Farsports vs Light Bicycle rim braking performance

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alanyu
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by alanyu

Depending on how the textures/grooves are designed and crafted. For dry it could be zero, and also could be 30%. For wet (but not for rainstorm) is of course, which is the main purpose of most brands.

If you or someone or some brands "donate" the wheels to those such as tour magzine, they will be very willing to perform the brake test. However, at least no brand is willing to do so any more after tour "delamination test" in 2018.

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Hexsense
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by Hexsense

alanyu wrote:
Wed Sep 30, 2020 12:21 pm
Not right again. The bite force depands on the fraction coefficient and the force on the rim, not the surface area -- simple junior physics f = mu * FN. The method and craft how different brands laser their rims can affect the coefficient. Also material can.
Counter example: wide tire is grippier than narrower tire.
That simple formula is only true for two smooth rigid body against each other. Rim brake pad (and tire) is hardly rigid, grooved braketrack (and road) is hardly smooth...
However, the rim texture create more small holes for the brake pad to lock into thus can have more sliding friction. I don't count shallow grooves as reduced surface area. The brake pad bend and get into the grooves anyway. So I expect some groove to create more friction, not reducing it... if the brake pad isn't rock hard.
Last edited by Hexsense on Wed Sep 30, 2020 8:36 pm, edited 1 time in total.

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wheelsONfire
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by wheelsONfire

A textured brake surface would lump up more goop, or?
That would translate to more rim wear.....
A flat clean brake surface should have easier to rinse itself it seems.

Wet weather rim braking, IMO always bad!!
Bikes:

Ax Lightness Vial EVO Race (2019.01.03)
Open *UP* (2016.04.14)
Paduano Racing Fidia (kind of shelved)


Ex bike; Vial EVO D, Vial EVO Ultra, Scott Foil, Paduano ti bike.

alanyu
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by alanyu

Hexsense wrote:
Wed Sep 30, 2020 8:25 pm
alanyu wrote:
Wed Sep 30, 2020 12:21 pm
Not right again. The bite force depands on the fraction coefficient and the force on the rim, not the surface area -- simple junior physics f = mu * FN. The method and craft how different brands laser their rims can affect the coefficient. Also material can.
Counter example: wide tire is grippier than narrower tire.
That simple formula is only true for two smooth rigid body against each other. Rim brake pad (and tire) is hardly rigid, grooved braketrack (and road) is hardly smooth...
However, the rim texture create more small holes for the brake pad to lock into thus can have more sliding friction. I don't count shallow grooves as reduced surface area. The brake pad bend and get into the grooves anyway. So I expect some groove to create more friction, not reducing it... if the brake pad isn't rock hard.
Tire is another story: it's a combination of rolling friction and sliding friction, and if you want more details, it is not only friction playing a role in the grip.

Also, f = mu * FN doesn't limit on smooth rigid body, but it is for sliding and static friction (with different mu), where the pad is.

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Mr.Gib
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by Mr.Gib

bosstja wrote:
Tue Sep 29, 2020 8:47 pm
Can someone also comment on difference in braking pover and pad wear with grooved vs. flat surface? I plan on buying LB wheels and don't know which surface to choose.
A lot of back and forth on grooved vs flat. I can only tell you this - my Farsports are the grooved version and the dry braking is fantastic. I assume LB will perform similarely. The grooves may be marketed as a solution to wet weather braking, but they sure don't hurt dry braking. No idea on how they perform in the wet, I have a disc bike for that. 8)
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

Hexsense
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by Hexsense

alanyu wrote:
Wed Sep 30, 2020 10:15 pm
Also, f = mu * FN doesn't limit on smooth rigid body, but it is for sliding and static friction (with different mu), where the pad is.
When things are not smooth and rigid. Keying happens. Certain area of one surface deform and interlock with another surface's valley. You can try to simplify the calculation and hide all these detail in mu. But when mu change as FN change (\ie keying effect does not grow linearly with FN). The formula is just a little off. Close enough as a ballpark estimation though.
Last edited by Hexsense on Wed Sep 30, 2020 11:49 pm, edited 1 time in total.

Orbital
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by Orbital

Mr.Gib wrote:
bosstja wrote:
Tue Sep 29, 2020 8:47 pm
Can someone also comment on difference in braking pover and pad wear with grooved vs. flat surface? I plan on buying LB wheels and don't know which surface to choose.
A lot of back and forth on grooved vs flat. I can only tell you this - my Farsports are the grooved version and the dry braking is fantastic. I assume LB will perform similarely. The grooves may be marketed as a solution to wet weather braking, but they sure don't hurt dry braking. No idea on how they perform in the wet, I have a disc bike for that. 8)
Same. My gravel bike gets rain duty.

bm0p700f
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by bm0p700f

Hexsense wrote:
Wed Sep 30, 2020 8:25 pm
alanyu wrote:
Wed Sep 30, 2020 12:21 pm
Not right again. The bite force depands on the fraction coefficient and the force on the rim, not the surface area -- simple junior physics f = mu * FN. The method and craft how different brands laser their rims can affect the coefficient. Also material can.
Counter example: wide tire is grippier than narrower tire.
That simple formula is only true for two smooth rigid body against each other. Rim brake pad (and tire) is hardly rigid, grooved braketrack (and road) is hardly smooth...
However, the rim texture create more small holes for the brake pad to lock into thus can have more sliding friction. I don't count shallow grooves as reduced surface area. The brake pad bend and get into the grooves anyway. So I expect some groove to create more friction, not reducing it... if the brake pad isn't rock hard.
With tyres the mechanism for wider tyres having more grip is not increase in surface area but more tyre means more energy can be stored in deformation during a turn before it snaps back. Thats grip. Surface area in general is not important to friction.

alcatraz
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by alcatraz

Winspace hyper-x wheels have the modern machined brake track without grooves. Can someone comment on their dry braking vs a grooved modern brake track? Farsports uses smaller grooves and lightbicycle larger, from what I can see.

I guess most don't have the wheels to compare with. They just have the one test sample.

Also how do you know the fantastic dry braking comes from the grooves and not from the carbon layup and the machined surface?

I thought grooves were very important for a long time but then when I noticed my other newer rims without grooves braked just as well or better than my old wheel with NSW style molded grooves, it got me wondering. Now I lean towards minimal grooves with sharp edges "laser cut". Too much like enve or zipp isn't what I'm looking for in a brake track. Do note that I live in a dry area where I get caught in rain maybe once a year. If I were doing tons of wet rides I'd probably choose differently.

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Mr.Gib
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by Mr.Gib

alcatraz wrote:
Thu Oct 01, 2020 2:10 am
Also how do you know the fantastic dry braking comes from the grooves and not from the carbon layup and the machined surface?
Well of course I have no idea whether grooves help or hurt. I just know the wheels stop really, really quickly if I want them to. And I am not experiencing any notable pad wear either....and my 35mm deep on Carbon ti weigh 1275 grams. Kudo's to Farsports (and LB as well). The big brands have nothing on these guys currently.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

AZR3
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by AZR3

I orderd a pair of Kaze tubs from farsport, using Carbon-ti hubs they weighed in at 1034g, and the braking has been top notch. I have a pair of FSE 25 clincher and I loved how those stopped but the FS Kaze wheelset is even better using the same brake pads. Ive only put just over 100 miles on them but they've been great.

alanyu
Posts: 1506
Joined: Thu Jun 06, 2019 1:10 pm

by alanyu

Hexsense wrote:
Wed Sep 30, 2020 11:46 pm
alanyu wrote:
Wed Sep 30, 2020 10:15 pm
Also, f = mu * FN doesn't limit on smooth rigid body, but it is for sliding and static friction (with different mu), where the pad is.
When things are not smooth and rigid. Keying happens. Certain area of one surface deform and interlock with another surface's valley. You can try to simplify the calculation and hide all these detail in mu. But when mu change as FN change (\ie keying effect does not grow linearly with FN). The formula is just a little off. Close enough as a ballpark estimation though.
For pads + carbon brake track interface, the roughness of the base side (brake track) under load is at the order of micrometer, where the friction principle dominates over 99.5%. It's more than enough for the industry.

jackie
Posts: 96
Joined: Mon Aug 01, 2011 6:04 am

by jackie

just wanted to share my latest wheelset from farsport .. this is my 3rd wheelbuild with them in this year so far. the 2 previously had been great..
i had a few LB wheelset too. they been great too. and of cos Enve and Reynolds.
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Last edited by jackie on Sun Oct 17, 2021 2:54 pm, edited 1 time in total.

Philippos
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Joined: Wed Nov 27, 2019 9:37 am

by Philippos

I think this is a legit warranty/bad qc issue. Have you contacted FS on this matter?

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pkaro
Posts: 51
Joined: Mon Oct 01, 2018 2:40 pm

by pkaro

alcatraz wrote:
Wed Sep 30, 2020 1:02 pm
How much is the friction coefficient of the gaps. Zero or almost zero?

I don't quite trust that chinese brake test where the Zipp's and Black Prince's came out first. It would be nice to see more tests to get a general concensus. Either way I wouldn't pick zipps for rain racing on rim brakes.

I maintain that texture is for wet braking, with the distinction that the jump from 0 to 0.1% texture helps to keep the pads clean.
Why don't you trust the test? I completely agree that it would be nice to see more tests released. In fact it would be great if manufacturers had to perform standardised brake tests and publish the results

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