in at 145lbs so close to your son.
On my first rides i immediately felt lack of confidence in the brakes, but after some riding on hilly trails they are better.
Upgrading the rear brake would be a waste of money in my opinion. The front however could have some better modularity(is this the right word?), the difference between slowing down and locking up is to small and doesn't inspire confidence.
Not sure what would be the best upgrade, 203mm rotor or standard rotor but a better brake-kit?
But i have to say that this isn't a big problem for me and i'll probably not upgrade in the near future. When i get more fit and confident as a rider i might look in to it.
Edit: Just had a look at 203mm rotor + adapter at my webshop, it's way cheaper than i imagined, about 40$! Tempting actually
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Some manufacturers have two types of pads available for us to choose from, metallic and resin. So there are those options. I also read where some put on new rotors and off they go. Hopefully they are bedding their brakes to transfer pad material to the disk. These two factors will affect your results in braking. I have several sets of XT and the pad selection affects the brakes in noticeable ways. More rotor is not usually the issue except in longer downhill runs. I never see enough of those runs.
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Years ago my sister, who was living in New York at the time, wanted to order a new BMW with cloth seats and manual shift. The dealer tried very hard to talk her out of it telling her it would be special order, she'd wait ages and she would never be able to sell it. She went ahead and bought it anyway but it lets you see the mindset of the average american car buyer.
IMHO, an upgrade may not be worthwhile in your case.
I'm about the same weight at 140 lbs geared and after trying different rotor size combos, all my bikes now have 180s front and 140s rear.
For the rear rotor, the 180mm will lock-up the back wheel quicker than the 160mm. 'might sound good in theory but on the trail, lock-up means skid, no traction and very little control of the bike.
The smaller rear rotors never locked-up on me in panic. Better control, modulation and restores confidence quick. I use shimanos "freezah" icetech 140s - they supposedly designed for better heat-dissipation.
I'm about the same weight at 140 lbs geared and after trying different rotor size combos, all my bikes now have 180s front and 140s rear.
For the rear rotor, the 180mm will lock-up the back wheel quicker than the 160mm. 'might sound good in theory but on the trail, lock-up means skid, no traction and very little control of the bike.
The smaller rear rotors never locked-up on me in panic. Better control, modulation and restores confidence quick. I use shimanos "freezah" icetech 140s - they supposedly designed for better heat-dissipation.
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Bigger rotors will give more power due to leverage and stay cooler. Weight difference tends to be minimal. I say go big. I run 203mm fro t and rear, even on my xc(ish) bike. I love having loads of power and not having to think about heat fade on big mountains.
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Pig! You use one foot for the gas and the other foot for the brake? Sorry, we can't be friends after all.
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Lol. I'm a left foot braker. Learned it while doing autox and kept at it on the track. Great way to shave tenths.
Obviously you can learn to pull different ratios left to right and balance your brakes. I have always had the best luck balancing my leavers engagement point and overall pressure. I do this on all my bikes.
I'm also not a rear brake dragger, but ride with guys that are and they prefer a larger rear rotor to handle the heat. Brake setup is personal and each of us has to find a setup that works best for you.
With that said I have never seen a smaller rotor on the front and prefer a 203 on the front, unless it's a flat xc race.
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