Chris Cohalis fundó Pivot Cycles en el 2007 y en el 2008 presentó la primera versión de la M429, un modelo de XC con 100mm de recorrido, ruedas de 29'' y un sistema tipo DW Link con amortiguador horizontal. Durante todos estos años este modelo ha ido evolucionando poco a poco, pero el sistema de suspensión se ha mantenido con muy pocos cambios. La nueva Pivot M429 SL estrena una nueva versión del sistema DW Link y además ha conseguido mejorar muchísimo en dos apartados muy importantes: El peso (1.930g sin amortiguador) y la estética, convirtiendose en mi opinión en el modelo mas bonito de toda la gama de Pivot...
Como podéis ver en la tabla de excel y en las gráficas anteriores la nueva Pivot M4 SL tiene una Eficacia de Pedaleo muy elevada y se adapta perfectamente a una transmisión tipo 1x12 con desarrollos de competición. Pivot ha decidido incluir el sistema Fox Live Valve de manera opcional, pero hay que tener claro que en este caso el amortiguador es "un capricho" y que el sistema se defiende muy bien por si solo, es decir con un amortiguador de aire normal y corriente... El resto de parámetros son los típicos de un sistema tipo DW Link: Pedal-Kickback (16.5º) y Brake-Squat (91%) situados un poco por encima de la media, incluso cuando los comparamos con otros sistemas de Pivote Virtual.
En la gráfica del Leverage Ratio vemos como el sistema es del tipo Progresivo-Lineal (2.65-2.5), unas cifras muy correctas para un modelo de XC. En cuanto al amortiguador Pivot ofrece varias opciones en función del montaje y como ya he comentado anteriormente creo que el sistema va a funcionar perfectamente con un Fox Float DPS, no hace falta irse a por el Fox Live Valve, es mas yo creo que el sistema ni siquiera necesita un amortiguador con bloqueo remoto...
En la gráfica del Leverage Ratio vemos como el sistema es del tipo Progresivo-Lineal (2.65-2.5), unas cifras muy correctas para un modelo de XC. En cuanto al amortiguador Pivot ofrece varias opciones en función del montaje y como ya he comentado anteriormente creo que el sistema va a funcionar perfectamente con un Fox Float DPS, no hace falta irse a por el Fox Live Valve, es mas yo creo que el sistema ni siquiera necesita un amortiguador con bloqueo remoto...
Un saludo.
9 comentarios:
Hello Antonio,
I really like the job you are doing on this blog. I would like to use some of your graphs for an article on vojomag.com. You would of course be quoted in the caption of each image. Do you agree for this ?
Léo - Vojomag
Gracias Antonio por volver
estoy muy interesado en tu análisis de la nueva Mondraker f-podiun
UN saludo
Pivot released a new version of the Mach 4 SL this summer. This is one bike I'm considering and I wanted to understand how the suspension works. I used Linkage Design to model both the old (2020) version and new 2023 version. Later one has two different linkage options, so there are two models. Flipchip changes the travel and leverage ration put not much else.
So the flipchip works like change in the shock pressure and nothing else.
I used images from Pivot site to do the models:
Old one: https://global.pivotcycles.com/products/mach-4-sl-v2
New one: https://global.pivotcycles.com/products/mach-4-sl
Both are size L frames. I published the models in Linkage Design. My model of the old version gives very similar results as the model in this site. So I hope I did not do too big mistakes.
What surprised me was how much they have increased the anti-squat. I'm not totally sure that I haven't done any errors, this is why I post here. I prepared some graphs to show the changes. I put the CG at -36,738 relative to bottom bracket that seemed to be a common position in other models. In reality my CG will be even higher - my saddle height is 820mm, so I expect the CG be around 880mm. This means that the anti-squat values will be even bigger.
First, 32/50 graph that is very similar to the one published here: https://home.cyber.ee/~arne/32-50.png
Blue line is for reduced travel flipchip position. Anti-squat is increased by 10%
Then 32/10 graph https://home.cyber.ee/~arne/32-10.png Anti-squat is increased by 30%
I also did 28/10 that I would use https://home.cyber.ee/~arne/28-10.png Those numbers are huge IMO.
I have an theory that they wanted to improve the pedaling efficiency when using bigger gear. E.g. 34t or 36t instead of 32t. That would make the bike better in World Cup.
https://home.cyber.ee/~arne/32-36-18.png
Now the anti-squat values are similar with old version but you can go faster. I asked Pivot also about this and will let you know what their answer was.
I would be happy if you could check my models - perhaps there is something wrong.
Also what is your opinion about the anti-squat values with 28t chainring. Is it too bad?
First thing I want to say, I like it when people try to build their own models. You learn a lot that way!!! much more than just looking at graphs made by other people.
I think your model is not as accurate as mine, but that's OK. I've just uploaded mine so yau can check it out.
The first thing you are going to notice is the drawing is very nice, it takes a couple of minutes to do and it's worth it. The second part is more important and it's about getting the right fork and fixing the geometry so the model is more accurate. It takes a few minutes too to fight with the model until it's 100% perfect, but getting the right BB height and Wheelbase is important.
Another mistake I think you made is the size, I think the drawing in Pivot Website is a medium and this is important because a lot of new models have different chainstays, so if you get the size wrong, the whole model is out of scale. You can fix that using the scale tool on the edit panel, but you get the idea.
In my model the Anti-squat values have not changet too much compared to the old model. I think they just shaved a bit of weight and make it a bit more progessive.
I'm going to post a review soon, but if you want to ask me anything else here go for it.
Best regards,
Tony.
Thank you very much. I will try to redo my model.
I have one more question: do you think that with 28t chainring the anti-squat values would be too excessive?
Yes, a bit excessive, but only in the two smallest cogs. Being tall helps a little bit to make Anti-squat lower, but it's a race bike and it's designed for bigger gears.
Best regards,
Tony.
I just re-measured the photo.
Here is the CAD drawing with measurements in random units: https://home.cyber.ee/~arne/pivot-measures.png
Here is screenshot of the Excel table where I calculated the coefficients for different frame sizes: https://home.cyber.ee/~arne/pivot-scaling.png
Big dimensions agree best for size Large. Especially wheelbase and chainstay length where endpoints are easy to determine. Reach, stack and seattube length have little bit more variance because one point is not so precisely determined.
Fork a2c corresponds to Fox SC34 120mm fork.
Why do you use a photo, when the geometry drawing is so nice??? send me your email adress and I'll send you the picture that I used for my model. I can explain it, but when you see it it's going to make a lot more sense. I use a custom brush in photoshop to pinpoint the axles and it helps a lot...
Best regards,
Tony.
Good question :) I tried to use them, but some drawings have been very low resolution and some where clearly not exported from CAD program but rather created by visual designer, so I cannot be sure of their accuracy, so I've stopped looking at them and only try find good photos. But you are: good drawing would be much better.
I had some idea today, to install easily distinguishable markers to photo using drawing program, before importing it into Linkage Design.
BTW: I just got a thought that since the wheelbase is so important for anti-squat, I should probably modify the model, to make it correspond to my frame size.
Publicar un comentario