Sun CR18 rims...if I decide to go weight weenie, what could I get?

[JWestland]

Hi -

My XTC has Sun CR18 rims with single butted spokes, and 36 of them.

If I decide to go weight weenie, what rim could I get instead that would have the same strength? As in, laden per Thorn's configurations for the XTC it won't bust the rims.

And how much weight would that save me?

Just curious

Want to see how "fast" I can get it, if practical etc and staying true to it's touring heritage so no carbon rims, forks or seatposts soon 

[jags]

just put some slicks on

[JWestland]

Already have.. 1.3 continental sport contact

[jags]

well just stick with that set up if i were you.
lighter wheels are great but you still need the rubber to go faster.
i have slicks on my sherpa make a big difference compaired to marathon plus believe me.
put max pressure in them and give it some .
but hey listen your on a touring bike so forget about speed .

[triaesthete]

Hey Jags think of it as going at the same speed for less effort!

Jawine, are you using Continental Supersonic inner tubes? These are the most cost effective performance gain I have seen. If you can get them fitted without nipping there doesn't seem to be any other reliability penalty.

Best wishes
Ian

[jags]

Taught about that many a time Ian believe me 
but at the end of the day it's all down to the pilot.

[Pavel]

I think of it as a 2% payoff for the hills; with a 10% increase in mechanical problems; with a 25% decrease in load carrying ability; with a 50% decrease in my bank balance.  But the illusion is priceless!

[JWestland]

Phew, £16 for two inner tubes? Can give them a whirl at some point, but they seem to pinch REALLY easily. Saves 50 grams per bike.

Had a look MTB rim wise the CR18s actually aren't that heavy! The lighter ones are probably less suitable for loading use.

Mavic X517 (2003 thorn review setup) are 420 per rim, the Sun CR18 490 apparently. That's 140 grams of moving weight...the maybe another 10-20 if spokes are changed (single butted...so heavy...)

I saved more than that my changed my pedals from M324 to XTR 970 

Well we can always put carbon wheels on our bikes lol

[Danneaux]

Hi All!

If you're going for speed, then the usual 700C tricks apply for 26" as well. Anything that reduces rotating weight makes the wheels feel more lively, and accelerate to speed more quickly:

In order, here's what I have found to help most:

1) Lighter tires, preferably slicks, and narrow/high pressure.
2) Lighter tubes.
3) Lighter rim strips. For awhile, I tried the Velocity rim buttons. They only seem to fit really well on Velocity rims, but are lighter than many rim tapes and still allow ready spoke-well access in the event a spoke needs replacement.
4) Lighter rims.
5) Fewer spokes; 28 is plenty for unladen, non-touring use in a 26" wheel on good roads. Of course, this means a change of hubs as well.

I've had good luck with Sun Metal CR18 rims on my tandem with 36, 15-g spokes. I'm running light tubes and Matrix (Trek) Road Warrior 26x1.5 skinwall slicks. The thing flies. With the drag brake lightly on, Dad and I got it up to 63mph/101kph down Chambers Street hill and were still accelerating when the traffic light at the bottom of the hill turned red and the fun ended as we had to stop for cross-traffic.

I've been meaning to rob the tires off the tandem and give them a try on Sherpa, but am afraid I'll become addicted and won't like the heavier feel of the 26x2.0 Schwalbe Duremes I really need for loaded touring on Sherpa.

Best,

Dan.

[triaesthete]

I would amend number one on your list to say "more expensive AND lighter tyres" Dan.
The premium tyre materials and thin tubes really contribute to lower rolling resistance which I think is almost as important as inertia reduction through weight loss.

But for sure I would prefer a heavy bike with light wheels to a light bike with heavy wheels....

Jawine, look at it this way,  the 12 quid premium on two tubes would only push a car 80 miles or so. Think of all that cycling joy you'd get for hundreds of miles once those tubes are installed. EVERY mile a little easier....  They don't wear out faster like lighter tyres and are certainly easier and more practical  to achieve than low spoke counts and tinfoil rims....

My Sherpa runs on 32 spoke Rigida Grizzly CSS rims, 40mm Marathon Supremes and Supersonics. I run them below 50psi for comfort with such rigid frame but still get really easy rolling and good mileage. It climbs and decends well and it works in all weather except snow/ice. Money well spent.
Happy days
Ian

[JWestland]

Hi -

@Danneux: Wow, 101 KM per hour? I bricked it went I went downhill at 45 and started braking

Tx for the tips Yes makes sense to go for the quick and easy win first: Tires.

The rim tape is a French brand...it slipped my mind now, but they have been in business for a long, long time.

@Ian: So going from 1.3 SportContacts with their standard inner tubes (current setup) to Supremes/Supersonics how much of difference does this make? Weightweenies weren't impressed with the Supersonics inner, apparently pinch very easily and sun CR18 rim is quite deep.

(as it means new tires and inner tires...sigh...but can do it next time the tires wear out, just swapped them as there was a sale on and they got to the end)

[triaesthete]

Hi Jawine
this sort of comparison is hard to make objectively unless you do loads of empirical testing like Dan does. But you can do some reasoning.

The 40mm supremes are not the lightest tyre out there BUT they roll very well on a nice supple casing AND they have super good puncture protection to boot AND they give very good mileage AND they give good grip on tarmac wet or dry and feel really secure.
Over the years I have picked all sorts of flint, glass and metal out of the tread but none have ever gone through the casing. I never find myself wishing I'd saved a tenner and bought cheaper deader feeling tyres!

Because the tyres are reliable I feel safe using a light tube. I make sure they are assembled in very clean conditions with Velox cloth tape that fills the whole width of the rim bed. I have also had a lot of practice which helps. (After motorcycle tyre experience I have not had a modern bicycle tyre I can't fit or remove without tyre levers.) Large section 559/26" tyres practically fit themselves, most weenies will be talking about 23mm 700c which are usually a bit tighter and need better technique.

The only caveat here is that I carry the heavier Conti "race" tubes as spares because they are likely to need fitting in suboptimal conditions. However these too save weight and packing volume in your spares pack compared to thick cheap tubes.

With regard to puncturing, if something penetrates the tyre it will punture a tube of any thickness and pinch flats are not (I hpoe) an issue on large section tyres on road.

With regard to good rolling performance I think the following logic applies:
At the contact patch of a rolling tyre the tread, casing and tube all flex together as an assembly absorbing energy (yours!). More material anywhere here will absorb more energy so less of it is better up to a point.

QED a real world nice performance solution involes having more of the rubber outside of the tyre casing as tread rather than inside it as tube.

Convinced?
Happy pondering
Ian
Ps fit lots of tyres for your friends and it soon gets easier and tube nipping will seem like the schoolboy howler it is. Standard tubes will also seem absurdly thick and heavy.

[JWestland]

I accidentally bought some butyl inners too *I didn't know I got free conti inners and bought online* can give them a whirl, 1-1.5 say "super light". Also the conti inners don't seem to hold their pressure very well, need to inflate every week. Hm...

The Sportcontacts seem pretty tough, the old ones on it never punctured, as for fixing tires...whatever is stuck in my fixies rim/tyre got me again today on the way to work! GRRRRRRRRRR cleared out the rim/tape it must be microscopic, need to have another search.

Plenty of practice ahead 

[Andre Jute]

Probably less than totally relevant to this discussion because I use wide rims (Exal XL25, 25mm wide across the beads) and Big Apples that you fit with your fingers without any force, so reducing the danger of pinching the tube in the installation, but I've found the Schwalbe Type 19A Extraleicht to be 100% as serviceable as the heavier/thicker plain Type 19 standard tube. I mention this because my roads are bad but fast, and I think nothing of crashing through pothole after pothole at speed rather than disturb my line and perhaps catching the loose gravel in the corners and taking a spill. With over 5000k on a single pair of "racing" tubes, I imagine that if they were to suffer fishbites, it would have happened long since. I've had a couple of spare pairs of tubes standing by since I got the bike... (and also a pair of standard Type 19 which came with the bike -- I just didn't believe before I had the good experience that lightweight tubes could last so well).

Wish I had known about some narrower equivalent of the Schwalbe Type 19A in the days when, more relevant, I rode on Marathon Plus, which are an absolute ¡€#¢?§¶•ª to put on the rim, and which I once had to take off again because I managed in the wrangling to mangle the tube.

Andre Jute

[julk]

Jawine, Andre,
I got the superlight Schwalbe tubes about 2 years ago in an effort to reduce the rotating wheel weight at rim, I also moved to Schwalbe folding Hurricanes which are quite light for 26x2.

I have found the combination excellent as most of my riding is on tarmac, but the Hurricanes cope with 'farm tracks' as well having a smoothish centre with a lumpy edge tread.

The superlight tubes have been a cost effective way or reducing the rotating weight. I recently had one of them perish on the inside about where a spoke head would have been, but I use a Thorn fitted rim tape so it was truly a perished patch of tube. That tube was patched and is now carried as a spare.
Julian.