[burkawitz206]

Currently running 2018 Shred Dogg with a 2018 Fox 36 Factory 160mm. GG says you can run up to 180mm fork on the SD. The 27.5 Fox 36 170mm is damn near the same ATC as 29 Fox 36 150mm. Benefits of a 29er in the front sound nice. Is a SD with a 29er 150mm fork a horrible idea?

 

[Ganderson]

I've been contemplating this for a few weeks actually...

Since I found my sweet spot on the Shred Dogg set up as a Megatrail rear shock, trail mode (150mm) and 170mm fork (so, a Megatrail), that gives a 20mm differential between front and rear suspension.

Switching to a 150mm 29er version of the same fork changes the axle to crown by only 1mm. The additional offset of the 29er fork helps offset the larger wheel radius and according to my CAD model the geo is almost identical with just a tiny bit higher front end.

It just so happens I need to build up a new front wheel anyway, so I'm 80% sure on trying this experiment.

 

[burkawitz206]

I am very interested Ganderson. Would running the 29 front setup with the MT shock preclude you from using gravity mode as well as trail mode? I think I remember somewhere reading that it isn't a good idea to have more rear travel than front but I can't remember why. The only thing I could think of is that you may have to put more effort into keeping the front wheel weighted, especially during deep compression events.

I may also email GG and see what they think about this overall.

 

[Nurse Ben]

Currently running 2018 Shred Dogg with a 2018 Fox 36 Factory 160mm. GG says you can run up to 180mm fork on the SD. The 27.5 Fox 36 170mm is damn near the same ATC as 29 Fox 36 150mm. Benefits of a 29er in the front sound nice. Is a SD with a 29er 150mm fork a horrible idea?

I have the same set up as you, Fox 36 160, but I've got the Revved frame, so I can run a shorter lower cup to adjust stack which gives me another 10mm reduction to play with.

If you go mixed wheels, that's gonna make a big difference in front end height, probably equivalent to running a 180mm fork; there's about 20mm difference in tire radius, so going down to a 150mm fork will help, but it'll feel like a 170mm fork. A a 140mm fork would probably be closer to thh geo you have now.

If you give me a couple days I can mock it up for you using a Bomber Z1 29 150mm fork.

 

[Nurse Ben]

I've been contemplating this for a few weeks actually...

Since I found my sweet spot on the Shred Dogg set up as a Megatrail rear shock, trail mode (150mm) and 170mm fork (so, a Megatrail), that gives a 20mm differential between front and rear suspension.

Switching to a 150mm 29er version of the same fork changes the axle to crown by only 1mm. The additional offset of the 29er fork helps offset the larger wheel radius and according to my CAD model the geo is almost identical with just a tiny bit higher front end.

It just so happens I need to build up a new front wheel anyway, so I'm 80% sure on trying this experiment.

A-C difference between a same brand/model 29" and a 27.5" fork is 10-15mm depending on forks. Offset doesn't change geometry all that much. It's worth trying, but the key is keeping the front end from being too tall and wacking out the geo. A shorter travel fork is the best bet and running a short lower cup if you have a Revved frame.

I've run mixxed wheels a fair amount, it works better on some bikes than others; loved in my Mutz, didn't care for it on my Smash.

 

[dbolster24]

Following... Running 27.5 plus pike push acs3 150mm front fork on my AL shred Dogg and have been contemplating a 29 up front. 27.5 x 2. 6 tires.

Curious to see what people think or any advantages.

Sent from my SM-G950U using Tapatalk

 

[burkawitz206]

I have the same set up as you, Fox 36 160, but I've got the Revved frame, so I can run a shorter lower cup to adjust stack which gives me another 10mm reduction to play with.

If you go mixed wheels, that's gonna make a big difference in front end height, probably equivalent to running a 180mm fork; there's about 20mm difference in tire radius, so going down to a 150mm fork will help, but it'll feel like a 170mm fork. A a 140mm fork would probably be closer to thh geo you have now.

If you give me a couple days I can mock it up for you using a Bomber Z1 29 150mm fork.

Thanks Ben and Ganderson for the input. Even though GG says SD can be run with up to a 180mm fork the front end would probably feel really high like you said. Looking forward to seeing what you come up with.

 

[Curveball]

Here's a good discussion on the topic.

 

[Ganderson]

That Bike piece is encouraging. They mention the 20mm f/r travel differential as crucial which reinforces my thought that it might work for me.

They also mentioned that the measured axle height difference between the 27.5 and 29" front was only like 12-13mm, that's not as bad as I thought.

Fork axle-to-crown differences are pretty negligible.

Fox 36 150mm 29er 557.1
Fox 36 170mm 27.5 559.1
Lyrik 150mm 29er 561
Lyrik 170mm 27.5 562

 

[Nurse Ben]

I rode my Mutz as s mixer, quite a bit in BC, trip to St George, really liked it, not sure why I stopped running it, but I’m sure I’ll try it again once the fork arrives... it’s on the truck for delivery 👍

 

[burkawitz206]

Total axle-height/wheel radius difference probably varies, Ben said ~20mm and I have seen that number elsewhere too. If it was nearer to 10mm like you said it might be easier to deal with on the AL GGs. Anyone got a 29er wheel they can measure and list the tire type and size too?

 

[burkawitz206]

I am still trying to get my head around how much extra front wheel height I would be dealing with in different setups on a 2018 SD. The fork ATC numbers look pretty close (+/- ~2mm) between 27.5 170mm and 29er 150mm fork so that is promising.

As far as for the front wheel itself, I found the below numbers over at https://www.bikecalc.com/wheel_size_math; for those of you with 29er wheels do you think these are accurate within a few mm? I would like to keep running my rear wheel as a minion DHRII, current size is 2.4, and I could run a larger rear but I don't think I want the rear wider than the front so somewhat stuck there.

So far the best I can come up with in terms of minimizing the change in height of the front end in this setup is a 2.4 29er on the front, keeping 2.4 rear which according to these numbers would leave me with an extra ~16mm of front-end height in the mullet setup.

Wheel size Wheel diameter
650b/27.5 2.40 inch 705.92
650b/27.5 2.50 inch 711.00
650b/27.5 2.60 inch 716.08
-----
700c/29er 2.30 inch 738.84
700c/29er 2.35 inch 741.38
700c/29er 2.40 inch 743.92
700c/29er 2.50 inch 749.00

 

[Nurse Ben]

So what’s your goal?

If you choose the tallest 27.5 out back and the shortest 29 up from, you could just as easily use different 27.5 tires to achieve a similar though smaller gain.

I’ll go measure some tires and post back...

HHR 27.5 x 2.8 715mm
DHF 27.5 x 2.8 720mm
Rekon 27.5 x 2.8 710mm
Rekon 29 x 2.6 760mm
Kennebec 29 x2.6 765mm

So you’re looking at ~ 20mm difference between comparable tires. You could run a 29” Rekon in front and 27.5 DHR in back, but that would be retarded 🙄

I’m running s 29” Bomber Z1 150mm fork with the tall cup, it’s a great fork, rides tall in 29er mode and rides “normal” in 27.5 mode.

To balance your mullet to a normal geo on a Revved Shred Dogg with a 160mm fork, you could change to a short lower cup (-10mm), change to a 29” fork (+10mm) and reduce the fork to 140mm. On an aluminum Shred, I’d go with same plan, it’ll just be raked out like it would be with a 170mm fork.

 

[burkawitz206]

Hey Ben,

Rekon in the front front *shudder*

As far as my goals, I really like the idea of having more roll-over of the 29 inch wheel but I don't want to compromise the geometry of the bike. Also having more BB height and being able to more effectively use gravity mode would be really nice. Like you said, maybe I could just get a few mm more if I just run 2.6 front and back and not mess around with the 29er setup, I only have 30mm iw rims so I don't think I can step up to a 2.8.