Adding a front disc to a road bike !! And Now Hydro!

[MichaelB]

6.8 kg!

Discs and thru axles are not going to weigh down your bike.

I suppose I should put the link back up then.
http://www.bikerumor.com/2013/07/14/pri ... road-bike/" onclick="window.open(this.href);return false;

Nice, and with full Di2 to boot.

Another anti disc brake myth busted

[Mulger bill]

Too pretty for just a link.

[MichaelB]

And now Wilier jumps in with the Cento 1 disc ...

[barefoot]

That's a loooooooong chainstay on the Principia :-/

Wonder what they are thinking there? You could just about drive a bus between the tyre and seat tube.

Do they run long rear ends on their non-disc frames?

Each to his own, but I like sitting right on top of the rear wheel...

[jasonc]

Each to his own, but I like sitting right on top of the rear wheel...

+1

[andione1983]

And now Wilier jumps in with the Cento 1 disc ...

damn they are nice looking bikes

Sent from my GT-I9305 using Tapatalk 2

[MichaelB]

Be interesting to see if the frame geometries differ from the non disc versions.

Im still waiting to see the Canyon disc version shown earlier !!!

[Mark Kelly]

Each to his own, but I like sitting right on top of the rear wheel...

Indeed, each to his own: I dislike short wheelbases because I hate sitting right on top of the back wheel. I've yet to build a frame with a wheelbase I thought too long.

[barefoot]

Each to his own, but I like sitting right on top of the rear wheel...

Indeed, each to his own: I dislike short wheelbases because I hate sitting right on top of the back wheel. I've yet to build a frame with a wheelbase I thought too long.

In that case, I recommend you get yourself a Surly Long Haul Trucker, with 470mm chainstays.

Or you could solo a tandem, for a similar effect

I found my LHT to be like sitting on the front wheel, with the rear wheel somewhere waaaaay out the back, shortcutting corners and making the bike handle like a barge.

Of course, the LHT is made like that for a purpose, and I wasn't using it for that purpose. So I sold it and built my Ti disc roadie, which is a much snappier ride with 415mm stays (I still wanted room for big tyres and/or fenders, but not as much as a conventional ~425mm CX chainstay).

Looking at the photo above, I'm guessing they're up around that 425-430mm length. Which is long for a road bike.

tim

[jasonc]

So I sold it and built my Ti disc roadie, which is a much snappier ride with 415mm stays (I still wanted room for big tyres and/or fenders, but not as much as a conventional ~425mm CX chainstay).

so if I wanted to go to a 28/30mm tyre max (most of the time 23 or 25 - schwalbe marathon plus), what size stays/forks would I require?

[barefoot]

So I sold it and built my Ti disc roadie, which is a much snappier ride with 415mm stays (I still wanted room for big tyres and/or fenders, but not as much as a conventional ~425mm CX chainstay).

so if I wanted to go to a 28/30mm tyre max (most of the time 23 or 25 - schwalbe marathon plus), what size stays/forks would I require?

Many road frames run 405mm stays. My old DBR road frame has 405mm stays that can certainly fit 28mm tyres, probably 32mm at a pinch.

Most modern road frames are artificially crippled in their tyre clearance by the width between the stays, and by the location of the brake bridge and chainstay bridge.

If the stays and bridges are designed to give clearance, with really short stays, the next place your tyre is going to touch is the seat tube. That DBR of mine has loads of clearance there. I'm pretty sure this photo is with 25mm tyres:


You see some really tight track bikes with near-zero clearance there. Not sure what effective chainstay length they must be running (noting that track bikes have horizontal dropouts, so BB-to-axle length is variable).

For my disc-road bike, I wanted space for CX tyres. Plus mudguards / mud / smallfurryanimals. So this, 415mm, is about as tight as I wanted to go:


As for what length stays you want... that's not really up to me. But I'd reckon on 405mm being a good starting point, because that's what everybody uses.

tim

[jasonc]

As for what length stays you want... that's not really up to me. But I'd reckon on 405mm being a good starting point, because that's what everybody uses.

tim

Just checked and my roadie has a 410 rear stay (frame design doesn't allow for anything larger than a 23c)

[MichaelB]

As for what length stays you want... that's not really up to me. But I'd reckon on 405mm being a good starting point, because that's what everybody uses.

tim

Just checked and my roadie has a 410 rear stay (frame design doesn't allow for anything larger than a 23c)

I've found that the chainstay bridge placement is the usual issue (it was on my Kona Honky Inc) - otherwise could have fitted 32C tyres.

Chainstay length is not the sole limiting factor as others have highlighted.

Also, not all tyres are the same width/height despite their markings ....

[rkelsen]

For my disc-road bike...

Calling that bike a "road" bike is being a bit loose with the terminology. It is a nice bike, but it has the clearances of a tractor, not those of a road bike.

[barefoot]

For my disc-road bike...

Calling that bike a "road" bike is being a bit loose with the terminology. It is a nice bike, but it has the clearances of a tractor, not those of a road bike.

Oh, please carry on and explain why a bike with road gearing and road geometry is not a road bike?

It usually wears 25s, and the vast majority of it's use is on road bunch rides.

(that's after I fitted my new triple crank - mostly so I could have a more road-friendly 39T ring, for undulating roads, without losing out on serious climbing gears).

There's not a lot of difference between a road bike and a CX bike. The most obvious is brakes, but if we're talking disc-road v disc-CX that's a non-issue. The other differences are more subtle.

CX bikes tend to have longer chainstays and a high BB. I designed this one with fairly short chainstays and low BB - lower than many road bikes, actually.
CX bikes tend to have cables routed along the top of the top tube, thus requiring either a top-pull front derailer or a cable pulley. I designed this one with standard downtube cable routing.

Yes, I made sure it has ample tyre clearance. So is that your distinction between road and not-road? Road bikes must have arbitrarily limited tyre clearance? Strange, they never used to until about 10 years ago.

Should I install some kind of restrictor plates on my stay bridges to reduce tyre clearance and turn it into a proper road bike?

Seriously though... terminology is not such a big deal, and if I wanted a bike that neatly fitted into ANY category, I wouldn't have built this one

tim

[rkelsen]

Oh, please carry on and explain why a bike with road gearing and road geometry is not a road bike?

Isn't it funny that you deride the stay length of the Pricipia bike, when your own "road" bike is closer to a CX/touring bike in both appearance and clearances?

[jasonc]

Oh, please carry on and explain why a bike with road gearing and road geometry is not a road bike?

Isn't it funny that you deride the stay length of the Pricipia bike, when your own "road" bike is closer to a CX/touring bike in both appearance and clearances?

maybe he's better stating that, like me, he prefers shorter stays as they provide a sharper handling bike?

[barefoot]

Oh, please carry on and explain why a bike with road gearing and road geometry is not a road bike?

Isn't it funny that you deride the stay length of the Pricipia bike, when your own "road" bike is closer to a CX/touring bike in both appearance and clearances?

Let's compare the pair.




I reckon mine has less tyre clearance at the seat tube. Now, my seat tube angle is steep (75°), most likely steeper than theirs, so I'd be pretty certain theirs has significantly longer chainstays than mine. Mine were as short as I could get them while meeting my design objectives (re: tyre clearance); theirs are deliberately long, for no obvious reason other than handling.

Mine is "closer to a CX/touring bike in both appearance and clearances"... but not in geometry and handling. I'm all about function ahead of form.

I like the handling of a bike with short chainstays. That Principia is a bike with surprisingly long chainstays. Hence my comment.

tim

[MattyK]

http://road.cc/content/news/89025-speci ... ge-expands" onclick="window.open(this.href);return false;

...aaaaaand I'm spent.

[rkelsen]

I reckon mine has less tyre clearance at the seat tube.

Your photo is taken from an angle, so it is difficult to tell. Even still, there doesn't appear to be that much in it.

[lock_]

^What I really wanted to see was an SWorks SL5 Tarmac, but the Roubaix doesn't look so bad (even if it does require a -17deg stem). Ideally I'd go for Di2 disc over the SRAM Red; I'm curious about electronic shifting, but it's mainly my lack of faith in SRAMs discs that leads to this preference. As of last week the LBS had no idea what models would be coming to Australia, I read the UK will be missing the SRAM Red equipped disc braked bikes so there may not be a choice anyway. Yellow, really, I'm not against the idea but I've never really thought about owning a yellow bike up till now.

[jasonc]

^What I really wanted to see was an SWorks SL5 Tarmac, but the Roubaix doesn't look so bad (even if it does require a -17deg stem). Ideally I'd go for Di2 disc over the SRAM Red; I'm curious about electronic shifting, but it's mainly my lack of faith in SRAMs discs that leads to this preference. As of last week the LBS had no idea what models would be coming to Australia, I read the UK will be missing the SRAM Red equipped disc braked bikes so there may not be a choice anyway. Yellow, really, I'm not against the idea but I've never really thought about owning a yellow bike up till now.

warning: my opinion coming

I rode the tarmac, roubaix and venge back to back (to back). with a kilometre, I was ready to throw the roubaix away. it won't turn in, slow to respond. just not the frame for me. the tarmac was similar to my fuji (SST), and I loved the venge.

so, if they did a tarmac with di2 and mech (or hydro) discs, it'd be at the top of my list.

[lock_]

Thanks for that, duly noted. I'd be coming from a SuperSix/CAAD. This wouldn't be a race bike (mainly as it's not UCI compliant), but I'd still like the fit to line up with my race bike. Bike geometry/handling is a different matter and up till now I hadn't really heard any sharp opinions on Tarmac vs Roubaix. Keep meaning to get myself along to a "Test the best" event, should really make the effort before putting down what is likely a decent chunk of change.

[jasonc]

Keep meaning to get myself along to a "Test the best" event, should really make the effort before putting down what is likely a decent chunk of change.

probably my most worthwhile hour or so on a bike this year. learnt more about what geometry works for me more than any amount of reading

[MichaelB]

Conversion done and all good to a point.



Brake fluid and brake pads don't mix ....

The rears are fine, but the front still have a bit of contamination, but gradually clearing it up.

Short flat ride last night, first one for 3 weeks, so may get out again tonight to do some more bedding in.

So far so good, but took a bit of stuffing around with the bleeding to get it right.

Hose routing is great, so looking pretty good so far.

Went for a second ride last night, but this time with some hills. Got rid of some more contamination on the front pads, and they were much better, but in the end, I think there is still some contamination there. Picked up a set of sintered pads from the LBS (coz the resin ones were $7 more !! ).

Anyway, the end result is ...... BRILLIANT

The rear brakes work fantastic, and the front are 90%, but that's due to contamination. The modulation is great, as is the lever feel. Whilst it's early days, I am more than happy with it the end result.

Phew

Pics to come