29" inner tube in a Coker

Hi all,

I've read a number of posts on the subject of using a 29" tube in a
coker and as no one actually to have reported on actually doing it, I
though that I'd give it a go myself - out of curiosity as much as
anything so I got myself a 700x35-47 Hutchinson Buutyl inner tube and
popped it into the coker - it took a bit of fiddling to get the tyre on
but this was accomplished with out any pinch flats. I then inflated the
tyre to a bit less than 40 psi and then there was a loud woosh from the
tube and all the air decided it was time to leave - on removing the tube
I would about a 24" rip in it it where it had catastrophically failed.
Looking at the rip it pretty much runs down the middle of the tube so
not on any seems but at one poitn does seem to touch the fold line of
the tube where it was packed and the rubber there does show some signs
of perishing so possibly that was the cause of the flat.

So, the question is this, has any one actually tried it? and if so which
inner tube did you use? I was wondering whether it might be better to
use a latex tube as they're stretchier. I'm really keen to try this out
as the change of tube is going to save in the region of 400grams of
roatating weight which would be a most splendid thing however its
probably not worth the effort if it isn't going to be fairly reliable.
So if anyone as any thoughts post them as I'd be interested to here
about others experience. Am off to the bike shop now to see if they have
any other likely candidates onthe tube front

Cheers

Roland


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According to 'this' (http://tinyurl.com/6j5k9) thread, Tony has tried it
and it worked.


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Tony Melton has tried it, raced it, and as far as I know, not had any
problems with it.

I think it should work with a regular big 700C tube, but a 29" tube
might just give a bit more rubber contact.

I still would recommend a tubeless conversion over using a 29"/700C
inner tube though. More expensive, but it rides nicer and there is no
chance of pinch flats, and also there's gloop to seal up small holes.

Ken


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-daino149 -

-According to this thread, Tony has tried it and it worked.-

My search did turn up this thread but I was lazy and didn't read it due
to the title - thanks for flagging it up to me and I'll have more faith
in the search function in future

Thanks Ken for the recommendation on the tubeless conversion I'd read
your posts on doing this and thought that it perhaps sounded a bit of a
complex operationbut I might have more of a look into it although I
don't really understand how it works and keeps the air in - time for a
bit of research - you don't know what brand of tube Tony Melton is using
do you? as I said before, the failure of the hutchinson tube that I had
was fairly catastrophic jusdt about the time that it reached a suitable
pressure but perhaps I was just unlucky

Roland


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Hi Roland,

The tubeless conversion is not that complicated- I just measured the
circumference of the Coker rim with a piece of string, emailed Stan who
made me the rim strip. Stan might still have those measurements.
Anway, he sent me all the stuff needed to put it together (rim strip,
gloop and instructions), except I was too lazy to do that so I got my
local bike shop to do it. They didn't have any problems- said it was
straightforward as any other Stans Conversion

Tony checks RSU quite frequently, so probably expect him to reply early
in the week.


Ken


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I have been riding Coker with 700c WTB tube for 6 months. No problems
to date. It made my wheel noticeably lighter. The weight reduction was
most evident when accelerating and decelerating, but I even felt a
'swing weight' reduction when turning sharply. My Coker became more
responsive. I recommend it.

Installing the lighter tube began, for me, a bit explosively. When I
finally got it all back together and pumped it up to 50-60psi -- BANG!
After inspection I realized that I had pushed the rim strip aside and
exposed sharp surface nipples that popped the tube upon inflation.

I tried again, beginning the process by taping the rim strip in place
with a single wrap of electrical tape. I overinflated the tube alone
and stretched it a bit. Deflated it again and squished it in from the
side. Finished installing the tire, inflated it, and began riding. It
has been sweet ever since.

(I also think tubeless would be great, both reducing weight and
increasing performance, though I haven't tried it.)


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My Coker with 29" inner tube is still going strong - no problems yet. I
used either a WTB 29" inner or a Quality Bike Parts one. I needed a
washer to adapt the valve hole from schrader to presta (standard
schrader to presta valve adapters were too small for the hole.) A good
quality rim tape helps. I don't know what rim strip standard Cokers come
with, but it its a free rubber strip replace it with some wide rim tape
(the stick-in-place type).

Good luck Roland!

Do a search for username Dirtsurfer and you'll find some more tubeless
Coker threads. Dirtsurfer pioneered the tubeless Coker, I believe.


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Cheers for all the encouragement - I'm thinking that possibly my
"explosion" may have been caused by getting som grit in between the tyre
and the tub when I put the tyre in - so I'm going to get another tube
and try the 700c route again. Might then have a look at the tubeless
approach but the 700c tube version needs to be conquered first. I'll let
you know how it pans out - I'm prepared to perevere for that weight
saving


Roland


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