cshong88

Bah Humbug

Where did you see this? A 142TA is 135mm between the dropouts, just like a QR. I'd be stunned if the R5d rear weren't 142TA. I'm quite sure the R3d was 142TA when I looked.

mikeyp

I also race, and spend 25% of my time on a Kickr. I switched to disc road this year, but due to all the maintenance / rubbing associated with them, I've gone back to a rim brake bike. Disc brakes stop awesome, I just don't think road disc is quite there yet. In 2-3 years maybe? But for now I would go rim.

Seattle Forrest

I think road disc is "there" but then I ride a C3.

@OP, do you have any specific wheels in mind? Do you have the opportunity to test ride both versions of the bike?

Psimet2001 

carlos danger

it doesn't matter if its 142 through axle or 135QR in the rear. it will work just as good. You will probably have less problems with a regular qr.
135QR was the MTB standard for like 30 years. All disc hubs are available in this width and configuration.

3: there is no bike that is keeping up with the mad hacks who design them unfortunately...

most recent bike inventions and standards bring absolutely nothing that is actually "better" than the older standards, its just different. thinking about 10 different kinds of BB standards compared to the BSA threaded that are all worse than the BSA. 142/148/150/boost etc rear dropouts. tapered/conical headtubes. internal cabling.
postmount/direct mount disc mounts instead of ISO. I could go on...

And all these new standards will be obsolete as soon as they can invent something new to sell.

Regarding the discs. Yes discs are better (imo).
first: you dont wear out the rims.
second: you can get rims with other profiles since they dont have to have a machined brake track on them.
third: the disc are not 30mm from the ground and therefore dont get wet/dirty as easily.
fourth: you can put on everything from 200mm to 140mm discs to get the power you need or want.
fifth: avoid sram/avid hydros like the plague.
sixth: there are mechanical discs too. and when you get problems with hydros it can take several hours to solve, with mechanicals there is only a cable, how hard can that be to fix/adjust/setup? Personally I gave up on hydros about 4-5 years ago. too much of a hassle.

Very few people that try discs go back to rim brakes. Rim brakes can still be completely satisfactory though depending on what you demand from your brakes.

I think the best thing would to try before you buy.

Lazyass

I love rim brakes, in three decades I never crashed because my brakes were too weak. But now I have a bike with hyd discs and I'll never buy another new bike without them. Like you I wanted a bike completely modern and up to date. Mine don't have rotor rub, they don't squeal, complete silence. I don't notice the brakes until I use them, and then they're obviously more powerful. The best thing about the feel is the level pull is so smooth because there's no friction as with with cables/housing. Wheel changes don't take me any longer with thru axles. I had a gravel bike with mechanical discs and skewers and I would usually have to take some extra time to get the rotor centered between the pads, but with TA's it's not an issue.

carlos danger

I think the rotor rub is overblown. You just need to know how to set them up. The easiest way is to slip a business card beween the disc and pads, then gradually tighten both bolts in an alternate fashion until done. Thats usually everything thats needed. Both magura and hope and i guess shimano has videos on how to do this properly. there must be hundreds of vids on this. Sure they are for mtbs but it works exactly the same. Pistons should also be lubed and cleaned from time to time so they dont get sticky.

carlos danger

this one for example

Bah Humbug

There's nothing like riding past a P5-X with its brakes shrieking.

rubiksoval

rubiksoval

Until you switch wheels?

carlos danger

sometimes yes.

sometimes until the weather gets warmer and the fluid expands

Lazyass

You take 10 seconds to loosen the caliper, squeeze the brake lever and retighten.

rubiksoval

Yeah, sounds great. I bet that's super fun in a race.

Lazyass

I wasn't aware we were talking about racing on a team that has a support vehicle with spare wheels different from the ones being removed. What team are you on?

rubiksoval

We're not. We're talking about people that race, period. Which should make the above stop even better, seeing as how most people don't have matching spare wheels.

Lazyass

With your experience, how bad is the rotor rub issue when switching wheels in a race that come off a neutral support vehicle?

rubiksoval

I'm not sure what you're reading. What neutral service vehicle are you talking about? Most races have wheel trucks you put your own wheels in. And I don't use discs, hence the initial query about what happens when you change wheels.

According to you, you take out a tool and adjust them so they dont rub.

WhyFi

If they're your wheels, shim the rotor on one or the other so that they align and you won't have any rub when swapping. Hell, if you stick to CenterLock hubs, you probably don't even need to bother with that. Hydro also seems to give you a bit more leeway.

rubiksoval

Pretty sure I read a post in the 33 from the Psimet guy that said he can't even get wheels of the same make and model to fit without rubbing without adjusting things, regardless of shim use and all.

But if that's becoming a nonissue with newer tech, that's a good thing.

WhyFi

He's also a guy that's usually speaking from the perspective of servicing a fleet of racers. I'm sure that the difficulty goes up exponentially with additional bikes and wheels. A single rider servicing a couple of their own bikes and a few wheelsets? Might take a little time to work it out, but shouldn't be too tough. Neither of my bikes has a rotor alignment problem with a shared third wheelset (I do have to swap out the hub end caps and 140mm/160mm rear rotors, but that's a different story).

Campag4life

OP,
Tough call. Many bring their personal bias into the buying decision. I also believe it really depends on the racing venues you plan...are they mostly flat or do you plan on a fair amount of climbing and high speed descending.

Probably the most authoritative response to listen to is that of Psimet...who is a wheel builder and sees shift in trend more than we do. Fast guys I ride with are mostly on rim brakes...just about all of them. I believe you will still see a lot of rim brakes in this year's TdF coming up in a week and probably more disc brakes in the peloton as well as disc brake bikes become more prevalent.

I don't really buy into next 5 years owning a rim brake bike is going to be an issue with finding parts. Next 10 years things will likely change but so too maybe rotors, spacing and related bike design elements could you, me and others to want the next best thing.

Can go either way and why many leading manufactures offer both...like say another bike you could race competitively...like uber light Emonda SLR...or you could ride a Tarmac S-works that is offered in rim and disc.

Good luck with your racing. I am sure you will be fine with either choice. Probably a jump ball what you decide right now.

TimothyH

I'm also looking at an R5, or maybe an Argon 18 and am considering a build in the spring 2019.

I don't race and won't have spare wheels. Even so, the frame will be the classic version, not disk. I say this after having built a Niner RLT 9 RDO with flat mount hydraulic disks in the spring of 2017 and a fixed gear bike with Dura Ace 9100 rim brakes this past year.

Hydraulic disk is extra maintenance compared to rim brakes. Centering calipers is easy enough and people are free to work on them any way they want but the bolts should really be torqued and there are safety clips which go on the bolts. There are people who don't bother with the safety clips on the bolts and don't torque the bolts but that isn't me. Messing with caliper bolts away from a shop would be an emergency repair as far as I'm concerned.

The fact that the R5d uses flat mount is a plus however.


-Tim-

Lazyass

The bolts that mount the caliper to the mounting bracket have the fixing pins. The bolts that attach the bracket to the fork/chainstay don't have clips, and those are the ones you would loosen if you need to center the pads. And you only have to loosen them like a half turn, squeeze the lever, retighten. If you've already torqued the bolts just remember how much you loosen them so you can tighten them back the same amount. It's a non-issue. And I don't know what this extra maintenance is.