Bike pulls to the right after a big crash.

D4V1D

This is a bit embarrassing, I was on my Cube Acid and heading home after 2hr ride around a local wood when I met a tractor head on a B-lane. The tractor stopped so I hoped up on to he grass verge and continued to travel at speed, this is when I saw a big hole just the size for my front wheel to drop in to up to the spindle. I tried but failed to lift over the hole in time.
Long story short I went over the bars and landed on my head and then my back into the road. Burning pains in my arms and legs so took the safe option with an ambulance. All turned ok apart from long term pain in my shoulder and the fact that my bike isn't the same.
Front wheel of the bike was completely destroyed (spindle wouldn't even turn in the hub) so replaced it, the forks look ok and still function (Rock Shox Dart 3) but when I'm out riding it feels as though it wants to turn left, and I have to really force it to go to the right compared to how it goes to the left. At first I thought it was my shoulder problem but now I know it's the bike.

What would you check first and how. I've got the feeling it's got to go back to the bike shop for some major parts or a right off. :oops:

ricardo_smooth

check you have the stem fitted in the centre so that the wheel runs straight with the bars

StefanP

Have you check that the handlebars face the same way as the wheel? Even if its off by a little bit it can make a big difference at any sort of speed.

butcher of bakersfield

First thing to do would just be to inspect the bike visually.

As above. Check the stem. Make sure it runs straight with the wheel. In a crash it will often get knocked out of alignment and it's just a case of adjusting it again.

But, it could be something more serious. Check along all the lines of your bike. Does the wheel run straight with the forks. Do the forks run straight with the frame. Check along the lines of the frame. Does everything look symmetrical. Etc.

Also check for any cracks, dents, or ripples.

It could be something small. Or it could be the frame or fork damaged. Which would be unlucky. But even then I wouldn't call it a write off. That's still only one part of your bike. A major one perhaps, but a part non the less. It can be fixed.

The Rookie

The stem being offset is unlikley to cause the symtopms described of being hard to turn one way, more likely the frame or fork is bent out of true, had it on an old raleigh once after an OTB, when looked at from behind you could see the 2 wheels were not in line but that the front was inclined relative to the rear, this puts the CofG off to one side of the front tyre contact patch and makes the bike want to tuen all the time. You'll also get it to a lesser extent if one wheel isn't seated in one dropout properly....

Simon

agg25

Yeah I would say the fork or frame is bent too.

The Rookie

Thinking about it, one fork leg bent back (or both bent back, one more than the other) is probably most likely, may just need a new upper assembly of legs/crown/steerer.

Simon

D4V1D

The Beginner wrote:

Thinking about it, one fork leg bent back (or both bent back, one more than the other) is probably most likely, may just need a new upper assembly of legs/crown/steerer.

Simon

I have RockShox Dart 3 fitted to my cube, are these repairable or are they a replacement unit? As you can see from the photo below I made the wheel in to a banana shape right to left and an egg shape from side on (it's had a new one fitted now). The frame seems ok but I'm unsure about the forks.
Has anyone got a manual on how to service a set of forks? I've seen a clip on you tube but would like to have a service manual for torque settings and oil types. Where can replacement parts be brought from?
Many thanks to you all.

butcher of bakersfield

You really need to look at it. If it's the forks, the beginner is suggesting that it may well be the upper part of the forks. Which would mean replacing that item (which is the bulk of your fork! Kinda. Physically.) and rebuilding around it with the current parts. But that's assuming your legs/crown/steerer is bent.

It could be the dropouts. It could be the steerer tube on the frame. Sometimes it's not always the part that takes the initial impact that gets damaged. I once had a similar accident, expected to see the front wheel bent and was surprised to see the demise of the back wheel instead (from where the bike flipped over and it took a side impact on a rock). So I'd check the whole frame.

If it turns out to be the fork. Then it might just be worth upgrading the Dart for something else? But I wouldn't go spending money on a guess. It won;t be much of an upgrade if you're still pedalling round in circles!

D4V1D

Thanks, I'm glad of all the positive advice. I'm going to have a good visual this weekend and then take it from there,

gezebo

Sorry about the bike- clearly something's amiss with it. However from looking at the pictures i imagine to onlookers it would have looked really funny! Hope you get yourself and bike fixed soon..

The Rookie

I'm not sure I'd bother fixing a Dart, but if it is the forks it is most likely the upper which is easy to replace.

Simon

chopchop

Hopefully, it not the frame that's been damaged, although I would imagine the brunt of the impact was taken by the fork.

Ideal opportunity to take a positive from a negative situation though- swap out those darts for a recon or better (less than £100 for spring and £200 for air at On-one at the moment). I've had darts in the past and they are leagues behind even the Recon so it's well worth the change.

D4V1D

I found that a bolt on the seat clamp was loose and allowed one seat rail to move about more than the other and this made it a bit better. So I took the bike into the shop and they noticed that the steering stem was slightly off to the right so they adjusted it free of charge. It does feel alot better now than it did before, but I can't let go of the bars and just sit still on the seat as I could before. The bike wants to still turn to the left, but it's more manageable now.

I don't know so I'll ask, could I have squashed the bearing into there race and caused an imprint in the steering head?

The Rookie

No, I'd still bet on the forks being bent, have you tried measuring to make sure the straightened tyre sits in the middle of the forks? Measure rim to stanchion each side and compare!

Simon

gezebo

Mmm, sounds like something is amiss, but then you have to take into account that you may be a little bias in your thoughts after you crashed?

If anything is bent it would be likely to be the forks as they wont be as strong as the frame. Another way to check is to remove them completely and lay them on a flat surface- not sure how confident you would be to do this yourself? Its easy enough though...

If it was me id just carry on riding and see how you go...

DCR00

the forks look bent back to me from that pic

D4V1D

Cheers for the advice, the front and rear wheels are fitted in the middle of the forks/rear sub-frame. When I ride the bike and stand the frame upright and with the handle bar straight ahead it just wants to go to the left (i think I may have said to the right before but it defiantly to the left) so it feels as though I have to lean the bike to the right just to go straight. Doing this feels as if I'm scrubbing the rear tyre and using more effort.

I've come up with an idea to get the measurement from the crank bolt to the front wheel spindle of a new Cube Acid and compare it to mine.
I've also let some else have a go and they have come up with something is amiss as well.

DCR00

id put money on the forks being bent

D4V1D

Hi I took the cube up to Llandegla on Saturday. Forks seemed to work ok at the start, but after the first set of jumps the forks seemed to be locked and gave little in the way of suspension. It was a real shame as I was with four other people and we all came up with the forks must be sh6gg3d. But I know it might not be the end of my problems.

I've been looking at forks to buy and I'm right in thinking that solo air means only one of the tubes has the air pressure in it, and Dual air has pressure in both.
The other question I have is, If I upgrade the travel of the fork to a 140 or 150 will this affect the geometry of the bike. Or is it the same as standard but with just more travel.
I'd like to replace my Rock Shox Dart 3 with some thing like a Daul Air 120.

delcol

aint dual air, positive and negative air spring chambers

what size fork do the manufacturer recomend, if you put a fork thats to long on it will invalidate your warrenty, and possably mess the bikes handling up,, also may jeopardize your frame.....

best to stick with what the manufacturer states.

gezebo

This is fitted with 100mm travel forks? There will be a small amount of flexibility in what you can swap to but 100-140/50 is a massive jump and will definitely effect the geometry.
Prob best sticking to what you've got +/-10% unless you really know what you're doing and have a specific purpose for changing it.

Bigun6767

I had a similar accident,where the front wheel and forks took a huge pounding and i went OTB.Had to fit a new front wheel and forks--both fork uppers and lowers were bent/twisted.Same result of fork operation--worked once or twice and then siezed.It was a painfull way of ridding myself of those dreadful RST Gila's!!Once the new forks were fitted everything was back where it should be.

gtd.

D4V1D wrote:

I've been looking at forks to buy and I'm right in thinking that solo air means only one of the tubes has the air pressure in it, and Dual air has pressure in both.

Solo Air and Dual Air only have an air spring in one leg. The other leg contains the rebound and compression dampers.

Its mostly cheap forks with no dampers that have springs in both legs.

From Rock Shox web site

Dual Air
With independently adjustable positive and negative air spring chambers, Dual Air is race or trail ready, highly tunable, and one of the lightest air spring systems on the market.

An extremely durable spring system. The positive and negative air spring chambers are simultaneously filled to equal air pressures through a single Schrader valve, simplifying suspension setup while retaining the light weight and plush ride quality of Dual Air.

Air springs have 2 chambers positive and negative with a piston in the middle Solo air have the same pressure in both. Dual air you can adjust the pressure in each one.

Air Springs
Works like a piston with a plunger (piston head) compressing air inside a sealed chamber. The stiffness of the spring is controlled by the air pressure, which is adjusted via a shock pump. Air springs naturally have a progressive spring rate (the more the shock is compressed, the harder it is to compress it further) but shock manufacturers have done much to reduce this and provide a more linear rate. The volume of the air chamber controls how progressive the shock is. More air volume will provide a more linear spring, while less air volume will provide more ramp up at the end of the stroke to reduce bottom out.
Negative Spring
A small spring that tries to compress the shock. Mostly seen in air shocks but also in some coil shocks. The seals in a shock, especially the air seals have a lot of starting friction (stiction) which makes it difficult for the shock to react to small bumps. The negative spring pushes against the main (positive) spring and helps get the shock in motion. An air shock without a negative spring typically has a very harsh feel as it takes a medium to large size bump to get the fork moving. Some manufacturers use a separate air chamber for the negative spring while others use a coil.

The negative spring rate (pressure) should never be higher than the positive rate or it will overcome the positive spring, compress the shock until they become even, prevent the shock from fully extending, and limit the amount of travel. Setting the negative spring rate even with the positive rate will allow the shock to start moving on small bumps and give the most sensitive or plush performance. As the negative rate decreases relative to the positive, it will become increasingly difficult to activate the shock and give an increasingly harsh ride.

To set up a shock with a negative air spring, always deflate the negative chamber, set the positive pressure to achieve the desired amount of sag, and then set the negative pressure to match the positive pressure. If you feel the fork is too bouncy or too plush, try decreasing the negative pressure in 10 psi increments until you achieve the desired feel. If you set the negative pressure first, the fork will not get full travel.

http://www.cyclemonkey.com/suspension_101.shtml

D4V1D

Thanks GTD for the time taken, its cleared a few things up.

nicklouse

Keep the fork length the same and replace the headset at the same time as it will also be dead now.

Bikerguy15

D4V1D wrote:

Hi I took the cube up to Llandegla on Saturday. Forks seemed to work ok at the start, but after the first set of jumps the forks seemed to be locked and gave little in the way of suspension. It was a real shame as I was with four other people and we all came up with the forks must be sh6gg3d. But I know it might not be the end of my problems.

I've been looking at forks to buy and I'm right in thinking that solo air means only one of the tubes has the air pressure in it, and Dual air has pressure in both.
The other question I have is, If I upgrade the travel of the fork to a 140 or 150 will this affect the geometry of the bike. Or is it the same as standard but with just more travel.
I'd like to replace my Rock Shox Dart 3 with some thing like a Daul Air 120.

I think the fork lowers must be bent so the upper stanchions must be reluctant to move past the bushes. BTW putting 140 or 150 forks will severely affect the geometry, the frame isn't designed to take that much travel. You will be perfectly fine with 120's though, but no more though.

D4V1D

I've gone for a set of RockShox RL Dual air. 100mm.

After I removed mine from the bike it was easy to see that I'd bent the steering tube part which goes through the head stock. It was bent back and over to the right as you sit on the bike, so this in turn was throwing the front wheel out to the right forcing me to lean the bike to compensate for this.

bails87

Glad you finally IDd the problem. Hopefully you'll notice a real improvement with those forks too!