Mountain bike disc conversion

powell7

powell7

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chris
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Hi all
Iv just got a GT aggressor 2010 from eBay. It's mint and was only used for two weeks.

Anyway, it was an option to have discs from new.
It has all the mounts on the frame and forks.

Just wounded if anyone could recommend a starter disc set and I know I need new wheels to mount them too ???

Thanks chris :-)
 
You'll need different wheels probably as the hubs won't have disk mounts. If they have you're lucky. I bought a bigger disk for my bike think it was 205mm the standard was 160mm along with a hope caliper mount. I can't comment on what type of brakes to get but hope are a name that crops up an awful lot. Don't think they are the cheapest. A lot of bikes nowadays come with avid juicy brake setups so might be worthwhile checking them out :)
 
nickjohnwatson said:
You'll need different wheels probably as the hubs won't have disk mounts. If they have you're lucky. I bought a bigger disk for my bike think it was 205mm the standard was 160mm along with a hope caliper mount. I can't comment on what type of brakes to get but hope are a name that crops up an awful lot. Don't think they are the cheapest. A lot of bikes nowadays come with avid juicy brake setups so might be worthwhile checking them out :)
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Just watch out with getting big rotors like said here, some forks can not handle big rotors. If you are unsure ask your local bike shop or just get something like 180mm front and 160mm rear. I had an old set of forks I put a 203mm rotor on and ended up cracking them just by braking. On my trials bike I have 160mm up front on 24" wheel and the stopping power is unreal. They are Hope brakes but the are not the cheapest. If your bike is just for commuting there are even some decent mechanical brakes out there.

By the way nick I'm not moaning at you lol, just warning the OP because I had it happen to me:)
 
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yes what he said, most forks that have a regular 9mm quick release axle will only handle a ~180mm rotor (check your fork specs). you generally need a 15mm through/maxle to go larger. most wont need a ~200mm rotor.
 
My commuter bike came with Clarks CMD-11 mechanical disc brakes. The Clarks range seem fairly popular as OEM on cheaper bikes - despite being cheap they are much better than previous rim brakes I'm had, and it's so nice to know that the brakes aren't going to be compromised when its raining.
 
Thanks for the replies guys.

Most of my riding is up/across/down and around the South Downs.

I was looking at fitting discs because iv had afew close shaves with cars down some country lanes when my v brakes didn't slow me quite as fast as I'd have liked.
 
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a well set up set of Vs with good pads should be able to throw you over the bars.

whats your budget? a cheap set of disks wont offer much better results to what you currently have.
 
I don't want to spend much over £80.

I might see if I can finely tune the v's that are on it.

Any tips?
 
Yeh to be honest you won't benefit from having disks with that budget, especially if you need new wheels as well. Just give your rims and brakes a good clean and give them a fine tune.

To save buying new wheels to take discs you could always look for a used pair of hydraulic rim brakes. There are a few on Ebay. Or you could even try just getting a booster for your V-brakes if you want a bit more power. A booster is just a solid metal plate shaped like an arch that mounts to your rim brakes. It stops a bit of flexing in the forks when the brakes are applied. I haven't tried them myself but I'd imagine they could add a bit of firmness to the brakes, if they actually work. I couldn't tell you, I've just seen them for sale.
 
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Sure it's possible for £80 if the bike is spec'd up with disc-ready wheels and mounts.

Have a look over at http://www.chainreactioncycles.com/brakes?f=2258 - my preference would be for the Avid mechanicals http://www.chainreactioncycles.com/avid-bb7-mechanical-disc-brake/rp-prod79346

I've had a variety of mechanical & hydraulic discs and the avids are really very good - better than some hydros (Magura Julie, Hope Monos) and not far off Hayes HFX. They have the advantage of never boiling their hydraulic fluid and being very easy to set up clearance so that they don't rub (often an issue with Hydros). I have a pair with 185 rotors on my hack/MTB and they've been excellent for several years with minimal maintainence.

Vs are fine for summer riding and if you're a weight weanie, but forget it in winter for regular use. Sure they can work well, especially the shimano designs with adjustable leverage, but you'll go through a lot of rims.
 
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Nah. I ran shimano v's for years back in the day and never wore out my Mavic rims. Even through the gritty new forest winters.

For £80 you'll never get a good set of disks and wheels.

If you're insistent on getting disks look at shimano, they're excellent bang for buck at the moment. Worth saving for. As for rubbing issues on hydraulics, again, nah you're not doing it right ;)
 
I would advise getting a good set of pads for the V's first - they will set you back a tenner or so and would go a long way to helping you brake well! A set of swiss stops would be a great start.

Hydro discs start to come into their own in wet conditions really. Your best bet is to try and find an ebay/Facebook special set of disc ready wheels and then go for some shimano deore brakes. The deore brakes will set you back about £50 second hand if you can find a cheap set... It all hangs on finding the cheap parts really - some great deal to be found on Facebook by kids that don't care for what they're selling...
 
neil_g said:
Nah. I ran shimano v's for years back in the day and never wore out my Mavic rims. Even through the gritty new forest winters.

For £80 you'll never get a good set of disks and wheels.

If you're insistent on getting disks look at shimano, they're excellent bang for buck at the moment. Worth saving for. As for rubbing issues on hydraulics, again, nah you're not doing it right ;)
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I'm making the assumption he has disc-ready wheels, based on the OP. If they aren't (and they'll be cheap wheels anyway if they are, but that goes with the territory) then yes, I agree it's not possible.

Maybe it's Chilty grit, but lots of the guys I rode with went through Mavic 517 rims with V brakes before we pretty much all graduated to discs. I've done it on a road bike before now, though it took 2 seasons.

Trust me, I knew about adjusting disc calipers, but all the sets of maggies I owned weren't having any of it. Hayes have been fine though, apart from terrible squealing at times. The Avid cable discs have been pretty much the best, most reliable disc brakes I've ever owned, with the only weakness being slightly less feel than a really good set of hydros.
 
I had 521s but they'll be mostly the same. Also used to maintain a fleet of hire bikes and never had and rim issues from v's but then they were checked and maintained post each customer and pads were replaced regularly.

Never had any bother aligning several avid sets or my hopes :)
 
I think the 521s are a lot thicker - it's a downhill rim - so likely why they didn't go through (I have a 521 ceramic on one bike - that requires special pads and is incredibly slippery when wet with normal jobs!).

Avid and Hayes share the caliper positioning system and it works very well most of the time unless a piston starts sticking. Hopes relied on springs retract the pads IIRC. Mostly it works well, though IIRC some would drag because the springs wouldn't stay in place.

Maggies relied on the tendency of hydraulic brakes to self-centre and elasticity in the system to retract the pads. It kinda worked most of the time, except when it didn't and the brakes would bind, usually just after you started climbing a hill. I loved the huge amount of power available through the Julie with a 185 rotor (required care - it was very grabby and I broke 2 ribs going over the bars early on) but hated having to get off & kick the brakes to get them to release for a few minutes. They were on a Giant NRS, and while it was a brilliant machine for climbing, the geometry made descending frightening, and you either minced down a hill or fell off.
 
Never even wore the coating off the 521s :D but the hire bikes were all low end spec and never had any bother there either. Good pads and regular checking/maintenance is the key.

Avid get a lot of slating these days for reliability issues and I don't hear of anyone running maguras these days. Like I say shimano are where it's at for bang per buck presently. But generally I think we'll have to agree to disagree :)

To the OP - I'd make sure you've reached the limits of the setup of your v's by checking the setup. If you do decide to switch I'd recommend not buying rock bottom cheap, like everything in this world you'll end up spending more money down the line.
 
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I would just keep an eye on ebay for a set that would bolt on - I love my Hope DH4's & 203's F & R. They give you the feeling that no matter what, you will stop.. & its right. I use mine in the French Alps every year. You will be just fine with a 160mm for your purposes.
 
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