Flex

supersonic

Who feels it? And on what parts? Is it good or bad? And how much would you pay/add weight to stop it if bad?

R.lepecha

i dont feel any, the only place ive felt flex is in the tyres/tubes. and maybe a little in brake levers. but generaly i dont feel it when riding, i know there is flex, in cranks and that but its not noticable.

The Northern Monkey

Have you seen my bike? if something flexes, its probably broken

supersonic

But you are fat!

;-)

The Northern Monkey

supersonic wrote:

But you are fat!

;-)

hmmmm... fat and heavy are 2 different things

Ho hum

My handlebars.

I like it because it makes me feel 'ard

lawman

my frame flexes alittle, its comfier than most ali frames, bit of flex in the seat, not a hint of flex in my forks, with the stiff-tastic dt rws, im only 10.5 stone though, so not at all fat

nicklouse

what is this flex you mention?

I have seen parts deform.

robertpb

I have more flex on my Meta 5.5 than a house full of electrical appliances at the moment due to the shot bearings.

Even when they are replaced there is a lot more flex than I had with my 14" rigid, but do I notice it, not a lot, one of those subconscious adjustment things.

GHill

It's not always bad, a little bit of give in the handlebar and seatpost (for a hardtail) can do a nice job of absorbing trail buzz.

I noticed my Fox Float fork was pretty flexy, easily knocked off line by relatively small trail obstacles. Relatively cheaply fixed with a 9 mm RWS (and hub conversion) and it feels much better to me.

Flex in a frame? Depends what sort of riding. A little bit is good for comfort IMO.

gezzza

I feel abit of flex in the rear of my carbon spark and on my Fox F100's with Kcnc Ti QR
Nothing that bothers me and i would add weight to reduce it

Northwind

I don't feel flex, but I can feel bikes acting in different ways- like, the only time I was consciously aware of my Scandal flexing was if I pushed it sideways and watched the whole frame twang. But I could feel the difference over a longer ride or on rough ground, I never felt "Oh, that's nice and flexy" but it passed on less knocks than the Carrera frame it replaced.

popstar

While crossing deep/short streams or that kind of trench* ... I do not only see me Reckons flex, but see them violently vibrating from side to side ( lol ) together with front wheel. It may make me guess where my front wheel will end up, but the difference would be  no more than an inch, so I am ok with that. Bombing at speed through roots may give unwanted understeer in certain places but that I blame on hills with slight angle. Frame flex only noticable when going extreme, even then nothing to complain about ... gives a little thwang for little extra traction on back wheel.

Don't see any need of an upgrade yet, or adding some weight in that matter.

Tank-slapper

Used to notice a fair bit with my old wheels (717 rims), but since upgrading to the new wheels (Olympic rims) this has gone. The spoke tension in the new wheels is higher as well as the rims being stiffer.

There is a little flex in the rear stays (Scott Spark 30), but nothing worth worrying about.

bails87

In my saddle and carbon seatpost, but it's good there. I can feel it in the forks->stem->handlebars if I'm looking for it too, but not when I'm actually riding.

calummcgoff

you people should buy totems

ilovedirt

the rear end on my scott is a little flexy, or at least more so than my old patriot, which was an absolute beast

Daz555

I can feel it in my forks if I bother to think about it - so I don't.

Anonymous

i can feel it very clearly with my std sized carbon bars but not at all on my oversized ones.

i cant say ive ever felt it anywhere else though.

captainfly

The epicons on the teocali were horrile and flexed lots, problem solved with toras. Though after riding the tank like stp0 the teocali feels like it flexes everywhere, but in a good way

V5ade

I fitted CNT carbon bars on my rockhopper and straight away I they were a lot stiffer (so the original bars were probably flexing but to be honest I hadn't noticed any flex). or maybe it was just my imagination helping my mind justify the carbon bars :-/

lesz42

cranks, but nothing else,

Mr Rowlie

My Pace RC36 forks, plenty of flex!

just adds character

Salsa

I have a WCS carbon stem & can feel that flex under acceleration.
I used to have straight legged carbon Pace style forks (now have WCS curved ones) & they flexed a hell of a lot under braking & less but still noticeably whilst cornering.
Nearly all suspension forks I've ridden I can feel them twisting even under slow speed cornering. Cheaper ones are the worst for this but I can still feel it on my Fox forks on my FS.
Crank/BB flex is quite easy to feel as well, the difference between a square taper & a modern 2 piece is very obvious to me.
Some flex I like though, on my rigid bikes a little saddle, seatpost & bar flex is good.

bomberesque

I can feel the comparative vertical flex in my 3 HT frames riding over stutter bumps or cobbles in the saddle

20 yr old Cannondale M800 (uber stiff alu frame) - new back please
Evil Sov (heavy duty 853 frame) - not bad, but still stiff
Ibis Tranny (Carbon) - where's the shock? feels like a softtail

tyres will be helping the evil as I have bigger ones on that but the difference between the Cannondale and the Ibis is pretty stark. ofc 20 years development in frame detailing lies between the two.

lateral stiffness ... sometimes brakes rubbing under acceleration (wheels or frame flexing) and I do rekon that HT2 cranks are stiffer than any other I've tried, noticeable compared to square taper, not sure if it's a phantom feeling next to ISIS. The old foot on the BB shell yields results but whether I can really feel it on the trail or not, probably not

fork flex I think is the most noticable, next to vertical flex (let's call it compliance ) I swapped a steel fork for a carbon (nuke proof) one and felt an immediate difference in the way the bike held a line across a slope, the carbon fork worming away from me while the steel one carved straight. on sus forks it's more difficult to isolate flex from suspension action ofc but I'm pretty sure I could distinguish between the RS Sid on my Tranny and the pike that was on my Evil. I'm less sure whether I'd be able tell thhe same between the Pike and the 32 Talas I just replaced it with, pretty happy with the 15mm thro s far, although I s a little cynical of it to start with.

I Don\'t Get It

To what do test reporters refer when thy say that the cranks flex? Surely, a solid alloy crank can't flex in the up or down direction, and if they are referring to sideways distortion wouldn't such a force (to bend them) smash the bottom bracket and bearings to pieces?

The power produced by a gorilla type determined rider, stamping on the pedals with every ounce of muscle fibre while heaving the bike from side to side, must send horrendous leverage forces through the bottom bracket and bearings. Assuming the cranks are solidly bolted on, then surely it must be the frame that's bending. Why blame the cranks?

supersonic

You can often see the cranks bowing inwards! Doesn't always mean the axle is flexing though. Was more noticable on older, non hollow cranks with square taper bottom brackets.

Sometimes the frame flexes too - indeed there are high forces in that area.

I Don\'t Get It

Indeed you're correct sir! Leaned bike over and checked. I could see the cranks bending, as indeed did most of bike.

Quite how flex like that can alter the handling I don't know. After all, controlled give (suspension) improves handling, and don't some aver that steel bikes(and carbon bikes) with more forgiving frames than alloy are all the better for it?

At anyrate, it won't spoil my enjoyment one jot. I even saw the funny side in falling off trying cross a stream, which was nowt to do with flex, and more to do with sliding on something slimy.

supersonic

The whole point of the thread really, just to see whether people notice it, or think it is detrimental.

I think in can feel disconcerting to many. Maybe is a psychological thing too, as in wasting power.

joshtp

i can feel my frame flex under me when i flat a big drop, or really mash the pedals, and i can feel the forks flexing and juddering under heavy braking, but other wise not much..... i think you only notice it when its gone... like since my new wheels and forks i now realise how much my old ones flexed...