Thorn Cycles Forum
Community => Thorn General => Topic started by: rualexander on June 06, 2007, 09:13:45 PM
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What is the general opinion on these rims? Just had a rear rim blow on Raven Tour while on holiday in Western Isles, bike shop in Stornoway unable to help so had to buy a cheap front wheel and dismantle the original front wheel (identical cr18 rim so knew it would fit with spokes) and transfer the rim to the rear using existing spokes, then try to rebuild wheel as best as i could in the frame. It worked ok and managed to finish our tour thankfully but the rim that blew only had about 5000 miles on it, if that.
Also lost an eccentric BB shell bolt somewhere on the road, so worth carrying a spare I think. SJS sent one up to us c/o post office though.
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I've got CR18 rims on my RST and am also a little concerned about wear on them despite only having clocked up just short of 4,000 miles. I bought a new set of Shimano brake pads prior to my just completed tour of Britanny and they seem to have inflicted some heavy wear, wearing grooves into the rims and making some pretty horrendous grating noises unless the rims were wiped immediately in the wake of frequent wet weather. As SJS recommended CR18's as the best compromise ref wear/weight and judging from other comments ref Shimano pads, I'm inclined to conclude that its the pads which are at fault.
This is a bit of a known problem and from vague memory, others on this forum have recommended Aztec and Salmon Koolstop(!?) pads as more rim-friendly alternatives to Shimanos. Confirmation of the names in addition to suggested outlets from anyone on the forum here would be appreciated as I want to replace the Shimanos at the earliest opportunity. I'm also switching from Panracer tyres to the more reliable Schwalbes: my rear panracer tyre wall split in several places and had to swap it out: I could only get a 1.75 MTB tyre by way of replacement at the time in Britanny.
Ref BB bolt, using loctite really does help the diminish the scope for these bolts coming loose: I had a similar problem which is now definitively solved.
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I am at 4000miles on my CR18 rims on an RST and used kool stops from about 1000miles as the original shimano pads were eating the rims. My wear indicators disappeared a long time ago and this thread has encouraged me to remove the front wheel(most used for braking), remove one tyre bead and get in there with a micrometer, i will post later with results.
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the pads on my micrometer are too large, i just can't get them onto the rim to measure, anyone got a small enough micrometer?
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Can you put a ball bearing inside the rim and measure over the rim and the bearing?
All you need to do is subtract the diameter of the ball bearing from the reading.
regards
paul
ps my Sum rims have just worn down to the rim wear marks after 1500 miles. I think its the miles along the tow path in the wet weather.
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Thanks for the ball bearing tip.
Measured: Rim is ridged by brake pad wear on external surface so this is my best and most robust estimate 0.75 - 0.8mm. But it could be a deviation of 0.3mm either way; the chaos of accurate measurement. Its around 1mm!?!
My strategy is that this is too academic a pursuit, i really should be cycling! however, i plan to watch for cracks, splits, general deformation when giving the bike the once over as I do anyway. If i get 8,000 miles out of these rims given the commuting and touring i do, in all weathers, that would be fair.
I also went to the sun ringle site and they have a dimensioned drawing of all their rims showing as a cut through. I couldn't make out the dimensions as the text is too blurred, can anyone make them out?
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Dave
Looking at the CR18 diagram on the site I'd say that the two horizontal measurements are 22.5mm and 17.5mm and vertical ones 15.5mm and 11.5mm though it is difficult to read.
I'm a bit shocked to learn that these rims will only last 8,000 miles or possibly less! Is this normal!?
Have recently swapped Shimano blocks out for Aztecs and first impressions are that they are miles better as far as the rims are concerned, literally [:)]
Have also replaced the tractor tyre I that I was forced to replace the split panracer with in France with a Schwalbe Marathon Racer: extremely fast and much thicker walls than the panracer so am expecting it to last much longer, especially in view of the considerable cost and my previous experience of the Marathon range!
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No idea whats normal for wear on these rims, as i said i will look carefully for cracks etc and may get 10,000 or 20,000 miles; who knows, thats why we share info! With the originator of this post having a rim blow at 5,000 miles, they do not inspire confidence in their longevity.
I was on an island hop at the weekend and came down the hill from North Glen Sannox to Lochranza on Arran a 200m descent in 2.5km in the torrential rain (i had a ferry to catch) and had to brake a fair bit as was loaded with rear panniers and tent, so thats more surface off my rims.
thanks and keep sharing the info on these rims - anyone another alternative thats a good compromise with weights vs longevity?
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agree with comments about shimano brake blocks, they are like angle-grinders
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Hi, am going buy some strong touring wheels soon.
I gather that sun rhinos are the strongest though heavy. How do the rhinolite, cr18s,and rigida sputniks rank in the tough/weight table. ie which are the next toughest.
advice please
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My Raven came with CR18s, the rear wore the indicators away around 6,000 miles and I did another 1,000ish before replacing. The front is still on after around 14,000 miles, but the indicators have all but disapeared. So an average of over 10,000 miles, nor exceptionally good, but OK.
I ride a mix of on and off road, have always used decent blocks (Kool Stop or BBB triple compound)and the rims and blocks are the one part of the bike I do keep clean.
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My CR18 rims also failed to last long. Thorn fitted new rims for me, but so far they have seen no use as I also bought some of those lighter wheels described in the new xTc brochure. The difference is astonishing. At least 20% more speed for the same effort.
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Which rims do you mean, Bukidon? the Carbide coated rims??
Lewis
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quote:
Originally posted by lewisjnoble
Which rims do you mean, Bukidon? the Carbide coated rims??
Lewis
Sorry, but I'm not technical enough to know which rims have carbide coatings. I had some rims with big CR18 stickers on. They have worn out. I bought them as part of an xTc in mid-2004 and do not consider myself a big mileage cyclist, lacking dedication for regular training, although I had some decent tours out of them. Now I have some Mavic rims (XC717 ?), with Revolution spokes and XTR hubs. The new tyres are Hi-Roads. The performance difference is astonishing. Dent to Lancaster with a stop for tea at the Crook of Lune in 2 hours 30 mins is something I could not have got close to with CR18 rims and Pasella Tour Guard tyres.
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My experience with Sun CR18s is that they're an above-average rim: not too heavy, good braking, but not all that suited to full-on loaded ruff-stuff.
Mavic rims are the ones for me: XC717 for unloaded, 'road' bike lightweight speed (I can definitely see how you're amazed with them. Bukidnon) plus most mountain bike duties but it has to be the EX721 for general loaded use. Built tight, they rarely go out of true: my last ones lasted well over 6000 miles and (I kid you not) I never had to true them (a spoke broke at the same time that they finally wore out, but even then the wheel spun true). Sure they're a wee bit heavier but who notices a little more rotating mass when you've got three weeks' worth of pants and pasta in your panniers...?
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Oh yeah, and another thing, there seems to be some wildly differing rim-life-spans being thrown around. One poster mentions being happy if they get 8000 out of their rims. You might do, if you ride in the dry and stick to the flat...
In my humble experience, rims die eventually, even if you religiously wipe them down (which we should definitely do and I try to do...), replace the pads in good time (not with overpriced Shimano rubbish pads that are abrasive poo in pad-clothing) and make sure your brakes aren't rubbing (obvious, but all too common - balance your brake springs and true your wheels).
Rims are disposable. Shock, horror. Yup, it's a hassle when they wear out, but they do. Just put aside 50p a day and when they do wear out, get yourself a nice new set, always built by someone who knows what they're doing.
(No, I'm not a Shimano-hater. Shimano make great components, but their brake pads and some of their chains are quite awful.)
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Thanks for all the replies to my original post. Interesting stuff. I must look into the brake block brand suggestions, although I don't think these were shimano anyway.
I am used to rims lasting in excess of 10,000 miles which is why I was not expecting this one to blow yet.
Anyone tried Sun Rhyno Lite rims? I have had a Rhyno before but very (and noticeably) heavy, although probably saved a holiday one year when a rear hub flange broke and left me short of 3 spokes on my rear wheel drive side.
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This guy
http://www.crazyguyonabike.com/doc/page/?o=QzzM&page_id=33080&v=Ka
swears by the Rhyno-Lites, and BMX-ers use them. So I guess they're v. strong but will wear out quicker than the Rhynos.
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I'm appalled at the lack of mileage some of you seem to be getting from yours rims, what are you doing to them?
My RST has just passed 2000 miles and there is negligible wear on the rims (Mavic XC717's) and thats with riding in all weathers, using the original shimano brake blocks and only cleaning the rims occasionally. Going on the current rate of wear I'd expect to get 10000+ miles out of the rims.
Out of interest, how many set of brake pads do you get through before wearing out a rim? I seem to get 3000 to 4000 miles out of a set but have no idea if that is good or not.
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What am I doing wrong????? Why do my rims die (relatively) early?
Tricky one this, but I suspect it's because the vast majority of my miles are, sadly, London-based. I reckon that the constant slowing down for slow, fat cars and taxis takes its toll and eats my rims.
Anyone else find that city riding munches down on yer Mavics (or Suns, etc.)?
I will be VERY interested to see how these new Rigida tungsten carbide impregnated rims fare. If they work, I'm rebuilding all my wheels with them!
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You can never have too much grease.
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quote:
Originally posted by rualexander
What is the general opinion on these rims? Just had a rear rim blow on Raven Tour while on holiday in Western Isles, bike shop in Stornoway unable to help so had to buy a cheap front wheel and dismantle the original front wheel (identical cr18 rim so knew it would fit with spokes) and transfer the rim to the rear using existing spokes, then try to rebuild wheel as best as i could in the frame. It worked ok and managed to finish our tour thankfully but the rim that blew only had about 5000 miles on it, if that.
Also lost an eccentric BB shell bolt somewhere on the road, so worth carrying a spare I think. SJS sent one up to us c/o post office though.
I have a pair of 26" CR18s on my xTc, and IMHO they do wear quickly. My wife's Club Tour runs on the 700c version, and they're pretty much the same.
In the days of yore (ie 20 + years ago) brake blocks were soft, rims were hard, and braking (particularly in the wet) could be a bit of a hit and miss affair. In an effort to improve braking, manufacturers made brake pads harder and rims softer (and lighter/thinner-walled to improve acceleration). All these factors, of course, have contributed to a much reduced rim longevity.
As Chris Juden said in a CTC mag a couple of years back, rims these days must be considered a consumeable, much in the way brake pads are. Also, smaller diameter rims wear slightly faster.
I was using CR18s on my xTc (as well as my old Nomad). I found that Alex DM18s were a cheap alternative 'consumeable', and being the same diameter as CR18s, I could do an easy 90 minute rim-swap whilst keeping the same spokes.
For an extended tour, I think the only real option is to buy thicker walled rims, such as Rhynos, and put up with the more sluggish feel, or buy carbide coated rims.
Or use disc brakes. Given that the majority of 26"-wheeled bikes for sale in your LBS now have disc brakes, then 26" rims for rim brakes will start to become less common.
Cheers
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I've just invested in a Rigida Grizzly Carbide rim for the front, It'll be at least a year before I know if it was a good buy. I am hoping it's less of a consumable...It needs to be at £60[:0]