From: stevew@hal.COM (Steve Williams)
Newsgroups: rec.bicycles
Subject: Re: Mavic ceramic-oxide rims?
Summary: Followup by original requestor
Date: 30 Jul 92 04:44:48 GMT
Organization: HaL Computer Systems, Inc.
NNTP-Posting-Host: wave9.hal.com


Last week I posted an article requesting first-hand information about
Mavic ceramic-impregnated rims.  I asked that replies be mailed to me
rather than posted.  Replies came from only 3 people, two of whom actually
own wheels built with the ceramic rims.  The other respondent does not
own ceramic rims, but did bring up an interesting point that I hadn't
considered.

Because of the small number of responses, I really can't derive any
meaningful summary.  So, I'll take the easy way out and simply attach
my original article and most of the text of the replies.

My thanks to the three people who responded.  I still haven't made
my decision, but your information will help.

----------
My original request for information:
  I'm about to replace the 3-yr old, battered wheels of my mountain
  bike, and am considering going with the Mavic M-231 ceramic rims.
  The claim (which I tend to believe) is that these rims greatly
  improve braking power, especially in wet conditions.

  I would like to hear from people who either actually *own* (or have
  owned) Mavic ceramic rims (on- or off-road), or from experienced
  shop employees who have sold/replaced/trashed such rims.  Do they
  make a worthwhile contribution to braking?  Do they last?  Do they
  have any abnormal problems?  And of course, do they wear out brake
  pads at an astounding rate?

----------

Reply From: mk@prosun.first.gmd.de (Matthias Kessler)

  I have some first hand info. I own a pair of M-231s for three months.
  They're great. They definitely improve braking. In the wet they fade
  a little bit, there is a difference between braking in wet and dry
  conditions. But the braking is *much* better than on any other rim I
  have ridden so far. I have no problems with them, except for the
  price :). It looks like they don't wear at all. My dealer showed me
  his one's and claimed that they are 1 year old. They look unused!
  Brake wear is definitely higher than on other rims. I ride 20km
  every day to/from work and ~100km on weekends. My brake pads need
  replacement after three months.

----------
Reply From: praetzel@marconi.waterloo.edu

  It will be interesting to see a summary.  I believe the theoretical
  point against them was that the oxide coating is a good insulator
  and a problem may be melting of the pads under hard long braking.
  But then they may be no worse than normal anodized rims.

----------
Reply From: lars@craycos.com (Ron Larson)

  I built a set of wheels using the Open 4 cd ceramic rims for a road
  bike this spring.  I had talked to MAvic and they felt the ceramic rims
  would hold up to the wear of fine grit being ground into the rim when
  riding on wet roads or on mud (such as mountain bikes).  The reason
  these rims hold up is the hardness of the ceramic surface and the
  method of laying down the ceramic surface on the rim.  The Mavic
  spokesman said that he had seen rims with cracked ceramic from rim
  damage and the cracked ceramic did not flake or chip off.  At this
  point I would estimate that I have put almost 1500 miles on the
  wheels.  I can't say that they brake any better than my regular open 4
  cd wheels.  I will say that the ceramic surface has held up to grinding
  grit.  I built these wheels to ride on wet roads and diverse conditions
  and they have responded accordingly.  About two weeks ago I did notice
  that the rear rim had a small chip out of the ceramic on both
  surfaces.  After thinking about it for a while and inspecting the rim
  further, I remembered that I had "snakebit" the rear tire a week before
  by not taking the few minutes necessary to assure that the tire was up
  to preassure.  The only snakebite I have had this year - I have made a
  point of keeping tires up to preassure.  The snakebite culprit was
  confirmed by a flat spot in the rim and by the offset from the stem of
  the patch on the tube (now a spare).  This damage was my fault and has
  not spread - no additional chipping has occured.  You might consider
  how much rim damage you would do to a mountain bike rim.  I'm sure you
  know the cost of these rims or you wouldn't be asking for input.

  Hope this helps in some way.  I would be glad to answer specific
  questions if you have them.

----------
Reply From: lars@craycos.com (Ron Larson)

  I realized after sending the message that I meant to put in a little
  more on braking although it probably won't help much.  I do not notice
  any difference between the braking capability of the ceramic and non
  ceramic rims.  This is a very subjective statement. ("Duh...I squeeze
  on the handles and the bike stops!!!")  I have not attempted to perform
  any tests such as distance to stop from a given speed on the same
  section of road.  Without a more controlled, better calibrated
  instrument than my own forearms, I doubt that I could tell a
  difference.  I am switching back and forth between wheel sets over the
  next few days and will try to perform some simple test.  I will get
  back to you if there is a discernable difference in the braking
  distance.

----------
------------------------------------------------------------------------------
Steve Williams            stevew@hal.com          --------   __o
HaL Computer Systems                         -----------    -\<,
Austin, Texas                                   ......... (_)/(_)
Newsgroups: rec.bicycles,ott.general