greatwhite

Merry Christmas All! While meddling with my Shimano M181B shoes, I slipped and left the mark below - A kind donation from the metal in the studs on the front of the shoe. I've tried all manner of cleaning agent - meths, thinners, Jik, Handy Andy etc, but to no avail. I think the metal (What ever it is) has been forced into the glazing on the tile. The thought that goes through my mind is to use and acid to eat out the mark given that ceramics are generally fairly acid resistant and most metals are not. This is fairly extreme though and was wondering if anyone had a less risky (potential) solution I might try before jumping off the deep, as it were. The shoe model is mentioned because it might give some insight into the metal used and therefore a solution - although I'll concede it is a long shot! Thanks

I think you misunderstand me - I agree, if I had a square tube or round tube that had the same mass per meter and same wall thickness and it was constant diameter all the way there would be little in it in terms of stiffness (lets ignore buckling issues - the round tube wins there no question). If you are able to place the material further from the neutral axis, is would be stiffer - Agreed? (You have implied as much already) - In the late '80s, early '90s the likes of Columbus reached that conclusion and made products like 'MAX' which was elliptical to get the extra distance in the axis that required it, but it was still round tubes that had been made progressively more elliptical as it approached its ends. They were also butted which helped in the high stress areas. Now imagine making any shape you want with steel - as an example, imagine you could make the down tube grow in diameter from Ø34.9 where the Front derailleur clamps to say 60mm wide x 40mm at the BB shell and you could thin down the material without it buckling so you get maximum weight saving and the desired lateral rigidity. That's what I meant about changing section - not making it round or square. Problem is, making special highly variable sections with steel - especially super high strength alloys, it is difficult. And even if you could/did, to get the mass down, the wall thicknesses would be so thin, you would be dealing with buckling issues. Even with the same strength to mass ratio, this is all viable carbon fibre due to lower density(read thicker walls and reduced buckling) and the relatively easy shaping process. Now factor in the higher strength to mass ratio and better elastic modulus of good carbon fibre..... I agree, bicycles are not complex, which is, imo, one of the reasons we see carbon used so often - its easy to implement. It does bother me when I see frame advertising with FEA and CFD that on a few second inspection is rubbish - you won't see too much of that on a steel frame advert. As for the reason we don't see it in the peleton often - it doesn't win races. If it wins races it sells more. The other reason is the easiest measurable - mass. Its hard to sell a frame that weighs 50% more (going on Gummibears comment of a 1.2kg frame - though I could not substantiate it being that light) for the same money - which relates back to the reason it doesn't win races - too heavy!

valid point and and especially relating to stems, I agree. Bars are nice and straight though and lend themselves to carbon fibre. The right material in the right place is what it is about for me. I just feel most race frames benefit from carbon. I even have misgivings about steel being best for cobbles or 24he solo racing , but since I have no experience there so I'll concede it (has anyone on this thread done either?)

I think the description was perhaps narrow. I would say best for the largest portion of racing by both type and participation. 200km on cobbles and 24 hour mtb are the exception not the rule

Changing section of a tube along its length to deal with variable stresses is a whole lot better when your not just stuck to round (and constant diameter along length). As for aircraft - Airbus and Boeing invest heavily in carbon and other composites. As do all the major military aircraft builders. I suspect the limits for the aircraft to which you refer are budgetary constraints and/or ease of repair. although, I must concede, that I know a great deal about racing aricraft.

Just a thought: I think the marketing people have got most fooled - steel is real is a slogan developed to try and sell steel frames - at first, because they were loosing hands down to the new materials (ali, carbon) and now because they have realised there are plenty of people out there that will buy a steel bike in addition to their carbon, ali, Ti steeds, simply because it is cool and they have spare cash. Look at the whole fixie/retro thing that has popped up in recent years - makes little sense to me, but thousands are doing it - why not throw steel in there too?

I guess everything is relative. If you are looking for a comfortable bike for hours in the saddle, steel probably has its place - Ti too for that matter. I know how you feel about the lively feel (note many steel frames in previous post). This is a subjective thing though. I think you will find however, while they don't have the 'real' steel feel, the carbon and ali frames will actually give more acceleration even though you might perceive them otherwise. The other effect that I perceive in a similar way to this is the 'rubber band' effect of turbo cars that make them feel faster than similar powered normally aspirated cars. In this case you stamp on the frame and like an elastic band it springs back at you - it feels great, but what you have actually done is expended energy deflecting the frame, regained most on the springs back but wasted a little in the process. Despite the OP stating steel is back in the peleton, look up the Condor bike in question - frame weight 1800g for a 52cm frame. The other popular top end steel 953 e.g. Madison Genesis Volare, can get you down to 1600g for a similar size frame. At the top end of the sport, hauling an extra half kilo plus up hill isn't going to happen when a big race victory is on the cards. The condor in question weighs 7.2kg with everything else around the frame in...... you got it - carbon firbre! Incl super light climbing wheels it is still nearly half a kilo over the UCI weigh limit

Thanks! - Will do when I get home tonight Here are the pics

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