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I'm really scared y'all are going to yell at me...



 
 
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  #1  
Old September 1st 05, 03:55 AM
Paul Hobson
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Posts: n/a
Default I'm really scared y'all are going to yell at me...

Ok, so I "finished" the old Peugeot to fixie convert today. Truth be
told, I need a shorter bottom bracket spindle, but that'll come later
(after my next paycheck).

So, to adjust the chainline to pretty darn good, I used spacers with the
chainwheel on the inside of the spider. All in all, the chainline was
off by about 2 mm (I know...I know). I used old stack bolts from my
BMX bike, and they seemed to work fairly well. I had to turn them
around since the female end didn't fit through the spacers
(shoddier...it just gets shoddier).

Then, I'm taking it out on a test run to the center of campus and I'm
spinning pretty fast down a decent hill. PING! Two of the stack bolts
fly off. scary scary scary. I slam on my front brake (my buddy, from
now on) and sure enough...they're gone.

My theory is this: I didn't tighten them enough and with the spacers,
they really couldn't thread enough. Will normal new short stack bolts
be long enough to deal with the spacers that I need for now??? Should I
get double chainring stack bolts and put more spacers on until I get the
new BB spindle???

thanks already...I'm still recovering from seeing my life before my eyes.
\\paul

--
Paul M. Hobson
Georgia Institute of Technology
..:change the words numbers
if you want to reply to me:.
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  #2  
Old September 1st 05, 08:55 AM
Luke
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Posts: n/a
Default I'm really scared y'all are going to yell at me...

In article , Paul Hobson
wrote:

Ok, so I "finished" the old Peugeot to fixie convert today. Truth be
told, I need a shorter bottom bracket spindle, but that'll come later
(after my next paycheck).

So, to adjust the chainline to pretty darn good, I used spacers with the
chainwheel on the inside of the spider. All in all, the chainline was
off by about 2 mm (I know...I know). I used old stack bolts from my
BMX bike, and they seemed to work fairly well. I had to turn them
around since the female end didn't fit through the spacers
(shoddier...it just gets shoddier).

Then, I'm taking it out on a test run to the center of campus and I'm
spinning pretty fast down a decent hill. PING! Two of the stack bolts
fly off. scary scary scary. I slam on my front brake (my buddy, from
now on) and sure enough...they're gone.

My theory is this: I didn't tighten them enough and with the spacers,
they really couldn't thread enough. Will normal new short stack bolts
be long enough to deal with the spacers that I need for now??? Should I
get double chainring stack bolts and put more spacers on until I get the
new BB spindle???


Here are few thoughts and observations.

On all of my cranks the chainring bolts engage enough of the nut so
that the bolt ends (threaded portion) are just shy of being flush with
the nut (as viewed from the inner side of the chainring). If your
chainring bolt/nut relation is similar, I'd hazard that enough of the
nut has been engaged by the bolt.

That said, I'm skeptical that your BMX (i.e., single chainring) stack
bolts, when used with chainring spacers, could properly engage enough
of the bolts' threads.

Relating to the subject, how much have you spaced your chainring to the
insider of the spider? The less distance the better as greater spacing
will tend to promote a shearing action (correct term?) on the chainring
bolts. Perhaps this, in conjunction with your reversal of the stack
bolts), and their used condition, may be behind the liberation of your
fasteners: Are the bolts actually loosening or is the lip of the nut
shearing off and the bolt pulling through the spider? This has happened
to me on occasion with aged, overtightened - and correctly orientated -
stack bolts.

I suggest you start from scratch. Get spacers that allow for the proper
orientation of the stack bolts
http://sheldonbrown.com/harris/singlespeed.html#cranks and dual
chainring stackbolts, then give it another try. Though this time,
consider avoiding racing down hills on the maiden test run!!

Luke
  #3  
Old September 1st 05, 11:10 AM
trg
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Posts: n/a
Default I'm really scared y'all are going to yell at me...

"Luke" a écrit dans le message de news:
...
In article , Paul Hobson
wrote:

Ok, so I "finished" the old Peugeot to fixie convert today. Truth be
told, I need a shorter bottom bracket spindle, but that'll come later
(after my next paycheck).

So, to adjust the chainline to pretty darn good, I used spacers with the
chainwheel on the inside of the spider. All in all, the chainline was
off by about 2 mm (I know...I know). I used old stack bolts from my
BMX bike, and they seemed to work fairly well. I had to turn them
around since the female end didn't fit through the spacers
(shoddier...it just gets shoddier).

Then, I'm taking it out on a test run to the center of campus and I'm
spinning pretty fast down a decent hill. PING! Two of the stack bolts
fly off. scary scary scary. I slam on my front brake (my buddy, from
now on) and sure enough...they're gone.

My theory is this: I didn't tighten them enough and with the spacers,
they really couldn't thread enough. Will normal new short stack bolts
be long enough to deal with the spacers that I need for now??? Should I
get double chainring stack bolts and put more spacers on until I get the
new BB spindle???


Here are few thoughts and observations.

On all of my cranks the chainring bolts engage enough of the nut so
that the bolt ends (threaded portion) are just shy of being flush with
the nut (as viewed from the inner side of the chainring). If your
chainring bolt/nut relation is similar, I'd hazard that enough of the
nut has been engaged by the bolt.

That said, I'm skeptical that your BMX (i.e., single chainring) stack
bolts, when used with chainring spacers, could properly engage enough
of the bolts' threads.

Relating to the subject, how much have you spaced your chainring to the
insider of the spider? The less distance the better as greater spacing
will tend to promote a shearing action (correct term?) on the chainring
bolts. Perhaps this, in conjunction with your reversal of the stack
bolts), and their used condition, may be behind the liberation of your
fasteners: Are the bolts actually loosening or is the lip of the nut
shearing off and the bolt pulling through the spider? This has happened
to me on occasion with aged, overtightened - and correctly orientated -
stack bolts.

I suggest you start from scratch. Get spacers that allow for the proper
orientation of the stack bolts
http://sheldonbrown.com/harris/singlespeed.html#cranks and dual
chainring stackbolts, then give it another try. Though this time,
consider avoiding racing down hills on the maiden test run!!

Luke


I assume you tightened each one a bit before proceeding to the next bolt to
tighten (not an adjacent one), until all were done?
Make sure you retighten the bolts after riding a bit.


  #4  
Old September 1st 05, 02:17 PM
Qui si parla Campagnolo
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Posts: n/a
Default I'm really scared y'all are going to yell at me...


Paul Hobson wrote:
Ok, so I "finished" the old Peugeot to fixie convert today. Truth be
told, I need a shorter bottom bracket spindle, but that'll come later
(after my next paycheck).

So, to adjust the chainline to pretty darn good, I used spacers with the
chainwheel on the inside of the spider. All in all, the chainline was
off by about 2 mm (I know...I know). I used old stack bolts from my
BMX bike, and they seemed to work fairly well. I had to turn them
around since the female end didn't fit through the spacers
(shoddier...it just gets shoddier).

Then, I'm taking it out on a test run to the center of campus and I'm
spinning pretty fast down a decent hill. PING! Two of the stack bolts
fly off. scary scary scary. I slam on my front brake (my buddy, from
now on) and sure enough...they're gone.

My theory is this: I didn't tighten them enough and with the spacers,
they really couldn't thread enough. Will normal new short stack bolts
be long enough to deal with the spacers that I need for now??? Should I
get double chainring stack bolts and put more spacers on until I get the
new BB spindle???

thanks already...I'm still recovering from seeing my life before my eyes.



Get track chainring bolts, mount the single ring onto the inside of the
crank.

  #5  
Old September 1st 05, 05:08 PM
Paul Hobson
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Posts: n/a
Default I'm really scared y'all are going to yell at me...

Qui si parla Campagnolo wrote:
Paul Hobson wrote:

I'm a bad fixie mechanic

thanks already...I'm still recovering from seeing my life before my eyes.




Get track chainring bolts, mount the single ring onto the inside of the
crank.


The chainring is on the inside already, and had spacers pushing it more
towards the inside. I'm really considering calling up Harris right now
and getting a new BB spindle.

\\paul

--
Paul M. Hobson
Georgia Institute of Technology
..:change the words numbers
if you want to reply to me:.
  #6  
Old September 1st 05, 11:11 PM
Luke
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Posts: n/a
Default I'm really scared y'all are going to yell at me...

In article , Paul Hobson
wrote:


The chainring is on the inside already, and had spacers pushing it more
towards the inside. I'm really considering calling up Harris right now
and getting a new BB spindle.

\\paul


Paul, I caution against haste. The spindle length you require to ensure
a proper chainline (sans spacers) with your current setup may be less
than that which your crankset will accept: your square taper crank may
but up against the BB's mounting ring, precluding a proper press fit.
Of course, this is contingent on the specs of the crankset, so exercise
due diligence beforehand and determine if this constraint applies in
your case -- doing so will spare you future headaches.

My favourite - and cheap! - cranks for fixie conversions? Old Shimano
RSX Dual chainring cranksets. I've installed them on spindle's as short
as 103mm.

Luke
  #7  
Old September 2nd 05, 12:02 AM
Paul Hobson
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Posts: n/a
Default I'm really scared y'all are going to yell at me...

Luke wrote:
In article , Paul Hobson
wrote:


The chainring is on the inside already, and had spacers pushing it more
towards the inside. I'm really considering calling up Harris right now
and getting a new BB spindle.

\\paul



Paul, I caution against haste. The spindle length you require to ensure
a proper chainline (sans spacers) with your current setup may be less
than that which your crankset will accept: your square taper crank may
but up against the BB's mounting ring, precluding a proper press fit.
Of course, this is contingent on the specs of the crankset, so exercise
due diligence beforehand and determine if this constraint applies in
your case -- doing so will spare you future headaches.

My favourite - and cheap! - cranks for fixie conversions? Old Shimano
RSX Dual chainring cranksets. I've installed them on spindle's as short
as 103mm.

Luke


Luke...thanks for the cautions. I'm really excited about this and I get
quite easily carried away. Currently I've a Stronglight 120 mm spindle
in the BB. I turned it around and put 3 mm spacers in there today (had
1.5 mm yesterday. I'd say the chainline is much better (1 mm off?). The
shop had much more spacers, so I feel that 4 would get a very nice
chainline.

The problem I'm now having is getting a proper and uniform chain tension
around the entire 6.2832 radian path. I'm thinking I need to drive
over to the rich old uncle's house and use his stand so that I can spine
the cranks/wheel and keep the bike upright.

\\paul

--
Paul M. Hobson
Georgia Institute of Technology
..:change the words numbers
if you want to reply to me:.
  #8  
Old September 2nd 05, 12:08 AM
Paul Hobson
external usenet poster
 
Posts: n/a
Default I'm really scared y'all are going to yell at me...

Luke wrote:
In article , Paul Hobson
wrote:


The chainring is on the inside already, and had spacers pushing it more
towards the inside. I'm really considering calling up Harris right now
and getting a new BB spindle.

\\paul



Paul, I caution against haste. The spindle length you require to ensure
a proper chainline (sans spacers) with your current setup may be less
than that which your crankset will accept: your square taper crank may
but up against the BB's mounting ring, precluding a proper press fit.
Of course, this is contingent on the specs of the crankset, so exercise
due diligence beforehand and determine if this constraint applies in
your case -- doing so will spare you future headaches.

My favourite - and cheap! - cranks for fixie conversions? Old Shimano
RSX Dual chainring cranksets. I've installed them on spindle's as short
as 103mm.

Luke


Oh...and look at this:
http://sheldonbrown.com/harris/bottombrackets.html
scroll down to "Old-style Cup-and-Cone Bottom Bracket Parts"

and this:
http://sheldonbrown.com/harris/frenc...ks.html#bottom
scroll down to "T.A. Bottom Bracket Spindles/Axle"

What is different about these spindles (aside from $35)?
Looking at my spindle, it's shaped exactly like the first link, and its
dimensions match that exactly. But, the website and shop make me think
that I should be replacing a Stronglight 120 mm spindle with the TA
Spindles?

SHELDON HELP!!!

\\paul
--
Paul M. Hobson
Georgia Institute of Technology
..:change the words numbers
if you want to reply to me:.
  #9  
Old September 2nd 05, 12:34 AM
Ravi
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Posts: n/a
Default I'm really scared y'all are going to yell at me...

Paul Hobson wrote:
Ok, so I "finished" the old Peugeot to fixie convert today. Truth be
told, I need a shorter bottom bracket spindle, but that'll come later
(after my next paycheck).


i cannot comment in this regard, since i just finished a Schwinn Varsity
- Fixie conversion and i decided to stay with the OPC (one piece crank)
it came with and hence the lone (small chainring). So all i had to do
was spacing the rear axle. i didn't want to change the cranks yet -
because these cranks are nice - except for the fact that i have to get
my LBS to special order me a pair of 1/2" pedals and clips.


Then, I'm taking it out on a test run to the center of campus and I'm
spinning pretty fast down a decent hill. PING! Two of the stack bolts
fly off. scary scary scary. I slam on my front brake (my buddy, from
now on) and sure enough...they're gone.


during my first test ride, there was a false flat and i was going down
it and i was spinning fast and the chain popped off. I had a longer
chain... I took a pair of links and it was all just fine. When the chain
popped off, i was lucky to have brakes to come to a gradual stop and
that the popped chain didn't interfere with the rotating wheel/cogs.
Also, i wasn't wearing a helm*t, coz i hadn't planned on riding that far
from home. Original plan was riding around in the parking lot

good luck and safe riding,
+ravi

My theory is this: I didn't tighten them enough and with the spacers,
they really couldn't thread enough. Will normal new short stack bolts
be long enough to deal with the spacers that I need for now??? Should I
get double chainring stack bolts and put more spacers on until I get the
new BB spindle???

thanks already...I'm still recovering from seeing my life before my eyes.
\\paul

  #10  
Old September 2nd 05, 03:45 AM
Luke
external usenet poster
 
Posts: n/a
Default I'm really scared y'all are going to yell at me...

In article , Paul Hobson
wrote:

Luke...thanks for the cautions. I'm really excited about this and I get
quite easily carried away. Currently I've a Stronglight 120 mm spindle
in the BB. I turned it around and put 3 mm spacers in there today (had
1.5 mm yesterday. I'd say the chainline is much better (1 mm off?). The
shop had much more spacers, so I feel that 4 would get a very nice
chainline.



The problem I'm now having is getting a proper and uniform chain tension
around the entire 6.2832 radian path. I'm thinking I need to drive
over to the rich old uncle's house and use his stand so that I can spine
the cranks/wheel and keep the bike upright.

\\paul


If I read you correctly, the chain tension varies with respect to the
crankset position. Even with fixie specific hardware this is the rule;
there isn't a chainring (regardless of price) that's perfectly
symmetrical; expect slight discrepancies in chain tension as the cranks
rotate. Set the chain tension while the cranks are positioned in their
'high spot' to avoid chain binding, and don't unduly trouble yourself.

This, of course, is assuming that the chainring or the crank's spider
is not deformed through impact or mechanical misadventure; placing them
on glass should determine whether there are significant shortcomings in
this regard.

Hope ya enjoy the fixie; they are fun! And once you master trackstands,
the girls on campus will be impressed!!! ;-)

Luke
 




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