Got Any DH Questions? Ask Them Here

PB Forum :: Downhill
Got Any DH Questions? Ask Them Here
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Posted: Mar 29, 2018 at 12:49 Quote
ThunderChunk wrote:
I have a gambler with adjustable chainstays. Running it in the short setting right now. How would the longer wheelbase affect handling? Better or worse? I mostly stick to flow and blue tech trails. I don't do anything too aggressive.

What you´re asking here is a common misconception.
The chainstay length really is dependent on the length of your front center and head angle or better said, it works in conjuction with those other variables.

Generally speaking, longer chainstays put more weight on your front wheel. As reach and head angle grow/get slacker, chainstays should increase in length to account for the shift of weight.

To illustrate things, imagine a 30cm ruler lying in front of you on your desk. This is your wheelbase. The front is where your front axle sits, the rear is where your rear axle would be. Ideally you, the rider, wanna be in the center of this line in order to weight front and back evenly (or at least somewhere around center). Now imagine you put another 2cm in the front (slacker head angle or longer reach). Suddenly the weight distribution has changed and your front is harder to weight than before. Now if you´d add another 2cm at the rear, we´d end up with the same weight distribution as before, just a longer wheelbase. So now we basically see it all comes down to wheelbase as all three of those variables, front center, chainstay length and head angle are part of what makes up the wheelbase of the bike.
Hope this isn´t too confusing and helps to visualize things a little.

This is also the reason why some manufacturers like Norco have decided to make chainstays longer for each frame size.
And it is also the reason why one cannot simply rely on chainstay length as the sole reason for good/bad cornering of any given bike. Chainstay length always works in conjunction with other geometry variables.

Regarding your Gambler.
It really depends on how much trust you put in Scott and their ability to design a bike.
Personally i´d imagine they designed the bike to be either ridden long/slack or short/steep (chainstay length/headangle), because i imagine they started at some of those points when designing the bike and it would make sense really.
So i´d take that as a starting point. One is more stable, the other more snappy handling.
Then if for some reason you desire more/less pressure on the front, change chainstay length accordingly or if you´d like a more snappy/composed handling bike, adjust HA accordingly.

Posted: Mar 29, 2018 at 12:56 Quote
ThunderChunk wrote:
I have a gambler with adjustable chainstays. Running it in the short setting right now. How would the longer wheelbase affect handling? Better or worse? I mostly stick to flow and blue tech trails. I don't do anything too aggressive.

More stable, particularly at high speed but a shade less nimble. It’s not a big difference although it is affected by whether you have in either high or low B.B. positions.

Posted: Mar 29, 2018 at 14:34 Quote
ThunderChunk wrote:
I have a gambler with adjustable chainstays. Running it in the short setting right now. How would the longer wheelbase affect handling? Better or worse? I mostly stick to flow and blue tech trails. I don't do anything too aggressive.

What head angle and BB height setting are you running? For WBP blue tech I would probably run it in steep HTA, short chain stays and low BB. The blue tech trails are slow and tight enough turns that slacker HTA/long chainstay will make the bike sluggish (which should be paired as Loki points out). If you are going fast on the double black tech then the slack/long setting will feel more stable and planted.

Low BB = better cornering and WBP trails are groomed/well designed enough that pedal/BB strikes are not a concern unless you get way off line.

Posted: Mar 29, 2018 at 19:17 Quote
Wow thanks for all the detailed info everyone! Really helped a lot, I now understand there's more to it then just the chainstay length. Great explanation loki87 Smile .

Gramboh I currently run it at the stock head angle (64 deg I think), high BB and short stays. I have to run it in the high setting as I'm running 26" wheels. Even in the high setting the BB is super low. Since I can't change the head angle (I bought the frame used and it didn't come with a headset so I installed a cane Creek) or the BB height I think it would be best to keep it in the short chainstay option. I don't go excessively fast on the black flow trails but it feels stable enough, definitely more stable than my old gambler.

Posted: Mar 29, 2018 at 20:51 Quote
Hey guys! so, the ghetto tubeless stuff did work!

Ghetto tubeless with 20 inch tube and 2oz stans no tubes

But i'm running into a number of leakage issues, i did not notice that there was small hole close to a knob and the sealant is struggling to seal it, it also leaks a bit by some parts very close to the bead, i've tried the "hula hoop" and used a tub of water to submerge the tire and look for leaks, then tilting it to where the leak is and it seems to stop, i'm not very sure tho.

Going back to the small hole i mentioned, can you use conventional patches inside the tire? i used 2oz (59ml) of sealant, should i add more? it's a 26 x 2.4 tire, all help is greatly appreciated!

Posted: Mar 29, 2018 at 21:55 Quote
MetalheadWolfRider wrote:
Hey guys! so, the ghetto tubeless stuff did work!

Ghetto tubeless with 20 inch tube and 2oz stans no tubes

But i'm running into a number of leakage issues, i did not notice that there was small hole close to a knob and the sealant is struggling to seal it, it also leaks a bit by some parts very close to the bead, i've tried the "hula hoop" and used a tub of water to submerge the tire and look for leaks, then tilting it to where the leak is and it seems to stop, i'm not very sure tho.

Going back to the small hole i mentioned, can you use conventional patches inside the tire? i used 2oz (59ml) of sealant, should i add more? it's a 26 x 2.4 tire, all help is greatly appreciated!

I used brand new tires for my tubeless setup. Maxxis wire beads and mtx 33 wheels. Old tires with kinked beads would be the reason for leaks. You absolutely could patch it but I'd be worried about the patch failing while riding.

What's the reason for the inner tube? I just did tape and sealant and it's been working great!

Posted: Mar 29, 2018 at 22:24 Quote
ThunderChunk wrote:
MetalheadWolfRider wrote:
Hey guys! so, the ghetto tubeless stuff did work!



But i'm running into a number of leakage issues, i did not notice that there was small hole close to a knob and the sealant is struggling to seal it, it also leaks a bit by some parts very close to the bead, i've tried the "hula hoop" and used a tub of water to submerge the tire and look for leaks, then tilting it to where the leak is and it seems to stop, i'm not very sure tho.

Going back to the small hole i mentioned, can you use conventional patches inside the tire? i used 2oz (59ml) of sealant, should i add more? it's a 26 x 2.4 tire, all help is greatly appreciated!

I used brand new tires for my tubeless setup. Maxxis wire beads and mtx 33 wheels. Old tires with kinked beads would be the reason for leaks. You absolutely could patch it but I'd be worried about the patch failing while riding.

What's the reason for the inner tube? I just did tape and sealant and it's been working great!

because i had it at hand, and couldn't buy fancy valves at the moment. Thanks for the imput by the way, these tires are 1 year old though.

Posted: Mar 30, 2018 at 16:57 Quote
In my experience, tire plugs work better than patches when running tubeless.

Posted: Mar 31, 2018 at 0:23 Quote
Kitejumping wrote:
In my experience, tire plugs work better than patches when running tubeless.

I use tire plugs a lot at work on our equioment. I was thinking this may work but not positive if it would on bike tires. Good to know it does work.

Posted: Mar 31, 2018 at 3:22 Quote
Does anyone know the dimensions of IFP chamber for Marzocchi Roco RC?

I need the depth (length), and diameter of the chamber. I am trying to make a new one, since the old one got broken off while transporting the bike.

Thanks.

Posted: Apr 1, 2018 at 0:11 Quote
I know that there are Kashima coats and dvo do emerald coats on their suspension, but I am wondering would different colour coats on different suspension work. I get that this is a DH thread, but I couldn't find a suspension specific one. different colour suspension would fit with different bikes e.g. blue pivot dh carbon with blue fox 40s?

Posted: Apr 1, 2018 at 0:53 Quote
timosv10 wrote:
I know that there are Kashima coats and dvo do emerald coats on their suspension, but I am wondering would different colour coats on different suspension work. I get that this is a DH thread, but I couldn't find a suspension specific one. different colour suspension would fit with different bikes e.g. blue pivot dh carbon with blue fox 40s?

There are coloured stanchions out there, I've often though about some red ones but I'm not sure my local park is ready for that kind of awesomeness

Posted: Apr 1, 2018 at 7:14 Quote
timosv10 wrote:
I know that there are Kashima coats and dvo do emerald coats on their suspension, but I am wondering would different colour coats on different suspension work. I get that this is a DH thread, but I couldn't find a suspension specific one. different colour suspension would fit with different bikes e.g. blue pivot dh carbon with blue fox 40s?
there was an Aussie company based inMelbourne if I’m not mistaken. Might have been blonde bikes or something? They did fork coatings in a few colours so it might be worth checking out if they’re still in business

Posted: Apr 2, 2018 at 10:59 Quote
any advice on how to hit 35-40foot gap? my friend thats been riding for 5 months hit one

I need to do it no since ive been riding for 3 years

Posted: Apr 2, 2018 at 12:05 Quote
sniperboy13 wrote:
any advice on how to hit 35-40foot gap? my friend thats been riding for 5 months hit one

I need to do it no since ive been riding for 3 years

Well yea if he did it, you've GOT to. Salute


 
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