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

[MichaelB]

Anyone know what the piston size of the Hope X2 calipers are ?

The 22mm piston size used by the XTs is fairly common and several other brakes, like Formula R1s and Hope X2s use pistons of the same diameter.

http://forums.mtbr.com/brake-time/shima ... 08363.html

Ta, the Parabox pistons are 21mm

[MichaelB]

It has finally landed

Stay tuned for abuild thread and some pics.

[Mulger bill]

I give you seven days!

[MichaelB]

I give you seven days!

It may take a bit longer as there are some new things on this bike that I haven't dealt with before.

1st job today is to get the lower bearing put onto the fork !!

[Crittski]

Fantastic mate, long wait, enjoy the build! Looking forward to seeing your pics!

[Nobody]

Just linking some threads:

MichaelB's Volagi Liscio (Gen 2) build thread

Shimano Di2 hydraulic road disc brakes spotted

[MichaelB]

Can someone say "That's not a disc ....."

Wouldn't catch me riding this on the road ....



From CN report on NAHBS bike show.

Hopefully this setup is show only ...

[barefoot]

Can someone say "That's not a disc ....."

...that's a cheese grater!

As mentioned elsewhere, I work in an automotive braking test lab.

There's a fashion, on "modified" street cars (fullysickmoite), to fit slotted and/or drilled brake rotors. There's no shortage of internet (and old-wives... ahem... old-timers) expert opinions on how much improvement these slots and holes make to your braking, and why. The explanations always include the word "outgassing", which is a word I've never seen used other than in the context of slotted/drilled rotors, and which I have never seen used in any academic publications on the subject. But I digress.

On a brake performance dyno, time and time again, I've seen demonstrated that the only measurable differences [1] between a plain rotor and a slotted rotor are in pad wear rate and noise. The slots just shave friction material off the pad every time they pass. Chew them up and turn them into brake dust. No change in performance at all. And of course, every time a slot passes the pad, you can hear it.

I understand that on bikes, they also need to cut material out to save rotor weight - the "drillium" principle. But I look at those rotors and imagine how the pads deform under load. The inner and outer edges of the pad are fully supported by a solid bit of rotor, so they'll compress slightly under caliper load. The centre of the pad will bulge out relative to the edges... until one of the grater blades swings through, shaving the pad surface clean with its sharp edge. When the brake is released, the compressed edges will relax - I reckon you'd end up with measurably concave pads

tim

[1] except for one case, where a car-maker wanted to offer slotted rotors as a "dealer option" on their boy-racer models. As they would be fitted on behalf of the manufacturer, the car had to be proven to meet Australian Design Rules on delivery, which meant a validation brake test. Everybody assumed it would just be a formality, because everybody knows that slotted rotors are just a silly cosmetic thing. Everybody was surprised when the slotted rotors reduced brake performance, repeatably, by more than the ADR acceptance limit. The car maker changed their mind about offering "genuine" slotted rotors...

[MichaelB]

Can someone say "That's not a disc ....."

...that's a cheese grater!

As mentioned elsewhere, I work in an automotive braking test lab.


...

Well, that has been interesting. As a past circuit racer, what you had above is what I was lead to believe (slotted/drilled is better).

Is there a reason then, that for auto racing, and specifically F1, that this practice persists ? Or is it a weight issue for them ?

Thanks for the info

[Mulger bill]

Bbut but...
This

looks so much sexier than this

How can it not work better? Methinks you're just envious of people with nicer rotors

Shaun
Who is off to see if he can find any Roundagons...

[Nobody]

I've heard Roundagons do actually have more grip on the pads. My brake pads have lasted and extremely long time too. Don't know if you can get them anymore though. The closest thing to them are the Specialized specific rotors, but they are G3 so I can't use them. They are on clearance too. Like a lot of things, fashion has more to do with it than reality. Form before function. Magura discs seem fairly solid.

Also Shaun, if you are using a G3 with BB7s, you should be using a G2 or Roundagon according to Avid. The G2 are wider in profile I believe.

[Mulger bill]

I'm good thanks Nobody, my Lola runs a Roundagon on the rear and a G2 front. I might look at swapping them over...

G3s on the Elixir CRs on the MTB tho'

[AndrewBurns]

I'm strongly considering a TRP parabox hydraulic conversion to my Boardman CX Pro commuter bike but I don't really know why

The current BB7's stop me plenty well enough, the pads seem to be lasting just fine. If I had to pick out problems I'd say they squeal horribly in the wet, I get fade if I use them a lot in a short amount of time and the lever feel is a bit flexy but the only thing hydros might help would be the slightly mushy feeling, I don't think they'd make any difference with my other two gripes...

[cobba]

...that's a cheese grater!

EBC Brakes used to have the following warning on their website about rotors like those.

THERE IS NO WARRANTY USING EBC PADS ON THESE DESIGNS OF DISCS DUE TO EXTREMELY LOW BRAKING AREA AND FAST PAD WEAR THAT HAS BEEN REPORTED USING RESIN PADS SUCH AS EBC RED & GREEN AND OTHERS.

Well, that has been interesting. As a past circuit racer, what you had above is what I was lead to believe (slotted/drilled is better).

Is there a reason then, that for auto racing, and specifically F1, that this practice persists ? Or is it a weight issue for them ?

No slots or drill holes in this F1 rotor.

[MichaelB]

I'm strongly considering a TRP parabox hydraulic conversion to my Boardman CX Pro commuter bike but I don't really know why

The current BB7's stop me plenty well enough, the pads seem to be lasting just fine. If I had to pick out problems I'd say they squeal horribly in the wet, I get fade if I use them a lot in a short amount of time and the lever feel is a bit flexy but the only thing hydros might help would be the slightly mushy feeling, I don't think they'd make any difference with my other two gripes...

From my experience, and note this is with the 1st Gen version is that braking is 95% the same. Possibly better modulation, but that may also be a bit of placebo.

MAIN benefit is not having to adjust pads, looks a bit bettrer too.

If you do hget it, make sure you get the 2013 version.

Cheapest price that I have seen is ebay from the US for US$340 delivered.

I'm holding out for either the SRAM or Shimano hyd systems

[AndrewBurns]

I'm strongly considering a TRP parabox hydraulic conversion to my Boardman CX Pro commuter bike but I don't really know why

The current BB7's stop me plenty well enough, the pads seem to be lasting just fine. If I had to pick out problems I'd say they squeal horribly in the wet, I get fade if I use them a lot in a short amount of time and the lever feel is a bit flexy but the only thing hydros might help would be the slightly mushy feeling, I don't think they'd make any difference with my other two gripes...

From my experience, and note this is with the 1st Gen version is that braking is 95% the same. Possibly better modulation, but that may also be a bit of placebo.

MAIN benefit is not having to adjust pads, looks a bit bettrer too.

If you do hget it, make sure you get the 2013 version.

Cheapest price that I have seen is ebay from the US for US$340 delivered.

I'm holding out for either the SRAM or Shimano hyd systems

Yeah looking into it I think I'll just wait for hydro brifters, the current solution works well enough that there's no reason to change for a kludge.

[MichaelB]

Yeah looking into it I think I'll just wait for hydro brifters, the current solution works well enough that there's no reason to change for a kludge.

Sensible decision, especially if you are happy with the current system.

BTW, how are your FS wheels going ? What tyres do you run on them and at what pressure ?

[AndrewBurns]

Sensible decision, especially if you are happy with the current system.

BTW, how are your FS wheels going ? What tyres do you run on them and at what pressure ?

Couldn't be happier with the FS wheels because I haven't had to touch them from the day I installed them. I'm running 28c conti GP 4 seasons tyres, they're very hard to get on and off the rims but I can do it as long as I have two tyre levers (which I always carry with me). I run them at 80-85 psi front and rear, I weigh 65 kg but the bike with all the stuff on it is fairly heavy at about 13 kg and I'm usually carrying a few kg of things in a pannier too. I routinely take pretty savage bumps at speed and have had a few impacts that made me wince recently but they don't seen to mind. I've only done maybe 1200 or 1500 km on them to date.

[barefoot]

Well, that has been interesting. As a past circuit racer, what you had above is what I was lead to believe (slotted/drilled is better).

Is there a reason then, that for auto racing, and specifically F1, that this practice persists ? Or is it a weight issue for them ?

Thanks for the info

That still puzzles me.

I'll admit my knowledge of brakes is very much biased toward conventional road-going materials. But that includes the stuff that's factory-fitted to various high-end European sports cars, which have to be capable of repeated stops from >250km/h... as well as being capable of pulling up at the end of your driveway on a -20°C Scandinavian morning. I know some such materials also moonlight as mid-level motorsport pads... but there are another level of serious race pads above that, even before you get to the sintered metal used on aircraft and high-speed trains, and the carbon-on-carbon brakes used in F1.

The conventional wisdom is that slots are needed to scrape the wear debris off the surface of the pad, so you can brake using fresh clean material. That may have had some validity on the friction materials of several decades ago. Modern friction materials are designed to use these wear and combustion products as part of the friction material. It's long been known that most materials perform better after they've been given a good hard work out (to "burn the resins out", as it's said); now, most materials are manufactured using a scorching process, to give this same performance gain without the need to loan your car to a P-plater. Scorching involves sitting the pads face-down on a 600° hot plate for about 2 minutes. Once they're on the car, the scorch layer tends to replenish itself as the pad wears.

Using slotted rotors with scorched materials - whether that's factory scorch or in-service scorch - will chew out the scorch layer, and leave you with under-performing pads. Still, the fast-and-furious boys love showing off their slotted rotors through their 22" chromies.

And yet... Ferraris come from the factory with slotted and/or drilled rotors. I can only assume those guys know something I don't about real high performance braking. They're not as beholden to fashion and folklore as certain domestic taxi-with-a-body-kit "performance car" manufacturers, who fit slotted rotors to their vehicles with full knowledge that there is, at best, no benefit to brake performance.

tim

[MichaelB]

.... now, most materials are manufactured using a scorching process, to give this same performance gain without the need to loan your car to a P-plater. ...

tim

Love that bit

Cheers for the info Tim. So I guess it's a hangover from the old days with asbestos pads .... eeeeek, not the A word ...

[Crawf]

Will be having a road disc frame built up soon (Ti), what are peoples thoughts on having a 132.5mm rear end, best of both worlds future proofing for 130mm or 135mm? Any complications foreseeable?

[Nobody]

As you probably know already, the Surly CC is 132.5 in steel. Currently using 135, but also used 130. Both seem unnoticeable in fitting. I believe all CX disc hubs are heading in the direction of 135, so either 132.5 or 135 should be fine. I can't see anyone going back to 130 once they move away from it.

[MichaelB]

I'd vote for 135, for the same reason as Nobody mentioned above.

Are you liikely to build a 130mm disc hub up ?

135 seems to be the defacto standard amongst road disc bikes.

The fact that Volagi changed from 130 to 135mm after only 1 year is a good example of that. All of the other frames that I have seen are 135mm.

Is the FM-166 135mm ? - didn't have a look at that part of the pdfs yet

[barefoot]

Will be having a road disc frame built up soon (Ti), what are peoples thoughts on having a 132.5mm rear end, best of both worlds future proofing for 130mm or 135mm? Any complications foreseeable?

Definitely 135mm.

How many 130mm disc hubs are there on the market? How many do you think there will be when you've worn your first wheelset out and need to build up another new wheel? 135mm disc hubs will be available pretty much forever.

One thing to be mindful of, though, is chainline. MTB triple crank chainline is 2.5mm wider than road triple chainline (comparing like for like, since doubles are measured differently). It's no coincidence that a MTB hub is 2.5mm wider each side than a road hub.

It's only 2.5mm, which is not far at all. A bit more than half a gear (10-speed sprocket spacing is 3.95mm). Just be aware that your cassette will be slightly outboard of where you cranks expect it to be - so cross-chaining in small-small will be very slightly worse than it ordinarily would be. You might even catch the chain with the shifting pins of your big ring, because the sprocket is just that little bit further out. Easy solution - avoid small-small.

tim

[Nobody]

It's only 2.5mm, which is not far at all. A bit more than half a gear (10-speed sprocket spacing is 3.95mm). Just be aware that your cassette will be slightly outboard of where you cranks expect it to be - so cross-chaining in small-small will be very slightly worse than it ordinarily would be. You might even catch the chain with the shifting pins of your big ring, because the sprocket is just that little bit further out. Easy solution - avoid small-small.

So, therefore big-big is even better, which is much more likely to be used.