Rigid forks + rear sus? Why not?

Reading the STW review of Exotic carbon forks and saw “…riding a rigid bike (I’m assuming no one would be foolish enough to attempt a rigid front end, suspended rear set up… I’m still mentally scarred by the early 90s attempts)…”

I don’t remember those bikes. The first bikes I remember with rear sus were full sus (‘Dale Super V, GT LTS etc). But, why not? I guess I’ve always just accepted that it’s either full sus or hard tail. Now though, I can’t for the life of me see why rigid forks and squishy rear would be a bad idea. Weight back to use the suspension when needed. I suspect that your legs support the vast majority of your weight when riding / landing / moving the bike underneath you…

Are there really obvious reasons it wouldn’t work that I just haven’t thought of?

Ask anyone who just got to the end of a descent with their forks locked out…

That and can doesn’t always equal should

The hard-nose (?) efforts from the 90s were fairly odd. Wasn’t it basically Klein?

IIRC, the suspension was effectively locked out a lot of the time anyway.

Isn’t the point that with a hardtail, you work the fork and keep the back end nice and light so that the back largely follows the front. Whereas with a hardnose, how you’re going over terrain is dictated by the fact that you’re riding a rigid fork, and the real wheel being suspended doesn’t really add very much?

It wouldn’t be a bad idea as such, it would just act more-or-less like a rigid bike, but with all the drawbacks (weight, flex, maintenance, complexity) of a full-sus.

That Mantra ^^^ may be Clubber’s – discussion here.

Sounds like Klein thought that the way the URT was built, both wheels were to some extent suspended. No-one builds URTs anymore, I think that theory died a death.

Page 41 of this 1999 Trek Manual… under “True Full Suspension.

🙂

The early proflex models should be enough to show you that it doesn’t work.

Bromptons are still giving it a go. Not so good off road though…

Actually, those Klein bikes are effectively front suspension hardtails because the BB in on the rear triangle so it is the front end of the bike that is pivoting up and down while your weight is bearing down on the rear of the bike through the crank – you can’t ride light all of the time, that would be called hovering. Maybe it was intended to be a front suspension solution before suspension forks could be made to work well enough, rather than a rear suspension bike. Actually it doesn’t really do either particularly well.

I’m not quite sure what problem a rear suss bike fixes. The point of front suspension is to increase front end grip and make sure your front wheel is in contact with the ground more of the time, and to save fatigue on your arms. Something which the Klein effort above doesn’t fix.

I’ve still got my Klein Mantra which is currently setup single speed. Have been toying with putting some rigid forks on it as the original Manitous aren’t great and I ride fully rigid on other bikes more often than not anyway.

Sounds like Klein thought that the way the URT was built, both wheels were to some extent suspended.

We should remember or realise that the majority of ‘compliant rear’ bikes are those that have flex in the centre, ie the TT and DT. So a Mantra, slingshot etc just takes that flex further.
Also long travel hardtails, just ride along stood up and look at the fork and you see the fork dip and compress as the rear hits a bump. Hardly noticeable on a shorter, racy fork set up but with a soft 150mm it’s quite obvious. A very similar effect makes a mid-hinge bike comfy.

It’s not a great way to suspend a bike but it’s not as daft as it first appears.

I like experimenting with locking out my front end on my cove hustler- as I’m climbing or on a non too rocky flat the rear track the ground fantastic and I make up good ground…

However.. to commit to a rigid front end would be insane, it’s like riding a buckaroo with all the wrist pain and none of the run!

URT is a different idea entirely as has been said.

A standard full suss with rigid forks is daft. A hard tail works because your legs are robust and your knees are excellent shock absorbers. Hands are more delicate and require suspension to be able to keep up with the punishment your legs can take.

doing it the other way around is just silly.

I slapped an on one steel fat fork and fat wheel into my specialized epic last winter as a hack bike.

It worked ok, but that’s a short travel bike.

Frankenbike was its nickname and it looked pretty horrible

Also, due to the direction of travel “here: >>>>” and the direction of deflection “?”, the resultant forces are, broadly speaking, in line with the plane of movement of suspension forks : “\”

With most rear suspension systems the movement is either in the wrong plane: “/” or some complicated curved path which is only partly in that plane: “?”

As such it doesn’t work well at all, certainly not like front suspension where you’re getting a ride that is, maybe, 70% as smooth as FS.

There’s a guy on another forum put a rigid carbon fork on his S-Works epic. He reckons it’s the best thing ever, but he also thinks that Lauf make the best forks ever so take that as you will.

Wobbliscott has it.

Suspension serves to increase grip and absorb bumps

Front end grip is more important than rear
Your legs naturally absorb bumps better than your arms

So the first place to add suspension is naturally the front.
Feel free to try the opposite, it’s just a bit pointless that’s all.

When Joe Murray first started Voodoo bikes, I read in one of the brochures how he used to ride the full-sus frame with a rigid fork.

Joe Murray? What does he know?….

i tried this the other day when i tried keeping up with a friend down The Devil’s Elbow. 5″ full-suspension, but for some reason i had the forks locked out.

it was shite, and my wrists hurt like hell.

(i didn’t know the forks were locked out until i started looking for excuses. Excuse #1: i’m a ****ing idiot)

A hard tail works because your legs are robust and your knees are excellent shock absorbers.

Yes, also that to ride well you pivot around your c of g and/or the rear axle, like a BMX racer in speed bumps/whoops sections. A sus fork can help a rider work with that motion.

SebK on Weight Weenies?

Odd bloke. Probably the archetypal “I’m an engineer” of bike shop legend.

When Joe Murray first started Voodoo bikes, I read in one of the brochures how he used to ride the full-sus frame with a rigid fork.

Joe Murray? What does he know?…. does he still do it ? this was probably back in the day when suspension forks were garbage but nowadays an air fork with 150mm of travel is relatively common

ir_bandito – Joe Murray? What does he know?…

He told me you cant fit taper forks in a Voodoo Bizango but you can.

I’d still happily own one of these (as this thread has gone off on a URT tangent)

I can’t imagine much worse. Just the thought of it makes me squirm.

When I’m on my rigid I tend to clumsily manual everything and smash the rear wheel into things. So if I were looking for the wrong hardware fix for my self-inflicted stupid software problem I might consider a soft-tail

I ride one of these every day… Brompton 😉

This is a journey in to time…..

’87.

When riding rigid, the limit on your speed is the battering your hands take. Not your legs or arse.

It’s the lack of tracking cornering on rough ground with rigid forks. Adding suspension to the rear only isn’t going to combat that.

I posted a reply to the thread but for some reason it isn’t showing up.

Interesting replies.

Yep, they were obvious reasons for it being a bad idea mostly the fact that it’s the front that takes a battering, your arms are weaker and oversteer is better than understeer.