21" knobbies with SM brakes... how bad of an idea is this?

[Jon]

So I've got myself pretty much sold on picking up the SM currently for sale in Colorado. Going to check it out Saturday.

As we can all agree: this is a good idea and I should buy it.

However, this would leave me with 2 dirt bikes: my EX and the SM. I would like to be able to bring my wife dirt riding with me, so I would buy another wheel set for the SM. However, the SM has the large diameter radial brake mount, which would make it nearly impossible to make an adapter for smaller brakes. So I would be stuck putting an SM rotor on a 21" front wheel, and running the SM brakes.

Is this a terrible idea? I could probably handle the touchy-er front brake, but the wife might have trouble. Would the external reservoir on the handle bars brake if dropped? What rocks and other impacts on that big rotor?

 

[snydes]

I think this was talked about before, the SM caliper will hit the spokes of the 21” wheel I believe was the issue.

 

[Philip]

I think this was talked about before, the SM caliper will hit the spokes of the 21” wheel I believe was the issue.

SM wheels and brakes on a non-SM

 

[Jon]

I think this was talked about before, the SM caliper will hit the spokes of the 21” wheel I believe was the issue.

Ah, yeah that makes sense. I had not considered spoke clearance as an issue... I've use the SM caliper on my EX, but only with my 17" wheels.

So it would be 17" knobbies if I want to take the SM in the dirt... at that point, I think I would just ride the sketchy SM and give my better half the well sorted EX for some lazy dirt rides.

Still not totally sold on having 2 Altas... It would be nice to have more range to do longer trails. I keep flipping back and forth.

 

[leeo45]

The 'solution' which has been adopted by a number of people is to mount knobby tires on the 17 inch rims. Admittedly it is a compromise, however you don't really have a dirt bike suspension on the SM anyway.

I have ridden my KTM SM on 17" knobs and it is a pretty capable dual sport; but I wouldn't take it on a MX track or try to race an enduro. If you are going to turn the SM into a fully capable dirt bike with appropriate ground clearance and performance you really need the shock, the forks+brake, the wheels and tires, and probably a few other bits. That has also been done by people here.

 

[C5tor]

Is your wife an experienced dirt rider? If not, how about something like the Sur-ron Light Bee?

 

[Jon]

Is your wife an experienced dirt rider? If not, how about something like the Sur-ron Light Bee?

No, she's not very experienced. But she is really into electrics, and doesn't like to ride very far... so the SM seems like a great street bike for her. It would replace her Honda CB300F.

When we hit the dirt, I would give her the EX. Since we go slow, I could probably screw around on the SM and still keep up.

 

[B. FRANK]

So I've got myself pretty much sold on picking up the SM currently for sale in Colorado. Going to check it out Saturday.

As we can all agree: this is a good idea and I should buy it.

However, this would leave me with 2 dirt bikes: my EX and the SM. I would like to be able to bring my wife dirt riding with me, so I would buy another wheel set for the SM. However, the SM has the large diameter radial brake mount, which would make it nearly impossible to make an adapter for smaller brakes. So I would be stuck putting an SM rotor on a 21" front wheel, and running the SM brakes.

Is this a terrible idea? I could probably handle the touchy-er front brake, but the wife might have trouble. Would the external reservoir on the handle bars brake if dropped? What rocks and other impacts on that big rotor?

I am running knobbies on my sm for the winter. I am running irc ve33 and ve 35 460/100/17 front and 510/100/17 rear. I bought extra sm wheels from liquid performance off of eBay and the wheels came with sprockets, rotors and spacers. first I tried 19 and 21inch alta wheels(also from liquid) but due to a slighter spoke angle on the front wheel the caliper does not clear the spokes, the wheel spun but heard a slight ting,ting,ting as the spokes hit the caliper(bummer, wasted $). the sm does not have great off road suspension but is still a blast in the dirt if you don't push too hard. ps. both tires are rear tires. also get a slide plate and rear brake pedal support. I have heard of people lacing wheels slightly offset(I assume you loosen spokes on one side and tighten on the other) but I didn't want to try that. you would only need a tiny offset if you wanted to go that route. I also do not know if switching to a 2 piston front caliper would mount up. I just went with the 17's.

 

[Philip]

View attachment 6780

I love the looks. Fun and badass at the same time!