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Chinese Carbon Road Bikes => Road Bike Frames, Wheels & Components => Topic started by: 325racer on April 14, 2015, 06:06:44 PM

Title: Let's talk disc brake road bikes
Post by: 325racer on April 14, 2015, 06:06:44 PM
I'm thinking about adding a road bike to my stable and have a few criteria in mind, so I'm just starting to gather data and look at options.

1. Pretty sure I want to go with Disc brakes, why because I love them on my Mtn Bikes.
2. Want some that is an "Endurance/Sportive" bike
3. Can fit at least a 25mm tire, but would like to fit a 28mm if possible.
4. Will most likely go traditional cable controlled Ultegra groupo.

What I have found already.

I'm pretty sure I need to be on a 56cm frame, I tested a Cannondale Synapse, which had a relatively good fit, and a BMC Gran Fondo, which would need a lot of adjustment to fit, although I like the BMC bars.

So looking at geometry, nothing quite lines up to the Cannondale for dimensions, or at least that I can find.

Looking at a good blog, there are a couple choices, but not sure on them..
http://snakesthatbite.blogspot.com/2013/10/disc-brake-road-bike-part-1-frame.html

So what do people know or say about the options?



Title: Re: Let's talk disc brake road bikes
Post by: PeterXu on April 14, 2015, 09:18:04 PM
What do you think about thru axle type disc road bike frame ?

Here is one picture of our newest road disc frame for reference, it is a super light model 092 SL road frame, the other is V-brake version 082 Sl road frame.

BTW, we make these 2 models frames with BB86, no other options
Title: Re: Let's talk disc brake road bikes
Post by: Carbon_Dude on April 14, 2015, 10:40:21 PM
I am happy you started this thread CMH, I am also looking for a dic road bike, but also flat bars.
Title: Re: Let's talk disc brake road bikes
Post by: carbonazza on April 15, 2015, 12:29:01 AM
Disc brakes may become mainstream quicker than thought:
http://road.cc/content/news/148229-disc-brakes-appear-pro-peloton-year

Once a standard for thru axle stand from the crowd, I jump!

Title: Re: Let's talk disc brake road bikes
Post by: 325racer on April 15, 2015, 12:47:29 AM
What do you think about thru axle type disc road bike frame ?

Here is one picture of our newest road disc frame for reference, it is a super light model 092 SL road frame, the other is V-brake version 082 Sl road frame.

BTW, we make these 2 models frames with BB86, no other options

Peter,

The second Pic of the disc brake frame looks very interesting.  I'd be interested in more details about the geometry on this frame.
Title: Re: Let's talk disc brake road bikes
Post by: PeterXu on April 15, 2015, 03:56:16 AM
Here it is   :)
Title: Re: Let's talk disc brake road bikes
Post by: 325racer on April 15, 2015, 09:15:29 AM
Peter,

Those numbers look the closest to the Cannondale Synapse that I've seen, except there is no 56cm listed, which is pretty much the size I would need.
Title: Re: Let's talk disc brake road bikes
Post by: Carbon_Dude on April 15, 2015, 10:15:51 AM
Seems odd to me the chart goes from 52cm, 54cm, to 58cm, skipping 56cm.  I wonder, since it's a new frame design, if the 56cm tooling isn't ready yet.
Title: Re: Let's talk disc brake road bikes
Post by: Carbon_Dude on April 15, 2015, 10:18:03 AM
What do you think about thru axle type disc road bike frame ?

Here is one picture of our newest road disc frame for reference, it is a super light model 092 SL road frame, the other is V-brake version 082 Sl road frame.

BTW, we make these 2 models frames with BB86, no other options

I am also wondering why there is a big hole at the seat tube.  I admit I don't know much about road bikes, so maybe it's obvious to others but someone please explain the design.
Title: Re: Let's talk disc brake road bikes
Post by: 325racer on April 15, 2015, 11:47:55 AM
From the pictures it looks like the post clamp might sit down inside a pocket and the hole is to access the clamp?

What size post does this frame use?  And is it standard round or a proprietary shape as many road bike posts are.
Title: Re: Let's talk disc brake road bikes
Post by: 325racer on April 15, 2015, 08:32:17 PM
Peter,

Can we see the front fork brake cable clamp.  One complaint about the other China disc brake bikes has been the method of clamping/securing the front brake line.
Title: Re: Let's talk disc brake road bikes
Post by: Carbon_Dude on April 15, 2015, 08:49:46 PM
Also, what is the front derailleur mounting on the 092 SL?
Title: Re: Let's talk disc brake road bikes
Post by: Patrick C. on April 16, 2015, 01:10:05 AM
It's got disc brakes and a thru axle- shouldn't it also have a 1X drivetrain?  :)
Title: Re: Let's talk disc brake road bikes
Post by: carbonazza on April 16, 2015, 06:22:52 AM
What do you think about thru axle type disc road bike frame ?

Peter,
I'm interested by the 092 frame too.
What is the weight of the frame? And the fork?
Title: Re: Let's talk disc brake road bikes
Post by: Carbon_Dude on April 16, 2015, 09:11:38 AM
It's got disc brakes and a thru axle- shouldn't it also have a 1X drivetrain?  :)

If I build one it will be 11-spd but because it's road bike, most likely 2x11.
Title: Re: Let's talk disc brake road bikes
Post by: PeterXu on April 16, 2015, 09:34:19 AM
From the pictures it looks like the post clamp might sit down inside a pocket and the hole is to access the clamp?

What size post does this frame use?  And is it standard round or a proprietary shape as many road bike posts are.

You are right, it is a proprietary shape seat post.
Title: Re: Let's talk disc brake road bikes
Post by: PeterXu on April 16, 2015, 09:37:32 AM
What do you think about thru axle type disc road bike frame ?

Peter,
I'm interested by the 092 frame too.
What is the weight of the frame? And the fork?

Around 875+/-30g for size 52cm, and 400+/-15g for fork

Title: Re: Let's talk disc brake road bikes
Post by: 325racer on April 16, 2015, 01:38:59 PM
Peter,

What's the word on a 56cm frame in this design, and is there a zero setback seatpost available if people need to be more over the pedals?

What are the axle standards on this frame?  15 or 20mm front and 12x142 rear? 

This info will help those looking so they can look at hubs too.
Title: Re: Let's talk disc brake road bikes
Post by: carbonazza on April 16, 2015, 02:23:57 PM
It's got disc brakes and a thru axle- shouldn't it also have a 1X drivetrain?  :)

Here it is!
http://road.cc/content/news/148381-sram-announces-single-ring-transmissions-road
Title: Re: Let's talk disc brake road bikes
Post by: Patrick C. on April 16, 2015, 05:58:51 PM
When jokes come true :)

Reminds me of this-
http://www.theonion.com/articles/fuck-everything-were-doing-five-blades,11056/
Title: Re: Let's talk disc brake road bikes
Post by: Carbon_Dude on April 16, 2015, 07:49:58 PM
That was pretty funny Patrick!
Title: Re: Let's talk disc brake road bikes
Post by: PeterXu on April 17, 2015, 04:51:14 AM
Peter,

What's the word on a 56cm frame in this design, and is there a zero setback seatpost available if people need to be more over the pedals?

What are the axle standards on this frame?  15 or 20mm front and 12x142 rear? 

This info will help those looking so they can look at hubs too.

Size 56cm mold will be made in June.  Sorry, I don't think there will be a zero setback seat post for this frame. almost our road bicycle frame seat posts do have setback.

The axle standards ate front 100x15 and rear 142x12

Thanks for your questions.
Title: Re: Let's talk disc brake road bikes
Post by: Carbon_Dude on April 17, 2015, 07:42:04 AM
Hi Peter, thanks for providing an update.  I may be interested in a 56cm 092, please keep us updated on availability.
Title: Re: Let's talk disc brake road bikes
Post by: velofranner on April 17, 2015, 12:01:25 PM
I might also be interested in the 56cm 092, it looks fast and nice!
Title: Re: Let's talk disc brake road bikes
Post by: 325racer on April 17, 2015, 01:45:14 PM
Same here, 56cm 092.  I have to start saving pennies.

Where are you guys located?  Maybe we can get a deal if we all purchase together?
Title: Re: Let's talk disc brake road bikes
Post by: cmh on April 17, 2015, 09:50:14 PM
I am happy you started this thread CMH, I am also looking for a dic road bike, but also flat bars.

Wasn't me, man! :D
Title: Re: Let's talk disc brake road bikes
Post by: Carbon_Dude on April 19, 2015, 11:32:20 AM
This bike is like what I am thinking about building, 1x11 drivetrain, SRAM Rival 1 shifters although I'm not sure if I'd go drop bar or flat bar.  I know, I know, if I went flat bar it would be basically a mountain bike with a rigid fork and road wheels.

(http://cdn.mos.bikeradar.imdserve.com/images/news/2015/03/18/1429076251605-8orpzbemi5wo-1960-540.jpg)

The above frame appears to be a Specialized Diverge.
Title: Re: Let's talk disc brake road bikes
Post by: Carbon_Dude on April 19, 2015, 11:35:31 AM
From the pictures it looks like the post clamp might sit down inside a pocket and the hole is to access the clamp?

What size post does this frame use?  And is it standard round or a proprietary shape as many road bike posts are.

You are right, it is a proprietary shape seat post.

BTW, I don't mind the D-shaped seat post, this is like what Giant has on the Defy road bike.
Title: Re: Let's talk disc brake road bikes
Post by: Sitar_Ned on April 19, 2015, 04:46:34 PM
I thought you weren't a road bike guy, CD?

I'd also like to have a bike similar to what you're talking about. I owned a road bike for about two months and sold it bc I just couldn't get used to the drop bars, shifters, and brakes. Thing is, if I were to build I bike like this with flat bars then my initial response is that I might as well just buy some road wheels and tires for my 057 and lockout the front fork and save about a grand. On the other hand, the road bike was awesome because of how light, fast, and efficient  it was.. the significant added weight on my 057 and more importantly the lower gear range would probably leave a lot to be desired. I'm just not sure if that would be enough to justify the cost of the build.

I'm jonesin to do another build. It's either a bike like this or a full suspension that I'd probably end up spending double what I would on a build like this.
Title: Re: Let's talk disc brake road bikes
Post by: Carbon_Dude on April 19, 2015, 05:05:29 PM
SN, I'm still not convinced that I am a road bike guy.  It's just that I love bikes and like you said, I'm kinda wanting to do another build.  Not sure I would want a Fatbike either so I'm keeping my options open.

I rode four road bikes yesterday at a new local bike shop, a Giant Defy Advanced 1, Giant Defy Advanced Pro 1, Giant Fastroad Comax 2, and a Cannondale Badboy.  Here is what I thought of each road bike:

1)  Giant Defy Advanced 1 - Nice bike, decent price, mech disc brakes were a bit weak, shifted okay, rode just okay. ($2,300)
2)  Giant Defy Advanced Pro 1 - Very nice bike, shifted nice, hydro disc brakes worked well, rode very nice. ($3,300)
3)  Giant Fastroad Comax 2 - Nice bike, very good price, hydro disc brakes pretty good, comfortable flat bar, familiar shifting, good ride. ($1,350)
4)  Cannondale Badboy - Interesting bike, a bit heavy, kinda like a basic mountain bike with road wheels and 75mm travel on the front fork, road wheels, disc brakes, reasonable price. ($1,750)

One thing that was common among all the bikes was they seem to all feel a bit on the small side.  Partly because road bikes have a smaller wheelbase, skinny tires, lighter weight, and the two Defy road bikes having the drop bars also made them feel awkward.  Again, I'm not really a road bike guy but am wondering if I would enjoy an occasional road ride.

So far nothing has really got my attention, the store did not have a Giant Fastroad Comax 1 available to ride but it might come in in a few weeks.  Overall I'm glad I got to ride a few road bikes, now I know that I'm only luke warm on getting a disc road bike.  Since I'm in no hurry, I can wait until SRAM releases all of their road bike 1x11 options in July.


Title: Re: Let's talk disc brake road bikes
Post by: 325racer on April 19, 2015, 07:44:16 PM
Some issues I've seen with comparing road bikes is they come in SOOOO many different flavors and visually it's hard to tell them apart.

You've got Race Bikes, Endurance bikes, gravel bikes, cyclo cross bikes, touring bikes, etc, etc.  Then within each variety, each vendor does things a little different.  In the Mtn bike world once you get into a category, things are pretty much the same.

I didn't ride, but sat on the trainer on 2 "Endurance" bikes the other day.  One a BMC Gran Fondo, the other a Cannondale Synapse.  Both were 56cm frame, both were meant for long rides.  The BMC had a very nice wide comfortable (to me) bar, but the seat was set to far back and the bar was to far forward.  The Cannondale, I didn't care for the bar, also sat a little to far back, but not so far it couldn't be adjusted and the bars were much closer to where I'd like them.

While I didn't ride either, I suspect they both rode slightly different as well, but would think shifting, brakes etc would feel the same as they were the same component groups, I didn't ride them (on purpose) but neither had disc brakes, but you could get them on a different version of the same bikes.

I did do a 56 miler last weekend with some friends who are wanting to do more, so I'm thinking about getting my own bike instead of borrowing my fathers, because sooner or later he's going to want it back, even though I probably shouldn't let him do any road rides by himself....
Title: Re: Let's talk disc brake road bikes
Post by: Sitar_Ned on April 20, 2015, 10:41:43 PM
Yes. Lots of subtle differences in road frames. How stretched out you are, how aggressively you're leaned forward, etc.. Gets pretty confusing.
Title: Re: Let's talk disc brake road bikes
Post by: MTNRCKT on April 21, 2015, 09:09:33 PM
I'm loving the trend of road frames coming with disc brakes.

I'm of the opinion that it would definitely be worth it to build a road specific bike rather than buying some road wheels for your MTB, even if you built it up with a flat bar. The body position and light weight (7-9 lbs will make a huge difference) can't really be replicated with an MTB imo, and like you said, will leave a lot to be desired. Also the road components like Dura-Ace or SRAM Red not only have optimal road gearing but also have a different lighter feel to them. I also suggest you guys give a a reconsideration to drop bars. Everybody uses them for a reason. When you get really comfortable with the various integrated braking and shifting systems from Shimano and SRAM the "oneness" with the bike can't be beat. Also, a tip, do some reading of fitting a road frame too your body. On an MTB you have a little more leeway than you do with a road frame.
Title: Re: Let's talk disc brake road bikes
Post by: seahog32 on May 08, 2015, 05:25:54 PM
Hi

My name is Karl and I am a roadie (as we say at Roadies Anonynous meetings) and here are my 2 cents from a roadie's perspective.

Road bikes with disk breaks look weird. Now that may be a ridiculous argument but I am very sure that all of you have noticed that a bike look of which you like rides way better. Anyway, this does not seem to bother any of the participant in this thread so we can move on.

Disk breaks are noisy. I don't mean to say horribly noisy but you may/will be surprised by the subtle noises that on a MTB are completely overshadowed by all the trail noises or even by riding knobby tires on the pavement. I am not talking about misalignments affecting the functionality so this is just a warning and we can move further on to the more serious objections.

Disc breaks are not widely used hence not well tested on road bikes. There is a thread on this forum regarding a rigid mtb fork failure. Typical road forks (and to some extent chain- and seatstays too) are way thinner than their mtb counterparts which allows for less real estate to beef them up structurally. Do you feel like relying integrity of your bones and possibly more on untested anonymous chinese products? Crushes are less common, in my case anyway, than when riding mtb's but speeds are much higher and possible consequences more serious. Just a food for thought, you don't need to stone me (yet). I myself am riding a no-name chinese carbon fibre fork on my commuter/cross bike. However, it is a sturdy mtb rigid fork ridden with 40 mm semi-slick tires. It would feel and look inappropriet on my light road bike.

Now the most important issue of the road disc breaks is their functionality. The common argument is the stopping power followed closely by "modulation". Trust me that you can easily lock up your wheels using the common road breaks so that should be no objective. With one exeption though which are the carbon fibre rims in wet conditions. If you are planning on riding your road bike in pouring rain regularly and you insist on using carbon wheels on those days then discs may really be the only borderline sane way to go. Modulation is in my personal opinion more a marketing slogan than a real argument but you may feel different about it. Admittedly, it can be difficult to get used to the regular road calipers for someone used to the disc break feel only.

Finally, if we are talking hydraulic disc breaks, there is the issue of their overheating to the point of failure. Depends on what do you expect to use you road bike for but in the "real" road biking the descends are often way longer  + speeds much higher than what you may be accustomed to as a mountain biker. Road components tend to be smaller due to our obsession with grams and aerodynamics. This likely makes them less effective at dissipating the heat. I don't need to preach to the choir here what are the consequences of the boiling break fluid.


Title: Re: Let's talk disc brake road bikes
Post by: Sitar_Ned on May 08, 2015, 07:43:42 PM
Hey Karl, good post. You make a lot of good, well thought out points. Prior to reading your post, I would've considered disc brakes a no brainer, but if I were to do a road build now I'd definitely give serious consideration to conventional rim brakes. Your point about the carbon fiber fork failure makes a lot of sense.. Disc brakes are going to transfer the braking force to the lower blade of the fork that would usually be absorbed at the crown of the fork where traditional rim brakes mount. If road oriented carbon forks are less beefy then their MTB counterparts, then maybe transferring those forces down there isn't such a great idea. This is, of course, more applicable if you're going to be flying down paved mountain roads at 50 mph (which I most likely wouldn't be).

That said, it could be the case that the carbon road forks are perfectly capable of handling the braking forces. You cited the example of the MTB fork that failed here, and while that does indeed serve to backup your point, perhaps the fact that fork had been ridden through rocky, unforgiving MTB terrain had more to do with the failure than the braking force? Are there many known incidents where these forks failed on a road bike due to disc brakes?

I'm not claiming you're wrong; I'm really not sure either way.
Title: Re: Let's talk disc brake road bikes
Post by: Carbon_Dude on May 09, 2015, 08:29:50 AM
In my opinion it's still a no brainer, disc brakes are still the way to go and the industry is obviously moving in that direction.  In a few more years, most road bikes will have disc brakes.  Today, most CX bikes and many commuter bikes have disc brakes, most brands have at least a couple disc road bike models.  For me the advantages outweigh the disadvantages.  Disc brakes are what I would have if I got a road bike.  I've ridden both rim, mechanical disc, and hydraulic disc brake equipped road bikes.  I much prefer hydraulic disc brakes on any bike I own. 

1)  A properly designed fork with a disc brake mount can be made plenty strong to resist the braking forces imparted to the rotor.  With carbon fiber technology, a stronger fork designed for a disc brake only weighs a few ounces more.  Non-rim brake wheels therefore can be lighter since they no longer need that braking surface.

2)  On my carbon rim, I would rather wear a brake pad against an inexpensive rotor instead of a disc brake pad against my high dollar carbon wheels.

3)  Overheating isn't a big issue, the rotor and caliper are out in the airstream, hydraulic brakes can use high temp fluid, pads have aluminum fins for sinking heat.  Downhill bikes generate massive braking forces, no issues with overheating brakes there.  Not to mention, with any braking application, the user needs to be smart with how they use their brakes, rim or disc, the user can cause any number of issues with improper application of brakes.

4)  In the wet, disc brakes work infinitely better than rim brakes.

5)  If I have a rim that is slightly out of true, no problem for disc brakes.

6) Disc brakes are well tested on mountain bikes, CX bikes, road bikes, motorcycles, ebikes, an countless other forms of transpiration.  Other than the need to  make a fork and hub a bit stronger, which has been done on all the new disc road and cyclocross bikes, it's a well known technology that is safe and reliable.

BTW, seahog32, not sure if English is your first language, but "break" is not the correct word for a mechanism that slows or stops a rotating wheel.
Title: Re: Let's talk disc brake road bikes
Post by: carbonazza on May 09, 2015, 11:37:24 AM
David Millar is quite against disc brakes and may have a strong point.
A pity the page looks like a car ad but there are some interesting bits:
http://road.cc/content/feature/149577-david-millar-changing-technology-pro-peloton-and-whether-disc-brakes-have

I understand that the small tire patch can't handle the full stopping power of the brake.
But I still think the combination of both more power and a smaller diameter will offer much more modularity before blocking the wheel.

Title: Re: Let's talk disc brake road bikes
Post by: Carbon_Dude on May 09, 2015, 12:59:05 PM
Most any brake, even a poor one will lock the wheel given the small contact patch of a road bike tire.  That's why disc brakes are not about stopping power, it's all about the other benefits that come  along with a better brake design.
Title: Re: Let's talk disc brake road bikes
Post by: cmh on May 13, 2015, 09:15:58 AM
Road bikes with disk breaks look weird...

Road bikes with sloped top tubes looked weird until they were fashionable. :)

Quote
Disk breaks are noisy...

Although anything with the name "Avid" seems to howl like a mournful dog in the wet, I don't find this to be the case, including my 'cross bike which I ride on the road.

Quote
Disc breaks are not widely used hence not well tested on road bikes.

...but have been widely used and tested many, many other places.

Quote
...Typical road forks (and to some extent chain- and seatstays too) are way thinner than their mtb counterparts which allows for less real estate to beef them up structurally...

In the case of the "anonymous chinese products" I'd tend to give you this one, but carbon can do some pretty wonderful things if it's designed and used properly, so I'm not so concerned about this, at least from the big brands for the foreseeable future.

Quote
Now the most important issue of the road disc breaks is their functionality. The common argument is the stopping power followed closely by "modulation". Trust me that you can easily lock up your wheels using the common road breaks so that should be no objective. With one exeption though which are the carbon fibre rims in wet conditions. If you are planning on riding your road bike in pouring rain regularly and you insist on using carbon wheels on those days then discs may really be the only borderline sane way to go. Modulation is in my personal opinion more a marketing slogan than a real argument but you may feel different about it. Admittedly, it can be difficult to get used to the regular road calipers for someone used to the disc break feel only.

I've ridden a bike with some borderline terrifyingly bad (rim) brakes. I could still lock up the rear tire. I don't get how everyone uses that as the benchmark of brake performance. (Also, the odds are REALLY good that you can't lock up your front wheel with any brakes.) What made those brakes terrifying was loads of squish in the levers with very little braking force until it was getting near lockup. Slowing predictably with those was... interesting.

Quote
Finally, if we are talking hydraulic disc breaks, there is the issue of their overheating to the point of failure. Depends on what do you expect to use you road bike for but in the "real" road biking the descends are often way longer  + speeds much higher than what you may be accustomed to as a mountain biker. Road components tend to be smaller due to our obsession with grams and aerodynamics. This likely makes them less effective at dissipating the heat. I don't need to preach to the choir here what are the consequences of the boiling break fluid.

This I agree with wholeheartedly. Back in 2012, BikeRumor did a bit on disk brakes (http://www.bikerumor.com/2012/02/14/road-bike-disc-brakes-are-coming-but-will-they-work/) on the road after one of their editors had a big crash after brake failure that kinda summarizes most of my concerns with road disks. So many folks focus on the small contact patch of a road tire and miss the fact that that small contact patch gives far, far more grip than the comparatively huge contact patch of MTB tires, even knobbies on the road. Combine that with higher speeds and potentially longer descents and heat is a real issue.

David Millar says we don't need disk brakes. Pros said we didn't need carbon fiber and a whole bunch of other things that they insist on now. If anything, it seems like road pros are the slowest to adopt something new. He also says how great rim brakes are now - sure is nice when you don't have to pay for Shimano's Dura Ace and all the other super high end parts, and someone else builds the bikes for you. :) Plus, the guy is the "cycling ambassador" for Maserati. I wonder what he thinks about rim brakes on his car? :D
Title: Re: Let's talk disc brake road bikes
Post by: 325racer on May 15, 2015, 06:04:16 PM
I'm still keeping an eye on this.  For an endurance road bike, discs are the way to go in the future.  I got a quote from Peter, but I'm waiting to see the final specs on the 56cm 092 frame.  I would build it up with Ultegra components and a set of carbon wheels.  I will probably source the stem and bars locally, actually I already have a stem I'd probably use, although it's red, I think my build would be using black components.  For a Bar, I think I need something in a 460, which narrows down the choices.

I'm envisioning something fully painted with some stripes masked so the carbon will come through as stripes or something....  Coloring will probably be all white, some sort of metallic blue or maybe a combination.
Title: Re: Let's talk disc brake road bikes
Post by: seahog32 on May 18, 2015, 06:59:03 PM
I am using both kind of brakes regularly. I don't feel any particular need to play an advocate to either of the sides. I would be similarly likely to point out advantages of disk brakes on a traditionalist road bike forum. I have no intention trying to change the minds of people who have already made them up. I simply believe that both sides need to be heard before making a decision. What I wrote above was just a short list of concerns that you can typically hear in the road cycling world that someone not quite familiar with road bikes may want to take in consideration before jumping on the train. I personally  find some of them a bit ridiculous. Sorry if I did not make myself clear enough about that.

That said, I must admit that I am actually one of those who find the look of disk brakes on a road bike to be "wrong". That is of course completely irrational view. I mentioned that one just to show that some arguments against them are rather laughable and I am mentioning it again to show that I may be biased. On the other hand, I got quite comfortable using disc brakes on my commuter hybrid (Spesh Crosstrail) with a no-name Chinese carbon (MTB) fork. If anybody is interested, my commute in the morning includes 700 meters over less than 10 km of a continuous descend. Due to shortage of time I do that on a highway while coming home in the afternoon I enjoy the luxury of a mixture of paved back roads, gravel FSR's and singletrack trails. The point of "knowing how to use"  hydraulic brakes on a long descend is quite obvious. However, sometimes it is not reasonably safe for me to pass those pesky logging trucks whose (strangely sane) drivers insist on not going any faster than 60km/h on that descend and thus I am forced to drag/ride the brakes whether I like it or not. The discs tend to get quite hot in the process (to the point that the spit boils on them instantly). Never had any problems with brakes performance but would not be comfortable pushing them much further (like on a descend twice that long). Those are MTB brakes, even if rather cheap ones (Shimano M446 if I remember correctly), though, and there is/will be a significant push to make the existing/coming dedicated road bike disc brakes as light and generally as small as reasonable possible. The placement of the reasonability line is rather uncertain at this point IMO. Hence the overheating concern.

It is an indisputable fact that the industry is moving towards road disc brakes. What are the incentives for doing that should stay open for another thread if any one is interested to start it. I am certainly not hearing too many demands for them from the road cyclists but maybe I am struck by selective deafness or some other condition middle aged men are prone to. My wife would be happy to give you the full list, I'm sure.  Anyway, the industry will keep coming with new stuff. Whether it is a real improvement only the time can always tell. Btw. our LBS owner just came back from some bike expo and is raving about the new S-Works Allez. For those who are unfamiliar with the Spesh lineup, Allez used to be the cheap, alloy alternatives to the top of the line carbon road racing frames. Well, not anymore. These frames are supposedly  as light as the carbon models now and likely stiffer. Not trying to bash the carbon here, just a response to the remark that road pros used to be against the carbon when it was first introduced.


I personally am unaware of any disc carbon road bike fork failures. That comes with them being untested in the real (road cycling) world. And sorry, cyclocross does not count. Bunch of short steep hills is not a very typical course profile in road cycling. Strangely, and I am actually honestly surprised in this case, not all cyclocross riders are switching to discs either now when they are UCI legal.


Whether one can and will trust the strength of a carbon fibre fork in general and which fork that would be in particular is a question I leave open, too. I am no hater of China-direct carbon and I think it is a great alternative to the hugely overpriced (and similarly China-made) brandname carbon parts. Maybe I am just not an early adopter. Again, everything I wrote here should be taken only as a food for for thought. I am not speaking from any position of authority. If you are ready then by all means go for it. We need the real world testers after all.

Lastly, before I forget, English is not my first language and, chronologically speaking, not my second, third or forth language either. I am greatly thankful for the free English lesson offered as well as any other that may come in the future.
Title: Re: Let's talk disc brake road bikes
Post by: cmh on May 21, 2015, 08:52:57 PM
...And sorry, cyclocross does not count. Bunch of short steep hills is not a very typical course profile in road cycling. Strangely, and I am actually honestly surprised in this case, not all cyclocross riders are switching to discs either now when they are UCI legal.

I think that's a combination of things - retro-grouchiness that is common in top level pros - it's always been done this way, why would I wanna change - as well as a good set of rim cantilevers being lighter than a disk setup. Look at Sven Nys - he has access to disk frames that he'll use if it's REALLY muddy, but he prefers the old design that he knows and is lighter. Racers like Lars Van Der Haar are younger and so less inclined to stick with the old-school stuff.

Quote
Lastly, before I forget, English is not my first language and, chronologically speaking, not my second, third or forth language either. I am greatly thankful for the free English lesson offered as well as any other that may come in the future.

I certainly wouldn't have guessed - your English is probably better than mine and it's all I know! :D
Title: Re: Let's talk disc brake road bikes
Post by: ibike on July 22, 2015, 04:32:46 AM
I am curious about that why there is a big hole at the seat tube?Sorry,in fact I agree that there no necessary to equip the disc road bikes ,I think it more suitable for wet days . :-[
Title: Re: Let's talk disc brake road bikes
Post by: PeterXu on July 28, 2015, 01:46:34 AM
CS-092 SL frame in 56cm could be ordered to customize and book now.

Attached revised geometry for reference.
Title: Re: Let's talk disc brake road bikes
Post by: Vipassana on July 28, 2015, 12:47:35 PM
Oh, I'm very interested in this frame!  I think this might be my next purchase.  Please let us know when you have it listed on your website, Peter.  And when you will have other sizes.  I am either needing a 54 or 56.
 

I am looking to build a decently road bike, but with disks.  My target is 15-16 lbs.
Title: Re: Let's talk disc brake road bikes
Post by: aldsfkjw3421 on July 31, 2015, 05:22:24 PM
CS-092 SL frame in 56cm could be ordered to customize and book now.

Attached revised geometry for reference.

That's an awesome looking frame.  I'm in the market for a carbon disc frame but I don't like how cheap the fork hydraulic hose routing looks on a lot of chinese frames out there.  Can you take pictures of the fork and frame on the non-drive side and post them? 

Thanks Peter.
Title: Re: Let's talk disc brake road bikes
Post by: aldsfkjw3421 on July 31, 2015, 09:28:03 PM
Peter, does this frame use the shimano flat mount standard?
Title: Re: Let's talk disc brake road bikes
Post by: Joelk on September 05, 2015, 09:20:09 AM
I have been emailing with Peter about ordering a 92sl.  I just have to figure out which rims I want to get (as I don't really want brake tracks on a disc brake bike),  and make a few more parts choices.

As the frame will be made to order (approx 45 days) I may just order the frame and get everything else sorted out while I wait.
Title: Re: Let's talk disc brake road bikes
Post by: cmh on September 06, 2015, 05:07:31 PM
I have been emailing with Peter about ordering a 92sl.  I just have to figure out which rims I want to get (as I don't really want brake tracks on a disc brake bike),  and make a few more parts choices.

As the frame will be made to order (approx 45 days) I may just order the frame and get everything else sorted out while I wait.

I've gotta say - the new FHR928C offset rims (http://www.xmcarbonspeed.com/Productinfo.asp?f=1403) look sweet - 360g, offset for better spoke tension balance, decently wide for 'cross use. I contacted Peter about prices, forget the exact number but I was really happy with it. Still recovering from the Epic purchase, and then I think I want to build a pair of those on a spare set of American Classic hubs that I have for a _sweet_ lightweight XC/'cross wheelset.

Obviously, I've got zero experience with the rims, but they might just be worth a closer look.

Oh, derp, we're talking disk road bikes - might be wider than you want for a road bike, but still... considering the trend to wider rims on road bikes, it might still be worth a look.
Title: Re: Let's talk disc brake road bikes
Post by: Joelk on September 06, 2015, 07:05:54 PM
Thanks for the suggestion CMH,  the width is in the ballpark and they look like very nice rims, but the problem I have seen with most of the mtb rims is that they are rated for a much lower pressure than the rims designed for road use.

I will check with Peter when I email him tomorrow, but tonight I am kicking back and relaxing after riding Blue Marsh Lake today, which always kicks my ass.
Title: Re: Let's talk disc brake road bikes
Post by: cmh on September 06, 2015, 08:25:24 PM
Thanks for the suggestion CMH,  the width is in the ballpark and they look like very nice rims, but the problem I have seen with most of the mtb rims is that they are rated for a much lower pressure than the rims designed for road use.

Yeah, that was the other thing I was realizing - unless you're running something along the line of a 28c with that rim, you'd probably be wanting to run a higher pressure than it might be rated for. I got somehow locked into the idea that it was a cross bike and that was okay.

FWIW, I run ~60-70psi on Conti 23c's mounted on Pacenti SL23 rims, and I'm no svelte climber.

I will check with Peter when I email him tomorrow, but tonight I am kicking back and relaxing after riding Blue Marsh Lake today, which always kicks my ass.

Oh, cool, you're a local! I've only been to Blue Marsh a couple times, but it's always been good.
Title: Re: Let's talk disc brake road bikes
Post by: Joelk on September 18, 2015, 08:36:35 PM
Oh, cool, you're a local! I've only been to Blue Marsh a couple times, but it's always been good.
Yep, just across the Delaware river in NJ.  We will have to get together for a ride some time.

I ordered a 092 frame, starting the build thread tonight.
Title: Re: Let's talk disc brake road bikes
Post by: cmh on September 21, 2015, 09:54:52 AM
Oh, cool, you're a local! I've only been to Blue Marsh a couple times, but it's always been good.
Yep, just across the Delaware river in NJ.  We will have to get together for a ride some time.

I ordered a 092 frame, starting the build thread tonight.

Sounds good to me, maybe we could get Trekcarbonboy in on it as well!
Title: Re: Let's talk disc brake road bikes
Post by: cmh on September 21, 2015, 06:00:19 PM
Thanks for the suggestion CMH,  the width is in the ballpark and they look like very nice rims, but the problem I have seen with most of the mtb rims is that they are rated for a much lower pressure than the rims designed for road use.

So I was farting around aimlessly and came across what looks like the same rim on Nextie's site:

http://www.nextie-bike.com/mtb/asymmetric/NXT29AS28

Notice - maximum pressure 70psi.

Sounds low for a road tire until I tell you that running 23c tires on Pacenti wide rims (makes them just shy of 25c) I run around 70psi anyway, and I'm ~215lb. If you're running 28c tires, 70psi is borderline too high, especially depending on how much you weigh.

so... they _could_ be decent rims for road use if you're going with bigger tires.

Just saw that and figured it was worth mentioning. Probably just as well to stick with actual road rims.
Title: Re: Let's talk disc brake road bikes
Post by: carbonazza on September 22, 2015, 04:55:23 AM
The purpose of an asymmetric rim is to have the same spokes length/tension on both sides or the rear wheel. Right ?
Is there any requirements about the hub and the frame to fit with these rims?
Title: Re: Let's talk disc brake road bikes
Post by: cmh on September 23, 2015, 10:13:45 AM
The purpose of an asymmetric rim is to have the same spokes length/tension on both sides or the rear wheel. Right ?
Is there any requirements about the hub and the frame to fit with these rims?

Not necessarily the same spokes, but closer. Since the flanges are offset, an offset rim is attempting to keep the bracing angle closer to equal. No requirements on the hub, and when built properly, the spokes are offset, but the rim is still centered between the ends of the hub, so will work with any standard frame.

Another trick to even out spoke tension is triplet lacing, where there are twice as many spokes on the drive side of a rear hub as on the non-drive side. If the flange spacing on the drive side is half of the non-drive, then having twice as many spokes results in an almost equal  spoke tension. That, however, requires special hubs and rims designed for that type of lacing.