Demo 7 Anyone Else have this sorta problem?

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Demo 7 Anyone Else have this sorta problem?
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flag cyclebean
O+
Posted: Mar 29, 2009 at 3:19 Quote
howsit Guys
I love my demo 7 however does anyone else find that the bb is waay to low? I find im constantly hitting my pedals over rocks and on roots and stuff.. does anyone else have this problem? It resulted in me having a serious crash today which really sucks.. I am buying a triple clamp and am hoping this is going to raise the bb up slightly... I am also thinking of buying short cranks like 65mm... has anyone else had this sort of problem with the demo and does anyone know another way of lifting the bb height abit more?
Ryan
flag NorcoLouis
Posted: Mar 29, 2009 at 3:26 Quote
how much sag you running?
flag spamela
Posted: Mar 29, 2009 at 3:31 Quote
NorcoLouis wrote:
how much sag you running?
How do you measure sag?? what exactly is it?
flag NorcoLouis
Posted: Mar 29, 2009 at 3:34 Quote
u measure sag by putting the bumpstop on your shock to the top and a cable tie on your forks then wil all your riding gear on etc. you sit on the bike and see how much the cable tie and bumpstop moves, for dh riding it should be around 1/3 of the total travel.

hope that helpsSmile

and sag is how much travel is used when you sit on the bike.
flag cyclebean
O+
Posted: Mar 29, 2009 at 3:39 Quote
cool Smile thanks alot dude! so obviously if theres to much sag you just run the coil harder>?
flag pug5ley
Posted: Mar 29, 2009 at 3:41 Quote
I have the same problem but thats the low bb of most spesh bikes. I take it you hav t on high bb not low? I riun mine on low so get a few hits but this was reduced when it was set in the high position. I also have the travel shim removed so got a bit more travel now.
flag NorcoLouis
Posted: Mar 29, 2009 at 3:42 Quote
norcorider121 wrote:
cool Smile thanks alot dude! so obviously if theres to much sag you just run the coil harder>?

ye, or jus put a bit more air in forks or shock depends how much more u have.
flag cyclebean
O+
Posted: Mar 29, 2009 at 3:57 Quote
sorry what do you mean by t on high or low?
flag pbuser102331
Posted: Mar 29, 2009 at 5:17 Quote
norcorider121 wrote:
sorry what do you mean by t on high or low?

the shuttle that your shock is atached too is flippable so you can raise the bb height.

photo

high position


photo

also gives a better head angle
flag cyclebean
O+
Posted: Mar 29, 2009 at 7:43 Quote
so the bit which connects the shock to the frame must just be flipped round? marquis do you have this problem coz it seems like your bb is way higher then mine..
flag comacruz
Posted: Mar 29, 2009 at 8:10 Quote
marquis rides his in the high bb setting....there's a difference of 0.47" from low to high (14.25" to 14.72")....i ride mine in the low setting with 170mm cranks and thinner pedals....i rarely clip rocks or roots but i am always conscious of my crank position in respect to the terrain
flag wirenut013
Posted: Mar 29, 2009 at 8:21 Quote
NorcoLouis wrote:
norcorider121 wrote:
cool Smile thanks alot dude! so obviously if theres to much sag you just run the coil harder>?

ye, or jus put a bit more air in forks or shock depends how much more u have.

if youve got the dhx 5.0 the col is the preload.. to reduce sag add more air pressure.. u can get the online manual on fox's website.. it helped me.. it expalins how to adjust the shock and what each adjustment does so u can find the settings u want
flag cyclebean
O+
Posted: Mar 29, 2009 at 8:32 Quote
cool thanks I have a dhx 4 on the rear but i will look at their manual I think the bb setting and a triple clamp w2ill hopefully manage to lift it enough, also when i start riding clipless i think it wont bother me as much
flag hampsteadbandit
Posted: Mar 29, 2009 at 11:13 Quote
first place to start is to put your information into a good spring rate calculator like found on Mojo or TF Tuned Shox websites

you need to work out what the correct weight coil shock is for your Demo 7, against your body weight (including your typical riding gear as this adds weight, put it all on and weigh yourself on your bathroom scales)

you will need your weight, shock stroke and amount of rear travel to enter into the spring calculator

something to understand is that when Specialized ship their frame or bike, they include an "average" spring weight for an "average" rider - typically 11 stone

if you are lighter or heavier, its critical to purchase a new DHX coil spring of the correct weight, so you can get your rear suspension "sag" (settlement movement under rider weight)correct

if your sag is incorrect,your bike's suspension will not work as intended, and things like pedal strikes will be very common as the bike is sitting too low in its travel

you can only put 2 full turns of pre-load onto a coil spring (using the pre-load collar) before you need to change the spring to a different weight - these 2 turns only make a 1% spring rate difference

its scary how many bikes we get through our workshop where the rider has no understanding of sag or coil spring weights and has put 10-15 turns of pre-load onto their coil shock, often winding the collar half way down the shock body!!!

this causes all kinds of problems like coil binding, shock valving / sealing failure and can even shear off the rebound knob on certain setups

getting the spring rate correct on your rear shock and front forks is so critical to having a suspension bike that works properly

I'm always sad when a rider spends £2,500 on their bike and won't spend another £55 on a coil spring for the rear shock and £40 for a fork spring because they can't be bothered to spend a little more and some extra time - might as well buy a hardtail if you are not going to set it up correctly!

getting the spring rate right is the first step of suspension tuning and bike setup - adjusting the air pressure in the DHX coil shock does not compensate for the improper spring rate
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