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how much more air in cris holm rim?

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ÆX

Turbo Monkey
Sep 8, 2001
4,920
17
NM
OK, has anyone ever figed with the increase bead width how much
more air volume would the chis holm rim @ 38mm be over say
28mm of most other rims.

i got a pair now and really think it will help with pinch flats.

O also got a new fork. not running yet but close.

 
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Turbo Monkey
Sep 8, 2001
4,920
17
NM
yes, i cut it off. there was more flex after but i don't think any more than any other inverted fork. I am going to see how it rides, if it bugs me I will mold in a carbon arch.



 
hitekrdnk

hitekrdnk

Monkey
May 15, 2006
104
0
Bicyclist said:
Did you cut off the arch? I wonder if it'll be stiff enough.
Click to expand...
Doug Bradbury rode around all last summer on a through axle Travis with the arch cut off. He claims that the arch on a through axle fork is only there because people expect to see it there, not because it is needed.

I don't think your pinch flatting days are over yet with the Kris Holm rims Alex, that is the same setup I used on the SC Metisse in 05' with an Exi and pinch flats were the order of the day. Let's just put it this way, I set that bike back up as it was intended and no more front flats with a beefy sidewall tire. I am afraid that is what you are still going to be waiting for. Let me just say, patience is a virtue:clue: and you shouldn't have to be patient a whole lot longer.

I used a torus formula one time to calculate the difference in volume between 26" and 29" tires. It came out roughly that a 2.1 700c tire has the same volume as a 2.2 26" tire. Not sure if the rim width factors in a whole lot but here you go: http://whistleralley.com/torus/torus.htm
 
Bicyclist

Bicyclist

Turbo Monkey
Apr 4, 2004
10,152
2
SB
Yeah, I guess I just expected it to be there like you said.

Now that I think of it it's basically just as stiff as an inverted fork now.

I really want to try some 29s BCD. I wish they were more popular so I could hop on a pair and see if they were for me.
 
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Turbo Monkey
Sep 8, 2001
4,920
17
NM
I am really going to try and have a demo bcd 29 for next year.

People really have to see to believe or feel.
 
E

El Caballo

Chimp
Nov 21, 2004
61
0
East Bay, West Coast
<gets out the napkin>

Panaracer Rampage with 55mm casing width = 2374.6 mm2 cross section

Approximation: add an extra 10mm diameter from the 10mm extra width of the KH = 58.18mm wide on a KH = 2657.2 mm2 cross section

x2 / x1 = 1.119 = about 12% more air

The figure is probably somewhat larger because you add the 10mm as a chord, not around the circumference, and you get some air in the larger rim channel -- but that exceeds the capabilities of my napkin math. I can't imagine it would double the difference, though, so I'll guess about 15%.
 
shiggy

shiggy

Monkey
Oct 3, 2006
155
0
PDX
bcd said:
OK, has anyone ever figed with the increase bead width how much
more air volume would the chis holm rim @ 38mm be over say
28mm of most other rims.

i got a pair now and really think it will help with pinch flats.
Click to expand...
You can measure the tire on each with using the methods I use for my site. Casing width and casing height above the rim edge. Multiply width by height and you have the relative volume.
 
Lumberjack

Lumberjack

Monkey
Jan 24, 2003
633
0
PNW
Once the tire mfgr's use a dh type casing your pinch problems should go away. The width of the Kris Holm is right in line with the most popular dh rims Sun, Mavic, WTB, DT ect. 30.96-36 mm. Doesn't sound like the wait is going to be very long.
 
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ÆX

Turbo Monkey
Sep 8, 2001
4,920
17
NM
Lumberjack said:
Once the tire mfgr's use a dh type casing your pinch problems should go away. The width of the Kris Holm is right in line with the most popular dh rims Sun, Mavic, WTB, DT ect. 30.96-36 mm. Doesn't sound like the wait is going to be very long.
Click to expand...

a setup like slimes you can run XC sidewalls.

i ran a thorn proof road tube that i slit around the top so that it was
like a rinstrip that rapped around the bottom of my tube. its thick
rubber flapped out around the inside of my tire sidwalls and i stopped
getting flats. i really think dh sidwall 29 tires would weight too much.
i think we need just some extra rubber near the bead or a setup like
this slime tubless.

 
Lumberjack

Lumberjack

Monkey
Jan 24, 2003
633
0
PNW
A few years ago we tried a tire co out named Love Tires. They had us running their dh tire (which looked a lot like the old Onza tire) with dual compounds and were semi-tubeless.Their set up was very similar to Slime's. I have NOT run any of the Slime tires but you could not give me another set of Loves.
 
A

A.P

Monkey
Nov 21, 2005
423
0
boston
BCD, just throwing this out there but is it possible to put the reba 29'' lowers onto a boxxer? Seems like it would be solve you having to cut the arch off your fork.

There was a guy up here who ran a 29'' front wheel on his vp-free, for a tire he used 2 comp16's riveted together.
 
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Turbo Monkey
Sep 8, 2001
4,920
17
NM
A.P said:
BCD, just throwing this out there but is it possible to put the reba 29'' lowers onto a boxxer? Seems like it would be solve you having to cut the arch off your fork.

There was a guy up here who ran a 29'' front wheel on his vp-free, for a tire he used 2 comp16's riveted together.
Click to expand...
why has a reba to mesure? i think the leg spacing is to small.
you would have to run a QR front axle.
 
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ÆX

Turbo Monkey
Sep 8, 2001
4,920
17
NM
one point, i don't see the number differing more that .2mm
i was just wanting an average
 
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