fitting - my bike is dancing, unstable

haidy

Dear cyc-friends,

Since I purchased a new frame, my bike is dancing.

I feel like my frame is going left and right and so it looks when i look at my front wheel. Its just not going straight, but a bit left and right.
When i get off my saddle i have to be careful not to fall, for it looks like i'm loosing weight on the back wheel.

Now, i've been asking, fitting... and no-one seems to know what i'm dealing with.

I had a frame one size smaller and it was a disaster. It was even worse. (By mistake i was sent one size smaller and i tried to make it work... i almost crashed the frame into pieces one day)
Than i got one no# bigger frame. According to the table suggested by the frame company - the size was supposed to be ok now.

Since riding became horror for me this year(and it was my ultimate joy and love) .... i was hoping there was someone who could help me out.

Thank you in advance!!!

cooldad

The bike is?

Is everything tightened up - headset, skewers etc?

Are the wheels true?

No idea what this means "When i get off my saddle i have to be careful not to fall, for it looks like i'm loosing weight on the back wheel."

What did you have before?

fenix

Cant imagine a position that'd let you loose weight from the back wheel unless you're on a 25% incline....

How much cycling have you done ?What kind of bikes ? Road bikes are a bit more sporty than a fat tyred mountain bike - but I'm not getting whats the issue here.

Can you post a pic of the bike up ? And then a pic of you on the bike ?

haidy

Hi boys,

I've been riding ALU-Focus culebro for 2 years. After fitted, it was perfect. But I had a 50mm stem. And my fitter told me the bike was too big for me and it was the reason it caused me back pain.

Now I have http://www.fatbirds.co.uk/5919/products ... -fork.aspx
(110 mm stem)

Everything is tightened up.
The wheels should be true, are Rolf Prima Elan ES.

I do not have any picture of me on the bike.

When I get up, my front wheels seems as turning into both directions - left and right.
And when peddling - when i push the right leg, the frame goes left, and when the left leg, the frame goes right.
And if I look at my front wheel while driving it goes slight left, slight right.

I see the hub behind my handlebar.

thank you in advance

type:epyt

Trying to make sense of this, it might be that you are shifting your weight from side to side as you pedal, much the same as happens when you climb out of the saddle ...

If it is happening while in the saddle, and whilst spinning a lower gear, chances are that your saddle is too high and you are shifting your weight either side of the saddle on each pedal stroke making the bike 'wobble' ... Would also explain the sensation you describe when you get off the bike as you likely feel yourself falling off rather than getting off the bike ...

herb71

Rather than seeking forum advice, in the first instance, I would take the bike to a local trusted bike shop for a once over. Get them to check that the bike is assembled correctly and that there are no major build errors or faults. Then you can look to correct your position, style etc.

cooldad

Being Ti it's probably cracked.

haidy

Thank you all,

for the local dealer, mechanic, fitting expert,...
Fitter blamed TI. (when the frame was really too small for me) The other two had no idea.
One mechanic said the frame is completely straight (when building it together), when (a week later) I took it to the other (closer one) to tighten the cables, he said the bike is curved at the rear dropout,...
Dont know what to think anymore.

The bike is less than a month old and has 150km.

Cracked? not possible.

Matthewfalle

Is a video of you riding possible?

cougie

Hub behind handle bar usually means it's too long a frame or stem. Hubs usually blocked out by the bars.

Ti is described as more springy than Al. Is that part of it?

daniel_b

I reckon he keeps his bike under a bridge.

trailflow

How tall are you ? What size is your new bike ?

Going from a 50mm stem to 110mm will feel very different yes. Especially if the new bike has a different geometry and wheelbase.

This is what i suspect. You've been riding your old bike with a crazy short 50mm stem for so long you have got accustomed to it, and how that handled with the old geometry.

And the new bike with 110mm stem,different physical position,steering geometry. Feels alien and weird because you are not familiar with the new very different set up. The changes have all been changed drastically compared to your old bike.

My advice is just keeping riding it and give yourself time to adapt. Keep tweaking the position of the saddle, and the stem height, and even experiment with the stem length.

Also check your tyre pressures. If they are too low that could make your tyres feel squirmy and unstable.

trailflow

haidy wrote:

when (a week later) I took it to the other (closer one) to tighten the cables, he said the bike is curved at the rear dropout,...

Are both the front and rear wheels centered equally in the frame ? or is one of the wheels more dished to the left or right ?

N0bodyOfTheGoat

Daniel B wrote:

I reckon he keeps his bike under a bridge.

Does he also sometimes feel like he doesn't have a partner?

haidy

Thanks to all, i'll check the stem, tyres, wheels... i'll even try to get a recording of me on the bike...

Anyway... i'm 173cm, and have 52 frame.
I think i should be fine.

Its a crazy thing to ask, and i doubt this could cause it. My seatpost is at the min insert.
And if lower my knees hurt.


For now biking is a frustrating thing... and it was a blast.

I hope i can cound on your help in the future, still.

Thanks again

(In Some eastern countries is hard to get an expert ... )

drlodge

Sounds to me like the rider is too farward, CofG is too far forward causing instability.

I had a bit of this with an old 531 frame that had a very short head tube, I think a combination of being forward, low down and the steering geometry made the front a bit twitchy. IIRC it also had a steep heat tube angle, 74.5 degrees.

fenix

Have you measured the old bike position and recreated it on your new one ?


Your stem is too long for the rest of the bike I think hence why its so twitchy.

arthur_scrimshaw

The only experience I've had which mirrors some of this was when my rear tyre was starting to fail and had a bulge in one place on the edge of the tread and sidewall which made it feel like the back end was moving around seemingly randomly. It took me a couple of days to spot it.

haidy

Boys,

During the ride today... i held the handlebar closer to the stem (on width - arms closer together), and therefore closer to me... (on the stem length) felt better.

Could it be i have a handlebar to long/wide..., the stem definitely is. On my opinion.

trailflow

haidy wrote:

Boys,

During the ride today... i held the handlebar closer to the stem (on width - arms closer together), and therefore closer to me... (on the stem length) felt better.

Could it be i have a handlebar to long/wide..., the stem definitely is. On my opinion.

Yes that's possible, everybody has a difference preference in handlebar width and reach. There is no right or wrong formula. So you will have to experiment to find what will work for you. If you have 44cm bars, try 42cm. and also decrease the reach measurement if your instinct is telling you your current bars are too long. What bars do you currently have ? 'compact' style bars have a shorter reach usually around 70/80mm. More traditional shaped bars can be from 85/100mm.

Vino'sGhost

haidy wrote:

Boys,

During the ride today... i held the handlebar closer to the stem (on width - arms closer together), and therefore closer to me... (on the stem length) felt better.

Could it be i have a handlebar to long/wide..., the stem definitely is. On my opinion.

Ah this is a common problem and easily solved. If you go to the circus and see clowns performing tricks on their bikes you will see they use mitts with slightly thicker padding. This is important for them too.

I thought rubbish when they told me but a friend of mine who designs stabilisers for ships. He recommended stabilisers and thicker gloves for you too.

sloppyschleckonds

Has the OP fixed this yet or has he fallen off and died?

ovi

I once rod a bike that had a geared headset so when you turned the bars left the bike would go right... I think he has bought said bike.

darkhairedlord

Is the fork in backwards?

reformedfatty

I'd also point out that for most people the best technique for going straight is to look where you want to go, looking down at the front wheel makes it harder to maintain a consistent direction.

Of course it's tricky to figure out exactly whats being talked about with the language barrier!

dwanes

darkhairedlord wrote:

Is the fork in backwards?

I kid you not, a young boy turned up to the local kiddies cycle track on his brand new bike and his parents told me he was struggling with it.
So being a bike guru I said I would take a look at it, and amazingly the forks were the wrong way round!!
They had literally just picked it up from, no word of a lie, Halfords

The Rookie

And who had straightened the bars?

You can pick them up boxed.

daniel_b

dwanes wrote:

darkhairedlord wrote:

Is the fork in backwards?

I kid you not, a young boy turned up to the local kiddies cycle track on his brand new bike and his parents told me he was struggling with it.
So being a bike guru I said I would take a look at it, and amazingly the forks were the wrong way round!!
They had literally just picked it up from, no word of a lie, Halfords

Had exactly the same thing with Evans, after a PDI on a Spesh Hardrock :shock:
This was circa 2006.

And just to clarify - this was picked up fully assembled in the shop.

fenix

I saw a bloke riding with his forks on backwards just the other week. Stupid lives !