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Discussion Starter · #1 ·
I'm in the process of converting a scout 275 into a mullet or whatever they're called. Main reason is I love the way my 29er rolls but love the way this bike 'feels'. I'm hoping to get the best of both worlds with this setup. I'm looking to run 29x2.6 up front and 27.5x2.8 in the rear.

I understand that the larger front wheel is going to push the front end up slightly, increase my HTA and BB height. I'm happy with that as I don't think the changes are large enough to ruin the characteristics of the bike.

I need to change my fork however. 29x2.6 will not fit the stock 140mm RS Sektor I currently have. So I'm looking into what I should change it to:

RS Sektor 29" 140mm A2C 553
RS Revelation 29" 140mm A2C 551
RS Yari 29" 150mm A2C 561

All those shocks have a 51mm offset.

A2C measurement on the stock sektor is 534 with a 46mm offset.

As I understand, increasing the offset and a longer A2C both slow down the steering input. I'm a little concerned that the combined difference will make the bike a bit of a pig around corners. Am I thinking about this correctly?

Or does the larger offset (shorter trail) cancel out some of the increased A2C height?
 

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Might want to throw in slackening the seat tube angle as well as to some of the repercussions of going to a 29 front. If you are getting a new fork, you may want to reduce the travel a bit to keep the geometry in the same ballpark as what you have.
 

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Discussion Starter · #3 ·
Yeah I actually spoke to the resident mullet expert at a supplier. He pointed out that keeping the same travel together with the difference in wheel sizes will change the hta by up to 3°. Comparing what the ews guys are doing, they're fitting a 10mm shorter fork than the frame was specced with to offset the difference.

He also suggested running a slightly narrower front tyre (2.5) to rear (2.6) could help further keep geometry similar.

I've ended up going with a marzocchi Bomber fork which should get me Yari + like performance at 130mm travel. I've got all the bits I'll need order now so just need to wait until they all arrive.
 

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Discussion Starter · #5 ·
Sweet it's going to take a couple of weeks to get everything. Fork I should have this week. Wheels next week. I'm lowering the bar rise and shortening the stem to try offset the potential 2° slacker hta and the expected slower steering & increased stack. Those I should have this week.
 

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Discussion Starter · #7 ·
No worries I might start a seperate build thread. One thing is converting isn't cheap! Wheels & fork cost half as much as the bike. I am however taking the liberty of upgrading while I'm at it 😁.

It would be a lot cheaper to start off with a 29er than a 650b. Problem with that is lowering the BB if it's already low. The other is if you're a short rider or just don't fit most 29ers like me.

Based on what's being done by the pros, starting from a 650b seems the way to go but more expensive overall. Eager to see how it actually feels.

Worst case, I hate it, revert back to stock spec and have enough spares to build up another bike sans frame.
 

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Sounds like you've got a good plan :thumbsup: It's good to have options...and one can never have too many bikes :)

I'm pondering converting a 140mm 650b that's got a 150mm fork, but I don't want to slacken the too much. Even if I downsize to a 130mm 29 fork, I'll probably still be at least 1 degree slacker.

I like your idea about running a plus sized rear tyre, but I don't want to slow the bike down too much...
 

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Cool thread to see today, as I'm tinkering with a "mullet" right now too... in my case, just finding a way to use an extraneous 29+ front wheel/tire that has a 100mm thru axle. I ordered a boost converter and put the wheel on my 27.5+ hardtail (Norco Torrent). I have not had a chance to hit the trail yet but my neighborhood/side of the hill spin was fun. I will adjust the saddle a little before I go for an actual ride, I can feel the rear end is lower and my weight is back, but it climbed the hill fine.

Right now it has a 27.5x2.8 on the rear, but I ordered a 3.0 tire for cheap on eBay, so that should bring it up about 1/4". The bike has a 130mm fork, and was specced with 140mm, so that will also help restore some balance (I assume).

I don't know if it's a long term solution for anything, but for $60 invested it should be a fun experiment... I'll be listening to what you other mad scientists find out too.
 

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Discussion Starter · #12 ·

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I actually did the mullet thing with my last bike, a 2014 Pivot Mach 5.7c. While it was a 26" frame, Pivot had blessed the use of 27.5 on both ends. It required reducing the front and rear shock travel to make it 'OK'. I really didn't like it like that for a number of reasons (high bb, limited rear tire size were the main ones). Ended up putting a 26" rear wheel with a big volume tire and the bike just worked really well. Plus I got a little more rear travel back in the process. BB was still a bit taller than spec, but I could live with it. Moved on to another bike but that one found it's way to my son so I get to hop on it every now and then.
 

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That's a nice selfie Crankout, but this thread is about bikes!

We may need an official "post up your mullet (bike)" thread. Unless I missed it, I can't find one... though there is one a few years old that was focused on hairstyles 🤔.

If someone gets one started, I'll post up once I get a picture of mine (and after going for a few test rides).
 

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I've ended up going with a marzocchi Bomber fork which should get me Yari + like performance at 130mm travel. I've got all the bits I'll need order now so just need to wait until they all arrive.
I had a large scout mocked up, so i threw your new combination in to the model.
Wheel Bicycle tire Bicycle wheel rim Bicycle frame Bicycle wheel

It's shown with 2.25 tires and some of the build kit parts might not be right.
 

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I had a large scout mocked up, so i threw your new combination in to the model.
View attachment 1260185
It's shown with 2.25 tires and some of the build kit parts might not be right.
Huh... Looking at this I'm surprised to see changes to the reach and ETT (one shorter, one longer). I had not considered that. But it makes sense.

And longer wheelbase? HTA/STA was as far as I'd gone in my thoughts.
 

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Discussion Starter · #18 ·
Awesome mock up. What did you use to pull it together?

Makes complete sense. Stack rises so the ett intersects a new point on the st slightly father up, reach increases slightly.

13mm higher bb should actually work ok, the 275 has a pretty low BB to start with.

Wheelbase makes perfect sense too (hta) guessing the change in fork offset 46 to 51 helps mitigate that a little.

I expected a bigger impact to the hta tbh. 63° is where I thought it would end up.
 

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Awesome mock up. What did you use to pull it together?

Makes complete sense. Stack rises so the ett intersects a new point on the st slightly father up, reach increases slightly.

13mm higher bb should actually work ok, the 275 has a pretty low BB to start with.

Wheelbase makes perfect sense too (hta) guessing the change in fork offset 46 to 51 helps mitigate that a little.

I expected a bigger impact to the hta tbh. 63° is where I thought it would end up.
bikeCAD. I build frames occasionally, and like to mock up hardtails i find interesting.

FWIW, I see your proposed build as problematic. I would want a 110mm fork with a 29" wheel on a scout, tops. What you propose is too far 'off the back' for my taste, by a large margin. The geo change will be much more influential than the wheel size. But try it for yourself.

I forgot to change the fork offset in the image above. Fixed.
Bicycle tire Bicycle wheel Wheel Bicycle wheel rim Bicycle fork
 

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Discussion Starter · #20 ·
Interesting, that's more like what I was expecting. Being a small frame I'm not sure how things would change.

A 110mm might be difficult to stomach for the type of riding I'm doing. Even 130 I was thinking might be a little short ☹
 
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