CarloM

@bpcyclist - check out this YouTube video. Literally just came across it (thanks YouTube algorithm!), it's a few years old. But the guy they interview, Raoul from Leuscher Technik repairs carbon wheels and carbon frames and used to work for one of the airplane companies as an engineer (may have been Boeing?). I've followed him for a while and he really knows his stuff. Here he explains what's wrong with carbon clincher with rim brake tracks from a few years back (I'm sure manufacturers have gotten workarounds and fixes since then). Basically they took what worked on an aluminum rim (brake tracks) and said let's do the same thing but use carbon fiber instead...without fully working out the consequences, which he lays out in pretty clear and convincing fashion.

He also presents a theory about why the industry is pushing disc so hard (outside of it being a superior braking mechanism in his opinion). It's that they realize that serious riders now all want carbon wheels. But rim brakes on carbon wheels are a bad design. Because braking on descents (or any hard, sustained braking) heats up the resin in the carbon rim to over 200-250C whereas most of them have much lower points where their properties change and thus compromise the adhesion between the carbon layers (around 180C). And some companies tried to get around that by using resin with higher heat tolerance...but that leads to a more brittle rim so those that tolerate heat better tend to unfortunately be more susceptible to cracking/breaking under sharp stresses.


Worth a watch. So his conclusion is: disc braking, in addition to being just a better design, solves the heat problem for carbon wheels because the braking surface is no longer on the wheel, so the resin doesn't get compromised.

Here's part two, I haven't had a chance to watch it:
Remember these videos are from 2016, so it's not surprising that the industry soon thereafter started really pushing disc brakes so hard. I think given his experience and his knowledge, he makes a lot of sense in his theory.

Sy Reene

Boiled down.. this.
I'm presuming that this, along perhaps with the increased popularity of tubeless tires for road use, is also driving more engagement (service and support) at the LBS.

WhyFi

Without reading through the walls of text, have we figured out how many grams of drag the new TAs save? Asking for a friend.

CarloM

It’s good for at least a savings of 0.273 seconds over 100 miles at 25mph. At least.

WhyFi

Ordered. I mean... my friend will order them. Thanks.

CarloM

In all seriousness, I'm now four rides (totaling two hours and maybe 40 miles) into the new axles, and my initial impressions have held up. I've pushed the bike super hard most of the time (when I'm not recovering from the exertion) trying to get it to rub and it very rarely does, and only in the most extreme of circumstances.

This isn't due to any drag or weight savings, but I will say personally, I now ride harder and more aggressive because the rotor no longer rubs. You know how psychologically, if your bike does one thing that annoys you under a set of circumstances, you either purposely or subconsciously try to avoid those conditions that cause the issue? Well that one final mental barrier has been removed for me on my S3.

If your bike doesn't exhibit what my S3 did (and my TCR didn't) then what I described isn't applicable. But for some people, the approx. 60g in weight savings from standard TAs might be an appealing aspect, as well as the elimination of the TA lever, whether it's for minuscule aero gains, or just aesthetic improvement. Some day I'd like total internal cable routing not because of the 0.003 watt savings, but because it makes the cockpit look so damn clean.

bpcyclist

Really glad you posted these. I saw them first a couple years ago and Raoul and the Maven are the main reason I never added carbon clinchers to my rim-brake BMC. He scared the **** out of me. We are very hilly here. That said, I do a lot of riding on fairly flat surfaces, too, and so would like a bike that is fairly zippy on the flats as well. I do think disc it will probably be. I was looking last year at an R3, but I am now confused by Cervelo's line. Do they even make an R3 anymore? What is this R-Series thing? The R2 frame is supposed to be very similar to an R3, but can I get one with disc brakes? I don't think so, yet. And why are aero frames generally substantially more expensive than a traditional road frame? Is it worth it? I've never even ridden one.

CarloM

@bpcyclist honestly I don't even know Cervelo's current line. I bought my 2018 when it was on clearance this year. Don't get me wrong, especially now with the RAP TA fix I love my S3. That said, it MSRP'd for $8800. I was able to talk my LBS down to out-the-door at 5K flat (with 10% CA sales tax, that's essentially $4550). So just about half off. Given that it came with SRAM Red eTap 11spd and ENVE SES 5.6 with DT Swiss 240 hubs...I thought that was more than a fair price (basically at the time it was the cost of the wheels and groupset alone). I would never have considered this bike at anywhere near MSRP. Not even at the standard "talk 'em down to 15-20% off MSRP off" discount.

So unless the current generation has something that you absolutely want that isn't available on last year's model, I would look for an LBS (or e-tailer if you don't have an LBS) that's clearancing last year's models and go with that. You'll likely find some absolutely great deals.

bpcyclist

Wow, sounds like you got a deal. That's great. Yeah, it seems like the R-series disc with either Force eTap or Ultegra Di2 starts at around $6500 and the S3 is maybe a bit more, depending where you are looking. That's sometimes as much as $1000 more than some other brands. Cervelo really charges a premium.

melikebikey35

If you live/ride in a hilly area, you'll definitely benefit from disc brakes...more stopping power, less fade, and you won't cook your (carbon) wheels. I also wouldn't recommend going the aero route. As you noticed, they are more expensive (I think it's just down to the fact that they are new/trendy so they can charge more), heavier, and I'm still not buying the fact that aero trumps weight, for the general rider, while climbing. That said, I'd love to have an aero bike as a second bike, but wouldn't choose one as my only bike.

As far the the whole "R-Series" instead of R-3 thing goes...I'm not sure why they changed it. The only difference that I can see is that they added a Force Axes option, and a new color. As CarloM mentioned, I'd look for 2019, or '18 on closeout. It's the exact same bike

I ended up getting a good deal on a '19 with standard Ultegra, and just converted it to Di2 myself...worked out being A LOT cheaper than simply buying the Di2 model.

CarloM

So if price is an overriding factor, Canyon is pretty much best bang-for-buck, but it comes at the internet-direct, no dealer support cost. If you have a Giant shop near you, I'd recommend checking their bikes out. They're not as cheap as Canyon but they own the factory that makes their frames (and Trek's, and Colnago's, and others) so they don't have the added cost associated with another company making their frames. So you'll often see a similarly spec'd Giant for approx. 15% less than another big name brand (and 25% or more lower than boutique-y brands like Cervelo, S-Works, etc.). My TCR is still my daily driver, even after the S3 improvement. The TCR and Defy are respected racing and endurance bikes and each would cost less than a similarly spec'd Cervelo R.

If you have a local Giant dealer I'd highly recommend test riding to see if you like their feel. TCR Advanced Pro 1 Di2 is $5400 MSRP which is $1100 less than the R class you mentioned. The Pro 0 which has Force eTap is $6K. Prices are close to that for the Defy. And IME Giant dealers have leeway to cut deals, so if you establish a good rapport with them you may be pleasantly surprised at where you end up at price-wise. And of course those are 2020 prices, if they have 2019 models you'll likely score a better deal.

CarloM

Funny semi-related story today. Recently I've decided to ride my Trek to work. I have to navigate some narrow hallways and turns to my office where I keep my bike stored. Today I caught the thru-axle lever twice on narrow turns. Looks like I may be ordering some for that bike soon!

Tonight was my 5th ride on the S3 with RAP TAs. First four rides was me trying to push the bike to rub, so I didn't really do my full normal evening ride route. I would do parts of it, the parts I knew were problematic with rotor rub.

Tonight I decided I'd just ride my normal route. I actually didn't feel particularly strong, and the little lights to the left of my Wahoo Roam were indicating I was slow compared to my normal pace at the beginning of the ride. I figured it was one of those nights where I was tired, so I just stopped paying attention to the Roam and rode. I was surprised when my Strava app told me this after I got home (keep in mind this is my normal route, so the Strava has many data points for these segments):


3: PRs
7: 2nd best
7: 3rd best

To reiterate: I do not mean to imply that the RAP TAs made me faster through any weight or aero gain. But I think my earlier theory was borne out: since I no longer have any concern about rotor rub when putting the bike under stress, I just ride the bike worry-free. That likely was the reason behind all those achievements. Oh, and maybe I built a little more muscle strength over the last three days while doing what ended up being ad hoc interval training while trying to get the rotor to rub?

Dean V

So you and others have had issues with rotor rub during hard efforts with their TA bikes but somehow my QR disc brake bike has no issues with this!
How is this possible when one of the main selling points of TA was improved rigidity over QR?

CarloM

The common thread seems to be Cervélo’s TA.

My Giant one has been rotor rub free. Same with my Trek.

CarloM

The other axles arrived today. Installed the rear of the S3. Saved another 30g. Definitely faster now.


Stock rear Cervélo TA



Robert Axle rear TA

sfrider 

I tried the RAP 12x125 axle up front, but it made the brake rub continuously. Put the OEM back in.

CarloM

Did you try to re-align the brakes and it still rubbed, or it just rubbed as soon as you installed and so you put the OEMs right back in? Just asking because the torque difference may have changed rotor alignment slightly but a quick realignment might have solved it.

Installed the RAPs TAs on the TCR. I didn't have rub issues initially and installing them didn't introduce any either. Not sure I noticed any performance improvement but wasn't expecting to either, since the TCR has been near flawless for me. The only difference is 30g each (that seems to be the default weight savings with RAPs and stock TAs) and no protruding lever. Since the TCR is my lightweight bike, 60g is 60g


Stock Giant TCR rear TA


RAP rear TA


Stock Giant TCR front TA


RAP Front TA


Clean no-lever look on TCR

Also, for those who asked, for the TCR I just hand tightened to what I felt was about 12Nm. I was spinning the wheel while tightening, and it didn't rub after I got to maybe 3-4Nm until I got to what I thought was recommended torque--and it didn't while riding afterward.

Then I took it back inside and used torque wrench. My initial estimate was pretty close, it didn't move much to get to 12Nm (so hand-tightening was probably around 10 Nm) and a subsequent ride also didn't reveal any rub. So at least on my TCR the RAP TAs don't seem to be very finicky in terms of torque tension and rotor rub.

sfrider 

Yeah, I recentered the front brake by loosening the bolts holding it, and retightening while pinching the brake. It seems the RAP axle puts the rotor at a bit more of an angle than the OEM one, and the brake doesn't have enough adjustment leeway to make up for it.

CarloM

I'm not the one who originally posted about the preset 12Nm torque wrench, but the comment did get me curious so I found this:

https://www.amazon.com/Prestacycle-T.../dp/B06XCFBM1S
They come in 4, 5, 6, 7, 8, 10 and 12 Nm preset settings and are compatible with standard 1/4" hex bits which are sold separately, like these:

https://www.amazon.com/Wiha-71397-Me...dp/B0084B7S70/ or https://www.amazon.com/9-Piece-Metri.../dp/B00FA4RI9W

Hmm...now that I found those, I might pick up a 5Nm (the most common setting for many of the bolts on my bikes) and a 12Nm handle along with one of those bits sets. That would not be considerably bulkier than the multitool + the full 6mm Allen wrench in my saddle bag.

CarloM

Sorry to hear that!

Just out of curiosity, what is the make/model? It might be helpful to let the folks at RAP know too, in case there's something on their end they can check on to see if this is a possible issue with that specific model.

Sy Reene

Those look pretty good. Still, a pretty good sized tool for the saddlebag or pocket, just so you can repair a flat. Also, I'd think you'd need pretty good hand strength to apply 12Nm with a twisting action like these.

CarloM

If carrying those tools (or just a standard 6mm hex) in a saddle bag/pack is a stopping point, then RAPs aren't for you. On my rides this past week I have added a standard 6mm Allen key to my small Bontrager saddle bag where I keep my energy bars and it easily fit...and that was the smallest of my saddle bags, which I use on longer rides where I need to keep nutrition bars. I also have put that key in my Silca Premio pouch, which I use when I travel light (credit cards, phone) and again it fit with no noticeable added bulk or weight.

12Nm is does not require Herculean strength--I got to 10 pretty easily and I'd classify myself as average strength for my height/weight (5-7, 145). The tougher part is guesstimating where 12Nm is (which is why I only applied about 10Nm, because I was guessing). But that said, I don't think if you applied the RAPs at anywhere above 5Nm that it would go anywhere, nor would it affect performance.

Sy Reene

My comment and reply was specific to the referenced amazon tool, not a standard allen key. A standard 6mm allen key wouldn't be an issue getting to somewhere in the 12Nm vicinity and is a lot smaller (and probably lower weight) than the linked 12Nm tool. Probably best to self-teach what 12Nm feels like with the allen key and a benchmark tool to verify as it sounds like you're doing The linked tool looks like it would take at least half the space of a typical roadie saddlebag or be fairly uncomfortable in a jersey pocket.. might be nice for a home tool to have laying around tho.

sfrider 

It's a 2019 C3.

Maybe I'll ping RAP to see if they have any ideas...

CarloM

Just for science, on yesterday's 25 mile ride, at the halfway point, I took out my 6mm Allen wrench and untightened, then re-tightened the front RAP TA on my Giant. Since I didn't have a torque wrench, I approximated to the best of my ability and probably got it around 10Nm again (when I got home and tightened with a torque wrench it turned just a little more before clicking).

No rub issues at all on the way home, so while I would still recommend following their recommended setting, at least on my TCR if I'm close it doesn't seem to present any issues.

@sfrider I would definitely shoot them an email, they're very helpful and respond promptly during normal west coast business hours (they're a small shop so they won't have a CSR checking their emails at nights and on weekends).