Djrouge

Onza zoot Disk Wheels

14 posts in this topic

Hi, I've been searching the forums for an answer but couldn't find it so here's my question..

I want to move to disk brakes on my zoot so was hoping to find an easy straight forward solution.
I'm new to trials bikes and was a bit confused with crankset and didn't want to buy something incompatible with the bike.

 

So.. If someone has successfully converted their Onza Zoot to disk brakes and wheels and can point me in the right direction (hopefully not too expensive) that would be very much appreciated.

 

Cheers,

 

Dj.

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Hi it's really easy to move to disk brakes you need hubs with rotor attachment points and brakes obviously. The new hubs might mean you may need a new crank set 

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you can convert to discs no matter what type of cranks you have but the type of parts you need will vary. the zoot comes standard with a front free wheel setup, where the ratchet is screwed onto the cranks, and a fixed sprocket on the rear hub. this is also screwed on. the hub width is 135mm for the rear and usually 32 spokes (count them) . the hub has a thread on one side to screw on the sprocket and you will need one that has this thread on one side and 6 disc mounting holes on the other side.  as reference tartybikes sell a 'trialtech sport 135mm rear disc hub'  the front hub can be any standard mountain bike front disc hub. a trials brand one will usually have bolts instead of a quick release skewer, which do hold the wheel in better.

unfortunately the rear hubs are rather expensive, and may require a different length spoke when laced into your rims so be prepared for that extra cost. you may find it cheaper to buy a set of used wheels or even an entire bike which already has disc breaks and disc ready wheels to scavenge for parts

Edited by robkerly
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19 minutes ago, robkerly said:

you can convert to discs no matter what type of cranks you have but the type of parts you need will vary. the zoot comes standard with a front free wheel setup, where the ratchet is screwed onto the cranks, and a fixed sprocket on the rear hub. this is also screwed on. the hub width is 135mm for the rear and usually 32 spokes (count them) . the hub has a thread on one side to screw on the sprocket and you will need one that has this thread on one side and 6 disc mounting holes on the other side.  as reference tartybikes sell a 'trialtech sport 135mm rear disc hub'  the front hub can be any standard mountain bike front disc hub. a trials brand one will usually have bolts instead of a quick release skewer, which do hold the wheel in better.

unfortunately the rear hubs are rather expensive, and may require a different length spoke when laced into your rims so be prepared for that extra cost. you may find it cheaper to buy a set of used wheels or even an entire bike which already has disc breaks and disc ready wheels to scavenge for parts

You're point about the fixed sprocket and ratchet on the crank is exactly where the uncertainty is for me.
Thanks for the info, very helpful..

I've got the brakes and rotors.
I'll do some more research and have a look at that Trailtech rear disk hub and once I've sussed it out, I'll repost to update on what I end up doing just in case it's helpful.

Cheers!

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doesnt need to be that one specifically, im not even sure its in stock. i have previously found dmr singlespeed hubs on ebay cheap that have the same kind of fittings for sprocket and disc. also, there are now splined type ones which wouldnt be compatible with your current sprocket, and older tryall branded ones floating about that use a traditional shimano cassete type spline. either could work but you would need to use the right type of sprocket for them

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1 hour ago, robkerly said:

doesnt need to be that one specifically, im not even sure its in stock. i have previously found dmr singlespeed hubs on ebay cheap that have the same kind of fittings for sprocket and disc. also, there are now splined type ones which wouldnt be compatible with your current sprocket, and older tryall branded ones floating about that use a traditional shimano cassete type spline. either could work but you would need to use the right type of sprocket for them

Yes, I'll have a dig around at other hubs now I know about the fittings, Tarty's Trialtech one is on order but that's no problem as I'm taking my time to plan the shopping list and grab the bits and bobs needed hopefully at a reasonable price.

Thanks again man.

 

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One quick thing - if you're trying to work out whether you've got a front or rear freewheel setup, there's a simple test.  Stand the bike up and spin the cranks around backwards.  If your chain moves, you've got a freewheel on your rear hub (or a rear freehub, like a Hope).  If your chain doesn't move, you've got a front freewheel setup.

The Zoot has front freewheel (you'll see people call that "FFW" too), so as said before you'd just need to get a normal 135mm spaced fixed hub for it.  You can use your existing rear sprocket from your Zoot, but they can be hassle to get off.  If you've got access to a vice and a bit of old chain it's not too bad.  Aside from that, you could just get a new sprocket to go with your new hub.  The Trialtech Screw-On would be a prime one to go for, and to maintain your standard gear ratio you'd need 14t from memory.  You can always count the teeth on your old sprocket to check though.

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Yes I definitely have a FFW on my Zoot, I'll try removing the screw on rear sprocket, I've never took one off but I'm just as interested in getting into the technical side of working on the bikes so it'll be a learning experience and I'll probably need one of those cassette removal tools with the bit of chain on it.. One of the lads I MTB with should have one if I don't want to buy one.

Like you say though, if it's stuck on there I can always buy another sprocket.

Thanks for the input Mark, all you guys seem really helpful, seems like a great community here.

Tony.

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Doooooon't get a chain whip!  They're OK for using to undo cassette lockrings, but they're in no way strong enough to take a fixed sprocket off.  The amount of calls I got when I was at TartyBikes from shops saying "It's impossible to take off, I've broken ___ chain whips trying" was mental.

This is a rough idea of what to do: 

But essentially, wrap some chain around the sprocket, clamp that in a vice then turn the wheel off.  It's best if you've got two people involved - shocking works best, so giving it a 3 count then trying to unscrew simultaneously is the way to go, not just gradually loading it up with more power.  Tyre on and inflated to make life easier!

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Excellent video guide, didn't realise the amount of torque required but I suppose we're constantly beating down on it clockwise so it gets pretty tight, I take it people don't need locktight on the thread for that reason.
I've been watching a few of these TartyBikes guides for other bits, hadn't seen this one though mate so thanks, looks relatively straight forward with a beefy vice and a bit of chain.

Thanks again Mark. (Y)

Tony.

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No worries (Y)

Can't remember if it covers it in the video, but if you find the chain/wheel slip around in the vice, you can 'pinch' a little triangle of chain (so instead of wrapping around like it normally would, you create a little peak by one tooth by making a little triangle of chain).  That stops it being able to spin as it can't force it's way through the vice.

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Aaaahh, I get you now. Thanks Mark and Adam for explaining that. I can imagine pulling my hair out with it slipping in the vice. Very clever solution to that, you guys have obviously done a few of these ;)

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Welcome - and yes, done quite a few!

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