Originally Posted by
mstateglfr
- A rim brake frame can be lighter than a disc brake frame, agreed. 10oz or less in the end. If you are an elite performer, that could definitely make a difference. If you arent, then you are using it as a weak justification.
- Rim brake wheels are not necessarily lighter than disc brake wheels. Rim brake wheels can be lighter, but that doesnt mean they all are lighter. Very few people riding have wheels that weigh less than 1500g so this argument is quite worthless for most people. Disc brake wheels can weigh under 1300g too, so at that point, is this really an argument to make? What are your rim brake wheels and what do they weigh? Again, rim can be lighter, but its not like everyone on rim brakes is riding on wheels that are lighter than disc brake wheels. Stock rim brake wheels on Ultegra level bikes or lower just a few years ago were commonly 1750g to 2050g as a set.
- Rim brake forks can be more compliant. If they have to pass that testing, they will be bulked up well past what most anyone needs, just like disc brake forks. A handmade steel rim brake fork can be very compliant, I do agree with that. .6% of people ride such a fork.
- Rim brake wheels can be more aero. That doesnt mean they all are more aero. There are a ton of disc brake wheels that are clearly more aero than the wheels on any of my rim brake road bikes. Once again you put forth a claim that could be true, but also could be incorrect.
- Rim brakes dont slice you or friends in a crash. Disc brakes also dont slice you of friends in a crash. Lets call this a tie, mkay?
- Rim brakes are cheaper and easier to work on, that is almost universally correct so I will award you this claim as one to continue using. Congrats, you finally got another one.
- A disc wheel up front is perhaps weaker in theory compared to a rim brake wheel due to spoke imbalance. Add 4 spokes and call it good. Thats what November suggests, and I have read similar from many others. Seriously, this is all thats needed and the benefits are wider rims for more comfortable tires, deeper rims for more aero gains, and rims that dont wear out or delaminate from use.
- A rear disc wheel is 142mm vs 130mm for a rim brake wheel. Once the thruaxle is accounted for, a disc wheel is set up as 135mm. The wheel can therefore be plenty strong, contrary to your claim.
- Wider stays dont mean heel strike is an issue. I have size 14 shoes and dont have heel strike. Drop this claim.
- My gravel bike has 43mm tires, it can fit 50mm tires, and I use a road crank and subcompact rings with 147mm Q factor. Drop your claim of needing a wider Q factor. Yes GRX has a wider Q factor, but that isnt needed. Also, wider stay spacing is more for wider tires than disc brakes. Same with a wider Q crank design- you will notice thats associated to a gravel groupset.
- Discs dont tend to eject front wheels. Good lord, settle down with the over the top claims. My kids have MTBs with QR disc forks and there is no ejecting wheel fear. The dropouts are designed differently to account for this and its a non-issue. Drop this claim.
- How many people forget thru-axles at the trailhead? And why are they forgetting thru-axles at the trailhead?
- Thru-axles are not load bearing, correct. They are a piece of metal which GOES THRU THE AXLE and retains the wheel. Who claims they are load bearing? They are no more load bearing than a QR skewer.
- Thru-axles arent just some lawyer creation- they are a better design for centering the rotor each time. You just complained about QR disc design and now you complain about the design that addresses QR discs?
You did manage to make 2 good points in all that.
And as a reminder, my main road bike, backup road bike, backup to the backup road bike, commuter bike and single speed bike are all rim brake. I love rim brakes.
OK, back from a delightful ride on my superior 'rim brake' technology bike. I should trademark this term. But I have no doubt that one of the 'big-3' will reintroduce some variation of rim brake road bikes in about 10 years and trumpet about how much lighter and responsive and newer it is. Just think: the rims and the braking surface are integrated, dispensing with the need for rotors! It will be patented and defended with scorched-earth lawsuits - no doubt.
Anyway, not surprised this thread has still not flamed out. I'll give you credit here, in that unlike most of the terse 'hair on fire' pro-disc responses, your listing was somewhat fulsome and thoughtful. Although mostly wrong. Most of the pro-disc responses go like this: "It's the new thing... so it must be better!".
On my new road bike I'm going for light weight, particularly wheel rotating mass, as this is the single biggest performance attribute. Aero: don't need it - at speeds high enough so that aero is important, I'm probably drafting some big guy. Wide tires... they are heavy, less aero and have higher rolling resistance. Regardless: there are only trivial rolling resistance differences between road tires. Besides, I'm not a fatty, so I don't need tires >25mm.
So you list 1,300 gram disc wheels. I don't want 1,300g wheels - I want 1,100 g wheels or less, like my Zipps. And I want 16 radial spokes. So if you can direct me to some 1,100 gram 16-spoke disc wheels (including rotors), I'm interested. I also want a sub-800 gram frameset and a 350 gram fork. That is painted with the derailleur hanger - no cheating.
No thru-axles; I'm competent enough to use standard QRs. I have no trouble aligning the wheel in my fork ends.
I also want a bike with rear 130mm stays, and a tight a Q-factor as possible. So 145 mm Ultra-Torque spec or lower. I don't want riding a bike to feel like riding a horse.
So if I can get all of that with discs - I'm all in!