I currently have a rigid do-everything kind of mtb with two sets of wheels, one fairly burly (650b rear, 29 front and 2.6 inch tyres), the other much less so (xc rims, both 650b and 2.1inch tyres.)

This works nicely as I use the big wheels for trail centre black and red stuff and natural stuff locally and in the Dales, but a 5 min wheel swap has me a nice fast xc bike which not only has much lighter wheels but is a bit steeper and longer as the front wheel drops the front end down.

I thought I was done with suspension, but I’m rapidly changing my mind… So I’m thinking of putting some sus forks on, and rotating between them and rigids every couple of months (or whenever I feel like it*).

My frame (2014 Genesis High Latitude LT) is designed for 120mm 650b forks, but can likely take 140mm as it’s not particularly slack and has a couple of sturdy looking gussets on the headtube.

But I’d still like the ability to do the wheel swap thing and have two quite different bikes in one. So, I’m thinking of going for a 100mm 29er fork and 29er wheel instead of a 120/140mm 650b fork and wheel. (As obviously I can put a 650b wheel in a 29er fork but not vice versa).

Good/bad/terrible idea? Anyone else done anything similar?

I know the more obvious answer is another bike, but I don’t have the (physical or emotional…) space

*This won’t even correlate with seasons, i.e. rigid-winter and front-sus-summer, as I’m likely to hit trail centres more often in winter and that’s where I want the front bounce

27.5+ x 2.8 Trailblazer on a Dually fits ok in a Reba..

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My SIR.9 is set up like this.

100mm Reba / Rigid Niner Steel forks, identical length steerers, with same crown race.

29″ normal wheels, 27.5″+ / 29+ wheels.

TBH, since I bought the Puffin, its not been out at all…

Adapters left on each fork so caliper swaps easy.

Easier with post mount brakes, as you can loosen-brake-tighten & its all lined up again.

Meaning to try a wide 29″ rim (30mm) & a 2.6″ tyre, that is probably best of both worlds. My mate runs that on his Trek Stash & rates it.

I know the more obvious answer is another bike, but I don’t have the (physical or emotional…) space

Find a way to make the emotional space, and the physical space will follow.

But your plan sounds reasonable especially if you want something a bit steeper for your 650b both ends set up.

It will probably end up a bit slacker than it currently is in all guises though.

I know the more obvious answer is another bike, but I don’t have the (physical or emotional…) space

Find a way to make the emotional space, and the physical space will follow.

Ha! That’s annoyingly excellent advice 🙂

Yep, it’ll definitely slacken the thing out. Currently my rigids are about 450mm long, compared to 490mm for some 100mm travel 29er forks with 20% sag. So it’d take nearly 2deg off my current 70deg headangle.

I’m all for making bikes flexible, and what you propose is doable. Be mindful of how it’ll impact BB height too, it’ll probably be just fine but the extra A-C height and slacker HA is at the expense of raising the BB height, not in isolation from it…

TBH, I can understand where you’re coming from with finding the emotional space. I have more than one mtb, but spend too much time thinking about going down to one bike or what would improve either bike, or what needs fixing on either..a source of low level anxiety I can do without sometimes. If only it were that easy to make it stop 🙂

Find a way to make the emotional space, and the physical space will follow.

That’s a great N+1 mantra right there 👍🏼

I think my concern with this plan is that, even if I can have a front-29er set up that matches the height of the frame’s intended 650b set up, the geometry when bottomed out will be significantly different.

Specifically, a 100mm 29er fork + 29er wheel crown-to-floor height is about the same as a 140mm 650b fork with 650b wheel (because the 29er fork is 20mm longer for the same travel, and the wheel radius adds another 20mm)

But when bottomed out, the 29er set up will be 40mm higher.

For handling perhaps that’s better, actually, for for headtube forces it’ll likely be worse.

TBH, I can understand where you’re coming from with finding the emotional space. I have more than one mtb, but spend too much time thinking about going down to one bike or what would improve either bike, or what needs fixing on either..a source of low level anxiety I can do without sometimes. If only it were that easy to make it stop 🙂

Yep, that’s how I am. I have one MTB and a road/gravel bike, which together cover just about anything. I can handle the majority of techy ground with suspension as I’ve been riding for ages (rigid and otherwise). And there is a lot less to maintain and tinker with.

What I can’t handle without suspension are jumps, which have always been my nemesis. Drops I don’t mind, but anything with a steep ramp scares me and with rigid forks most things are a no-go…

For handling perhaps that’s better, actually, for for headtube forces it’ll likely be worse.

This is true, it will reduce the lifespan of the head tube by far more than the increase in moment you’re putting through the HT by increasing the lever length…

But, as long as you’re carefully inspecting for cracks (which you should be anyway) and aren’t on the top end of the weight scale anyway, that should make up for the increased leverage.

FWIW I’ve weighed between 80 and 96kg over the past 18 or so years (so mid to high range of weight!), and have consistently run forks that are 20-30mm longer than the frame was made for, and not (yet) ripped a head tube off despite breaking many parts, including 3 cracked MTB frames (none cracked at the HT).

So, how heavy are you? How much do you trust the frame as it is?

Yep, that’s how I am. I have one MTB and a road/gravel bike, which together cover just about anything. I can handle the majority of techy ground with suspension as I’ve been riding for ages (rigid and otherwise). And there is a lot less to maintain and tinker with.

Ditto for me too, have a road/CX bike too but also a rigid mountain bike. Aiming to find the right frame for a bike that can take a chunky front rigid and be a 120mm HT when needed. Good luck trying it out, you’ll have to post photos when done!

Ditto for me too, have a road/CX bike too but also a rigid mountain bike. Aiming to find the right frame for a bike that can take a chunky front rigid and be a 120mm HT when needed. Good luck trying it out, you’ll have to post photos when done!

Yep, exactly, I think this is quite doable actually… I may commit a bit more to this plan and pick up another frame that clears a 2.6 at the rear more comfortably and has a shorter seat-tube (mine’s 19″, and even with the seat slammed down I don’t have the room to move about as much as I’d like). Tricky to find a frame with geometry that suits that’s non-boost, but I reckon the new BFe or Stanton Switchback would do it.

So, how heavy are you? How much do you trust the frame as it is?

I trust the frame, I think, Reynolds 631 with headtube gussets. I’m 75-80kg and ride reasonably smoothly (or would like to think so)

Done that a few years ago to the NS Eccentric frame.  It wasn’t too bad – accelerated nicely and handled the bumps really well but somehow it wasn’t the most enjoyable ride when cornering so I’ve shifted it…

https://photos.app.goo.gl/Ca7THuvCBw1aKfej6

https://photos.app.goo.gl/aTk5sWnaY5j4aCBS8

I’d say your frame should be fine considering your weight/riding style and the construction of the High Lat, but I’m not a frame builder.  just happened to have a HL for quite a long time and was doing stupid things to it and on it 😉

I did it this year as a bit of an experiment with a Dartmoor Hornet frame. 29er front 150mm fork and 650b rear. It rode really well but I got sick of the the rear wheel getting hung up on things that the front just rolls over and so have since returned to full 29er. I wasn’t concerned about the head tube as the Hornet frames are massively strong and are one of the few hardtail frames that can run a triple clamp fork without voiding the warranty.

I have slimmed the bikes down to one retro MTB and two current MTB’s. Previously, I had a retro MTB, road bike, 29 rigid SS MTB, a modern (for the time) hardtail and full suspension bike.

I prefer having fewer bikes. It feels less excessive. Admittedly, both are very nice indeed – but I feel that I’m dragging around less possessions. I know I could enjoy a BMX and probably a road bike again, however I don’t feel I ‘need’ one. Obviously, I understand that any MTB is not a necessity for me on a material level – but hopefully you know what I am getting at.