Why A Bike Fitter Still Chooses To Buy Rim Brake Bikes

[fa63]

Some inaccurate information in that video:

- He says disc wheels are heavier. It is the opposite; when you don't have to rely on the rim for braking, the wheels can be made lighter.
- He says rotors constantly rub the pads; I have been primarily on disc brake bikes for the 4 years, and I have never had any sort of persistent pad rub, ever. Sure, sometimes they rub for a few seconds after heavy braking, but that is about it. I also work as a mechanic and don't hear our customers complaining about brake rub (and we have some picky ones).
- I ride in the wet and mud (gravel) frequently and brake pad contamination is not as big an issue as he made it out to be. On the other hand, I have done rides in the wet on rim brakes and carbon wheels and damaged the brake track because some grit got stuck in the brake pads and did a number on the rims.

To be fair, there is also plenty of accurate information in there Rim brake parts are indeed cheaper and groupsets are about a pound lighter.

To me, the biggest benefit of disc brakes is that it allows running very large tires in the frame. The Specialized Cruxs of the world wouldn't exist on rim brakes.

[Kirk007]

Originally Posted by fa63

To me, the biggest benefit of disc brakes is that it allows running very large tires in the frame. The Specialized Cruxs of the world wouldn't exist on rim brakes.

Yep, for me 30 or so and under - rim; much bigger than that and 'specially 650b - disc.

Nice to have both options.

[jimoots]

Originally Posted by fa63

- He says disc wheels are heavier. It is the opposite; when you don't have to rely on the rim for braking, the wheels can be made lighter.
.

As a unit, the wheel including disc rotor is heavier, no?

Understand that weight can be shaved off the rim, especially with hookless (and that's a polarising discussion we can have elsewhere... or just not have), but you are adding a 100-120g rotor on as well as handful more spokes which also add up in weight.

The hubs also seem to look chunkier but after a quick comparo of DT240 rim vs disc brake it's a wash, maybe the thru axle is heavier but maybe not, I don't know.

Either way, conservatively saying 120-150g (from rotor and at least 4 spokes) per wheel puts even the lightest of the disc brake wheels back into or above rim brake territory.

Which kinda makes sense, given that most disc brake bikes are half a kilo heavier than what you would've expected from a rim brake with the same spec component. Portion of that is in the wheels, the rest is in the actual caliper, cables/fluid. I would've even been tempted to say the frame has to be chunkier but 700g frames still seem to exist (they just build to a 7kg bike).

Originally Posted by fa63

- He says rotors constantly rub the pads; I have been primarily on disc brake bikes for the 4 years, and I have never had any sort of persistent pad rub, ever. Sure, sometimes they rub for a few seconds after heavy braking, but that is about it. I also work as a mechanic and don't hear our customers complaining about brake rub (and we have some picky ones).

Yeah I think if you note the point he makes... that some people don't seem to have issues with rotors rubbing constantly/intermittently/whatever-you-want-to-call-it-ly. But plenty of people I know get a disc brake bike and then proceed to complain about paying good money for a bike that needs more time on the stand... It's not like it doesn't happen.

And... I... digress.

[carlucci1106]

A few thoughts

-This horse is definitely beaten to a bloody pulp, but I'm also still eschewing the sewing machine and pining for high quality manual darning instruments

-RoadBoost axle spacing; without a doubt, going to happen. Can't fit more gears without widening it. We accepted 135/142mmTA, so we'll accept the next thing

-Everything that is new is related to disc brakes, or as a result of it.
*discs work better with thru bolts
* frames/wheels have to be stouter and resist more forces
* Aerodynamics has to be enhanced to offset the drag of the rotors (hidden cables won't do it, but it's a psychological win for people anyway)
*Wider and wider tires (larger contact patch for which to send braking power to road surface, as well as improve ride from aforementioned stouter frame/wheels)

Heard someone say that disc brake wheels can be made lighter because of the rim. Well, it hasn't happened yet. Because braking forces are resisted by an imbalance of spokes, the rotor side MUST be built up to provide durability and predictable braking. Maybe there are some sub-1200g disc wheels out there, but I would be wary of trying them, even with my puny bodyweight. I'm sorry, but whoever said this has not likely serviced hundreds of wheels, and felt the weight differences, and noticed the tension requirements across the board. The marketing "line" is that you can make them lighter. More true in theory than in practice.

As someone said, the paradigm shift is rather complete.

The point of this video, for those who want the crib notes, IS , get this:

Ride what is right for your individual needs
Rainy climate/ heavier rider/ more demanding mountain descents/weak hand grip/etc= discs are great

Light rider/fair-weather rider/rolling terrain/home mechanic/etc= rim brake might be the choice

[mstateglfr]

Originally Posted by fa63

- He says disc wheels are heavier. It is the opposite; when you don't have to rely on the rim for braking, the wheels can be made lighter.


To me, the biggest benefit of disc brakes is that it allows running very large tires in the frame. The Specialized Cruxs of the world wouldn't exist on rim brakes.

Disc wheels do tend to be heavier. That doesnt mean they must be heavier, but they sure tend to be heavier. Take a typical wheelset for disc and rim bikes at pricepoints of $1500, $3000, and $5000- I really doubt you will find the disc wheels to be lighter.
BTLOS WRC-35 and WGX35 wheels pretty much show this. And honestly, I think the difference in weight is the front wheel of the rim brake set is 20h instead of 24h as 20h isnt even an option in disc. Regardless, the rim brake wheelset weighs less...though it is effectively a wash in my eyes.
Point is, you dont see crazy light disc wheelsets out there at most OE spec'd price points, and when you do see one, a rim wheelset would have been just as light at that pricepoint.

Why wouldnt a Crux exist without disc brakes? It would have canti posts and use cantilever, mini-V, or V-brakes.

[krooj]

Originally Posted by fa63

- I ride in the wet and mud (gravel) frequently and brake pad contamination is not as big an issue as he made it out to be. On the other hand, I have done rides in the wet on rim brakes and carbon wheels and damaged the brake track because some grit got stuck in the brake pads and did a number on the rims.

The contamination thing must come from some dandies that think their brakes should look, sound, and feel like they do from the showroom floor. Cars also largely use disc brakes so try to think of the pad contamination that occurs there... hmmmm....

Pad scrubbing is a thing. Each type of brake system comes with its positives and negatives, and from where I stand you can learn to be just as good with either system (on the road). Rim brakes have way better modulation and give you the ability to confidently scrub speed, where discs aren't treating a structural component as a wear item. Pros/cons.

[dddd]

I think that mstateglfr makes a good point about comparing rim-vs.-disc weights at the same price point, otherwise the arguments turn vague.

Speaking of price points:
At the really lower end, where flimsy suspension forks might still be used with either brake type, the tendency for the steering to pull sharply to the left when a front disc brake is applied can be enough to steer a sudden-braking rider right off of the trail!
This explains why a disc-brake fork needs so much added flex resistance built in, with it's own effect on a bike's compliance.
The same fatter tires that tended to encourage use of disc brakes help negate the added fork stiffness, but you'll need MUCH plumper tires to exceed the overall compliance of a similar rim-braked bike if the build priorities, weight and and price point are kept about the same.
...But the weight won't be the same at the same price point, not until there are no rim-braked bikes left on the market with which to compare!

I marvel at how good the V-brakes on my $40 (used) Schwinn department-store hybrid are. With little setup fussing, and with no tendency toward twisting the suspension fork having lowers built entirely from steel sheet (ok, the dropouts actually appear to be plugged-in alloy forgings).
I added much fatter 2.9x2.1" tires, and the V-brakes had no issues with clearance. Yeah, kind of needed the single front brake booster to realize GREAT braking because of the flimsy 24mm-diameter fork!
Loving the feel of the Hutchinson Python tires by the way, both on pavement and on dirt.

[carlucci1106]

Originally Posted by krooj

Rim brakes have way better modulation and give you the ability to confidently scrub speed, where discs aren't treating a structural component as a wear item. Pros/cons.

This is subtle, but I like what you did here. With a carbon rim, this is a major $$ consumer, if you have to replace rims.

With an aluminum rim, you're likely going to get 2 to 3 rotors-worth of use before needing replaced, and it's about the same cost (when factoring in brake pads with each rotor, as you should do). But excellent point on the "for" side of disc brakes. Show my work for this:

Ultegra Rotor 59.99*3= 179.97
L02/LO3 Pads 24.99*3= 74.97
= $254.94

DT Swiss RR 411 Rim= $128
28 DT 14/15g spokes @$2.99= let's say 83.72
= 211.72

Let's assume you've replaced the rim pads in there twice, which you may/may not have done, and it's about even. Replacement rim pad inserts are as cheap as $9-13 with a little Google shopping. As much as $25 for OEM.

The labor for replacing the rotors and pads three times should be about $90, as likely the caliper would need to be adjusted. This is assuming $10/per itemized labor/job. And this factors out brake bleeds which are always needed on SRAM, almost always needed on Shimano. @$20-30/wheel, so you could also factor this in, if you think 2 rotors would last what a rim would. Truing rotors/rims is probably a wash, too. Minor true on a rotor @$10, minor true on a wheel $15-20, but needed less often. Rotors warp pretty easily.

The labor for rebuilding wheel should not exceed this at most shops. $60-80

I should have said in my post about the causal nature of discs probably started when carbon rim brakes were not performing well in the wet, tires blowing off rims, etc.

But the whole bike was overhauled from an engineering standpoint as a result of this. Was carbon rims enough to warrant a wholesale change across the board, or should it have been restricted to top-level race bikes?

I think most rational consumers know the answer to that. A $400-500 hardtail or hybrid is going to have brake maintenance at some point that for most people is going to "total" the bike (replace rotors/calipers, and maybe brake levers/shifters too).

[5oakterrace]

I wonder how many folks will bother with bleeding the brakes every year, especially those who are not avid cyclists. Seems to me that lots of people ride with chains that are not maintained. What are the implications down the line. I do not know.
At least with rim brakes you can see whether the pads need replacement. Disc fluid has to be changed as a matter of yearly maintenance. Wow. I hope these manufacturers have made real durable brakes and fluids. Perhaps not an issue for the conscientious but just another headache.

[carlucci1106]

Originally Posted by 5oakterrace

I wonder how many folks will bother with bleeding the brakes every year, especially those who are not avid cyclists. Seems to me that lots of people ride with chains that are not maintained. What are the implications down the line. I do not know.
At least with rim brakes you can see whether the pads need replacement. Disc fluid has to be changed as a matter of yearly maintenance. Wow. I hope these manufacturers have made real durable brakes and fluids. Perhaps not an issue for the conscientious but just another headache.

The truth, from experience at the shop, is they go until the lever is to the bar. And yes, everything needs to get done, typically. Pads need replacement, rotors torched, need bleed BADLY.

I have Shimano hydraulics on my MTB. Don't have to bleed them every year, but I don't MTB as much as I would like to. If you are an everyday rider, for sure, every year, maybe twice a year you need bleeds. And labor to do varies widely. I've heard everything from $10-35ish/wheel.

It used to be more headache, cause you never knew when a SRAM one had the problem where the master cylinder was sticking, because they were known to be too large for the bore of the brake lever. If they got too hot, they would expand and jam the brake system. But faulty pistons, and other problems can be just as common an issue. Traditionally SRAM has more problems, but others are not perfect, either.

[oldpotatoe]

Originally Posted by carlucci1106

This is subtle, but I like what you did here. With a carbon rim, this is a major $$ consumer, if you have to replace rims.

With an aluminum rim, you're likely going to get 2 to 3 rotors-worth of use before needing replaced, and it's about the same cost (when factoring in brake pads with each rotor, as you should do). But excellent point on the "for" side of disc brakes. Show my work for this:

Ultegra Rotor 59.99*3= 179.97
L02/LO3 Pads 24.99*3= 74.97
= $254.94

DT Swiss RR 411 Rim= $128
28 DT 14/15g spokes @$2.99= let's say 83.72
= 211.72
.

Lots snipped BUT...a Ultegra rotor is 60BUCKS?? $25 for pads??Yikes..

And y'all sell DT Comp spokes for $3 per? Gotta raise me prices...PLUS, LBS built that wheel or install that roar and bleed those brakes? Labor too.

[carlucci1106]

Originally Posted by oldpotatoe

Lots snipped BUT...a Ultegra rotor is 60BUCKS?? $25 for pads??Yikes..

And y'all sell DT Comp spokes for $3 per? Gotta raise me prices...PLUS, LBS built that wheel or install that roar and bleed those brakes? Labor too.

Yeah, Peter. As they say, sh*& is getting real

I'm quoting prices for pads/rotors just from standard internet-order places.

The $2.99 is what we used to charge for DT Comps, in house, yes. I protested heavily, and said that's a ridiculous markup, as I did for many things.

Recently, now that I pay consumer prices for things, I have noticed how high we had been on a lot of consumables in general. I picked a full housing run for a rear brake, and an inner cable for just over 10 bucks.

I think the Spesh Rep(tiles) would regularly encourage you to raise margins on bulk consumables, so that their paltry bike/accessory margins would be balanced and hurt less. You see how evil they are, when it seems like an innocent "nudge?"