[Closed] OH NO!--not another 27.5/650b vs 29er question. 🙂 Help...could use some input.

I had the same dilemma and ultimately went with 650B partly because I'd had a 29er FS bike and found it boring, and partly I wanted 16.5" chainstays and going 650B gave the builder an easy life!

The bike was originally had a 65 degree head angle with a 150mm Revelation and the bike was great on the steeps but the steering was very 'floppy'. I changed the fork to a Suntour Auron and lowered it to 130mm which gave a 66 degree HA and the steering is infinitely better. Still great on the DHs but much more predictable when cornering. I'm not bike designer but it might be something to think about. Maybe the offset on the Rev didn't work with the head angle.

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Go 29" with enough clearence for 2.8 tyres and a BB height that will allow you to drop 10mm without major clearance issues.

In a year you'll thank me.

+1 chainstay length is the key IMO.

29er all the way if you can live with the longer stays.

Personally, I think slack hardtails don't handle well at all. 67/68 is fine for a hardtail. Anything slacker and they handle like a bus on anything other than steep, fast stuff. On a FS you can get away with it, as you ride/corner them differently and carry more speed. On a hardtail the front end is key, and that needs to steer well. Just my 1p. Have you ridden a 65deg 26er hardtail? I have (456 SS) - it was awful.

Tough one, but I think I'd go 29er with enough clearance in the back to also take a B+ rim and tyre (27.5 x 3.25) just to give you more options

+1 for 29er.
+1 for chain length is key.

The angles you describe are pretty similar to the Stanton Switchback which seems popular with its owners. That's a 650b jobbie.

I've just bought one which should be ready for the weekend. Will let you know how I get on with it.

Personally, I quite like slack hardtails. My previous Slackline was reasonably slack, especially with 150mm Z1's on the front.

Thanks for all the quick input. Why can't y'all (I live in Texas) all think the same way like robots? 🙂

My latest geometry for 29er calls for a 16.4" chainstay length -- pretty short. For 27.5, the latest design is around 16.7". I am also thinking that with 27.5 frame, I can go with "wider/bigger" tires without making the tires/wheels as heavy as doing the same with 29ers.

-walleater: I'm likely to go with 140mm Pike or MRP Stage forks. If I go with 29er, the frame design will be similar to that of 2Soul's QH, which will have short chainstay and won't be an issue to my builder.

-reggiegasket: I've never ridden a 65 HA 26er. My previous 29er had a 70.5 HA, which was way too steep; of course, that was my XC rig. I think my HA is right around your mentioned range.

-JCL/scottfitz: why the 29er and 2.8" tyre clearance? I was thinking 2.5" would be plenty. Please educate me.

-mindmap3: You are right about the geometry's similarity to that of Switchback. In short, I've been studying the geometry of Switchback, Privee-Production 27.5, and a few other well-known 27.5/650b bikes. I do remember your getting a Switchback frame and you are still waiting on parts. If I do 650b, I'd go with either 140mm or 150mm fork.

I like the look of the geo on this frame: http://zealousbikeco.com/?portfolio=division-frameset

What fork length is you HA based on?

-mindmap3: You are right about the geometry's similarity to that of Switchback. In short, I've been studying the geometry of Switchback, Privee-Production 27.5, and a few other well-known 27.5/650b bikes. I do remember your getting a Switchback frame and you are still waiting on parts. If I do 650b, I'd go with either 140mm or 150mm fork.

The last few bits will be here this week.

I've gone for 140mm forks. I thought it was slack enough without adding longer forks. I can increase the travel to 160mm though if I want.

-scottfitz: HA is based on 140mm MRP Stage fork.

Here you go.

http://enduro-mtb.com/en/di-a-2015-breakout-sessions-650b-wheels-are-they-the-future/

Don't be scared of chainstay length. Especially at 6'+. Short chainstays (and slack seat angle) means poor steep climbing ability. Think balanced with front centre length and optimal rather than short as possible.

Thanks much, JCL. Good stuff.

for the use you are wanting, i'd go 650b and forget all about 29.

JCL speaks sense

Not criticising (honest), but how come you're getting a custom frame if you're not even decided what wheel size you want?

And my two pennies (or cents for you), consider 29in if it's rough where you ride, 650b if trails are tight but smooth.

chakaping +1. I'd after have a really clear idea of exactly what I wanted before I splashed a significant amount of money on a custom frame.

I'm guessing you've not thought about rear axle length?

Personally I don't think 650B+ will take off. I wouldn't bother building a bike around something that may or may not take off in a years time.

Most of that stuff mentioned in the link that JCL posted is total marketing bollocks. Even the Rocky Mountain guy who designed the Sherpa thing thinks that the idea 650b+ will replace normal trail bikes is a load of balls.

That 2.8 wtb tyre actually has a tread pattern that is no wider or even narrower than many 2.4 tyres. It's just the carcass that is huge, so you're gaining undamped comfort at the expense of travel ie damped comfort.

Mountain bikers won't let common sense or logic dictate their buying choices though. You will get ****tards putting these tyres on Enduro 29ers instead of buying 170mm 650b bikes.

I'm hoping its not going to take that long.

-chakaping/Bregante: I have yet to spend any money, so no issues there. I just found a reputable, quality builder who has shared some thoughts with me. Thought I would get some more input here.

-scotroutes: Actually, I have thought about the rear-axle length, but have not come to any conclusion. It will be an outcome of my frame decision.

- Tom_W1987: I was wondering about that. I do know somewhere who put a 650b+ tire/wheel on the rear of his Diamondback Mason (29er) and he's liking it so far. He didn't do it in the front because, as you mentioned, there's basically no tread-width difference between the WTB 2.8" and his 2.35" 29er tire; though, the additional volume of the 650b+ carcass on the rear gave him some marginal cushioning for the hardtail.

Mountain bikers won't let common sense or logic dictate their buying choices though. You will get ****tards putting these tyres on Enduro 29ers instead of buying 170mm 650b bikes.

Maybe they're already doing that and finding that they're faster than 170mm 650b...

No doubt you have experience of set-up though.