Brian Engelen

The "pulsing brake" thing has happened to me on my winter mountain bike
wheels. Most noticeable when I install a high pressure tire, like a
commuter tire. The higher air pressure creates more side force on the rim,
causing it to bulge outward.

Just for fun, or educational reasons, cut the old rim crosswise and take a
look at the cross section. Also, you will probably be surprised how easy it
is to bend the rim.

Brian

-----Original Message-----
From: obra-bounces@list.obra.org [mailto:obra-bounces@list.obra.org] On
Behalf Of Jeff Wills
Sent: Tuesday, August 22, 2006 10:19 PM
To: obra@list.obra.org; news4joel@gmail.com
Subject: [OBRA Chat] worn rims

>How can you tell when your rims need replacing? I noticed that the rear
rim
>on my commuter is getting a concave profile on the braking surface and I'm
>wondering when it's unsafe to ride.

If you can measure the minimum thickness, I'd replace the rim when it gets
below 0.9mm. This is what happens if you let it go too long:
http://home.pacifier.com/~jwills/rites2005/pages/rites042.htm

--
Jeff Wills

------------------------------------------------------------
Make plans now to attend the Portland Human Power Challenge:
http://www.ohpv.org/PIR/index.htm
and the Recumbent Retreat:
http://www.recumbentretreat.org/
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Jeff Wills

>How can you tell when your rims need replacing? I noticed that the rear rim
>on my commuter is getting a concave profile on the braking surface and I'm
>wondering when it's unsafe to ride.

If you can measure the minimum thickness, I'd replace the rim when it gets below 0.9mm. This is what happens if you let it go too long:
http://home.pacifier.com/~jwills/rites2005/pages/rites042.htm

--
Jeff Wills

------------------------------------------------------------
Make plans now to attend the Portland Human Power Challenge:
http://www.ohpv.org/PIR/index.htm
and the Recumbent Retreat:
http://www.recumbentretreat.org/
------------------------------------------------------------

Joel Morrissette

Eyeletted rims. Looks like the nipple was crushed somehow. Looks like I
can back it out, replace and true without any issues. I'm the second owner
- who knows what happened before me. Ditto on the braking technique. I'm
really diligent about front-braking, but the guy before me may not have
been.

On 8/22/06, Dan H wrote:
>
> Is the rim eyeleted? Are the nipples alloy? Nipple heads pop off because
> they got scored when the wheel was built. When I build a non eyeleted wheel
> like a Velocity for example, I chamfer the nipple holes and antisieze the
> bearing shoulder of the nipple to help protect it and facilitate smooth
> turning action.
> You can probably get away with just replacing the broken nipple.
>
>
> ----- Original Message -----
> *From:* Joel Morrissette
> *To:* obra@list.obra.org
> *Sent:* Tuesday, August 22, 2006 1:54 PM
> *Subject:* Re: [OBRA Chat] worn rims
>
> Wow - great responses. Going to get a new rim tonight.
>
> Followup question. I had a spoke nipple crack on the front wheel, which I
> plan to back out and replace when I rebuild the rear (it's still intact
> through the rim). Is this indicative of aging of the nipples in general,
> and should I rebuild the front while I'm at it?
>
> -Joel
>
> On 8/22/06, Joel Morrissette wrote:
> >
> > How can you tell when your rims need replacing? I noticed that the rear
> > rim on my commuter is getting a concave profile on the braking surface and
> > I'm wondering when it's unsafe to ride.
> >
> > Thanks.
> > -Joel
> >
> > --
> > __o "It never gets easier,
> > _ \<_ you just go faster."
> > (_)/(_) -- Greg LeMond
> >
>
>
>
> --
> __o "It never gets easier,
> _ \<_ you just go faster."
> (_)/(_) -- Greg LeMond
>
> ------------------------------
>
> _______________________________________________
> OBRA mailing list
> obra@list.obra.org
> http://list.obra.org/mailman/listinfo/obra
> Unsubscribe: obra-unsubscribe@list.obra.org
>
>

--
__o "It never gets easier,
_ \<_ you just go faster."
(_)/(_) -- Greg LeMond

Dan H

Is the rim eyeleted? Are the nipples alloy? Nipple heads pop off because they got scored when the wheel was built. When I build a non eyeleted wheel like a Velocity for example, I chamfer the nipple holes and antisieze the bearing shoulder of the nipple to help protect it and facilitate smooth turning action.
You can probably get away with just replacing the broken nipple.

----- Original Message -----
From: Joel Morrissette
To: obra@list.obra.org
Sent: Tuesday, August 22, 2006 1:54 PM
Subject: Re: [OBRA Chat] worn rims

Wow - great responses. Going to get a new rim tonight.

Followup question. I had a spoke nipple crack on the front wheel, which I plan to back out and replace when I rebuild the rear (it's still intact through the rim). Is this indicative of aging of the nipples in general, and should I rebuild the front while I'm at it?

-Joel

On 8/22/06, Joel Morrissette wrote:
How can you tell when your rims need replacing? I noticed that the rear rim on my commuter is getting a concave profile on the braking surface and I'm wondering when it's unsafe to ride.

Thanks.
-Joel

--
__o "It never gets easier,
_ \<_ you just go faster."
(_)/(_) -- Greg LeMond

--
__o "It never gets easier,
_ \<_ you just go faster."
(_)/(_) -- Greg LeMond

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Dan H

KG and David are right. That thing could fail at the worst time. I've seen several. Another point; if your rear rim (and pads) is wearing faster than your front, your braking technique is backwards. Consider swapping the controls so right lever is front brake. Emphasis should be on the front brake for optimal braking performance and control.
Did your mom tell you "don't use the front brake, you'll flip over the bars!" I have practiced trying to flip over the bars and it's not that easy.
----- Original Message -----
From: Joel Morrissette
To: obra@list.obra.org
Sent: Tuesday, August 22, 2006 11:07 AM
Subject: [OBRA Chat] worn rims

How can you tell when your rims need replacing? I noticed that the rear rim on my commuter is getting a concave profile on the braking surface and I'm wondering when it's unsafe to ride.

Thanks.
-Joel

--
__o "It never gets easier,
_ \<_ you just go faster."
(_)/(_) -- Greg LeMond

------------------------------------------------------------------------------

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John Parsons

Replace them now. If the rim looks concave, it's on the way out. When
the rims on my commuter wore through, I replaced them with
ceramic-coated ones. They are supposed to be much more resistant to
that time of wear.

>>> "Joel Morrissette" 8/22/2006 11:07:36 AM >>>
How can you tell when your rims need replacing? I noticed that the
rear rim
on my commuter is getting a concave profile on the braking surface and
I'm
wondering when it's unsafe to ride.

Thanks.
-Joel

--
__o "It never gets easier,
_ \<_ you just go faster."
(_)/(_) -- Greg LeMond

Joel Morrissette

Wow - great responses. Going to get a new rim tonight.

Followup question. I had a spoke nipple crack on the front wheel, which I
plan to back out and replace when I rebuild the rear (it's still intact
through the rim). Is this indicative of aging of the nipples in general,
and should I rebuild the front while I'm at it?

-Joel

On 8/22/06, Joel Morrissette wrote:
>
> How can you tell when your rims need replacing? I noticed that the rear
> rim on my commuter is getting a concave profile on the braking surface and
> I'm wondering when it's unsafe to ride.
>
> Thanks.
> -Joel
>
> --
> __o "It never gets easier,
> _ \<_ you just go faster."
> (_)/(_) -- Greg LeMond
>

--
__o "It never gets easier,
_ \<_ you just go faster."
(_)/(_) -- Greg LeMond

.David.Auker.

I don't know of any actual measurement to make on the rim, but yes, they
crack after long use by braking (especially in the grimy, gritty
winter...another benefit of fendered fixed-gear in the wet; wear your
legs, not your rims!). A clincher rim holding the tire pressure will
push the crack open...once, when sprinting up a little hill with Carl
Roberts, we heard a fairly loud CRACK! right as we summited, and it was
his rim signaling its end of life. (Luckily, we had a cell phone, and
Carl had a wheel delivered to out location out on Wisteria, West Linn!)

David

Joel Morrissette wrote:

> How can you tell when your rims need replacing? I noticed that the
> rear rim on my commuter is getting a concave profile on the braking
> surface and I'm wondering when it's unsafe to ride.
>
> Thanks.
> -Joel
>
> --
> __o "It never gets easier,
> _ \<_ you just go faster."
> (_)/(_) -- Greg LeMond
>
>------------------------------------------------------------------------
>
>_______________________________________________
>
>

KG

It's unsafe to ride. I had a rim blow out on me from that. Most wheels now have a wear indicator groove that shows how much width you have left on your rim.

----- Original Message ----
From: Joel Morrissette
To: obra@list.obra.org
Sent: Tuesday, August 22, 2006 11:07:36 AM
Subject: [OBRA Chat] worn rims

How can you tell when your rims need replacing? I noticed that the rear rim on my commuter is getting a concave profile on the braking surface and I'm wondering when it's unsafe to ride.

Thanks.
-Joel

--
__o "It never gets easier,
_ \<_ you just go faster."
(_)/(_) -- Greg LeMond_______________________________________________
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obra@list.obra.org
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Unsubscribe: obra-unsubscribe@list.obra.org

Joel Morrissette

How can you tell when your rims need replacing? I noticed that the rear rim
on my commuter is getting a concave profile on the braking surface and I'm
wondering when it's unsafe to ride.

Thanks.
-Joel

--
__o "It never gets easier,
_ \<_ you just go faster."
(_)/(_) -- Greg LeMond