Wheel lateral stiffness. WHat makes it stiff?
#76
Senior Member
Join Date: May 2008
Location: Fredericksburg, Va
Posts: 9,579
Bikes: '65 Frejus TDF, '73 Bottecchia Giro d'Italia, '83 Colnago Superissimo, '84 Trek 610, '84 Trek 760, '88 Pinarello Veneto, '88 De Rosa Pro, '89 Pinarello Montello, '94 Burley Duet, 97 Specialized RockHopper, 2010 Langster, Tern Link D8
Mentioned: 73 Post(s)
Tagged: 0 Thread(s)
Quoted: 1608 Post(s)
Liked 2,216 Times
in
1,103 Posts
@FBinNY - LOL, I only continued reading because I wanted to see if you would make an additional contribution!
I appreciate your efforts to educate the masses. It is a systemic problem that people over simplify problems and are not able to think at a system level (many engineers of all disciplines), therefore missing the root cause or understanding how the whole works. The system is greater than the sum of the parts. It is difficult for some to grasp. I applaud your attempts and greatly appreciate your tenacity!
I appreciate your efforts to educate the masses. It is a systemic problem that people over simplify problems and are not able to think at a system level (many engineers of all disciplines), therefore missing the root cause or understanding how the whole works. The system is greater than the sum of the parts. It is difficult for some to grasp. I applaud your attempts and greatly appreciate your tenacity!
__________________
Bikes don't stand alone. They are two tired.
Bikes don't stand alone. They are two tired.
#78
Senior Member
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,725
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 140 Post(s)
Tagged: 1 Thread(s)
Quoted: 5791 Post(s)
Liked 2,581 Times
in
1,431 Posts
Pretty much, yeah. Barring any more complicated effects from the interaction at the crossing, which I've yet to see anyone try to quantify.
Spokes in a 3x build are slightly longer, which means they elongate slightly more under the same load. They also meet the flange a bit farther from the rim, which (for the same flange spacing and diameter) makes the bracing angle a bit smaller.
Of course, it also becomes slightly less torsionally stiff.
Spokes in a 3x build are slightly longer, which means they elongate slightly more under the same load. They also meet the flange a bit farther from the rim, which (for the same flange spacing and diameter) makes the bracing angle a bit smaller.
Of course, it also becomes slightly less torsionally stiff.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#79
Senior Member
Join Date: Mar 2009
Location: Nova Scotia
Posts: 855
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
This is correct, but when discussing details like this it pays to have a sense of context or scale. So for a typical front 32h hub, the difference in spoke length is roughly 6mm, or 2% of the length. So reducing crosses does increase stiffness, but by an order of 2% or so, which isn't exactly a sea change, and is highly unlikely to be noticed in the real world.
I'd love to see the carnage that would ensue if the bicycle market could somehow be subjected to a rash of double-blind testing. Everyone thinks they can feel every little nuance. I can barely register where my toes are pointing from one ride to the next, let alone make any kind of precise mechanical judgement.
#80
Senior Member
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,725
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 140 Post(s)
Tagged: 1 Thread(s)
Quoted: 5791 Post(s)
Liked 2,581 Times
in
1,431 Posts
Very much agreed.
I'd love to see the carnage that would ensue if the bicycle market could somehow be subjected to a rash of double-blind testing. Everyone thinks they can feel every little nuance. I can barely register where my toes are pointing from one ride to the next, let alone make any kind of precise mechanical judgement.
I'd love to see the carnage that would ensue if the bicycle market could somehow be subjected to a rash of double-blind testing. Everyone thinks they can feel every little nuance. I can barely register where my toes are pointing from one ride to the next, let alone make any kind of precise mechanical judgement.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#81
Senior Member
Join Date: Sep 2014
Location: Siberia West .. aka Central Wisconsin... USA
Posts: 308
Bikes: 2000 Litespeed Appalachian, 1998 Litespeed BlueRidge.. 1977? Schwinn LeTour 12.2 'Rain Daze'
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 64 Post(s)
Likes: 0
Liked 17 Times
in
14 Posts
JB is the piper for those who do not get the practical side of wheel building concepts. Graphs and endless 'theories' are not real world mileage
and the lessons learned actually building and riding different designs.
ONE size does not fit all... when weight & cost are factored into a wheel build. Main thing is good execution of the build and it staying 'put'.
#82
Senior Member
Join Date: Jul 2013
Location: Somewhere in TX
Posts: 2,266
Bikes: BH, Cervelo, Cube, Canyon
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 212 Post(s)
Likes: 0
Liked 6 Times
in
6 Posts
For what it's worth, using finite element analysis, this author's model corroborated Jobst Brandt's results, leading to the conclusion that, the average compressive spoke [apparently 5 out of the 32 spokes analyzed] contributes 133 times as much lift force as the average tensile spoke.
See: Ian's Bicycle Wheel Analysis
See: Ian's Bicycle Wheel Analysis
#84
Senior Member
Join Date: May 2005
Location: Portland, OR metro area
Posts: 984
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
I read most but not all of this.
My question to the OP - Why are you asking? What are you trying to accomplish?
Is there a particular problem you need to solve?
My question to the OP - Why are you asking? What are you trying to accomplish?
Is there a particular problem you need to solve?
#85
Senior Member
#86
Senior Member
Join Date: May 2011
Location: Midwest
Posts: 369
Bikes: '10 Fuji Cross Comp, '12 Brompton S-Type, '14 All City Mr Pink
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Whatever your real-world experience, an accurate mechanical model will support it (unless the experience is a product of placebo effect and confirmation bias).
#87
Senior Member
Thread Starter
Join Date: Jan 2015
Location: Long Island, NY
Posts: 866
Bikes: 2014 Specialized Secteur Sport
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
Reduce the amount of flex laterally. My OEM wheels did not rub the brakes but the new ones do when given the same spacing. Should the wheels need adjusting or spoke replacement, I would like to improve things when the opportunity arises or just do a complete spoke replacement now. not sure if this will do it or not. Could be, these wheels are not for me but riding, they really rarely rub. Adding a mm or two is OK but I already added a shim to the brifters due to reach and do not have as much room for braking as I would like. Plus I like my brakes to grab as soon as the slightest movement of the brifter is made meaning that the brakes need to be close to the rims.
#89
Senior Member
Is the hub flange width the same between the two wheel sets --e.g., did you add more gears (as that would affect the flange spacing -- the distance of the hub flanges from the center of the hub)? Otherwise, the only other factors affecting lateral stiffness in addition to the flange spacing are rim strength and the number and thickness of spokes.
#90
Senior Member
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,725
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 140 Post(s)
Tagged: 1 Thread(s)
Quoted: 5791 Post(s)
Liked 2,581 Times
in
1,431 Posts
Call PETA!
This horse is well and truly dead from exhaustion. A decent burial is the only merciful option.
This horse is well and truly dead from exhaustion. A decent burial is the only merciful option.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#92
Senior Member
Brad
#93
Senior Member
Join Date: Apr 2015
Location: Morris County, NJ
Posts: 1,102
Bikes: 90's Bianchi Premio, Raleigh-framed fixed gear, Trek 3500, Centurion hybrid, Dunelt 3-spd, Trek 800
Mentioned: 40 Post(s)
Tagged: 0 Thread(s)
Quoted: 2167 Post(s)
Likes: 0
Liked 2 Times
in
2 Posts
This is when I notice my front wheel (ref. post 29) deflecting laterally. I did run a different wheel set on the bike for some light touring experiments that didn't flex and seems to validate what @FBinNY stated in post 25. That wheel set is a CXP22 (very similar to the CXP23) with 32 14 ga. spokes on Sora hubs and it does not deflect at all.
Brad
Brad
#94
Senior Member
Join Date: May 2005
Location: Portland, OR metro area
Posts: 984
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
My first thought was that when you do a slow tight turn, your brake cable is affected due to cable routing and the caliper closes slightly. Slight out-of-true variations could explain the brake shoe rubbing on one wheel vs another. I am not so familiar with the wheel sets you are using, but modern rims are really stiff and if spokes are properly tensioned, the wheels should not deflect laterally by any appreciable amount.
My recommendation is to look really carefully at your brake cable routing and see if your calipers move when you turn the handle bars. If so - you've got your root cause.
Check that the wheels are true and properly dished with a good truing stand and dishing gage.
You should be able to get the wheels true within around 1 mm of side to side variation on high quality wheels. Lower quality wheels or damaged rims will wobble more and there's not much you can do about that (except get new wheels).
Open the calipers using the barrel adjuster is another way to make the rubbing disappear. I know you don't like to do that, but sometimes we gotta just make it work....
My recommendation is to look really carefully at your brake cable routing and see if your calipers move when you turn the handle bars. If so - you've got your root cause.
Check that the wheels are true and properly dished with a good truing stand and dishing gage.
You should be able to get the wheels true within around 1 mm of side to side variation on high quality wheels. Lower quality wheels or damaged rims will wobble more and there's not much you can do about that (except get new wheels).
Open the calipers using the barrel adjuster is another way to make the rubbing disappear. I know you don't like to do that, but sometimes we gotta just make it work....
#95
Senior Member
Join Date: May 2005
Location: Portland, OR metro area
Posts: 984
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
It is also possible that the width between the braking surfaces of the two rims you are experimenting with are different. A wider rim will need more caliper clearance...
#96
Senior Member
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,725
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 140 Post(s)
Tagged: 1 Thread(s)
Quoted: 5791 Post(s)
Liked 2,581 Times
in
1,431 Posts
One problem with the thread is that the OP asked about stiffness in general without specifying that he had a problem of any kind. So we had a general discussion about wheel stiffness, and wheels in general.
Had the OP said, "I have a front brake rub problem in turns", wheel stiffness might jot have been brought up at all, and we'd be discussing how to diagnose and solve the brake rub issue.
This is something that everybody with a problem can learn from.
If you have a problem ask about the problem Don't diagnose it, then ask about something you suspect might be the cause, because you'll limit the discussion and all the responses might be unrelated to the actual cause and remedies available.
Had the OP said, "I have a front brake rub problem in turns", wheel stiffness might jot have been brought up at all, and we'd be discussing how to diagnose and solve the brake rub issue.
This is something that everybody with a problem can learn from.
If you have a problem ask about the problem Don't diagnose it, then ask about something you suspect might be the cause, because you'll limit the discussion and all the responses might be unrelated to the actual cause and remedies available.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#97
Senior Member
Join Date: Apr 2015
Location: Morris County, NJ
Posts: 1,102
Bikes: 90's Bianchi Premio, Raleigh-framed fixed gear, Trek 3500, Centurion hybrid, Dunelt 3-spd, Trek 800
Mentioned: 40 Post(s)
Tagged: 0 Thread(s)
Quoted: 2167 Post(s)
Likes: 0
Liked 2 Times
in
2 Posts
Reduce the amount of flex laterally. My OEM wheels did not rub the brakes but the new ones do when given the same spacing. Should the wheels need adjusting or spoke replacement, I would like to improve things when the opportunity arises or just do a complete spoke replacement now. not sure if this will do it or not. Could be, these wheels are not for me but riding, they really rarely rub. Adding a mm or two is OK but I already added a shim to the brifters due to reach and do not have as much room for braking as I would like. Plus I like my brakes to grab as soon as the slightest movement of the brifter is made meaning that the brakes need to be close to the rims.
#98
Senior Member
Brad
#99
Senior Member
Join Date: Sep 2014
Location: Siberia West .. aka Central Wisconsin... USA
Posts: 308
Bikes: 2000 Litespeed Appalachian, 1998 Litespeed BlueRidge.. 1977? Schwinn LeTour 12.2 'Rain Daze'
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 64 Post(s)
Likes: 0
Liked 17 Times
in
14 Posts
I wonder.. if a few VIAGRA wouldn't make the 'rear' stiffer........
#100
Senior Member
Thread Starter
Join Date: Jan 2015
Location: Long Island, NY
Posts: 866
Bikes: 2014 Specialized Secteur Sport
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
I'll try another shot at this: Have you checked for too much bearing free play in the offending wheel? As long as the wheel spins freely with no discernible drag in the bearings, then ANY play felt in the bearings is excessive. If you can wiggle the rim from side to side such that it moves even a millimeter or two closer to one fork blade or the other, that could be the source of your brake rubbing.
Viagra? LOL. The real trick is getting it in the wheels. Of course, I would have to call a bike mechanic if the stiffness lasts over 4 hours