Zerothehero
Old School Hero
Can you put springs instead of the elastomers in a manitou 3 fork? Obviously as long as there the same length. Cheers.
manitou fork query.
- Thread starter Zerothehero
- Start date
syncrosfan
Senior Retro Guru
Re:
You can as long as they have the correct dimensions. Bear in mind that you won't have any damping. (pogo stick). Elastomers have a material inherent damping built in, springs do not have that so you will need to find a way to add a damper. I will be actually looking into converting a Manitou 4 to springs and I will see if I can add the damper unit of a Manitou Mach5 to keep the fork under control. Not sure if the internals will be compatible but the stanchion diameter is the same.
Otherwise there's the option to drop in Englund Total Air cartridges (for Manitou forks) to replace the elastomers. They're very rare though.
You can as long as they have the correct dimensions. Bear in mind that you won't have any damping. (pogo stick). Elastomers have a material inherent damping built in, springs do not have that so you will need to find a way to add a damper. I will be actually looking into converting a Manitou 4 to springs and I will see if I can add the damper unit of a Manitou Mach5 to keep the fork under control. Not sure if the internals will be compatible but the stanchion diameter is the same.
Otherwise there's the option to drop in Englund Total Air cartridges (for Manitou forks) to replace the elastomers. They're very rare though.
Zerothehero
Old School Hero
Thanks
Zerothehero
Old School Hero
Re: fork query
Have you tried the elastomer kits available on eBay from USA or are there any others?
Have you tried the elastomer kits available on eBay from USA or are there any others?
syncrosfan
Senior Retro Guru
I have tried them. Revived a buddy's original Bradbury Manitou fork with them. They work fine (a tad pricey though).
The problem with elastomers is: they don't last forever like a spring does. Eventually they will crumble, or melt, or both.
If you want to revive your fork with the least amount of work involved I would say go for the aftermarket elastomer kits.
Anything else will require a decent amount of tinkering.
The problem with elastomers is: they don't last forever like a spring does. Eventually they will crumble, or melt, or both.
If you want to revive your fork with the least amount of work involved I would say go for the aftermarket elastomer kits.
Anything else will require a decent amount of tinkering.
Thias
Klein Fan
Re: Re:
Several tests made by different mountainbike magazines (the german "bike" beeing one of them) prooved that fact in the mid nineties.
But I totally agree with the rest you said.
Thats actually wrong. They dont have any dampening just as the springs. Althow they always said it in their adverts. It was just a lie. :facepalm:syncrosfan":3rmjlpov said:
Several tests made by different mountainbike magazines (the german "bike" beeing one of them) prooved that fact in the mid nineties.
But I totally agree with the rest you said.
syncrosfan
Senior Retro Guru
Technically speaking there's some sort of damping on elastomer forks. It does not come from the material itself (as Thias pointed out) but from the fact that when compressed the elastomer stacks barrel out and rub against the stanchions which would make it more of friction damping if one wants to get technical about it. The difference to an un-damped spring is not big though. Bottom line is: elastomers are still kind of crappy (that's why they went extinct).
Zerothehero
Old School Hero
Re: fork query
Thanks.
Thanks.
Thias
Klein Fan
Imho with very little travel, as those early forks had, you dont feel the need for dampening. On my Manitou comp I exchanged the original elastomeres with springs and there is close to no difference in the characteristics. That fork as maybe 2 or 3 cm of travel.
On the other hand there is my Judys with 6 to 8 cm travel. Those are real pogo sticks without dampening.
The more travel the higher the need for a sphisticated dampening.
On the other hand there is my Judys with 6 to 8 cm travel. Those are real pogo sticks without dampening.
The more travel the higher the need for a sphisticated dampening.
Engages physics teacher geek pedant mode.
A steel or titanium spring should obey Hooke's law whereby the amount of compression increases linearly as the amount of force increases. If you wanted to graph the behaviour of the spring, it would look like this:
The amount of energy stored in the spring is equal to the area under the graph for a given amount of compression.
An elastomer is made of a polymer and so does not obey Hooke's law. Its graph looks like this:
The key point is that the elastomer behaves differently under compression than it does under extension. The area under the blue line on the graph is bigger than the area under the red area. This means that not all the energy stored in the elastomer as it compresses is returned as useful work when the spring extends. The difference can be accounted for by internal heating of the elastomer.
Broadly speaking, this is what a damper does too - it converts kinetic energy into heat but it does it in a somewhat more controlled and refined way than the elastomer does.
A steel or titanium spring should obey Hooke's law whereby the amount of compression increases linearly as the amount of force increases. If you wanted to graph the behaviour of the spring, it would look like this:
The amount of energy stored in the spring is equal to the area under the graph for a given amount of compression.
An elastomer is made of a polymer and so does not obey Hooke's law. Its graph looks like this:
The key point is that the elastomer behaves differently under compression than it does under extension. The area under the blue line on the graph is bigger than the area under the red area. This means that not all the energy stored in the elastomer as it compresses is returned as useful work when the spring extends. The difference can be accounted for by internal heating of the elastomer.
Broadly speaking, this is what a damper does too - it converts kinetic energy into heat but it does it in a somewhat more controlled and refined way than the elastomer does.
