rec.sport.unicycling · Public discussion

Tight frame-tire fit

harper · 2006-01-02T18:24:47+00:00

My geared 29er, BlueShift, has a Big Apple tire on it right now. I started with the Nanoraptor which had quite a bit more clearance than the Big Apple. I like the ride of the Big Apple better, especially at high pressure. Our group went on a ride Saturday and I pumped the tire up to 60psig and brought it along. It made a grinding noise like a garbage disposal. I could still barely see clearance from the top of the tire to the bottom of the crown but the wheel was slightly out of true and it rubbed occassionally. Not enough to make the horrible grinding noise I was hearing. I thought it was one of the bearings going out. Wobbly-John was in town and he surmised that the tire picked up bits of grit and ground against the crown. I still thought that was not the problem, it was too loud. When I got home I let air out of the tire (down to 35psig) and the problem disappeared. In 5psig increments I found that I could run the tire at 50psig and still have clearance. The tire must have stretched over time because I remember (as well as I can still remember) that I had run it at 60psig before. I left the tire deflated while stored and put a large label on it reading "50 psig MAX." -- harper -Greg Harper B L U E S H I F T *jc is the only main man. there can be no other.* This is still my nth post....*AWESOME!!!* ------------------------------------------------------------------------ harper's Profile: http://www.unicyclist.com/profile/426 View this thread: http://www.unicyclist.com/thread/45764

Started by harper · 2 January 2006 · Last activity 19 January 2006 · 22 posts · 642 views

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01 / Original postTight frame-tire fitharper · 2 Jan 2006 02 / This pagePosts 1–20Page 1 of 2 · chronological order 03 / Latest replyPost #22lleberg · 19 Jan 2006

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Original section: rec.sport.unicycling
Published: 2 January 2006
Last activity: 19 January 2006
Original author: harper
Posts: 22
Discussion status: Public discussion
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Original post
harper
Archived post

2 January 2006, 18:24 UTC #1

My geared 29er, BlueShift, has a Big Apple tire on it right now. I
started with the Nanoraptor which had quite a bit more clearance than
the Big Apple. I like the ride of the Big Apple better, especially at
high pressure.
Our group went on a ride Saturday and I pumped the tire up to 60psig
and brought it along. It made a grinding noise like a garbage disposal.
I could still barely see clearance from the top of the tire to the
bottom of the crown but the wheel was slightly out of true and it
rubbed occassionally. Not enough to make the horrible grinding noise I
was hearing. I thought it was one of the bearings going out.
Wobbly-John was in town and he surmised that the tire picked up bits of
grit and ground against the crown. I still thought that was not the
problem, it was too loud. When I got home I let air out of the tire
(down to 35psig) and the problem disappeared. In 5psig increments I
found that I could run the tire at 50psig and still have clearance.
The tire must have stretched over time because I remember (as well as I
can still remember) that I had run it at 60psig before. I left the tire
deflated while stored and put a large label on it reading "50 psig
MAX."
--
harper
-Greg Harper
B L U E S H I F T
*jc is the only main man. there can be no other.*
This is still my nth post....*AWESOME!!!*
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forrestunifreak
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2 January 2006, 18:32 UTC #2

So what made the grinding noise?
--
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U-Turn
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2 January 2006, 18:38 UTC #3

forrestunifreak said:
So what made the grinding noise?
Musta been the Starbucks he was passing at the time.
--
U-Turn
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harper
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2 January 2006, 18:42 UTC #4

forrestunifreak said:
So what made the grinding noise?
Wobbly-John and U-Turn are correct. Grit from the road and coffee chaf
from Satrbucks were grinding on the crown.
--
harper
-Greg Harper
B L U E S H I F T
*jc is the only main man. there can be no other.*
This is still my nth post....*AWESOME!!!*
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Evan Byrne
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3 January 2006, 04:43 UTC #5

pics of the clearance? sounds pretty close.
--
Evan Byrne
"Guns cause crime like flies cause garbage." -Harper
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Klaas Bil
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3 January 2006, 06:55 UTC #6

harper said:
and put a large label on it reading "50 psig MAX."
You should add "also for unicyclists!" as you know unicyclists tend to
ignore max pressure labels on tyres.
That's interesting that the BA seems to have stretched. I have
carefully measured my BA size when it was new. Must remember (as well
as I can remember) to do it again. Although on average I have only 40 -
50 psi in there. This could be a way to increase your wheel size for
free, as much as air is for free.
--
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harper
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3 January 2006, 07:06 UTC #7

Clearance at 60 psig is zero. Clearance at 50 psig is 1mm. The increased
wheel diameter doesn't buy you much speed if it's dragging on the
crown.
--
harper
-Greg Harper
B L U E S H I F T
*jc is the only main man. there can be no other.*
This is still my nth post....*AWESOME!!!*
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harper
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3 January 2006, 07:13 UTC #8

'Here's a link to the clearance with the Nanoraptor tire.'
(http://tinyurl.com/d6wgw)
--
harper
-Greg Harper
B L U E S H I F T
*jc is the only main man. there can be no other.*
This is still my nth post....*AWESOME!!!*
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Evan Byrne
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3 January 2006, 08:32 UTC #9

harper said:
'Here's a link to the clearance with the Nanoraptor tire.'
(http://tinyurl.com/d6wgw)
that looks like plent of clearance.
--
Evan Byrne
"Guns cause crime like flies cause garbage." -Harper
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Loosemoose
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3 January 2006, 11:16 UTC #10

Harper said the Nano had plenty of clearance, its the BA thats giving
him the clearance problems.
Don't worry Harper, once you've got a few hundred miles on the beast
you'll have worn an extra mm from the tyre and will be able to get it
to 60psi no problem 😄. Just get riding!
Loose.
--
Loosemoose
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Officially a & ~ expert.
_no1_quote_of_crawley_2005:_
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Baz: "I think he's upstairs, balancing The Bishop"
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flyer
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3 January 2006, 13:49 UTC #11

I've never seen the frame of blueshift up close before. That thing is
beautiful. 50psi isn't bad in the BA though. I'd be pretty happy with
that.
--
flyer
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harper
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5 January 2006, 04:06 UTC #12

Tire-crown clearance of BlueShift frame with Big Apple tire at 60 psig.
+-------------------------------------------------------------------+
|Filename: BlueShift60psig.jpg |
|Download: http://www.unicyclist.com/attachment/11458 |
+-------------------------------------------------------------------+
--
harper
-Greg Harper
B L U E S H I F T
*jc is the only main man. there can be no other.*
This is still my nth post....*AWESOME!!!*
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harper
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5 January 2006, 04:07 UTC #13

Tire-crown clearance of BlueShift frame with Big Apple tire at 50 psig.
+-------------------------------------------------------------------+
|Filename: BlueShift50psig.jpg |
|Download: http://www.unicyclist.com/attachment/11459 |
+-------------------------------------------------------------------+
--
harper
-Greg Harper
B L U E S H I F T
*jc is the only main man. there can be no other.*
This is still my nth post....*AWESOME!!!*
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harper
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5 January 2006, 04:11 UTC #14

Evan Byrne said:
that looks like plent of clearance.
Evan-
The above two photos show the clearance with the Big Apple tire at the
two different pressures. Sorry I got so much wash out from the flash in
the second one. You can see through the frame in it at least.
--
harper
-Greg Harper
B L U E S H I F T
*jc is the only main man. there can be no other.*
This is still my nth post....*AWESOME!!!*
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tholub
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5 January 2006, 04:15 UTC #15

I'm running a Big Apple in a Sem XL frame, and it has similar clearance
issues. But I don't think the irregularities are due to wheel
imperfections, I think they're due to tire imperfections; I noticed the
problem the first time I rode the tire after building and truing the
wheel. With that much air in it, slight differences in the way the
tire bead is seated can make enough difference to rub the frame.
Like you, I can reliably run the tire in the narrow frame at 50 psi.
--
tholub
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unisk8r
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5 January 2006, 05:57 UTC #16

Greg, I have a Dremel with sanding drums, and a nice blue magic
marker...
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harper
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5 January 2006, 16:48 UTC #17

unisk8r said:
Greg, I have a Dremel with sanding drums, and a nice blue magic
marker...
Why would I want to grind a rubber tire and then try to color it blue?
--
harper
-Greg Harper
B L U E S H I F T
*jc is the only main man. there can be no other.*
This is still my nth post....*AWESOME!!!*
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underdog
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5 January 2006, 20:19 UTC #18

harper said:
Why would I want to grind a rubber tire and then try to color it blue?
LOL 😄 😄 :p 😄
--
underdog
'I tell you, we are here on Earth to fart around, and don't let anybody
tell you different' - Kurt Vonnegut
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gerblefranklin
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6 January 2006, 06:10 UTC #19

Harper, really, why not just shave a bit off the crown right there? Who
needs a dremel, that could be done with a file (actually, a half round
file is preferrable, since it won't clog as readily as a sanding disc).
Well, I guess I that won't happen...
I do like the look of that frame... Is it professionaly anodized, or a
homebrew job? Kudos if you did it yourself.
--
gerblefranklin
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there yet--Not nearly."--Cold Duck Complex
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harper
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6 January 2006, 07:04 UTC #20

gerblefranklin said:
Harper, really, why not just shave a bit off the crown right there? Who
needs a dremel, that could be done with a file (actually, a half round
file is preferrable, since it won't clog as readily as a sanding disc).
Well, I guess I that won't happen...
I do like the look of that frame... Is it professionaly anodized, or a
homebrew job? Kudos if you did it yourself.
Steve Howard designed and built the frame. He had it professionally
anodized. You know I'm not about to touch that frame with a file. How
are your projects coming along? Are you buying accessories for your
machine tools?
--
harper
-Greg Harper
B L U E S H I F T
*jc is the only main man. there can be no other.*
This is still my nth post....*AWESOME!!!*
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