KH29" 38mm vs 47mm Comparison

Unicycles and Equipment
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KH29" 38mm vs 47mm Comparison from my blog at:
http://unplannedismounts.com/2009/06/11/kh-29-inch-rim-38mm-vs-47mm-comparison/

The new KH 47mm Freeride rim seems to have opened up a new world of off road riding on the KH 29′er. But can 9mm really make that much difference?

I thought a 38mm vs 47mm rim comparison would be fun and interesting, the method being ride sections of trail back to back, swapping between 29′er MUni’s fitted with the 38mm and 47mm rims, hopefully making any difference obvious.

(So you’re thinking… this clown has two 29′ers? In my defense I never intended to. I ended up with a spare 29″ frame due to a Schlumpf compatibility problem with my original 29″ last December, and have since gathered enough spare bits and pieces since to build up a second 29′er to sell/loan)

After a week or so of cold drizzly rain, the rain clouds finally parted and I headed out with the two 29′ers to one of my favorite parts of the forest which includes dirt road, bush track and single track set in hilly terrain. The slippery tracks would just add to the fun!

I warmed up soon enough, riding sections of trail, running back and forth swapping uni’s, and stopping now and then for photos.

The Bottom Line?

The short version is there wasn’t one situation where I preferred the feel of the 38mm rim over the 47mm. Climb or descent, single track or fire trail, smooth or rough. The 47mm comes with a dumb grin that gets plastered over your face as you roll along.

The 47mm feels much more stable than the 38mm. The 47mm seems able to eat rough terrain, or ‘run over children’ as Eric the Red described it. It encourages you to ride the 29′er harder and attempt more difficult terrain.

Swapping back to the 38mm rim it always felt ‘tall and narrow’ in comparison, a hybrid uni feel, not as stable even with 2.3-2.4 tires fitted — leading to an approach of weaving your way through terrain versus ploughing on through with the wider rim.

If there is a downside to the 47mm rim it’s the reduced brake clearance. With the Magura’s set right back there isn’t a lot of room to spare.

However… the slippery conditions magnified the differences between the two rims — the 47mm gives the 29′er tractor properties through mud and slush… FUN.

The new 47mmFreeride rim makes the KH 29″ a better off road machine (It also gives the 29′er a much clear identity in the KH line up IMO). That doesn’t mean however that in technical/extreme terrain the Freeride 29′er magically replaces smaller MUni’s like the 24″ - it’s still a 29″ wheel.

If you’re building up a new 29′er for off road use get the 47mm rim. 9mm does make a significant difference. It’s as clear as mud, IMO anyway! :slight_smile:

ps. Second 29′er now sold

KH29" 38mm vs 47mm Comparison from my blog at:
http://unplannedismounts.com/2009/06/11/kh-29-inch-rim-38mm-vs-47mm-comparison/

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Sold out in the USA! I’m checking shipping prices from the UK. Thanks for the write up! Anyone doing more extreme stuff on the new Freeride 29er rim?

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http://www.unicyclist.com/forums/showthread.php?t=77918&page=2

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Not extreme to some, but challenging to me:

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What tires were you using?

I really think that most unicyclists would benefit from a higher ratio of rim width to tire width.

I would like to do a bit more experimenting between 32 and 46mm 26" rims myself.

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Heya Eric, I should’ve mentioned that in the blog. I’ve actually been riding and comparing both uni’s/rims for a while now, using the Panaracer Rampage 2.35 but mainly the Schwalbe Racing Ralph 2.4 and more recently the WTB Stout 2.3. Regardless of which of these tires were in use I preferred the wider rim by a significant margin.

Riding sections of trail back to back with the different uni’s was a much better way of highlighting the differences between the two rims vs going out on the wide rim one day, the narrow one the next, imo anyway.

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I just ordered a KH29 with the 47MM rim from UDC on Wednesday. They did not mention they were out of stock - hope I snagged the last one :smiley:

Thanks for the review Luni - it supports the notion that I made the correct rim size choice! Also thanks to Tuscan - I found your posts influential too!

Cheers

Simon

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A tip for those who are getting new KH29s. There is an adjustment time. It will feel weird and scary at first to ride technical terrain. When I first got mine and started venturing out onto trails that I had been riding on my 24, it was awkward and a little scary. I was thinking then that I would only be using the 29 for pavement and easy XC. After a few rides, I got used to it and started to really like it. So be patient.

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road/pavement riding??

I ride the thinner KH29 rim with a Racing Ralph 2.4 tire. Almost all my off-road rides have a significant pavement ride to get to and from the trail head. I need a do-it-all kind of wheel/tire. Any comparison of the street riding/handling differences between the thinner and fatter rims?? maybe at different tire inflation pressures?? Any annoying issues: road crown broblems, not tracking a straight line, etc?
B

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I bet you did! I called about possibly ordering one, and they had just sold out. :stuck_out_tongue:

Thanks lunicycle for sharing, but now it may be harder to get my hands on one!

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I bought mine from Darren at Bedford Unicycles. Might be worth checking if he has any.

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Yeah, skillewis74, that stuff look pretty fun. Tell more of our impressions of the fat rim. Did it make a big difference for you on the drops? Thanks to all you guys posting you impressions of the wider rim. I’ve been riding my 29er more and I’m going to look into picking one up. UDC.USA says they are getting a new container in two weeks.

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The ‘extreme’ test

I’m the rider in that thread that skilewis74 posted (here). I actually have a 50mm prototype 29er rim, but it’s probably close enough to the performance of the 47mm production model. My 24" muni has a 65mm rim, so this thing still feels kinda skinny.

Vivalargo and I rode gspot trail today, and I took the 29er. For those that don’t know, gspot is a benchmark stunt trail in SoCal and by far the most technical in the Los Angeles area. It is truly extreme - in the last few years two experienced mountain unicyclists have literally broken their backs on that rattlesnake-infested hillside (and thankfully eventually recovered to full health). It is essentially a downhill boulderfield that has 20’+ drops, huge steep cliffs, sandy chutes, numerous dirt jumps and many tight banked corners. The only places I’ve found a greater challenge are north of the border (Vancouver). We’ve written about our rides here many times - lots of threads reference it.

So, how did the new wide rim do? In two words: no problem. I threw myself over half a dozen five foot drops, down cliff faces, over dirt jumps and across sand slides, and caused no major damage. It does need a serious truing now and the spokes are making funny noises, but that was expected. John might have a photo or two, but we were mostly concentrating on the ride. The links above have plenty of photos of the terrain anyway.

My one nit with the experience is that a 29er in general seems a bit too fast for the trail. Gspot is all about controlled descent and precision on terrain so steep it’s at the edge of being unrideable. Even on a 24 with a brake, downhill speed can get out of hand in half a wheel revolution. I did walk around some technical lines, but mostly because extreme 29er is a new mental game for me. In terms of abuse, it still got a full dose. The bottom line to add to lunicycle’s review: This thing is durable.

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Small ride thread here.