greatwhite

Mornin' All I'm in the process of trying to recon a rear campag 8 speed rear mech - poor thing has been abused and needs new wheel (one of the wheels looks like it has sharks teeth on it, it is so badly worn). Does anyone know where you can get wheels for these old units or even better is there by some small chance someone out there with on that has been crashed and bent, but the wheels are still intact? Thanks in advance

Just saw this post and how it evolved, so I'll resurrect it (I only get on the hub every few months these days :-( , so sorry for the 'late' reply) I think the material is irrelevant with regard to price, If the marketing people could sell you frame made from dog poo for R50k, they would, as long as it was the lightest and made it through the warranty period - I'm trying to divorce the marketing from the numbers here I think a lot of bike frames are made with fairly basic carbon fibre materials, which nowhere near use the full potential of the material - modern nanotubes have been found to have a young modulus of approx. 4.5 times that of steel (most steel alloys are around 200GPa), so you get the stiffness and with a UTS as high 126GPa (about 60x that of the best steel at about 2GPa), its fairly easy to get a mass advantage - I would give the more relevant proof strength which in the case of steel I guess is about 1.7-1.5Gpa but the manufacturers in both cases seem to think this rather important variable is irrelevant. The other thing missing here is fatigue characteristics. Suffice to say, though, the relatively mature steel technology losses hands down to the relatively recent CNT. Even if a steel or aluminium bike is as good now, I won't keep up as the tech filters down in coming years. Stiffness, pliance, comfort - those are more subjective things. Again they can be engineered, but steel is the worst in this regard, due to forming constraints. People make noises about the steel frame being lively blah blah. They probably are for many - I prefer the term 'whippy', because they lack lateral stiffness (my experience) and as for longevity, while I have the view that bike parts these days are engineered to almost sacrificial components especially if you are large lad like me, I've not had a carbon or aluminium frame fail on me, but I have had 5 steel frames and 1 titanium frame give up (I do, think the Ti frame gave up due to a manufacturing defect however). The steel frames were Reynolds 531, 531P (twice), 708 and Columbus SLX for what it is worth. That brings me to Ti, why not add that to this discussion - also gives 'lively' ride? Lastly @ 'Chro Mo': Please don't take this as an attack, but I had to chuckle - Your avatar Reynolds 531 is a manganese moly steel, not a chrome moly steel - try 501 or, I think Columbus SL is a Chro Mo.

Eldron: not so sure about the soft target comment - they and want a soft target and an easy offload. Practinoid is a good word, thats about how I am after hijacking as well, I guess. Not sure the car vs bike experience changes things, but I do find even on my bike I am more skeptical of 'pedestrians' Funilly, I think I am more nervous of breakins at home while you are asleep. BTW: Eldron back on the hub so quick with new job - slick....

It's a few months on and I'm curious to see how other C200 owners here did with the soniclink/weblink for uploading to the polar site. I saw this post back in December, but had no reason to comment since I could offer nothing useful. I did it last night for the 1st time - Followed the instructions on polars site to set up, worked fined despite my misgivings about using an audio based system which are historically prone to errors

And you posted this on the 1st of April?

Seems to be a pattern emerging here: Option 1 and 4 most mentioned as favoured Option 1,2 & 3 too hot due to high amount of black Personally I go for Option 4 top with option 1 shorts (a number of others have already made the same observation) Another though: I think if the black and white in option 3 top was reversed, I could really go for that.

You have discussed linear momentum only - a 29er, will have larger angular momentum due to the product of its larger diameter and the additional mass associated with such (in basic tech speak: mass and radius of gyration are both larger). In a nut shell assuming in all cases the rider + bike = say 90kg, the guy with the larger wheels will need to disapate more energy to slow him down. To answer the original question: To my mind, the main reason for larger discs on a 29er is the fact that a 29er creates about 10% more torque than a 26er that the rotors must overcome during breaking. This can be overcome 2 ways: 1. Make the rotor 10% larger 2. Apply 10% more force to the calipers on the same size disc. (This measn max breaking power is reduced by 10%) Personally I go for option 2. I had Ø160 XTR front and back. I found the 160 front to be inadequate on my 26" and changed to 180. It would be 10% worse on a 29er. I reckon a Ø185 front will be fine and if/when it warpes, grin and bear it, but don't change to smaller front disc. (That and the fact that such a large wheel looks lame with such a dinky disc on it - makes me think of these guys with golf 1/citi golfs that put 17" wheels on their car - the disc looks like a littre buscuit lost in the centre)

for how much?

Go for good old high spoke count wheels with double butted spokes and double eyelet rims. If you are a light weight, any wheel will probably do, but if you are quite a big lad like me, the above is the way to go. For reference, my last set of training wheels would last about 15000km rear and about 25000 front on the rims and spokes (Mavic open pro 32 hole initially and later Shimano/Pro R50 laced with DT spokes) and 50000km out of the hubs (Dura Ace - hubs were still 100% when I sold the wheels) - by comparison, for me, light weight race wheels like the ritchey WCS last a few thousand km before fatigue cracks set in rims and the spokes fail. Built a new set of training wheels about a year or so ago. Also Dura ace hubs and shimano R50 rims but now with Sapim spokes and 36 hole on the rear - hopefully that combo with get me 25000km front and back between rebuilds. They come in at about 1.8 - 1.9kg, so nor especially heavy.

@Drongo: So you joined the hub to tell us this...... OK, thanks

Hi Spidaman, Welcome to the hub. I'm sure you have your reasons for wanting credit to buy the bike and to give you a direct answer to your question, I can't offer any specific options to help you, although I guess most banks will give a loan as long as they get their 'pound of flesh' and there are also some guys on the hub offering cycle finance (do a search). Like the other guys here, I would strongly urge you to consider buying with cash that you have saved. Perhaps a second hand bike will do the trick until you have the cash available to get your dream machine. Also, have a look at the likes of www.cwcyles.co.za and www.solomons.co.za locally or www.chainreactioncycles.co.uk internationally and buy bit from them and save some cash. Whatever you do, avoid the urge to use a credit card to pay off over some months - with the exception of some of the private banking cards, they are just about the most costly way to buy things on credit.

lovely - I think that spelling was intentional. Now go and put some spaces in your username and add an 'a' to 'tea' Now that I have got that out of my system - please sir, may we have a PICTURE? Why not take the bike back and ask for a warranty claim?

EBC pads are expensive plenty of other options for less

As Johan says, no fixed time frame, just a function of contamination. However, if in doubt, clean is but make sure you put it back together properly - ie. you don't just tighten up. breloading bearings (overtightening) is a nice, quick, easy way to get early bearing failure. In simplest terms, tighten up the cones just enough to take out any play, but no more. As I have said on other posts in the tech Q & A on the same subject: Normal wheel bearing grease will do fine - the bearing speeds are so low on a bike wheel that viscous drag and other factors that complicate high speed bearing grease selction are a non issue. Setting up bearing properly and removing contamination will make much more difference than changing grease grade. With regards to waterproof grease - NOT all greases are waterproof. non waterproof greases will form an emultion when water is added then hydrolysis starts resulting in a change of viscosity and loss of lubrication properties. That said, regardless of whether waterproof or otherwise grease is used, a good portion of water in the bearing cavity is going to cause trouble eventaully, so if in doubt, clean it out.... And leave assembly grease alone - just 'cause it looks cool, doesn't mean it is right for the job

@TimHenman: not too sure the partial pressure of O2 changes with that much with altitude - rather the total absolute pressure of the air changes with altitude. At sea level at 20°C air pressure is approx 1.2kg/m3. At Reef altitude is is approx 1.0kg/m3 - 17% less. The higher you go, the thinner the air get and the body compensates for this with higher red corpusal count as you already noted

@ iragr: Oh dear, another sucker for misaplication of expensive grease. Not trying to be mean here, but just because the grease is great for sliding mechanisms, it is probably not really ideal for bike wheels. I know nothing of the viscosity of the grease or its thickeners/soap base etc, but from your limited description, there is a high likelyhood that the wheels bearing grease you buy from a motor spares shop is actually a better match for you application. Fortunately, bike bearing turn so slowly that they are very forgiving of almost all grades of grease. @davetapson: The amount of difference between the bearing types is so small that you won't see the difference. Rather consider the reliability and longterm viability of the solution. General: I tend to agree with what Johan has said, I'll also add, cartridges generally have less and/or smaller balls in them and are not well suited axial loads. They however replacable. Cup and cone arrangements will last longer given their higher load carrying capacity, but when the cups are hammered, you toss the hub away (you can replace the cones if need be). For reference, I've never had a cartridge last more than 10000km. On the otherhand, my last set of Dura Ace hubs (good quality cup and cone) did 50000km and were still fine when I sold them. However, I don't rate any shimano hubs except Dura Ace and XTR - I have XT hubs on my MTB and they just simply aren't in the same league as XTR (cup and cones are only ground and polished on Dura ace and XTR and it shows). In short for the MTB wheel if the options were XT or Hope, I would go with Hope. Given Hope hubs more than double XT in price and are almost the same price as XTR, then I would go with XTR. Another way of looking at it, if you can get a quality cup/cone, go for it, otherwise a cartridge might be a safer option. For downhill, cup and cone all the way - you are not doing massive milage, but you need something that can take the bumps and lateral loads (axial force) and cartridges don't suit either of those criteria.

18650 batteries are a reasonable option these day - many of the LED systems use them. They a Li-ion batteries and you can pick them up on ebay and other places for not too much money (don't get me wrong, thats not to say they are cheap). 4 of them would give you more than the 12v you need for you down lighter. All the above said, down lighters are power inefficient and you either have to have a massive battery pack or suffer from short run time. Most of the reason the newer bike light systems are LED based is because LEDs are massivley more efficient (approching 10x), so you don't need to carry 1kg of batteries to get 2 hours of run time. In short, what you save in batteries, you will be able to spend on LED parts, and you'll end up with a lighter, more robust system too (most LED are rated for at the very least 10000hrs mean time before failure, where as down lighters are rated for 2000hrs). Do a search on this site, there are guys who have made lights here and posted pics and part requirements. Soeul Semiconductors P7 (same as used in magicshine) is a nice option or look at a CREE MC-E (slightly lower lumens, I think, but more efficient). see http://www.cree.com/products/xlamp_mce.asp

@JB: Maybe you are right. In many respects it is a cost effective, simple design. I'm just concerned about longevity. The fact that there is relatively little adoption is either a function of others saying the same or everyone playing wait and see (not wanting to be the bleeding edge early adopter). You make a valide point about is being similar to the headset. Which leads me to: @Moegoe: The BB30 system is quite similar to a modern headset

I recon the upside of the BB30 is the replacement cost of bearings, the larger (read stiffer/lighter) crank shaft is also a plus. For me, the down side is the press fitting - putting extra strain onto the already highest stressed part of the bike and if it is too loose, you get creep instead. For the short term and as long as everything is made to correct, tight tolerances, it should be fine, but regular bearing changes could lead to problems.

BB30 is almost a pressed in version of an external BB see http://www.bb30standard.com/index.html . It's Cannondales wet dream that they are trying to get folks to buy into. It has some good technical merit, but also has some drawbacks. As far as you are concerned, if you have octolink, then you don't have BB30

Can I have a photo of that slap to the forehead? Getting back to the original question: A new octolink BB will be the cheaper solution, otherwise a full new Deore or SLX crank set with external BB might be an option. This will also provide new chain rings, eliminating that future headache (note: often a complete set of 3 rings will cost approx the same as a complete new crankset)

@Bos: I said nothing abount the BB lying in the muck - it seems I was unclear: My comment continued from JBs earlier comment that all the crap that collects inside the BB shell (rain getting down seat post etc) that has no chance to drain, will inevitibly run to the left, because bike are usually put down on the left side. While my explination seem relatively inplausible, no plausible explination has been offered. The JBs comment about torque possibly being the cause holds no water (pun intended) to me, the forces on the right (chain side) bearing will always be greater and I don't believe underloading of the left bearing will be the cause

I wish I knew the answer to that one. Some say it is because the left side is more exposed to the elements but I'm not so sure. The right side is a bit protected by the chainring but that type of protection doesn't keep water out. Most BBs fail prematurely because the BB shell doesn't have a drainage hole. The BB then rots from the inside out, so to speak. But why the left one goes first is a mystery to me and I have not yet seen a plausible explanation. We do know that torque is only transmitted along the BB spindle from the left crank, not the right but if that has an effect, I dunno. I'll give you an answer and your going to laugh when you hear it: Most folks lie their bike to the left, so all the contaminent goes to the left. Why do we all lie the bike down that way? because the drivetrain is on the right and ironically we don't want to get that full of contaminent Don't believe me, go to a race - all the bikes lying on the ground with chain etc facing the sun (or rain)

you notice no chain on there - show bike. Like you say, wouldn't last long That said the XTR M970 is a neat solution - Ti teeth with carbon composite reinforcement (looks like a carbon reinforced plastic). Those are more durable than the previous gen ali M960 middle rings. Or even the M770 middle that is steel and carbon comp - few grams more, but 1/3 the pricegreatwhite2010-06-15 08:06:54

wake up !! boone titanium stops to receive orders 3or 4 years ago @ Eliflap: You join the hub a week ago clearly trolling for business, make 22 post and in at least 2 posts you insult people (9% hit rate - not bad), including a potential customer (I assume you were insulting Koukie, since I clearly said "jokes aside" after my comment about carbon teeth"). You seem to be punting a nice product, but as far as your sales skills go, you clearly need to catch a .......... "wake up!!"