Semi-fat ?

16 02 2015

Plus? semi-fat? I’m not entirely clear what the nomenclature ought to be, but the ‘plus’ sized wheels are definitely here to stay.

As such, the range of useful components to build a plus wheel set is growing – rims and tyres.

After a fair amount of lurking around on forums, I decided to order up a set of Nextie hookless, semi-fat rims: 29″ front and 27.5″ rear. Both are 50mm wide and 34mm deep (if memory serves). They seem reasonably well made (more on this later) and are light for the sheer volume of the things. just above and below the 500g mark respectively.

I built them up today and mounted tyres. The weight saving was a mind boggling 300g for the front (1.3kg wheel to a 1kg wheel) and 150g (1.15kg to 1kg) for the rear. With an additional 200g for a tube on the front (albeit with 100g or so of sealant back in at both ends) the weight saving is 450g. This is at the rotating edge of the tyre so is keenly felt.

In addition to the weight loss the rear tyre ballooned. the casing on the 50mm rim is 73mm wide at 30psi and the tread sits at 61.5mm. obviously I expect the casing to shrink a little when the pressure is dropped to 10psi or so, but probably not much. Huge.

So, more on the build soon.




9 responses

16 02 2015

Hey Jon,
Interesting as always. It just so happens I have a pair of the Light Bicycle 50mm rims on order for the Krampus. Running tubeless, the weight savings versus Rabbit Holes plus tubes should make a big difference to the ride – I hope. Am actually equally interested in overall feel and how they perform compared to an al rim… Expecting them any day…. See you soon.

17 02 2015

nice one roddy! you’ll love the weight drop im sure! its very noticeable…taking a great bike and making it even better!….hope the family are good!

17 02 2015


You’re keen to pursue the 29+/27.5+ combination further – what does it offer you that makes it worthwhile? Slacker setup? More nimble? How’s it different to straight 29+ on your FortyFour? Thanks


17 02 2015

Tom, hows things?

my interest was piqued after a conversation with sean of vertigo cycles. basically this was around the diameter of the wheels and thus where the weight was and if this translated into less maneuverability in tight riding situations. sean has a trials and tech trail background and so was pretty interested in all this after building his own fatty and finding the traction/low pressure benefits were good.

the 44 bikes is pushed far into the nimble domain for 29+ … i doubt anything more can really be done realistically. what is good about 29+ is the diameter and the low pressure – excellent roll over and takes out trail buzz. but to get one nimble is a huge effort…the krampus is ace, the 44 is better and there are a few other folk doing good things with 29+ to try and thread the needle but its a big ask!….

the jones is a much smaller/shorter bike overall. ive used it for long rides – 12 hour race and 100 milers etc- but its main raison d’etre is fun riding. putting the fat front and 650b+ rear was interesting as was moving to 29+ front/650b+ rear.

you keep the low pressure effects – trail buzz reduction and traction – but you lose the angle of approach of the big wheels…though going to the 29+ front mitigates for this somewhat. it was really interesting to feel the effects of kicking back the geometry and feeling what i assume is also a gyroscopic effect of the bigger 29+ wheel compared to the 26×4″ – im sure you have some thoughts on this too?

my next bike is a 26×4 f and r. it will have HED rims, so this will keep wheel weight as low as realistically possible and it will be interesting to come back to all this. i think overall, for rigid bikes/hardtails – 29+ is the long distance, mildly rough bike of choice. 29ers just feel fast and maneuverable – aces for smoother trail, shorter rides or tight stuff in the trees. 27.5 is really pretty good, but we need better tyre choice to take advantage. i think it will probably end up being a very popular trend. it mixes and matches really well.

we will see! :-)~

i re read this and am aware i havent really answered! the 27.5+ is more nimble than 29+. the fatty front i had was very heavy so was hard to comment on, and the 29+ definitely rolls better – front and rear. how it all goes together in the mix im not quite sure yet!….i think with prudent geo 29+ front 27.5+ rear might well be a potent mix!

18 02 2015

Things are good – looking forward to some coastal riding w Scott F soon.

I’m pondering my wheel quiver for the AMPeirce. 26×4″ soft-going expedition, 29+/29+ everything else expedition and my trail wheel set. The last one is where I’m attracted to the 29+/27.5+ combo w a limited cassette rear hub and Talas fork. Part of the attraction is this would lower the rear some with a bit of weight reduction. Given that the AMP head angle isn’t that slack I’ve got some leeway. May try running 29+/26×4.0″ to see how the geo copes before shelling out for a 27.5+ rim and tyre.

Always more to try and tweak.

19 02 2015

In tassie? aces! looking forward to seeing a report and pics – would love to go there…..
i excpect it would work really well for your AMPeirce….you could fit the Vee 3.25 rear, right? or a trailblazer? i think the fatBnimble chupacabra and maxxis cant be far behind on a 27.5×3….i reckon it would do just the right amount of backward tilting….sounds like a good plan! a nate was within mm of a trailblazer in terms of diameter so trying it fat rear would give a very good indication….it tilts the jones back and makes it feel like ‘AM’ geo rather than xc. rides nice at speed and down. for the jones – the numbers on which are already a bit relaxed from xc ‘norm’ – its probably a *little* too much for general riding, but for fun/down/woodsy stuff its great. i get a little front wheel flop at low speed, compensate for this after riding for 5 mins and its all good!….

4 05 2015

Hi DrJon, just wondering how you’re getting on with the nextie rims / wheels?I’m in the process of planning a custom 29+ frame based around the characteristics of the Stooge but with rear 29+ capabilities. When out with Bryan Dawson last week he mentioned these rims where probably a good way to save rotating mass and suggested you might have a few things to say about them. Also looking for some of your thoughts on current 29+ geo / frame fettling so would welcome some well thought through considerations before I make any rash decisions. Thanks in anticipation….Ross

31 07 2015

Reblogged this on Kite*Surf*Bike*Rambling and commented:
When you thought there were too many tyre/carcass sizes along comes another. They all make sense in their own right but will it survive the market pressures.

31 12 2015
Hodag. | drj0nswanderings

[…] In saying that, the rims have seemed durable in use over the last 10 months – see my previous post for the first build with Nextie rims. Also, there are rumours they are using a different […]

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