RE: Rider Weight & Tire Size. WAS: Yet Another Tire Si ze Question

[Ingle, Bruce]

> I have been using ceramic rims for the last year with
> caliper brakes and in addition to very little rim wear
> the wheels are always nice and clean. The brake pads
> also last much longer than my first generation
> Avid mechanical disc brakes used to.

> The main drawback to ceramic rims is the relatively
> poor brake performance when the rims are soaking wet.

I expect the same could be said of chromed steel rims.

- Bruce

[littlecirclesvt.com :: mike beganyi]

I've not see horrible wet performance with my Mavic Classics and the
green ceramic pads.
I've also run them with the kool stop salmon pads... to no detriment
that I can see other than faster pad wear.

-Mike

[Kole Kantner]

I have been wondering how necessary it is to use ceramic specific pads as long as you don't brake too hard.  The main purpose of the special compound is to have it vaporise or turn to powder on overheating instead of melting and leaving a plastic glaze on the rim.  The ceramic surface is not as good a heat conductor and gets hotter at the brake pad surface than bare aluminum rims. With gentle braking I feel that melted pads would not be a problem. However, since the price is the same for both pads I don't currently have a problem using the appropriate pads.  If the salmon pads wear faster than green that would be more reason not to use them. 

I am interested in using the same ceramic rim with SON 20R hub on our tandem, but I have not been able to find ceramic compatible pads in the old post style pads currently on the tandem.  I thought of trying the standard pads, but the increased heat on the tandem would probably cause more melting problems than on a single bike.  I did just get a set of Tektro 720 brakes to try on the tandem and they use cartridge pads that I have ceramic compound for.  However, I am nervous to make any changes to the current setup that works fabulously.  In the distant past I have had terrible experiences trying to get cantilever brakes to work effectively or not squeal.  I suspect it was more due to worn out pads and poor quality replacement brakes than any inherent failing of cantilever brakes, but I'm still a little nervous about messing with something that is working well right now.  The occasional squealing I hear on cantilever brakes riding with me does not inspire confidence that I will have better success.  I think I have heard caliper brakes squeal, but it is almost always cantilever.  Of course more rando bikes are outfitted with cantilevers so maybe it is just a statistical phenomenon relating to who I ride with now.

--Kole--

[lei...@globalserve.net]

Hi all

With chrome steel rims you forget about braking in the wet. At least the alloy rims would start the stop eventually ..... Now disk brakes is another story .... They perform remarkably well in the rain

Peter

------Original Message------
From: Ingle, Bruce
Sender: ran...@googlegroups.com
To: ran...@googlegroups.com
Subject: [Randon] RE: Rider Weight & Tire Size. WAS: Yet Another Tire Si ze Question
Sent: Dec 14, 2009 7:45 AM

> I have been using ceramic rims for the last year with
> caliper brakes and in addition to very little rim wear
> the wheels are always nice and clean. The brake pads
> also last much longer than my first generation
> Avid mechanical disc brakes used to.

> The main drawback to ceramic rims is the relatively
> poor brake performance when the rims are soaking wet.

I expect the same could be said of chromed steel rims.

- Bruce

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[Kole Kantner]

I used the original 165mm Avid mechanical disc brakes for several years and then switched to the very similar 160mm version before the poorly designed non-round rotors.  Recently I have used a Nashbar branded Tektro mechanical disc system.  All worked quite nice when dry but squealed terribly when wet.  There seems to be sufficient braking available when wet, but the noise is awful and it feels like the pads must be getting damaged by the vibrations.  I know one set of Avid pads crumbled completely away during a single 100km ride in very wet conditions on steep hills.  I have tried cleaning the rotors with various degreasers with little or no improvement.

A new student showed up at school here a couple years ago with some of the non-round Avid brakes on his bike.  I asked him about wet condition squeal since I had heard it was especially bad for the non-round rotors Avid tried.  He told me the brakes always worked great with no noise.  He probably had only used his bike during the summer up until then.  Later in the winter he came back to me and asked what he could replace his brakes with as they were intolerable to him once he started riding to school regularly in the winter rains.

Does anyone have success using disc brakes in heavy rain without significant squealing?

--Kole--

[Ingle, Bruce]

> Now disk brakes is another story .... They perform remarkably well in
the rain

A drum brake also works well in the rain and circumvents any issues with
frame/fork compatibility, although it lacks the bike-flipping mechanical
advantage of a caliper in dry conditions. I enjoy having one for
pacelines, since I can use the brake to modulate my speed while
maintaining an even cadence without concern for rim wear.

I set a 200km PR on a bike equipped with Sturmey X-FD and AW hubs this
year, although I prefer lighter equipment for 600km and up.

- Bruce