E-bike / mountainbike suspension setup

[full-throttle]

Very impressive manitu!

There is one more thing. I would argue that is the most impotant aspect of rear suspension (especially when using hubmotors) - ignore it and your shock will eventually blow - oil volume.

DH shocks are designed for short (<10min) heats with long-ish breaks in-between, front-heavy weight distro and to be as light as possible. Just think of where all that energy dissipates when the compression damping is increased

[dogman]

That is one impressive thread I agree with.

Re the FSR, that's a crosscountry ride bike, which I think make the best street Ebikes. Not as much travel, but good for less pedal bob. The extreme shocks of DH bikes are not needed as much as a nice smooth ride across the cracks and smaller bumps common on the street. But it's still got the suspension you need when you discover a big fat speed bump, and happen to be going 35 mph.

For sure, Ebikes can wear the hell out of everything on a bike faster than designed for. Rear shocks, forks, rims. But nothing has lasted better for me than my current commuter. It's an old Giant DH bike. Tame by todays DH standards, but when you do need 5 inch travel on the rear wheel for a chuckhole you didn't see in time, it sure is nice. Even so, I'm on rear wheel number two and front fork two with about 5000 miles on the thing. The best thing about the bike is it's frame stiffness. The mongoose blackcombs have limp noodle frames by comparison. Even cheaper FS wallbikes are even worse.

[fizzit]

So triple crowns translate more force to the headtube than normal forks? I would think that it would be the other way around, so I am curious how that works. Does it mean that my headtube would be likely to snap, even for street riding?

[manitu]

About the FSR . The FSR Comp wich somebody mentioned earlier is a XC bike , yes. But FSR in itself is Specialized's name for the Horst Link , wich Horst Leitner patented in the early nineties. He was the first to design a bike suspension based on advanced brake and bump force calculations.
The FSR Demo 8 is defo not a XC Bike. I'll add some info on the different designs later.

Shock going hot.

Yeah , the shock heats up from hard riding , and harder compressions setting affects this too, but not to much , in my experience.
Only reasons I can come up with , is that when running harder compression settings , some of the force is distributed to tire, rim, and trough the saddle.

About the oil , yeah , more oil would be nice, to spread the heat , but you cannot just add more oil , you know. It will only lead to hydro-lock an loss of travel. You should ofcourse never use the shock with less oil than it is designed for. The trick of using different oil level is ONLY for those Marzocchi FORKS wich is designed for it. (and most motocross forks)

@ fizzit: Well , the total force transferred from the fork to the headtube is the same. But since a dual crown fork (or tripple clamped?) is much more rigid , and don't have the flex wich a single crown fork has between the fork legs and the steering tube (in the crown , that is) , the peak force will be higher. Just look down on the fork wile braking and you will see what I mean.

edit: Every frame has a max recomended axel to crown length. If you cant calculate the forces AND enshure yourself that the construction is suffient , NEVER exeed this. (by much , anyway)
.manitu

[fizzit]

Thanks for answering my dumb questions
So if I were to put too long of a fork on, I could be riding along and brake hard and due to the leverage, my head tube could snap off and I could die.

My bike is an old 1999 raleigh m7000, built from 7005 aluminum. It's pretty strong but I don't have a way to calculate the forces or anything like that, and I can't find any documentation on the maximum axle-crown length for it. If I adjusted the sag on the triple-crown fork so that it was 40% or so and the axle-crown was only increased by a couple of inches (right now it's at like 18" I think), would that be pushing it?

[manitu]

I dont think you would snap it from braking , but braking with a single crown fork , you clearly see the flex in the crown.
You most likely snap it on a hard landing or a square bump.

.manitu

[full-throttle]

Yeah , the shock heats up from hard riding , and harder compressions setting affects this too, but not to much , in my experience.

And how much experience have you had with running a 5+ kg hubmotor?

About the oil , yeah , more oil would be nice, to spread the heat , but you cannot just add more oil , you know. It will only lead to hydro-lock an loss of travel. You should ofcourse never use the shock with less oil than it is designed for. The trick of using different oil level is ONLY for those Marzocchi FORKS wich is designed for it. (and most motocross forks)

I didn't say oil level I said oil volume. Use a different shock full stop.

[manitu]

Yeah , the shock heats up from hard riding , and harder compressions setting affects this too, but not to much , in my experience.

And how much experience have you had with running a 5+ kg hubmotor?

About the oil , yeah , more oil would be nice, to spread the heat , but you cannot just add more oil , you know. It will only lead to hydro-lock an loss of travel. You should ofcourse never use the shock with less oil than it is designed for. The trick of using different oil level is ONLY for those Marzocchi FORKS wich is designed for it. (and most motocross forks)

I didn't say oil level I said oil volume. Use a different shock full stop.

No , No experience with hub motors, I got my experience on full suspension bikes and motorcycles. And yes you might be right , a proper Öhlins setup might be the way to go if you are really pushing it. Still , it does not heat up as much as calculated forces would imply. But yes it heats up.

Ahh. of course.. yes defenatly get a hi volume/ piggyback shock for off-road riding. Sorry , I misunderstood that one.

.manitu

[Ykick]

Manitu, thanks again for the great info - very helpful thread along with many of your other posts.

[geetarboy]

Just got back from my 1st test run w/ my "Rock Shox Tora 302" - OMG What a difference!!! It's AMAZING - I glide over potholes that used to give me a good jolt, The headshake I had disappeared so now I can ride 'no-hands' @ 35mph, It's 3 inches longer and heavier so it balances out my load better, and w/ the new "Avid BB7" disc brake - I can stop at least 3 times faster. IT'S LIKE A WHOLE NEW BIKE...

[hydro-one]

Thanks for the information on setting up suspension!! I am in the process of setting up the sus on my new "bullit" with 5th element , bombers, ht35. ill let you know how it works out!!


ps geeterboy, when you grow up you can graduate on to a real mans fork, but you are learning young grasshopper....

lol kidding man!!