Stripped single speed hub

Paul said:

I
cannibalized a plastic 10s spacer to put between the fixed cog and the
lockring. The lockring then was able to be very tightly screwed onto
the hub.

I'm curious - was the spacer still in good shape after the incident, or
was it chewed up a bit? Maybe the back/normal pedaling cycles furred it
enough to allow some slack on the sprocket, and that caused the
stripping later.

Urbane is very good - they probably have had a hand in 50% of the fixed
gears in Toronto.

In article <[email hidden]>,

Paul said:

1. Does this make any sense? It strikes me that the force on the
threads would be the same for any similar ratios, no matter how they
are arrived at.

Correct. You need a cog that has wider threads to full engage the hub.

Quoted message said:

2. The wheel was their least expensive. Should I spring for a wheel
with a more expensive hub (they also sell Dura-ace and Phil Wood)? I
found that I really like the feeling of a fixie and am willing to
invest more money after my first experiment. I'm 230 lbs, and fairly
strong, but I can't be generating the power of a real track racer, and
presumably they are not stripping their hubs every tenth ride.

They don't weigh 230 and aren't climbing steep hills out of the saddle.
You are probably putting as much or more strain on the threads of the
hub shell than any track racer. The possible exception is racers doing
the Kilo, since they start sprinting from a standing start.

Quoted message said:

3. Is my frequent back-pedalling the problem?

No. Well, probably not. But then again if you were rocking the cog
back and forth on the hub shell threads, you might have worn them a bit
and that might have contributed to them stripping. However, I read
complaints about the threads stripping out on cheap track hubs fairly
regularly.

Quoted message said:

4. Should the lockring not hold the cog on without intervening
spacers?

Correct. Or at least you should use a metal spacer.

Brian:

The spacer was just like new. I had not felt anything like a loosening
or slip of the cog when back pedalling.
Any opinion on the more expensive hub option?

Paul

Brian Huntley said:

Paul said:

I
cannibalized a plastic 10s spacer to put between the fixed cog and the
lockring. The lockring then was able to be very tightly screwed onto
the hub.

I'm curious - was the spacer still in good shape after the incident, or
was it chewed up a bit? Maybe the back/normal pedaling cycles furred it
enough to allow some slack on the sprocket, and that caused the
stripping later.

Urbane is very good - they probably have had a hand in 50% of the fixed
gears in Toronto.

Thanks for your quick reply.

Tim McNamara said:

In article <[email hidden]>,

Paul said:

1. Does this make any sense? It strikes me that the force on the
threads would be the same for any similar ratios, no matter how they
are arrived at.

Correct. You need a cog that has wider threads to full engage the hub.

I have two generic/no-name track cogs and now, a Phil Wood cog. They
are all the same width. Do you know of any cogs that are wider?

Quoted message said:

Quoted message said:

2. The wheel was their least expensive. Should I spring for a wheel
with a more expensive hub (they also sell Dura-ace and Phil Wood)? I
found that I really like the feeling of a fixie and am willing to
invest more money after my first experiment. I'm 230 lbs, and fairly
strong, but I can't be generating the power of a real track racer, and
presumably they are not stripping their hubs every tenth ride.

They don't weigh 230 and aren't climbing steep hills out of the saddle.
You are probably putting as much or more strain on the threads of the
hub shell than any track racer. The possible exception is racers doing
the Kilo, since they start sprinting from a standing start.

Quoted message said:

3. Is my frequent back-pedalling the problem?

No. Well, probably not. But then again if you were rocking the cog
back and forth on the hub shell threads, you might have worn them a bit
and that might have contributed to them stripping. However, I read
complaints about the threads stripping out on cheap track hubs fairly
regularly.

Until the day that it failed, the cog had not felt like it had even a
bit of "give". I don't know if imperceptible rocking might have
occurred. If you have read about the threads of cheap track hubs
giving out, would you then say that this would not occur with the
expensive kind?

Quoted message said:

Quoted message said:

4. Should the lockring not hold the cog on without intervening
spacers?

Correct. Or at least you should use a metal spacer.

Thanks again for advice.

Paul

Paul said:

This autumn, I converted a road bike to a fixed gear 34/15. I had
purchased a wheel with a QuandoXT fixed/free hub. My cog was not wide
enough to be held in place by the (left-threaded) lockring so I
cannibalized a plastic 10s spacer to put between the fixed cog and the
lockring. The lockring then was able to be very tightly screwed onto
the hub.
I live in a very hilly area, and was in the habit of "braking" going
down hill by putting backward pressure on the pedals. I had never
felt the cog loosen while back-pedalling. The chain was not too
tight, having about 1.5 cm of play. I also had to push very hard to
get up some of these short but steep hills.
On my last ride on this wheel, I was climbing one of these steep
hills, out of the saddle, when the cog slipped and the bike became
unrideable on any incline (I did get home by pedalling very gently on
the flats and walking the hills). This was perhaps my tenth ride on
this wheel. I took the wheel back to the bike shop that sold it to me
(Urbane Cyclist in Toronto) and they took the cog off, found the
threads on the hub to be stripped, and without any hassle, gave me
another identical wheel. I asked the mechanic what to do to prevent
this, and he suggested using a larger cog (18) with a larger
chainring (42) to give an approximately similar gear ratio. He said
that this would decrease the torque on the cog, and therefore on the
threads.
1. Does this make any sense? It strikes me that the force on the
threads would be the same for any similar ratios, no matter how they
are arrived at.

You are correct. The mechanic was confusing the force on the threads for
chain tension. Chain tension goes down when a chainring is larger.

Quoted message said:

2. The wheel was their least expensive. Should I spring for a wheel
with a more expensive hub (they also sell Dura-ace and Phil Wood)? I
found that I really like the feeling of a fixie and am willing to
invest more money after my first experiment. I'm 230 lbs, and fairly
strong, but I can't be generating the power of a real track racer, and
presumably they are not stripping their hubs every tenth ride.

You could steepen your gearing to lessen the force on the threads.

Quoted message said:

4. Should the lockring not hold the cog on without intervening
spacers?

Not if you're having problems. Try to find a wider cog, a Surly perhaps?

--
Phil

In article <[email hidden]>,

Paul said:

Thanks for your quick reply.

Tim McNamara said:

In article <[email hidden]>,

Paul said:

1. Does this make any sense? It strikes me that the force on
the threads would be the same for any similar ratios, no matter
how they are arrived at.

Correct. You need a cog that has wider threads to full engage the
hub.

I have two generic/no-name track cogs and now, a Phil Wood cog. They
are all the same width. Do you know of any cogs that are wider?

They are the same width at the threaded part of the cog (not the
thickness of the teeth)? Hmm. I've had track cogs from of various
makers including Dura-Ace, Superbe, Campagnolo and cheapo generic cogs.
The generic cogs were not as wide at the threads as the high quality
ones. But Phil is well-made stuff.

Quoted message said:

Quoted message said:

Quoted message said:

3. Is my frequent back-pedalling the problem?

No. Well, probably not. But then again if you were rocking the
cog back and forth on the hub shell threads, you might have worn
them a bit and that might have contributed to them stripping.
However, I read complaints about the threads stripping out on cheap
track hubs fairly regularly.

Until the day that it failed, the cog had not felt like it had even a
bit of "give". I don't know if imperceptible rocking might have
occurred. If you have read about the threads of cheap track hubs
giving out, would you then say that this would not occur with the
expensive kind?

Well, one would *hope*! ;-) Personally I would be inclined towards the
Phil, but shop around for track hubs. You can often find a good deal
out there. At least you should comparison shop. I have no idea about
shipping costs and duties for stuff coming into Canada. I think that
the odds of stripping out the threads on a high quality hub are less
than on a cheap hub.

FWIW you can use a road freewheel hub, just not as a backpedal brake,
and can often find very good quality road freewheel hubs for a pittance.
I have done this for years rather than plunking out for a spendy track
hub. But you really have to have brakes on the bike, since there is no
reverse threaded lockring.

Paul said:

4. Should the lockring not hold the cog on without intervening
spacers?

If there is room for spacers, put them between cog and hubbody. This
blanks off the thread run out area and gives better thread engagement

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Paul said:

This autumn, I converted a road bike to a fixed gear 34/15. I had
purchased a wheel with a QuandoXT fixed/free hub. My cog was not wide
enough to be held in place by the (left-threaded) lockring so I
cannibalized a plastic 10s spacer to put between the fixed cog and the
lockring. The lockring then was able to be very tightly screwed onto
the hub.
I live in a very hilly area, and was in the habit of "braking" going
down hill by putting backward pressure on the pedals. I had never felt
the cog loosen while back-pedalling. The chain was not too tight,
having about 1.5 cm of play. I also had to push very hard to get up
some of these short but steep hills.
On my last ride on this wheel, I was climbing one of these steep hills,
out of the saddle, when the cog slipped and the bike became unrideable
on any incline (I did get home by pedalling very gently on the flats
and walking the hills). This was perhaps my tenth ride on this wheel.
I took the wheel back to the bike shop that sold it to me (Urbane
Cyclist in Toronto) and they took the cog off, found the threads on the
hub to be stripped, and without any hassle, gave me another identical
wheel. I asked the mechanic what to do to prevent this, and he
suggested using a larger cog (18) with a larger chainring (42) to give
an approximately similar gear ratio. He said that this would decrease
the torque on the cog, and therefore on the threads.
1. Does this make any sense? It strikes me that the force on the
threads would be the same for any similar ratios, no matter how they
are arrived at.
2. The wheel was their least expensive. Should I spring for a wheel
with a more expensive hub (they also sell Dura-ace and Phil Wood)? I
found that I really like the feeling of a fixie and am willing to
invest more money after my first experiment. I'm 230 lbs, and fairly
strong, but I can't be generating the power of a real track racer, and
presumably they are not stripping their hubs every tenth ride.
3. Is my frequent back-pedalling the problem?
4. Should the lockring not hold the cog on without intervening
spacers?

Thanks in advance for all advice,
Paul

1. Doesn't make sense to me.

2. I'm in the 230 neighborhood, and I ride a fixed with a cheap rear
hub on hilly roads. The wheel came with a narrow stamped steel cog that
I ditched before the first ride. I replaced it with a Surley which has
a much more substantial thread area. I haven't had any problems. Don't
"waste" you money on a more expensive hub when maybe you just need a
more expensive cog.

3. With the cog and lockring suitably tight, back pedaling shouldn't be
a problem.

4. No spacers should be needed. This makes me think the cog is a narrow
cheap stamped steel one without lots of thread area.

Joseph

Tim McNamara said:

Quoted message said:

2. The wheel was their least expensive. Should I spring for a wheel
with a more expensive hub (they also sell Dura-ace and Phil Wood)? I
found that I really like the feeling of a fixie and am willing to
invest more money after my first experiment. I'm 230 lbs, and fairly
strong, but I can't be generating the power of a real track racer, and
presumably they are not stripping their hubs every tenth ride.

They don't weigh 230 and aren't climbing steep hills out of the saddle.
You are probably putting as much or more strain on the threads of the
hub shell than any track racer. The possible exception is racers doing
the Kilo, since they start sprinting from a standing start.

I don't know about that. At 230, one is placing more strain on other
components like wheels and seat posts, but in terms of force at the
cog, the racers have us beat by a long shot. Using myself as an
example, I am 220, an avid hobby cyclist and I ride on hilly roads.
Sounds a lot like the OP. When I am on a ride, my most intense efforts
are just as you imply, out of the saddle up short steep hills. It is
just on these efforts that my cadence drops, and thus pedal force
increases. Say if I'm lucky for a short burst I manage 500W at 80 rpm.
Lets assume a pedal circle is 1m. At 80 rpm, my pedals are going 1.33
m/s. To get to my 500W, I need to apply 376 N or 38 kgf. When Chris Hoy
or Theo Bos are stomping out 2000W at 150 rpm they are pushing the
pedals at about 80 kgf. Twice as much. I am assuming pedal force is a
good proxy for cog force. Is that reasonable?

Joseph

Paul said:

...On my last ride .. the cog slipped and the bike became unrideable...I asked the mechanic what to do to prevent this, and he
suggested using a larger cog (18) with a larger chainring (42) ...
1. Does this make any sense?

No, it doesn't. If you had stripped the teeth then it would have made sense, as bigger cogs holds more teeth engaged. It has no impact on risk for stripping threads at the hub.

Paul said:

2. The wheel was their least expensive. Should I spring for a wheel
with a more expensive hub

Don't know, it depends on why the hub is more expensive. Strength of a thread will vary depending on if the thread is cut or rolled, the material itself, and the precision of the thread. Unless a more expensive hub can promise to be of a stronger material, or rolled as opposed to cut, or having better precision there's not much to be gained by switching to another type of hub.
Strength of a threaded interface is dependent on the fit and the overlapping area. Longer isn't always better though. Old engineering handbooks state that only three threads are to be used in calculations, due to flexing and various imperfections. Still, in order to have those three threads engaged you need a few more to choose from.

dabac wrote:
Old engineering

Quoted message said:

handbooks state that only three threads are to be used in calculations,
due to flexing and various imperfections.

I'm sure they also stated that this was for male and female threads of
the same material

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

quote='M-gineering'dabac said:

Old engineering handbooks state that only three threads are to be used in
calculations, due to flexing and various imperfections.

I'm sure they also stated that this was for male and female threads of
the same material.[/QUOTE]

Well, not as such. The last I looked in simply stated that if different materials were used (obviously) the weaker material dictated what load the joint could handle. If strength was insufficient then back to square one and try a coarser thread. Oh, and a pointer about materials compatibility...

Paul said:

This autumn, I converted a road bike to a fixed gear 34/15. I had
purchased a wheel with a QuandoXT fixed/free hub. My cog was not wide
enough to be held in place by the (left-threaded) lockring so I
cannibalized a plastic 10s spacer to put between the fixed cog and the
lockring. The lockring then was able to be very tightly screwed onto
the hub.
I live in a very hilly area, and was in the habit of "braking" going
down hill by putting backward pressure on the pedals. I had never felt
the cog loosen while back-pedalling. The chain was not too tight,
having about 1.5 cm of play. I also had to push very hard to get up
some of these short but steep hills.
On my last ride on this wheel, I was climbing one of these steep hills,
out of the saddle, when the cog slipped and the bike became unrideable
on any incline (I did get home by pedalling very gently on the flats
and walking the hills). This was perhaps my tenth ride on this wheel.
I took the wheel back to the bike shop that sold it to me (Urbane
Cyclist in Toronto) and they took the cog off, found the threads on the
hub to be stripped, and without any hassle, gave me another identical
wheel. I asked the mechanic what to do to prevent this, and he
suggested using a larger cog (18) with a larger chainring (42) to give
an approximately similar gear ratio. He said that this would decrease
the torque on the cog, and therefore on the threads.
1. Does this make any sense? It strikes me that the force on the
threads would be the same for any similar ratios, no matter how they
are arrived at.

Nope, torque the same..cheap hub is the problem.

Quoted message said:

2. The wheel was their least expensive. Should I spring for a wheel
with a more expensive hub (they also sell Dura-ace and Phil Wood)? I
found that I really like the feeling of a fixie and am willing to
invest more money after my first experiment. I'm 230 lbs, and fairly
strong, but I can't be generating the power of a real track racer, and
presumably they are not stripping their hubs every tenth ride.

See above, get the Phil, best fixie hub there is.

Quoted message said:

3. Is my frequent back-pedalling the problem?

Nope, cheap hub.

Quoted message said:

4. Should the lockring not hold the cog on without intervening
spacers?

Ideally, get a proper track cog, proper width, and use the lockring.

Quoted message said:

Thanks in advance for all advice,
Paul

Paul said:

This autumn, I converted a road bike to a fixed gear 34/15. I had
purchased a wheel with a QuandoXT fixed/free hub. My cog was not wide
enough to be held in place by the (left-threaded) lockring

That is odd. Indicates probably that you have a real cheapo cog. This
could be the problem, because some of the threads on such cogs are
haphazard.

Quoted message said:

took the wheel back to the bike shop that sold it to me (Urbane Cyclist
in Toronto) and they took the cog off, found the threads on the hub to
be stripped, and without any hassle, gave me another identical wheel.

Which will probably fail in the same way.

I

Quoted message said:

asked the mechanic what to do to prevent this, and he suggested using a
larger cog (18) with a larger chainring (42) to give an approximately
similar gear ratio. He said that this would decrease the torque on the
cog, and therefore on the threads. 1. Does this make any sense?

Not really. The _chain_ is under higher tension with the smaller cog (and
the same gear ratio), but the thread tension will be the same with
both. Only changing the diameter of the threaded connection would alter
that.

It

Quoted message said:

strikes me that the force on the threads would be the same for any
similar ratios, no matter how they are arrived at. 2. The wheel was
their least expensive. Should I spring for a wheel with a more
expensive hub (they also sell Dura-ace and Phil Wood)?

IMO a Phil Wood is overkill. I have a dura-ace (double-sided) hub, and it
is a beautifully made part.

Replace the sprocket with a better one. Sub-11 is good, Shimano is better.

Quoted message said:

3. Is my frequent
back-pedalling the problem?

No

Quoted message said:

4. Should the lockring not hold the cog on
without intervening spacers?

It should.

--

David L. Johnson

__o | Anyone who is capable of getting themselves made President
_`\(,_ | should on no account be allowed to do the job. -- Douglas Adams
(_)/ (_) |

Paul said:

This autumn, I converted a road bike to a fixed gear 34/15. I had
purchased a wheel with a QuandoXT fixed/free hub. My cog was not wide
enough to be held in place by the (left-threaded) lockring so I
cannibalized a plastic 10s spacer to put between the fixed cog and the
lockring. The lockring then was able to be very tightly screwed onto
the hub.
I live in a very hilly area, and was in the habit of "braking" going
down hill by putting backward pressure on the pedals. I had never felt
the cog loosen while back-pedalling. The chain was not too tight,
having about 1.5 cm of play. I also had to push very hard to get up
some of these short but steep hills.
On my last ride on this wheel, I was climbing one of these steep hills,
out of the saddle, when the cog slipped and the bike became unrideable
on any incline (I did get home by pedalling very gently on the flats
and walking the hills). This was perhaps my tenth ride on this wheel.
I took the wheel back to the bike shop that sold it to me (Urbane
Cyclist in Toronto) and they took the cog off, found the threads on the
hub to be stripped, and without any hassle, gave me another identical
wheel. I asked the mechanic what to do to prevent this, and he
suggested using a larger cog (18) with a larger chainring (42) to give
an approximately similar gear ratio. He said that this would decrease
the torque on the cog, and therefore on the threads.
1. Does this make any sense? It strikes me that the force on the
threads would be the same for any similar ratios, no matter how they
are arrived at.
2. The wheel was their least expensive. Should I spring for a wheel
with a more expensive hub (they also sell Dura-ace and Phil Wood)? I
found that I really like the feeling of a fixie and am willing to
invest more money after my first experiment. I'm 230 lbs, and fairly
strong, but I can't be generating the power of a real track racer, and
presumably they are not stripping their hubs every tenth ride.
3. Is my frequent back-pedalling the problem?
4. Should the lockring not hold the cog on without intervening
spacers?

Thanks in advance for all advice,
Paul

The torque argument is bogus. I think the hub is just junk.

I am also 230lb, and have been riding a fixer for years. I've used a
rather cheap flip/flop (Sovos or Suzue, can't remember which) and a Dura
Ace sprocket (42x15, I think). I don't "leg brake", since I don't like
the feeling, but I do crank hard. I have broken one frame (head tube)
and one stem (Nitto forged), but the wheel & drivetrain have been pretty
reliable, except for a couple of broken axles.

When I replace this wheel, I'm going to use a standard rear wheel by
brazing/welding the freehub body to prevent freewheeling. I'll use a
standard sprocket with cassette spacers & standard lockring. I hate
crappy seals, I hate solid/nutted axles, I hate cracking axles, I hate
shelling out $20+ for a sprocket. I want to be able to use standard
frame spacing, I want to be able to adjust chain line without screwing
with axle spacers, I want something as good as a Shimano hub for Shimano
prices. I don't want to ride made-for-the-track stuff on the street or
kludge up something from old-style hubs. A fixer should be cheap and
reliable, a lot of what's available is neither, nothing seems to be both.

Peter Cole said:

When I replace this wheel, I'm going to use a standard rear wheel by
brazing/welding the freehub body to prevent freewheeling. I'll use a
standard sprocket with cassette spacers & standard lockring. I hate
crappy seals, I hate solid/nutted axles, I hate cracking axles, I hate
shelling out $20+ for a sprocket. I want to be able to use standard
frame spacing, I want to be able to adjust chain line without screwing
with axle spacers, I want something as good as a Shimano hub for Shimano
prices.

That seems like passing up a good opportunity to get a dishless wheel,
unless you start with something like this:

http://sheldonbrown.com/harris/singlespeed.html#shimano

Furthermore, I would not trust the Shimano freehub mounting spline to
be reliable under reversing torque unless I heard it from a big rider
who had a lot of hard miles on such a setup.

Chalo

FWIW, a good kilo rider will put about 100Nm of torque into the
sprocket, based on a 90kg rider pushing the pedal with a bit more than
twice his own weight (i.e. all his actual weight + the sum of the
upward pulls of both hands) on 165mm cranks and a gear of 50/15

Without doing anything more than just standing on the pedal, a 120kg
rider on 175s and 40/16 puts 82Nm into the sprocket.

Our glorious leader and multiple national hill climb champ, at a
featherweight 52kg running 170 cranks and 42/21 gearing could hit
about 86Nm

Time, I think, for Carl Fogel to rig something up in his garage to
check which combinations of sprocket and hub can withstand, say,
300Nm. Maybe a new use for the tension meter if he puts a length of
2mm wire somewhere in the test rig :-)

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

Quoted message said:

Paul said:

...On my last ride .. the cog slipped and the bike became
unrideable...I asked the mechanic what to do to prevent this, and he
suggested using a larger cog (18) with a larger chainring (42) ...
1. Does this make any sense?

dabac said:

No, it doesn't. If you had stripped *the teeth* then it would have made
sense, as bigger cogs holds more teeth engaged. It has no impact on risk
for stripping threads at the hub.

Quoted message said:

Paul said:

2. The wheel was their least expensive. Should I spring for a wheel
with a more expensive hub

dabac said:

Don't know, it depends on why the hub is more expensive. Strength of a
thread will vary depending on if the thread is cut or rolled, the
material itself, and the precision of the thread. Unless a more
expensive hub can promise to be of a stronger material, or rolled as
opposed to cut, or having better precision there's not much to be
gained by switching to another type of hub.
Strength of a threaded interface is dependent on the fit and the
overlapping area. Longer isn't always better though. Old engineering
handbooks state that only three threads are to be used in calculations,
due to flexing and various imperfections. Still, in order to have those
three threads engaged you need a few more to choose from.

I don't believe there is such a thing as a rolled thread on an aluminum
track hub

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

Chalo said:

Peter Cole said:

When I replace this wheel, I'm going to use a standard rear wheel by
brazing/welding the freehub body to prevent freewheeling. I'll use a
standard sprocket with cassette spacers & standard lockring. I hate
crappy seals, I hate solid/nutted axles, I hate cracking axles, I hate
shelling out $20+ for a sprocket. I want to be able to use standard
frame spacing, I want to be able to adjust chain line without screwing
with axle spacers, I want something as good as a Shimano hub for Shimano
prices.

That seems like passing up a good opportunity to get a dishless wheel,
unless you start with something like this:

http://sheldonbrown.com/harris/singlespeed.html#shimano

All of my bikes have dished wheels, and that's never been a problem. My
current fixed hub has broken a couple of axles. It also has really
crappy seals.

BMX stuff looks interesting, but I don't care to modify it with long
axles or "unspread" my frames. It just seems easier to use a generic
wheel & modify the freehub.

Quoted message said:

Furthermore, I would not trust the Shimano freehub mounting spline to
be reliable under reversing torque unless I heard it from a big rider
who had a lot of hard miles on such a setup.

Maybe. It looks pretty beefy to me. I don't really consider it an issue
for the kind of riding I do because I never use "reversing torque" -- I
hate the way it makes my knees feel. I just using boring old brakes.