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Aké kolesá na MTB? # MTB # plášte # kolesá # poradenstvo # kompatibilita # technické otázky # cenový limit # nákup

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penovak • 15. 11. 2009 o 11:51

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Ahojte bikeri,
Pred zaciatkom novej sezony by som si chcel obstarat nove 26" MTB kolesa. Potreboval by som kolesa pre diskove brzdy s uchytenim kotuca Center Lock. Moj cenovy strop je cca. 250 EUR. Oslovili ma tieto:

Mavic Crossride disc:
http://www.bikesport.cz/cz/zapletena-kola-mtb-kola/mavic-crossride-disc-2009_1670

Shimano XT disc:
http://www.kupkolo.cz/produkty/kola-mavic-shimano-fulcrum_70/MTB-zapletena-kola_86/shimano_269/Shimano-WH-M775_3035.html

Fulcrum Red Metal 5 disc:
http://www.kupkolo.cz/produkty/kola-mavic-shimano-fulcrum_70/MTB-zapletena-kola_86/fulcrum_777/

ktore z tychto zapletenych kolies by ste mi odporucili a preco?

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MageZ • 24. 2. 2017 o 18:40

a brzdy vyzeraju ako Magura

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Marinada • 24. 2. 2017 o 18:41

A kolko ma vazit sportovec/biker? Hadam nie 95kg ako je priemer na fore.

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KinDo • 24. 2. 2017 o 22:51

priemer hadam nie

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Tesak • 25. 2. 2017 o 1:08

Mario, daj si facku

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imro1 • 25. 2. 2017 o 1:20

Marinada asi si viacerých urazil, tipujem ten priemer na rovných 100

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Turbi • 25. 2. 2017 o 7:18

Priemer na fóre je dôležitý! Tí skutoční športovci bicyklujú a ostatný čiže väčšina čo práve číta moju teóriu sú internetový pivný cyklisti kde väčšina rozmýšla že kolko pív si dá keď sa odkolečkuje okolo bytovky.

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Gusto0 • 27. 2. 2017 o 22:40

vie niekto vahu kolies ktore ma seriovo Lector 3 r.2017?
na kuchynskej vahe som navazil predne 2.1kg, zadne 2.68kg - po odcitani hmotnosti hole kolesa by mali mat okolo - predne 1.13kg, zadne 1.26kg. co sa mi zda vela. navyse nieje moznost z toho spravit bezduse - ktore by som rad vyskusal.
otazka znie - ak by sa mi este chcelo minut nejake € ake kolesa? (29") po akej vahe sa pozerat aby nieco vydrzali - jazdim sice dost asfaltu ale aj rozbite lesne cesty plne sutrov a obcas aj rozbite chodniky. teraz su tam rafky rodi black rock vnutorna sirka rafku 21mm a vaha podla netu 580-620g (vsade inak) - uzsi by som nechcel, mozno este o 1-2mm sirsi. naboje bohuzial neviem co su zac - okrem toho ze su loziskove. rozmyslam aj nad moznostou vymenit len rafik (pripadne aj vyplet ak by nesedela dlzka) a niple.
ma nad zmenou kolies vobec zmysel uvazovat? - prezil by som aj bez bezdusi, bolo by tu usporu hmotnosti aj realne citit? - nejazdim maratony, ale bavia ma celodenne dlhe vyjazdy.

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Hazard • 2. 3. 2017 o 17:11

Ľudia, aká váha kolies na MTB je ešte prijateľná - 29 palcov? (Na mojom bicykli od výroby sú Mavic Crossride FTS-X a tie majú 2090g/pár, tak nejak)... Na XC za 250 - 300 eur. Ale to je maximálne maximum

A asi skôr dať zapliesť ako z fabriky, či?

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imro1 • 2. 3. 2017 o 19:28

Myslím, že v tej cene sú v pohode aj tieto http://www.suncycle.sk/sk/produkt/mtb-zapletane-kolesa-dt-swiss-x1900-spline-29/8458, možno aj nejaké shimano, no osobne som skôr za DT, prípadne aj niečo iné, mnohí asi napišú, že to nie je bohvičo a že to je základ, no pokiaľ by si chcel skladať, tak neviem či by si niečo zaujímavé v tej cene zložil...možno na podobnej úrovni. Nemám na nich moc najazdené, no zatiaľ sa mi zdajú ok

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Hack3r • 2. 3. 2017 o 20:01

Realne budu mat cca 1900g a kvoli 200 gramom nema vyznam investovat 250 eur do novych kolies. Osobne by som nekupoval nove kolesa ak by som na nich memal usetrit aspon 300g. Aj to by som hodne zvazoval ci vobec. Ak by som mal kolesa 2090 g tak upgrade na 1700g a menej, inac nie. Tot moj nazor

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dobi235 • 2. 3. 2017 o 20:07

napr.
http://www.bikestacja.pl/en/wheels-novatec-711-712-qr15-ztr-crest-29-cn-aero-424-1534-g-27710.html
http://www.bikestacja.pl/en/bicycle-parts/mtb/wheels-mtb/wheels-dt-swiss-350-x392-straightpull-29-1665g-45378.html

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imro1 • 2. 3. 2017 o 20:07

Hack3r možno máš pravdu, že to za to nestojí, iba ak by mal tie svoje kolesá v horšom stave a zaslžili by si výmenu, 1700 by boli určite lepšie, no za 2 násobok jelho limitu, to by som už asi niečo skladal, za nejakých 400 by sa dalo poskladať niečo schopné myslím, no aj tak je to cez Hazardov rozpočet

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zihadlo 5 • 2. 3. 2017 o 20:09

a čo tak toto?
http://www.suncycle.sk/sk/produkt/mtb-zapletane-kolesa-fsa-non-series-29/7530
po mojich skusenostiach s praskajucou osou novatecku už novatec 771 eeee ,712 zatial drží...jazdený občasne

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Hack3r • 2. 3. 2017 o 20:38

tie som zvazoval aj ja, no podla Demy ktora ich distribuje na ne nie je xD orech tak som od nich upustil a kupil tie co mam za dobru cenu z BD

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Gusto0 • 2. 3. 2017 o 21:27

a ma niekto realnu skusenost ci je naozaj ten hmotnostny rozdiel na kolesach citit ? oplati sa do toho investovat? mam ponuku na novatec par 1700g tusim flow trail. len sirka rafika je len 20mm co sa mi na bezdusu moc nepaci koli nizsiemu tlaku.

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dymONE • 2. 3. 2017 o 22:02

I can't believe that people keep arguing that rotating mass climbs slower than non-rotating mass under the same power. When you are working against gravity, mass is mass, it doesn't matter if it rotates or not. The idea that micro-accelerations due to pedal force fluctations make a difference in the overall picture is a strawman. During pedal force fluctuations, accelerations are decelerations cancel out. All that really matters is average power output vs. gravity.

Since Ras11 complained that no math has been offered, I decided to set up a model to simulate the accelerations/decelerations due to pedal fluctuations. The equations and variable values were taken from the Analytic Cycling web page.

Pedaling force: The propulsion force (from pedaling) was modeled as a sinusoidal. Since it is assumed average power is constant, the nomimal drive force will vary inversely with velocity. So, the propulsion force is modeled as:

Fp = (P/V)(1+Sine(2RT))

Fp = Propulsion force (pedaling)
P = Average power
V = Velocity
R = Pedaling revolution rate
T = Time

(Note: The angle in the sine term is double the pedal revolution rate, since there are two power strokes per revolution)

The drag forces on the rider are aerodynamic drag, rolling resistance, and gravity. These three terms together are:

Fd = (1/2)CdRhoAV^2 + MgCrrCosine(S) + MgSin(S)

Fd = drag force
Cd = Coefficient of aerodynamic drag
Rho = Density of air
A = Frontal area
M = total mass of bike and rider
Crr= Coefficient of Rolling Resistance
g = Acceleration of gravity
S = Slope of road

The total force is thus:

F = Fp - Fd

From Newton's second law, the equation of motion is:

dV/dt = F/I

I = Inertia

Because there is both rotating and non-rotating mass, total mass and total inertial will not be the same. Because mass at the periphery of the wheel as twice the inertia as non-rotating weight, the total mass and inertia of a bike are:

M = Ms + Mr
I = Ms + 2Mr

Ms = Static mass

Mr = Rotating mass

The complete equation of motion is thus:

dV/dt = {(P/V)(1+sin(2RT)) - [ (1/2)CdRhoAV^2 + (Ms+Mr)gCrrCosine(S) + (Ms+Mr)gSine(S) ] } / (Ms + 2Mr)

This equation is non-linear, so I solved it numerically with a 4th order Runge-Kutta numerical differentiation.

Borrowing the default values in the Analytic Cycling web page for "Speed given Power" page, the values used are:

P = 250 Watts, Cd = 0.5, Rho = 1.226 Kg/m^3, A = 0.5 m^2, Crr = 0.004, g = 9.806 m/s^2, S = 3% (= 1.718 deg.)

(http://www.analyticcycling.com/ForcesSpeed_Page.html)

For this simulation, the pedal revolution rate was selected as 540 deg/sec. (90 rpm cadence)

To solve this equation, a 4th order Runge-Kutta numerical differentiation was set up using an Excel spread sheet. Step size was selected at 0.01 sec., and the initial Velocity was 1 m/sec. The solution was calculated for 3 cases of equal total mass, but different distributions of static and rotating mass, calculated over a 200 second period, by which time each case had reached steady state. As expected, the velocity oscillated with the pedal strokes. The average, maximum, and minimum velocities during the oscillilations during stead state were:

Case 1:
Ms = 75 kg, Mr = 0 kg (0% rotating mass)
Average Velocity: 7.457831059 m/s
Maximum Velocity: 7.481487113 m/s
Minimum Velocity: 7.434183890 m/s
Speed fluctuation: 0.047303224 m/s

Case 2:
Ms = 70 kg, Mr = 5 kg (5.33% rotating mass)
Average Velocity: 7.457834727 m/s
Maximum Velocity: 7.480016980 m/s
Minimum Velocity: 7.435662980 m/s
Speed fluctuation: 0.044354000 m/s

Case 3:
Ms = 65 kg, Mr = 10 kg (10.67% rotating mass)
Average Velocity: 7.457837584 m/s
Maximum Velocity: 7.478718985 m/s
Minimum Velocity: 7.436967847 m/s
Speed fluctuation: 0.041751139 m/s

These results agree very strongly with the solution on the Analytic Cycling web page, which predicted an average speed with constant power of 7.46 m/s (16.7 mph)

The results show that as expected, the smaller the percentage of rotating mass, the greater the magnitude of the velocity oscillations (which are quite small). But a more interesting result is in the average speed. As the amount of rotating mass decreased, the more the average velocity _decreased_, not increased (at steady stage). This result is actually not unexpected. The drag forces are not constant, but vary with velocity, especially aerodynamic drage (Because aerodynamic drag increases with the square of velocity, power losses are increase out of proportion with speeds - so, for example, aerodynamic losses at 20 mph are 4 times as much as they would be at 10 mph). Because speed fluctuates as the propulsion force oscillations, in the cases of the low rotating mass, the maximum peak speeds reached are higher than for the cases with the high rotating mass. This means that when a lower percentage of rotating mass there will be greater losses during the speed peaks. Because of the total drag losses will be greater over the long run, the greater momentary accelerations with lower rotating mass actually results in a lower average speed.

To see what happens at a steeper slope, which will have a lower speed (and presumably larger speed oscillattions), I ran the model again with a 10% (5.7 deg.) slope. Here are the results:

Case 1:
Ms = 75 kg, Mr = 0 kg (0% rotating mass)
Average Velocity: 3.217606390 m/s
Maximum Velocity: 3.272312291 m/s
Minimum Velocity: 3.162540662 m/s
Speed fluctuation: 0.109771630 m/s

Case 2:
Ms = 70 kg, Mr = 5 kg (5.33% rotating mass)
Average Velocity: 3.217613139 m/s
Maximum Velocity: 3.268918539 m/s
Minimum Velocity: 3.165997726 m/s
Speed fluctuation: 0.102920813 m/s

Case 3:
Ms = 65 kg, Mr = 10 kg (10.67% rotating mass)
Average Velocity: 3.217618914 m/s
Maximum Velocity: 3.265921742 m/s
Minimum Velocity: 3.169047012 m/s
Speed fluctuation: 0.096874730 m/s

This data follows the same pattern as above. The speed oscillations (micro-accelerations) are greater with the lower rotating mass, but the average speed is also slightly lower with lower rotating mass. So next time you want to claim that lower rotating mass allows faster accelerations, remember too that the greater speed fluctuations (due to greater accelerations) will also results in greater energy losses due to drag forces.

But, in reality, the differences in speed fluctions and average speeds are really very small between all these cases. For all practical purposes, when climbing, it is only total mass that matters, not how it is distributed.

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Hack3r • 2. 3. 2017 o 22:39

Niekto zobral dedkove tabletky

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MageZ • 2. 3. 2017 o 22:56

Mam na jednom biku kolesa povodne co maju cca 2,1 kg a casom som dokupil druhe co maju cca 1,75. Rozdiel v akceleracii obrovsky. Ale ked je v strmom vyslape napr. zopar korenov, tak s tymi tazsimi sa cez tu pasaz lepsie prechadza, mensia strata rychlosti, mensi boj. Aspon taky bol moj pocit z toho.

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dymONE • 2. 3. 2017 o 23:06

Hack3r napísal:

Niekto zobral dedkove tabletky

Asi to malo byt vtipne ci nieco take, no zjavne ti tvoje IQ nepostacuje na pochopenie aj vcelku nie zlozitej matematiky

MageZ nieje to len tvoj pocit, presne to je vysledok aj toho vypoctu vyssie

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Gusto0 • 2. 3. 2017 o 23:14

och som myslel ze jednoznacne lahke kolesa - len na aku vahu ist aby sa to casto neservisovalo a ci ma vyznam kupovat cele nove kola za stovky € koli 300-400g.
ale ono - lahke kolesa - lepsia akceleracia, lahsi bike / tazke kolesa - zotrvacnost, odolnost hmm