Cervelo R5 - disc vs rim

Discuss light weight issues concerning road bikes & parts.
cshong88
Posts: 7
Joined: Fri Jan 16, 2009 4:49 am

by cshong88

Hi guys, would appreciate some third party input to help me decide on this next purchase. Cat 1, former UCI conti pro who has been a loyal Cervelo R5 rider for the past 5 years. In the market for a new Cervelo R5 and now having to consider for the first time whether or not to purchase a disc brake bike as this was never an option before. Some riding habits about myself.

1. Current/lifetime job (medicine) means 80% of riding is indoors on my Wahoo Kickr
2. Performance-oriented - goals of riding/training are still to go fast and if job permits, compete in local races and hill climbs in next couple years - as such wheel compatilibity in races (neutral support etc) is a factor for me. As a side note, I've been reading the rear 142mm axle is fast becoming the standard for discs. Supposedly the Cervelo R5 disc is a 135mm standard? Is this true? And if so, will this cause issues if I had a disc version for races?
3. Hard to predict but I'd like to have a bike that is in keeping with the times, both now and in the next couple years. Would be a bummer to invest in a rim bike and see the pro peloton and racing scene transition to disc brakes full time in the next year or so.

Ultimately, I anticipate buying another bike in 3-4 years but I want my next purchase to be performance oriented and in line with the standards of contemporary bike racing now and for the next few years. I know it's a hotly debated topic but any thoughts on rim vs disc for my situation? Thanks for all input, much appreciated.

by Weenie


wingguy
Posts: 4193
Joined: Thu Mar 08, 2012 11:43 pm

by wingguy

First, not sure what you’ve been reading but the R5 disc is a 12x142 rear end, just like everything else. It has a proprietary keyed thru axle system rather than threaded but that doesn’t change wheel compatibility at all and it works fine with a Kickr - IF you have the latest 2017/18 version. Older kickrs (v1/v2) are not compatible with the keyed axle.

Second, what do you want out of the disc? Tyre clearance is much bigger, you could get a measured 35 or even close to a 40 in the Disc R5, but that’s not really race relevant. The Rim version still clears a 30mm anyway. Wet weather performance is obviously better too, but if most riding is on the turbo that probably doesn’t matter.

The rim version, well the whole thing builds lighter, obviously, and there are no compatibility issues with anything.

Maybe the disc version would have slightly better resale but honestly all high end road bikes depreciate like rocks so it’s probably gonna be more even than you might think.

cshong88
Posts: 7
Joined: Fri Jan 16, 2009 4:49 am

by cshong88

Hm, I have the original Wahoo Kickr. Is the Cervelo R5 disc not compatible with this model/no adapters I could get to make it work? Might be a deal breaker otherwise...

What I mainly want out of disc vs rim is a choosing a technology that is not obsolete in a few years and one in which the local/national/international racing scene adheres to if/when I get back into elite level racing. I've always been used to rim but this whole disc bike trend now making its way into high level racing has me pause to consider buying a disc bike if this is where racing is heading in the next few years. Likewise, for current purposes, despite riding mostly indoors due to the job, I'm after a performance oriented set up that is most optimal for the fast group ride and to be competitive at the local hill climbs. Thanks in advance for your input.

Mr.Gib
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Joined: Fri Mar 18, 2005 4:12 pm
Location: eh?

by Mr.Gib

Welcome to the clusterf**k that is the changing state of cycling technology.

When everyone else is on discs you'll think you should have 'em. When your on the limit in an uphill finish of some race trying to recapture some of your former glory you'll wish you didn't.

The fact that you're even wondering about this suggest to me that you should just get discs. This sport won't go backward in that regard so you will be more future proof. Shame to add at least a pound to what could easily be a very light bike.

As for not fitting on your Kickr etc., that might be the least of your worries. How pairs of nice wheels to you have in your basement that you will never be able to use?
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

stevod
Posts: 17
Joined: Tue Aug 18, 2015 8:09 am

by stevod

wingguy wrote: ↑
Fri Jun 29, 2018 3:01 pm
Tyre clearance is much bigger, you could get a measured 35 or even close to a 40 in the Disc R5, but that’s not really race relevant. The Rim version still clears a 30mm anyway.
I didn't realise this - thought they were both the same re the frame - officially a 28mm although as you say a bit more in practice.

I can see the clearance in the fork without the caliper, but could a 35-40 really fit between the chainstays or behind the seat tube?

S

wingguy
Posts: 4193
Joined: Thu Mar 08, 2012 11:43 pm

by wingguy

Ah good call, not between the chain stays no. Measured 32mm for sure though, and maybe even a bit bigger than that.

On the rim model the seat stay bridge is the limiting factor, and the disc model doesn’t have one. The disc fork clearance is monstrous.

cshong88
Posts: 7
Joined: Fri Jan 16, 2009 4:49 am

by cshong88

Well I've had a chance to ride both the rim and disc brake versions of this bike. The front end of the disc version felt harsh and the bike felt a bit "dead" when climbing especially out of the saddle while the rim bike felt more responsive and forgiving.

Gut feeling is the rim bike was a bit more enjoyable to ride.

That being said, I can't shake the nagging feeling that it would be foolish to not invest in a disc brake bike in 2019 as this seems to be the way top level bikes are going, including new technology and the pro cycling racing scene. Whose not to say Sunweb will be on R5 discs this year too?

With the release of the new S5 being only disc and more of the professional peloton jumping onto discs...I wonder whether I should just go for the disc version of the R5 despite the fact the R5 rim just "feels" better? 'I ride in a place where having discs isn't of much benefit (no real big descents, fair weather rider) but I don't want to invest in a technology that will fade away in the next few years.

Advice??? Thanks.

stax
Posts: 84
Joined: Fri May 18, 2012 3:35 am

by stax

If I’d just had the experience you described then I would buy the rim brake in a heartbeat. It does seem that you are keen on discs from all you’ve written and you don’t want buyers remorse from the start, but I would absolutely go for the bike that felt best.

WorkonSunday
Posts: 33
Joined: Tue Jan 16, 2018 4:39 pm

by WorkonSunday

One advantage for disc is for smaller rider now the option for 650b or 650c is back without jave to worry about rim brake caliper positions. My wifes disc equiped cross bike now runs 27.5/650b as shes quite short. She really appricate the change.

jlok
Posts: 674
Joined: Tue Jun 30, 2015 3:30 am

by jlok

I think that adv applies to shorter crank and lesser bb drop frames?
Giant Propel Advanced SL Disc 1 < Propel Adv < TCR Adv SL Disc < KTM Revelator Sky < CAAD 12 Disc < Domane S Disc < Alize < CAAD 10

hannawald
Posts: 270
Joined: Sat Dec 17, 2016 7:28 pm

by hannawald

I have always wanted Bianchi, so I bought Specialissima. Had the same feeling as you - buying a rim brake bike in 2018 for huge amount of money is not wise. But I followed my brain many times in the past and realised that for my hobbies, I should follow my heart, it will be more expensive if i don't because I will end up selling the rational choice and buying heart choice anyway and loose money. I am sure rim brake bikes will be here in 4 years so i would buy what you feel is better now..there will be new choices in 4 years, manufacturers will make it so.

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Lewn777
Posts: 316
Joined: Thu Mar 09, 2017 5:35 am

by Lewn777

Betamax or VHS? :lol:

Personally you've just got to buy the current bike and that is the rim version. That's because you're bound to have tons of old sets of wheels, and your trainer can take the bike, and loads of pros are still on rim bikes, the world championship top three were all on rim brakes.
Image

I'm not totally convinced all of the the disk brake technology standards have been settled, what will be the axle and disk size end game? If you want to be sure you've got to wait at least another 18 months to be certain which direction rim or disk is is the right one.

I think disks are just the beginning of a pandoras box of manufacturer opportunity. Standards might never be settled, boosted rear ends for extra gears, who knows who'll team up? Trek, Giant and Shimano for a boosted 14 speed rear end? I'm hoping disks and rims both stay, or the market gets fractured into climbing bike rim, others incl aero disk.

I've ridden disks on mountain bikes for years and personally I wouldn't want them anywhere near my road bike unless I lived somewhere wet like Ireland. The long term mainenance is much more than made out, but to be fair most don't show up until the brakes have done over 10,000kms, but dirty dragging pistons, glazed pads, and fluid leaks do happen.

Just my 2c from a non-expert.

jlok
Posts: 674
Joined: Tue Jun 30, 2015 3:30 am

by jlok

Agree. For example the SRAM eTap brake calipers are just direct transplant of MTB so the the shape and hose port position are not optimized for RB (not saying brake performance is bad). Could use at least 1mm more pad clearance and maybe combining with the caliper shape as rotor guide so that the rotor would slide in quickly during wheel change (not essential for non-racing but nice to have for me). I hope SRAM could improve them with the next eTap HRD. I love wireless shifting and their brake lever feel. I want 12 speed. etc...
Giant Propel Advanced SL Disc 1 < Propel Adv < TCR Adv SL Disc < KTM Revelator Sky < CAAD 12 Disc < Domane S Disc < Alize < CAAD 10

angrylegs
Posts: 128
Joined: Mon May 21, 2012 2:32 pm

by angrylegs

Rim brakes for me. Having ridden and raced for over a decade (not Cat 1, however) I've never had any issues at all with stopping power on rim brakes - the main advantage afforded by disc brakes. Once in rain so heavy I could barely even see - and arguably should not have been riding - on a descent, I was a bit less than happy on rim brakes, but I came down just fine, simply having the experience to know the limits. Carbon wheels these days brake really well - Boras, Zipps and the like have excellent brake tracks and I have no issues using them as an every day wheel. I've got a handful of wheel sets and I don't want to lose their compatability. I've got a rim brake training bike, so my next bike (getting soon) will have rim brakes too. I really can't see the need, and, as someone mentioned above, having ridden both, I don't really like the feel of disc-equipped bikes either. I suppose someday if road bikes and higher end gruppo only come with disc brakes and no other choice I'd go that route, but until then, rim.

AJS914
Posts: 2239
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

No one should have fear of buying rim brakes. If you buy a frame today you'll be able to ride it for decades if it lasts that long. There will always be a way to get parts. The only reason to get discs is because you want them.
As a side note, I've been reading the rear 142mm axle is fast becoming the standard for discs. Supposedly the Cervelo R5 disc is a 135mm standard? Is this true? And if so, will this cause issues if I had a disc version for races?
I don't know specifically about this bike but 142mm thru axel is 135 inside diameter on the rear dropouts. It's just that they measure outside to outside on thru axel.

by Weenie


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