# Welding disc tabs onto non-disc frame?



## evdog (Mar 18, 2007)

Has anyone done this successfully? 

I have an old Rocky Mountain Stratos hardtail that has just v-brake mounts on the frame. I'd like to get it set up to run discs front and back. Brake Therapy conversion kits are $175. Has anyone here welded disc tabs onto a non-disc hardtail successfully? I would imagine the cost to do so could exceed the cost of the conversion kit. Any thoughts would be appreciated. Cost is a definite concern, and even at the cost of the conversion kit it may be worthwhile to start looking at inexpensive new frames instead, and sell this one.


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## edoz (Jan 16, 2004)

Coincidentally, I got hit up to perform this very modification today. My thoughts:
It would be cheaper than the conversion kit (minus any repainting) but you may run into a couple of issues. Most v brake frames weren't designed with disc brake forces in mind, so the seatstays may not be up to the task. You could also have a brace put in, or maybe a mount with a long tail like the Willits style that Paragon makes would work. (I've used them on the rear with some creative trimming) It might crack after a while, it might last forever. 
You also need to make sure that the seat and chainstays will clear a rotor, as that didn't need to be a consideration when they were deciding how the stays would be bent.


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## akacoke (May 11, 2011)

i assume you already have all the parts for disc brake conversion . 

in my opinion , its a lot of cheaper to just buy another frame and sell your frame than swap all the parts.


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## cable_actuated (Jun 7, 2012)

It's not that hard to do. I'm a total newb and I managed to braze on a disc tab, brace, and new cable guides.

You can buy a disc tab from Nova for $7.50. I harvested the tubing for the brace from a damaged frame. Cable guides are cheap.

The expensive part is the paint. A powder coat job runs at least $75, but usually between $100 and $125. If you don't care much about looks you can rattle can the modified area and be on your way. 

Like others said, you definitely want to check for clearance issues before you start. I chose to add a brace because it wasn't that much work, but I have two mass produced frames without them and they work fine. If you're modifying a mass produced steel frame it probably has pretty stout seat stays. I think the brace is only necessary with thin seat stays, most likely found on very high end mass production or custom frames. 

If you're paying someone else to do it for you ($50-100) and you want it to look nice ($75-125) it better have some sentimental value to you. Otherwise pick up a new frame.


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## evdog (Mar 18, 2007)

Thanks for the input guys. I hadn't thought of disc clearance as an issue. I put a couple rear wheels on to test. One contacts the chain stay just barely, the other clears by 2mm. I think I would want more clearance than that, and not knowing what wheel I would buy / build I would have to be real careful that it would clear. Seems this would be an issue with the Brake Therapy too.

XTR hub contacts









XT hub clears, barely









For comparison I checked my Ibis. It has about 5.5mm clearance with the XT hub









I killed the rear wheel on this bike over the last couple rides, which is the main reason for making a change. I could go with rim brakes again with my current bike setup, but I like not having to worry so much about wheel true-ness. And discs just work better for me for MTB.


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## edoz (Jan 16, 2004)

Oh crap, I didn't google your frame to see that it was aluminum. (my one track mind) That changes things a bit. You're going to have to figure out whether it will need to be heat treated again after the tab is welded on. It's not a deal breaker, but if it does need to be heat treated it will raise the price significantly.

FWIW, I'd run that XT hub.


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## j-ro (Feb 21, 2009)

It will probabally be just fine after welding the aluminum without heat treating. If you can give it a couple weeks before you start hucking the big lines then all the better to let it 'age' itself

You could also run a 140 rotor if you wanted a little more room.

Finding a welder for an AL bike will prove to be more difficult than for a steel bike.


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