Physics ?

[Scott]

I've read more than a few times that single pivot brake jacking/stink bugging is minimized with a disc setup-can anyone explain this in simple terms?  Seems it's the same amount of force being brought into the pivot whether disc or v. Well the vee is farther from the hub which transfers to the swinarm and pivot so maybe there's leverage apart from just slowing our wheel....

[Tom_A.]

It's not just the amount of force, it's the direction as well.



On V-brakes mounted to the swingarm, braking forces act perpendicular to the swingarm and can thereby impart large torques about the pivot.



On a disc brake equipped bike, the caliper can be oriented so that the forces are imparted into the swingarm in a direction parallel to it...or ideally pointing directly at the pivot location.  These forces don't impart as large of torques and therefore any "jacking"/"stink-bugging" effect is lessened.



My solution...don't use your brakes so damn much!

[Tom_A.]

It's not just the amount of force, it's the direction as well.

On V-brakes mounted to the swingarm, braking forces act perpendicular to the swingarm and can thereby impart large torques about the pivot.

On a disc brake equipped bike, the caliper can be oriented so that the forces are imparted into the swingarm in a direction parallel to it...or ideally pointing directly at the pivot location.  These forces don't impart as large of torques and therefore any "jacking"/"stink-bugging" effect is lessened.

My solution...don't use your brakes so damn much!

[Scott]

Thanks Tom.  With a long winter ahead I think I'l follow Matts example and  hand file an adapter for my dropouts.  Won't miss the grinder/stink bug side effects of V brakes but will miss the lightness factor.  

[Simon]

Thanks Tom.  With a long winter ahead I think I'l follow Matts example and  hand file an adapter for my dropouts.  Won't miss the grinder/stink bug side effects of V brakes but will miss the lightness factor.  

You won't miss any lightness if you fit Formula B4 SL's there that light but with all the performance.Simon [smiley=nod.gif]

[Matno]

You won't miss any lightness if you fit Formula B4 SL's there that light but with all the performance.Simon [smiley=nod.gif]

Yeah, and your wallet will be a lot lighter too!  

[Simon]

Yeah, and your wallet will be a lot lighter too!  

Found the price quite resonable over here not much more than a full set of XTR V's if your hubs are already disc compatable that is,but if you've made up your mind to go disc anyway and weight is an issue there's your answer and the price is comparable with other high quality makes.if costs an issue stick with V's, don't go for cheap disc systems you'll only end up wishing you'd saved a bit more and got a quality system for your steed, been there, happier now,Simon [smiley=laughing.gif]

[Matno]

You're absolutely right Simon. Of course, comparing the price of anything to retail value of XTR is a poor way to make it sound "reasonable." I'm just a little jaded about the high prices of bike components in general. I would never pay retail for XTR anything. Sure, it's the best, but the price difference between that and XT is so far out of proportion, it surprises me that they can make money off of it. Obviously there are enough of us gullible folks out here that have to have the latest and greatest that they can! I'm sure I'd have full XTR everything if I weren't on such a tight budget!

I must say though, I've been more than happy with my Avid mechanicals. Maybe not the best disc brakes. Certainly not the lightest, but a great all around brake set for a lot less money. The disc wheels were what killed me (in the weight department, that is). 1822g wheelset (including skewers) actually added a lot of rotating mass to my bike. I don't really notice it on the trail anymore, but just knowing it's there is a drag. All in all, the switch to discs only cost me about 1.7 lbs, but I was hoping to lighten the bike when I bought the $500 wheelset (for which I only paid $91 used).  

[Simon]

Never pay retail on anything bike related always find a bargain even on XTR stuff,bought my formula's(not sl's mind,b4's but nearly as light) with a set of h/built wheels (my old wheels weren't disc compatable) got big discount and no rotational weight gain and sold my old wheelset which helped offset the outlay,not had much to do with avids but just read an ad regarding there new juicy seven hydro brakes (www.avidbike.com) look and sound pretty good no news on price though, if your an avid fan worth a look, like to see a comparison against the all new hope mono's which look like they've raised the standards with no price increase over the old mini's,couldn't agree more about the excessive cost of bike related components especially from the large corporations (shimano etc) but I can see over here why some companys have to charge what they do,its just bloody expensive to manufacture over here (we have a crap goverment) there are a few small low volume cottage industry companys over here (Hope,Pace,Middleburn,Betd,X-lite,etc) making some superb components but if it wasn't for some of us buying these components what would we be left with (Shimano,Rockshox,etc) I like to have a choice.Simon [smiley=nod.gif]