650b+ Experiment

[ZeroDarkBivi]

Back in 2014, after the BB200, Mike Travers mentioned going 27.5+ on the front of my Rudy 29er. At the time I had other priorities, but the idea never quite went away. Skip forward a couple of years, and with the subsequent rise in popularity of that tyre size, offering lots of potential benefits (those marketing people never mention the inevitable compromises, do they?), I decided to take the plunge. This was not going to be simple, as I wanted to continue using the Rohloff hub I had already built into the 29er wheel, but my long suffering trusted wheel-builder, Jon at JRA, made a good offer on making a wide rimmed wheel set with the Rohloff and converting the rear 29er wheel back to a conventional XD drive hub.

IMG_1645 by Joe Blow, on Flickr
Before the conversion, with skinny 29er/700c tyres.

I used WTB i35 rims for the fatter tyres, as 35mm internal width seemed to be the best compromise between maximising the profile of the fatter tyre without over-exposing the sidewalls to trail damage. I wanted Derby carbon hoops to keep the weight down, but these have become too expensive, like many US imports, so the WTB seemed like a good enough compromise for what was still an experiment. The front wheel has a SON hub, and I'm really not sure why after my disappointing results with a PD8 dynamo hub, but maybe I just want it to work so much I am happy to delude myself for a little longer...

Tyre choice was difficult with rather a lot of options out there now and limited feedback. Researching the forums, Maxxis, WTB and Schwalbe where the front runners, and availability and pricing pushed me towards Schwalbe, a brand I had used a lot since around 2011 on 26, 650b & 29er. Shame I had to order them from Germany to get a good deal, but even with the poor Euro rate it was still better than anything I could find here. Not wanting to go crazy, I ordered the conservative sized 2.8" grippy Nobby Nic for the front, and faster Rocket Ron for the back. I did some measuring of the frame chainstays and knew it would be a bit tight, but thought 2.8 should still be OK. Getting the tyres seated tubeless was a proper bastard of a job, involving compressor, a lot of faffing and swearing, eventually removing the valve core to get the air in faster, but eventually they seated and all was well. Until I tried to put the rear in the frame.

Bugger!

IMG_1928 by Joe Blow, on Flickr
Tyre clearance (or lack of) on the rear with the 2.8

For some reason I thought I might get away with this; more self-delusion. 30 minutes into the 'test ride', before I had even left the tarmac, I stopped to check what that 'rubbing' noise was, as if it wasn't obvious...

IMG_1931 by Joe Blow, on Flickr
That score on the sidewall that aligns to the tightest bit of the chain stays...

Double Bugger. Still, I made it home before disaster struck, and the tyre wasn't so badly mangled that I could use it again in the front for dry summer trails, where it will be less draggy than the Nobby Nic. Did I mention how draggy it all felt on the road? Significantly.

So, another Rocket Ron was ordered, in 2.6" size, and this fitted a bit better.

IMG_1952 by Joe Blow, on Flickr
Clearance with the 2.6" tyre

This has now to be tested, and I will report back on the delights of the 'sweet-spot' of bikepacking tyre configurations in due course. I hope. Did I mention how heavy the bike is now? It certainly doesn't feel so sprightly, and when it went on the scales, I was a bit miffed by the number:

IMG_1942 by Joe Blow, on Flickr
Weight Weenies look away...

IMG_1943 by Joe Blow, on Flickr
They don't lie!

>3kg heavier than my other 29er, now set up as a 'gravel grinder', whatever that means. Now this is not a lardy build; Carbon fork, Carbon Loop bar, Ti Seat-post, Light Scoop Saddle, etc. Only the pedals are a bit over-kill (XT M785). But the combination of Rohloff and fattish tyres/wheels really has pushed this small Ti framed bike into the salad-dodger corner.

Regardless of the set-backs, I am really looking forward to giving this a good test, and see it as potentially the long haul off the beaten track tourer and with the extra saddle/rear tyre clearance, loop bars and rigid fork, it certainly has more capacity for carrying stuff.

I am already thinking about putting a 3" tyre on the front, to get the full benefit, especially as I am running it with a very rigid fork, but this will do odd things to the geometry which might compromise the handling even further.

To be continued

[ScotRoutes]

I can't recall weighing my B+ Pact but I'd be surprised if it's any lighter than that, even with the carbon forks instead of the Rebas I currently have fitted. I can't say the weight has ever bothered me.

[Bearbonesnorm]

I am already thinking about putting a 3" tyre on the front to get the full benefit[

In my experience, full benefit will only be realised with a wider rim than the 35mm you have.

[ZeroDarkBivi]

In my experience, full benefit will only be realised with a wider rim than the 35mm you have.

I thought 40mm internal width was the minimum for getting decent tyre profile, but a lot of 'forum trawling' and looking at some tyre manufacturers recommendations, revealed 35mm was preferred by many, not just for the lack of mass, and vulnerability to dents, but in reducing exposure of the sidewall to rips. I suppose that depends on the sort of terrain ridden, but for a bike I want to take 'anywhere', I really didn't want to have to handle torn sidewalls in the middle of nowhere, or at least minimise the risk. The Stan Hugo is a good example of getting it wrong, with a wheel that was, initially, wide and light, but utterly useless at absorbing knocks without denting, hence the second iteration where considerably heavier, and who wants heavy wheels...?

[Chew]

and who wants heavy wheels...?

I wouldnt necessarily knock heavy wheels. Yes, they can take more energy to get up to speed, but once they get the momentum in them, they just keep rolling.

If you're going to go plus, you need to go all in. Heavy burly tyres, wide rims, low pressures, otherwise you wont get the benefit.

[Bearbonesnorm]

Oi Craig, stop changing the rules

The benefit of plus tyres hinges on an increase in volume. To gain 'full benefit' from a 3" tyre as requested, you'll need a wider rim than 35mm.

and who wants heavy wheels...?

No one but that's what you'll most likely achieve by putting a 3" tyre on a narrower rim ... these tyres aren't exactly light and if the rim isn't wide enough to maximise volume, then really all you're doing is lugging a heavy tyre around for not much reward.

[ZeroDarkBivi]

I expect you are right Stu, and I'll just stick with my 2.6/2.8 combo for now.

and who wants heavy wheels...?

I wouldnt necessarily knock heavy wheels. Yes, they can take more energy to get up to speed, but once they get the momentum in them, they just keep rolling.

If you're going to go plus, you need to go all in. Heavy burly tyres, wide rims, low pressures, otherwise you wont get the benefit.

I need to play to my strengths Chew, and being light but not powerful, I'd rather have an incremental change rather than all the benefits along with all the extra mass/drag.

Time will tell, but I can't afford to get any new wheels for a while anyway!

[In Reverse]

How common is tearing the sidewall like that anyway? I've been running 3" and 2.4" tyres on 45mm rims for a few thousand km and no problems yet. Do I need to start worrying?

[ScotRoutes]

How common is tearing the sidewall like that anyway? I've been running 3" and 2.4" tyres on 45mm rims for a few thousand km and no problems yet. Do I need to start worrying?

Apparently, B+ tyres are made of fairy dust and will fall apart at the mere mention of gravel.

[jam bo]

How common is tearing the sidewall like that anyway? I've been running 3" and 2.4" tyres on 45mm rims for a few thousand km and no problems yet. Do I need to start worrying?

Apparently, B+ tyres are made of fairy dust and will fall apart at the mere mention of gravel.

2.8 nobby nics didn't mix well with dartmoor granite. 7 repairs in ~500 miles? I got fed up with repairing tyres so went back to 29r. One repair in the subsequent 500 miles on the same trails at the same speeds.

I got to the point to have any confidence in not pinch flatting on rocky trails, I was having to run so much pressure to negate the whole point of a plus tyre.

[mountainbaker]

2.8 nobby nics didn't mix well with dartmoor granite. 7 repairs in ~500 miles?

Schwalbe + Devon = fail

Conti ProTection, Maxxis EXO or WTB all work well for me. It's flintier in east devon, so even nastier.

[sean_iow]

Schwalbe + Devon = fail

Slight thread hijack, so would putting my Rocket Ron's on for the Braunton 150 be the wrong thing to do? I've currently got Panaracer Fire Pro's on which are tough but heavy and draggy, especially on tarmac sections so I was planning on switching back to the Schwalbe's which are my summer tyre. They cope ok on the Isle of Wight but any exposed rock here is mainly chalky.

[ZeroDarkBivi]

2.8 nobby nics didn't mix well with dartmoor granite. 7 repairs in ~500 miles? I got fed up with repairing tyres so went back to 29r. One repair in the subsequent 500 miles on the same trails at the same speeds.

I got to the point to have any confidence in not pinch flatting on rocky trails, I was having to run so much pressure to negate the whole point of a plus tyre.

Pinch Flats - are you using tubes?

Schwalbe + Devon = fail

Conti ProTection, Maxxis EXO or WTB all work well for me. It's flintier in east devon, so even nastier.

There will always be a balance between tyre weight and vulnerability Vs the terrain you ride. There are some interesting observations on some of the more objective internet threads about this, speculating that the wider rim results in more exposed sidewalls, which may increase the risk of damage.

Slight thread hijack, so would putting my Rocket Ron's on for the Braunton 150 be the wrong thing to do? I've currently got Panaracer Fire Pro's on which are tough but heavy and draggy, especially on tarmac sections so I was planning on switching back to the Schwalbe's which are my summer tyre. They cope ok on the Isle of Wight but any exposed rock here is mainly chalky.

I am planning on doing this with tubeless 2.25" 29er Racing Ralphs (SS)! The only part I can remember being a bit of a puncture concern was the descent off Dunkery Beacon. Lee Craigie got round the HT on a Ralph/Thunder Burt combo last year, but she is light and probably picks better lines than most of us!

[Bearbonesnorm]

There will always be a balance between tyre weight and vulnerability Vs the terrain you ride. There are some interesting observations on some of the more objective internet threads about this, speculating that the wider rim results in more exposed sidewalls, which may increase the risk of damage.

This is true, although tyre choice will make a big difference even for a given size ... it's one of the reasons I've changed from a 2.8 TrailBlazer to a 2.8 Ranger. Obviously the same size tyre but the increased sidewall protection offered by the Ranger over the TB is quite noticeable.

[sean_iow]

I am planning on doing this with tubeless 2.25" 29er Racing Ralphs (SS)!

I'm planning on running 2.25 front and 2.1 rear, 650B, tubeless, on Stans Arch Mk2 rims. I'm also going SS and I assume Javi will as well, so that's 3 of us? I'll set my target as 3rd singlespeed unless there are more yet in which case I'll revise my estimate.

[ZeroDarkBivi]

Not Single Speed for me: SS = Snake Skin sidewall protection! I am weak and need gears for those Exmoor hills...

[sean_iow]

I'll leave my target as 3rd singlespeed out of 2 then for now. At my age I need to manage my expectations mine are snskeskin as well. I have had a sidewall puncture before but only 1 in running snakeskin tyres for over 2000 miles on various bikes the last couple of years. I had to put a tube in as the stans wouldn't seal it and I didn't have any worms. I've not found them any less durable than my mates tyres of various other brands. I think riding style can have a big effect, the younger lads I ride with have more damaged tyres than I do but they're going quicker than me, on the downhills anyway.

[ZeroDarkBivi]

Update after a bit more riding.

So far I have done a few more miles on mixed terrain; mostly easy going, but muddy forest tracks with nothing rocky yet.
Fortunately the 2.6 has sufficient clearance in the rear, but only just and I will still be keeping an eye on it. Running 14/18 psi front / rear - probably a bit less now, which I haven't checked yet. The ride does feel notably different from the 29er configuration and I have noted the following observations:

- it is draggy on the road, and feels heavy on the climbs. Not horrendous, but noticeable. I definitely need a smaller chaining to down-gear the Rolhoff as I was consistently in the lower gears even on short climbs without much gear.
- it is slower to accelerate. Again, not a big deal - I'm not using it for lung busting XC sprints.
- whilst I have not tested the limits of grip, it does feel better, except on that 'slippy mud' where the bite of a thin nobbly tyre cuts through and is more secure. So, for 'all conditions' maybe a normal 2.2 tyre is the best compromise?
- the amount of mud thrown up by the big tyres feels a lot more than before - must get some extra big huggers.
- on faster steep descents, it is definitely better than thinner tyres, but lacks the control of a front sus fork, and a little bit of pogo is noticable from the undamped bounce.
- it is fun, despite some drawbacks, and makes for a nice laid back ride which I don't regret investing in, but I can still see me gravitating back to the Spearfish for anything that involves a significant amount of technical descending.

What might I do differently?
- 29+ hold no appeal to me, but 26+ may have some merit, especially if running 3.0 tyres; still have the grip with a bit less inertia.
- front suspension. Whilst this is primarily a laid back touring bike, Front sus would definitely make it a bit more comfortable on rougher stuff, especially sustained descents. I don't want the potential maintenance burden of a normal fork on longer trips, but might try swapping out the Lauf from the other bike (Yes, also undamped, but I won't be going that fast - just need a bit less battering on long tours). Only concern is I might like it too much...
- ditch the oversized stem cell; it just gets in the way and I don't want that much weight on the bars anyway (nothing to do with tyres)

[DoctorRad]

Tarmac, particularly climbing? Purgatory??

[ZeroDarkBivi]

Tarmac, particularly climbing? Purgatory??

Put it this way; not an ideal setup for something like Torino-Nice.

[DoctorRad]

Put it this way; not an ideal setup for something like Torino-Nice.

That's pretty much what I expected you to say...

[Bearbonesnorm]

Put it this way; not an ideal setup for something like Torino-Nice.

I don't know - how about the 2.8" Supermoto X?