Differential strength in rear rims

Given the significantly different loads and compromises in building that a rear rim must endure
compared to a front (esp on Campy hubs) why is that manufacturers do not sell "beefed up" rims with
greater endurance for the rear ?

If a wheel is going to give trouble, odds on it will be the rear, but why do we just accept this
must be so?

Or does somebody do this? - all the rims I see seem to start out with no structural differences
between front and rear when they leave the manufacturer.

best, Andrew

Andrew Price <arathorn@bigpond.net.au.x1> wrote:
> Given the significantly different loads and compromises in building that a rear rim must endure
> compared to a front (esp on Campy hubs) why is that manufacturers do not sell "beefed up" rims
> with greater endurance for the rear ?

> If a wheel is going to give trouble, odds on it will be the rear, but why do we just accept this
> must be so?

The "compromises" have to do with the dish required for the rear wheel, as well as the drive torque.
I don't see how a stronger rim would help that.

During normal riding, the rear wheel supports a bit more weight, but during hard braking, the front
wheel actually supports much more weight.

Nothing says you have to use the same rims or the same number of spokes front and rear. I'm really
not in favor of manufacturers selling "matched sets." One tire manufacturer is already doing that
(i.e., you can't buy one tire, you have to buy a "set").

Art Harris

"Andrew Price" <arathorn@bigpond.net.au.x1> wrote:

> Given the significantly different loads and compromises in building that a rear rim must endure
> compared to a front (esp on Campy hubs) why is that manufacturers do not sell "beefed up" rims
> with greater endurance for the rear ?

> If a wheel is going to give trouble, odds on it will be the rear, but why do we just accept this
> must be so?

> Or does somebody do this? - all the rims I see seem to start out with no structural differences
> between front and rear when they leave the manufacturer.

A few manufacturers - Bontrager and Ritchey, for example - have produced rear-specific rims with the
spoke bed offset leftward to reduce dish. A more common approach is simply to use more spokes in the
rear wheel than in the front. Many pre-built boutique wheels do so, and the norm in Britain for many
decades was a 32h front with a 40h rear, even for dishless (hub-gear and single-speed) wheels.

Faced with a cracked rear Mavic 517 recently, I began to wonder why Mavic hadn't seized the
opportunty to further pursue product differentiation with a rear-specific version - double eyelets
for the drive side spokes.

James Thomson

Andrew-<< Given the significantly different loads and compromises in building that a rear rim must
endure compared to a front (esp on Campy hubs) why is that manufacturers do not sell "beefed up"
rims with greater endurance for the rear ? >><BR><BR>

They do, all makers make heavier, beefier rims and they can be used on the front w/o penalty. Also a
lot make OCR rears, also a good idea. We build many wheelsets with say a Fusion in the rear and then
an Aerohead in the front, no big deal.

andrew<< If a wheel is going to give trouble, odds on it will be the rear, but why do we just accept
this must be so? >><BR><BR>

See above. I think you think using a beefier rim in the front is some sort of disadvantage,
it is not.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

"Andrew Price" <arathorn@bigpond.net.au.x1> wrote in message news:<8lxKb.80176$aT.792@news-server.bigpond.net.au>...
> Given the significantly different loads and compromises in building that a rear rim must endure
> compared to a front (esp on Campy hubs) why is that manufacturers do not sell "beefed up" rims
> with greater endurance for the rear ?

Don't they? From my perspective, which is tubular rims, the problem is the opposite- it's hard to
find rims for front wheels that are not excessively heavy because they are designed to take rear
wheel loads. Lightweight tubular rims that were completely satisfactory for front wheels have almost
disappeared in the last ten years or so.

There are those offset profile rims that are rear-specific.

JP

Adding to the list of offset rear rims; Velocity recently produced my fav. At 21mm ht.,20mm. wide,
420gm., it has everything I want. Tom

--
Bruni Bicycles
"Where art meets science"
brunibicycles.com
410.426.3420
Qui si parla Campagnolo <vecchio51@aol.com> wrote in message
news:20040106085823.11114.00002400@mb-m11.aol.com...
> Andrew-<< Given the significantly different loads and compromises in
building
> that a
> rear rim must endure compared to a front (esp on Campy hubs) why is that
> manufacturers do not sell "beefed up" rims with greater endurance for the
> rear ? >><BR><BR>
>
> They do, all makers make heavier, beefier rims and they can be used on the
> front w/o penalty. Also a lot make OCR rears, also a good idea. We build
many
> wheelsets with say a Fusion in the rear and then an Aerohead in the front,
no
> big deal.
>
> andrew<< If a wheel is going to give trouble, odds on it will be the rear,
but
> why do
> we just accept this must be so? >><BR><BR>
>
> See above. I think you think using a beefier rim in the front is some sort
of
> disadvantage, it is not.
>
>
>
>
> Peter Chisholm
> Vecchio's Bicicletteria
> 1833 Pearl St.
> Boulder, CO, 80302
> (303)440-3535
> http://www.vecchios.com
> "Ruote convenzionali costruite eccezionalmente bene"

James Thomson wrote:
> Faced with a cracked rear Mavic 517 recently, I began to wonder why Mavic hadn't seized the
> opportunty to further pursue product differentiation with a rear-specific version - double eyelets
> for the drive side spokes.

essentially, they have. the mavic x618 is pretty much the same as a 517, but with double eyelets. i
have them on the rear of my mtb & commuter and they've been great.

jb

On Tue, 6 Jan 2004 14:18:54 +0100, "James Thomson"
<yosnappyj@hotmail.com> wrote:

>Faced with a cracked rear Mavic 517 recently,

A cracked Mavic 517! There's a surprise.

Don't forget to buy another Mavic.

vecchio51@aol.com (Qui si parla Campagnolo) wrote in message news:<20040106085823.11114.00002400@mb-m11.aol.com>...
> Andrew-<< Given the significantly different loads and compromises in building that a rear rim must
> endure compared to a front (esp on Campy hubs) why is that manufacturers do not sell "beefed up"
> rims with greater endurance for the rear ? >><BR><BR>
>
> They do, all makers make heavier, beefier rims and they can be used on the front w/o penalty. Also
> a lot make OCR rears, also a good idea. We build many wheelsets with say a Fusion in the rear and
> then an Aerohead in the front, no big deal.
>
> andrew<< If a wheel is going to give trouble, odds on it will be the rear, but why do we just
> accept this must be so? >><BR><BR>
>
> See above. I think you think using a beefier rim in the front is some sort of disadvantage,
> it is not.

Nothing matches the reassuring feel of road-hugging weight in a beefy front rim.

JP

"jim beam" <uce@ftc.gov> wrote:

> James Thomson wrote:

> > Faced with a cracked rear Mavic 517 recently, I began to wonder why Mavic hadn't seized the
> > opportunty to further pursue product differentiation with a rear-specific version - double
> > eyelets for the drive side spokes.

> essentially, they have. the mavic x618 is pretty much the same as a 517, but with double eyelets.
> i have them on the rear of my mtb & commuter and they've been great.

I replaced my 517 with a 618, and have used 618s before (they don't seem to be in the 2004
product range, by the way). My point was that a rear rim that suffers cracking around only the
drive-side eyelets requires reinforcement only around the drive-side eyelets. Mavic have chosen
to strengthen the rim face as a whole (717). Product differentiation being the order of the day,
I'm surprised that they didn't see this opportunity to brach out into rear-specific rims with
differential eyelets.

James Thomson

"Chris B." <bikerider@-NOSPAM_THANKS-rogers.com> wrote:

> A cracked Mavic 517! There's a surprise.

It wasn't a great surprise to me at the time it happened: I'd already read of several cases of 517s
cracking. I hadn't come across these reports at the time I bought the rim, and the other two 517s
I'd used had been reliable.

> Don't forget to buy another Mavic.

Thank you for your kind advice. Which of Mavic's many models would you suggest I not forget to buy?

James Thomson

Socsec-<< Lightweight tubular rims that were completely satisfactory for front wheels have almost
disappeared in the last ten years or so. >><BR><BR>

Velocity Escape, really nice tubie rim.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

vecchio51@aol.com (Qui si parla Campagnolo) wrote in message news:<20040107090533.14191.00002770@mb-m28.aol.com>...
> Socsec-<< Lightweight tubular rims that were completely satisfactory for front wheels have almost
> disappeared in the last ten years or so. >><BR><BR>
>
> Velocity Escape, really nice tubie rim.
>
> Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
> (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

I have looked at them before, but they are still 390g when 330 would be more than enough. Machined
sidewalls and black anodizing are not what I want either. I have come close to ordering them,
though, because they do seem to me about the best of what's currently available.

JP

SocSecTrainWreck@earthlink.net (JP) wrote in message news:<1f323b67.0401060749.51b74e93@posting.google.com>...
> "Andrew Price" <arathorn@bigpond.net.au.x1> wrote in message

> From my perspective, which is tubular rims, the problem is the opposite- it's hard to find rims
> for front wheels that are not excessively heavy because they are designed to take rear wheel
> loads. Lightweight tubular rims that were completely satisfactory for front wheels have almost
> disappeared in the last ten years or so.
>
> There are those offset profile rims that are rear-specific.
>
> JP

In 700c size, the Zipp 280 rim (from 303 series wheels) is 285 grams and very durable
(excluding some early 2002 examples that had quality problems). Even with the offset rear
wheel, these have proven to be great commuter rims for me. Way better than Super Champion
Performance at 290 - 300 grams or Fiamme Ergal at 280 gram. Those aluminum rims had a tough
time with the offset of 6 speed hubs and low spoke count. My Zipp carbon rear is 28 spokes on
9speed hub and I weigh 170 lbs these days (ugh). But if your goal is to learn how to build
wheels, there is nothing like the Performance or Ergal rims. Once you get them to be reliable
on the rear with low spoke count, you'll be able to build anything.

Edd

"Andrew Price" <arathorn@bigpond.net.au.x1> wrote in message news:<8lxKb.80176$aT.792@news-server.bigpond.net.au>...

> Given the significantly different loads and compromises in building that a rear rim must endure
> compared to a front (esp on Campy hubs) why is that manufacturers do not sell "beefed up" rims
> with greater endurance for the rear ?

I often build wheels with more spokes in the rear. Generally 36 spoke rear and 32 spoke front or 32R
28F. I considered 36R 28F but the problem here is that few rims available in 36 hole also come in 28
and I like the rims to match.

> If a wheel is going to give trouble, odds on it will be the rear, but why do we just accept this
> must be so?

I find that most front rims wear out from braking long before the rears because experienced
riders use the front brakes more than rears. From this point of view the front rim should be
beefier than the rear.

Several years I had a short but very hilly commute to work. My front rims were wearing out with
alarming frequency. I looked for a cheap drum brake to build into my front wheel to solve this
problem but I couldn't turn anything up. Then I had an idea, I built a front wheel with an old steel
rim. This solved my problem. Cheap (I built my commuter bike from old parts and had little more than
$20 in the whole bike) and no more front rim wear. It was strange for a 531 db frame with good parts
to have a steel rim but it was the answer to my problem.

best,
--
Bruce Jackson - Sr. Systems Programmer - DMSP, a M/A/R/C Group comapny