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rear discs and trials?

Dirt rider

Pro Rider
Nov 18, 2001
505
0
redneck wasteland
OK so I went riding with a friend of mine who is very serouis about trials matter of fact thats pretty much all he rides. anyhow he told me its not a good idea to do trials on a bike with a rear disc as they can rip off, and the frame I have has no v- brake posts ( 15'' 04 kona stuff with hayes HFX-9 6inch discs) well damit trials is one of the reasons I bought the bike :help:

Edit: I find this odd as his bike (03 or 04 giant team trials) has rear disc tabs
 

oxygen_77

Monkey
Sep 20, 2003
124
0
Kent, WA
Originally posted by Dirt rider
OK so I went riding with a friend of mine who is very serouis about trials matter of fact thats pretty much all he rides. anyhow he told me its not a good idea to do trials on a bike with a rear disc as they can rip off, and the frame I have has no v- brake posts ( 15'' 04 kona stuff with hayes HFX-9 6inch discs) well damit trials is one of the reasons I bought the bike :help:

Edit: I find this odd as his bike (03 or 04 giant team trials) has rear disc tabs
I use a Specialized P.2 for trials. It also doesn't have V-Brake tabs so I'm forced to use rear disc brakes. One thing I would look for on your bike's rear stays is a brace for the disc tabs (should go from the left seatstay to the left chainstay). If you have that you could more securely ride trials with discs, but even that isn't totally necessary. My personal opinion is that if the bike is made well, the disc tabs will be ok for riding trials (it also helps if you don't weigh 200lbs). The really important thing to consider when using discs for the rear though is that you are reducing the lever length you use to stop. V-Brakes are like using a 26" disc brake because they grab the rim (26" on most MTB's). This means they put less force on their tabs to stop (i.e. longer lever, less force required). With disc brakes though, this doesn't exactly follow what would be considered a logical course. Larger discs put more force on the disc tabs because the tabs stay in place and the mounting gets extended away from the mounts. This puts more force on the tabs when braking. If you are going to use rear discs on a trials bike you should use a small 6" disc and make sure you get a powerful caliper that will lock up really well. Supposedly Maguras are good to use; I personally use Magura Gustav M's (total overkill) but some of the lower models are supposed to work really well. Also, Avid Mechanical brakes are said to work really well, but I prefer the feel of Hydraulic on my trials bike.
 

iridebikes

Monkey
Jan 31, 2004
960
0
seattle
I'm riding an identiti dr jekyll with rear disc for trials. it seems to work just fine. Kona should warrenty it if you crack your frame, but because its a stuf, the frame should be pretty well built and strong. I'm guessing the disc tab is reinforced somehow. maybe internaly, but I'm sure its strong enough.
 

Chutney

Monkey
Jul 27, 2003
155
0
Tacoma, Wa
Originally posted by Dirt rider
OK so I went riding with a friend of mine who is very serouis about trials matter of fact thats pretty much all he rides. anyhow he told me its not a good idea to do trials on a bike with a rear disc as they can rip off, and the frame I have has no v- brake posts ( 15'' 04 kona stuff with hayes HFX-9 6inch discs) well damit trials is one of the reasons I bought the bike :help:

Edit: I find this odd as his bike (03 or 04 giant team trials) has rear disc tabs
From my understanding rear disc isnt a terrible thing on a trials bike until you start doing the bigger moves whire you put a lot of torque on the wheel going the wrong direction (backwards). THis is when the tabs tend to rip off the frames. thats part of the reason that some disk specific trials frames have the disc mount in between the chainstay and the seatstay.

By the time you are doing these bigger moves, it will probably be time to move onto a trials specific frame anyways. Until then, you should be fine as long as you are wary about not landing on the disc (I have sooo many dings in my non drive side chainstay where the disc would have been from failed sidehops). Dont worry so much about the tabs - as iridebikes said, the stuff is a well built beefy bike that shouldnt have any issues.

Just dont land on it. :thumb:

Jonathan
 

Ascentrek

Monkey
Jul 17, 2003
653
0
Golden, CO
Disc brakes don't have the power you can get with V or Maggies with a rim grind. Again, as mentioned above, you'll eventually break the frame in no time. Giant and Specialized don't really make a Trials specific bike, they're a street/jump bike that ends up getting used for some trials type moves. Disc is okay at that point. V-brakes and Magura Hydrualic rim brakes are the way to go.
 

Ascentrek

Monkey
Jul 17, 2003
653
0
Golden, CO
Dirt rider said:
OK so I went riding with a friend of mine who is very serouis about trials matter of fact thats pretty much all he rides. anyhow he told me its not a good idea to do trials on a bike with a rear disc as they can rip off, and the frame I have has no v- brake posts ( 15'' 04 kona stuff with hayes HFX-9 6inch discs) well damit trials is one of the reasons I bought the bike :help:

Edit: I find this odd as his bike (03 or 04 giant team trials) has rear disc tabs
You have a very entry type bike. A lot of people start with short frames of a standard stock mtn bike. Real Trials bikes are like Coustellier, Koxx, Echo, Zoo!, and the Planet X Zebdi. There are others. Go to www.observedtrials.net , they'll have all the information you seek.
 

sHasta

Chimp
Jun 23, 2004
26
0
Charlotte, NC
I wieght in at about 215lbs and have snapped a GT Ruckus doing trials moves because of a disc in the rear. If you are a heavy rider be careful using discs.

Now I ride a Brisa B26D and use disc's front and rear with little problem. The brisa is built for (and warranties) disc use on the rear, they're about the only company that does.

I use 2004 Magura Lousie with stock pads and rotors, they are very powerful.

Good luck with Trials'n
 

Gk. Willie

Chimp
May 24, 2004
28
0
Rochester, NY
Nothing beats the Magura V's. The adjustable levers are so key. Pain in the ass to keep working right all the time. You'll definetly become very experienced in brake service, but you wanted to learn that anyway right.
 

ioscope

Turbo Monkey
Jul 3, 2004
2,002
0
Vashon, WA
hmmmnnn

I got a crazy idea...

Wrap a hoseclamp-ish metal strap around your seatstay and bolt the IS bolts through it!
Shouldn't interfere with Hayes' design.

plenty strong!
 

Chutney

Monkey
Jul 27, 2003
155
0
Tacoma, Wa
ioscope said:
hmmmnnn

I got a crazy idea...

Wrap a hoseclamp-ish metal strap around your seatstay and bolt the IS bolts through it!
Shouldn't interfere with Hayes' design.

plenty strong!
That should help keep the disk mounts from ripping off, but the problem isnt only the mount, its also the stays. Seat stays not built for the ginourmous (j-eye-nor-mous) torque that trials puts on a rear disk brake will likely crack. take a look at the megamo, or PX tibo frames - they have a cross bar between the seat and chain stays to counter the torque from the disk brake.

The hopes are supposed to be nice, but Avid still rules all in the trials world as far as disks go.
 

Polytics

Chimp
Mar 28, 2005
48
0
Vancouver, BC, Canadistan
Magura is now THE Hydraulic rim brake maker. So if you saw Hydraulic rim brakes they were Magura.

I've never seen a well enforced (as in on a Freeride HT) Disk tab rip off due to trials type riding; however, I have seen the tabs on a couple Hayes brake calipers crack from the, afore mentioned, back wards torque that they are not designed to take.

With a big bike like a Kona Stuff, or a Norco Bigfoot etc it is way more likely that you will break the brake caliper itself and not the frame.
 

JTVW

Monkey
Jun 17, 2004
373
0
somewhere hot
I've got a p.1 and it can only run discs, now I know this isn't made for trials but will it last for a beginner? It has that brace between the seatstay and chainstay, but since it wasn't designed for trials, I'm thinking that might not be enough. Anybody know for sure?
 

bikerpunk98199

Turbo Monkey
Apr 24, 2005
1,313
0
the hood
i had a fuji and was trials in it and from doing all the rear wheel hops i cracked the chain stay all the way through. run a v-brake. some companys wont take bikes back b/c of trials. get a magura rim brake the are great.

trials on yo