MA3-to-Open Sport rims and tight 700c tires

[Scott Gordo]

I just had a wheel with a cracked MA3 rim replaced with an Open Sport,
and I'm having more trouble than usual getting the tire mounted.
Usually I can get them on without levers or with very minor
persuasion, but the same exact "worn-in" Michelin Axial tires that fit
fine on the MA3s needed significant plastic leverage to pop them on.
We're not talking hernia-inducing industrial strength force here, but
a good deal more than normal. What's worse is that while riding I
noticed the tire has a bit of a flat spot.

After checking for any inconsistencies in the rim itself, I swapped
the Axial with another used tire, a Bontrager this time. This one came
smoothly off a Mavic Reflex rim, but I had the same issues when
installed on the new Open Sport. (I should include that I also
installed a brand new, unpatched tube as well, even though the
previous tube looked fine.) I checked the tire's alignment on the rim
while inflating and pushed/pulled where it looked uneven, but without
much luck.

I think that the ERD between the MA3 and Open Sport rims is identical
or within a mm.

Is the diameter of the Open Sports much wider than the MA3s? If so,
are there tires people find work well with them? I hate to buy a new
tire because this is my "trickle down" bike, but if it gets rid of the
maddening flat spot then so be it.

TIA.

Scott

 

[jim beam]

Scott Gordo wrote:
> I just had a wheel with a cracked MA3 rim replaced with an Open Sport,
> and I'm having more trouble than usual getting the tire mounted.
> Usually I can get them on without levers or with very minor
> persuasion, but the same exact "worn-in" Michelin Axial tires that fit
> fine on the MA3s needed significant plastic leverage to pop them on.
> We're not talking hernia-inducing industrial strength force here, but
> a good deal more than normal. What's worse is that while riding I
> noticed the tire has a bit of a flat spot.
>
> After checking for any inconsistencies in the rim itself, I swapped
> the Axial with another used tire, a Bontrager this time. This one came
> smoothly off a Mavic Reflex rim, but I had the same issues when
> installed on the new Open Sport. (I should include that I also
> installed a brand new, unpatched tube as well, even though the
> previous tube looked fine.) I checked the tire's alignment on the rim
> while inflating and pushed/pulled where it looked uneven, but without
> much luck.
>
> I think that the ERD between the MA3 and Open Sport rims is identical
> or within a mm.
>
> Is the diameter of the Open Sports much wider than the MA3s? If so,
> are there tires people find work well with them? I hate to buy a new
> tire because this is my "trickle down" bike, but if it gets rid of the
> maddening flat spot then so be it.
>
> TIA.
>
> Scott
>

to me, the open sport seems to have a deeper central channel, not
shallower than the ma3. on that basis, the tire beads ought to be
looser, not tighter. are you making sure the beads are centered into
the channel as you go?

 

[daveornee]

I just had a wheel with a cracked MA3 rim replaced with an Open Sport,
and I'm having more trouble than usual getting the tire mounted.
Usually I can get them on without levers or with very minor
persuasion, but the same exact "worn-in" Michelin Axial tires that fit
fine on the MA3s needed significant plastic leverage to pop them on.
We're not talking hernia-inducing industrial strength force here, but
a good deal more than normal. What's worse is that while riding I
noticed the tire has a bit of a flat spot.

After checking for any inconsistencies in the rim itself, I swapped
the Axial with another used tire, a Bontrager this time. This one came
smoothly off a Mavic Reflex rim, but I had the same issues when
installed on the new Open Sport. (I should include that I also
installed a brand new, unpatched tube as well, even though the
previous tube looked fine.) I checked the tire's alignment on the rim
while inflating and pushed/pulled where it looked uneven, but without
much luck.

I think that the ERD between the MA3 and Open Sport rims is identical
or within a mm.

Is the diameter of the Open Sports much wider than the MA3s? If so,
are there tires people find work well with them? I hate to buy a new
tire because this is my "trickle down" bike, but if it gets rid of the
maddening flat spot then so be it.

TIA.

Scott

The Effective Rim Diameter is a dimension for spokes, not tire Bead Seat Diameter. 622 mm is the "standard" for Bead Seat Diameter (BSD). All 700C rims & tires are to meeet the 622 mm BSD. However, due to manufacturing tolerances and even spoke tension, exactly meeting the 622 mm standard rarely happens.

 

[Scott Gordo]

On Jul 31, 9:11 am, daveornee <daveornee.2ul...@no-
mx.forums.cyclingforums.com> wrote:
> Scott Gordo Wrote:
>
>
>
> > I just had a wheel with a cracked MA3 rim replaced with an Open Sport,
> > and I'm having more trouble than usual getting the tire mounted.
> > Usually I can get them on without levers or with very minor
> > persuasion, but the same exact "worn-in" Michelin Axial tires that fit
> > fine on the MA3s needed significant plastic leverage to pop them on.
> > We're not talking hernia-inducing industrial strength force here, but
> > a good deal more than normal. What's worse is that while riding I
> > noticed the tire has a bit of a flat spot.
>
> > After checking for any inconsistencies in the rim itself, I swapped
> > the Axial with another used tire, a Bontrager this time. This one came
> > smoothly off a Mavic Reflex rim, but I had the same issues when
> > installed on the new Open Sport. (I should include that I also
> > installed a brand new, unpatched tube as well, even though the
> > previous tube looked fine.) I checked the tire's alignment on the rim
> > while inflating and pushed/pulled where it looked uneven, but without
> > much luck.
>
> > I think that the ERD between the MA3 and Open Sport rims is identical
> > or within a mm.
>
> > Is the diameter of the Open Sports much wider than the MA3s? If so,
> > are there tires people find work well with them? I hate to buy a new
> > tire because this is my "trickle down" bike, but if it gets rid of the
> > maddening flat spot then so be it.
>
> > TIA.
>
> > Scott
>
> The Effective Rim Diameter is a dimension for spokes, not tire Bead
> Seat Diameter. 622 mm is the "standard" for Bead Seat Diameter (BSD).
> All 700C rims & tires are to meeet the 622 mm BSD. However, due to
> manufacturing tolerances and even spoke tension, exactly meeting the
> 622 mm standard rarely happens.
>
> --
> daveornee- Hide quoted text -
>
> - Show quoted text -

I just flatted on the way in, so I'll get another opportunity to be
sure that the beads sit properly pre-inflation
Thanks for the info on BSD. I knew ERD wasn't the same thing, I was
just using it to suggest that the rim is the same dimensionally as far
as spoke length goes anyway. The fact that all 700s should have a
622mm BSD makes that moot, obviously.
With that said, I've definitely had tires that fit tighter or more
loosely on my MTB's rims. This is, as you said, likely due to
inconsistencies in the manufacturing process, but are there any
recommendation for road tires that have a tendency to run slightly
bigger?

/s

 

[A Muzi]

>> Scott Gordo Wrote:
>>> I just had a wheel with a cracked MA3 rim replaced with an Open Sport,
>>> and I'm having more trouble than usual getting the tire mounted.
>>> Usually I can get them on without levers or with very minor
>>> persuasion, but the same exact "worn-in" Michelin Axial tires that fit
>>> fine on the MA3s needed significant plastic leverage to pop them on.
>>> We're not talking hernia-inducing industrial strength force here, but
>>> a good deal more than normal. What's worse is that while riding I
>>> noticed the tire has a bit of a flat spot.
>>> After checking for any inconsistencies in the rim itself, I swapped
>>> the Axial with another used tire, a Bontrager this time. This one came
>>> smoothly off a Mavic Reflex rim, but I had the same issues when
>>> installed on the new Open Sport. (I should include that I also
>>> installed a brand new, unpatched tube as well, even though the
>>> previous tube looked fine.) I checked the tire's alignment on the rim
>>> while inflating and pushed/pulled where it looked uneven, but without
>>> much luck.
>>> I think that the ERD between the MA3 and Open Sport rims is identical
>>> or within a mm.
>>> Is the diameter of the Open Sports much wider than the MA3s? If so,
>>> are there tires people find work well with them? I hate to buy a new
>>> tire because this is my "trickle down" bike, but if it gets rid of the
>>> maddening flat spot then so be it.

> daveornee <[email protected]> wrote:
>> The Effective Rim Diameter is a dimension for spokes, not tire Bead
>> Seat Diameter. 622 mm is the "standard" for Bead Seat Diameter (BSD).
>> All 700C rims & tires are to meeet the 622 mm BSD. However, due to
>> manufacturing tolerances and even spoke tension, exactly meeting the
>> 622 mm standard rarely happens.

Scott Gordo wrote:
> I just flatted on the way in, so I'll get another opportunity to be
> sure that the beads sit properly pre-inflation
> Thanks for the info on BSD. I knew ERD wasn't the same thing, I was
> just using it to suggest that the rim is the same dimensionally as far
> as spoke length goes anyway. The fact that all 700s should have a
> 622mm BSD makes that moot, obviously.
> With that said, I've definitely had tires that fit tighter or more
> loosely on my MTB's rims. This is, as you said, likely due to
> inconsistencies in the manufacturing process, but are there any
> recommendation for road tires that have a tendency to run slightly
> bigger?

A regular customer was just in *****ing and moaning about how hard his
tire was to remove. After we took out 2 thick rim liners and installed
one thin Torelli rim liner the tire mounted easily (normally). Check that.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971