27.5+ front / 29 rear combo - thoughts?

[thenorthwind]

Pondering different options for some imminent big rides, I had this thought: would it be worth swapping the rear wheel of my rigid plus bike (Genesis Longitude) from a 27.5x2.6" tyre on a 35mm rim, for a narrower rim and tyre (say 29x2.25"), but keeping the plus-sized front?

As I understand it, the rear wheel contributes more to rolling resistance (depending on weight distribution), so that would be somewhat reduced at the expense of a little grip/traction and seated comfort, and probably weigh a bit less, but I'd keep the "suspension" and grip at the front for the rougher parts.

I'd guess the rolling diameter wouldn't be hugely different and so the geometry wouldn't be affected much.

I can't be the first person to think of this? I'd just try it, since I have a 25mm internal rim laced to a 10 speed hub, but the widest 700c/29" tyres I have are 40mm.

[Bearbonesnorm]

I sometimes run my stooge 29 rear and 29+ front but never considered B+ up front unless I've fitted B+ out back. As long as the overall diameter is 'near enough' I can't see a problem, although rolling resistance isn't just about tyre or wheel size and you might find a faster rolling 650 x 2.6" will make quite a difference.

[thenorthwind]

True enough. Pressure has a big part to play too, but that's opening up a whole can of worms.

Will have to get the tape measure out and check how true my assumption about rolling diameter is.

Just wanted to check I wasn't doing something completely stupid

[In Reverse]

I've done it quite a bit and am definitely a fan. 2.8 x 27.5 Nobby Nic on the front, 2.35 x 29 Ikon on the back. Difference in outside diameter is only about 10mm, I've tended to address that by increasing fork length from 140 to 160mm:



It's probably all in the mind but the "smaller" front tyre feels a bit nipper on techy stuff and I can't say I notice any difference in rolling.

[thenorthwind]

Aha! Very interesting, thanks.

Will have to find a 29er tyre and give it a go I suppose.

[techno]

I've run my longitude with a very similar setup before (27.5 x 2.8 on 45mm rim up front and 29 X 2.25 on 20mm rear) to improve mud clearance in winter.
The difference in Outside diameter is only small, about 15mm. I mive some stem spacers under the stem. All sorted.

[thenorthwind]

To give this thread the closure no-one asked for... I ran my bike like this for the Dales Divide:



27.5x2.8" WTB Trailblazer on a 35mm rim on the front
29x2.2" Specialized "The Captain" on a 22mm rim on the rear

I think it worked pretty well. The wider tyre on the front was definitely still appreciated on some of the boggier bits and rocky/stony climbs, and it felt less draggy even if that was only psychological. I span out on a wet rocky climb near the beginning and thought "uh-oh" but didn't notice a lack of grip at any other point.

Hard to say if it was any better than chubby-at-both-ends, but if I did the same route or similar again, I'd probably run the same setup, even with the minor inconvenience of borrowing the wheel from my gravel bike and swapping tyres/cassettes.

[Escape Goat]

I sometimes run my stooge 29 rear and 29+ front

I've considered this many a time. How do you find it? Not on a stooge mind, just on my hardtail.

[jameso]

I remember an article Jeff Jones wrote about fat bikes and why he was a bigger fan of fat-front / 29er rear for technical trails on a rigid bike. Riding it like a hardtail, pivoting around the rear axle and the cush is up front. I don't need a plus front living in the south east but if I was to start riding somewhere rockier I'd go for a 27.5 x 3.25 or so at the front long before giving up on a rigid.

27.5x2.8" WTB Trailblazer on a 35mm rim on the front
29x2.2" Specialized "The Captain" on a 22mm rim on the rear

- looks great, "giz a go" kind of fun. Fast too?

[thenorthwind]

- looks great, "giz a go" kind of fun. Fast too?

Define "fast"

It felt fast than 27.5x2.8" on the rear, but that may be all or partially psychological.

[jameso]

^ that'll do

[Lazarus]

i often ride mine in 29 er guise - same bike
I am now going to try mixing and matching both ways round to see what i think
Full 29 er does seem faster but i have to ride 5 ish miles of country lanes to get to the trails