NotSoBigBen Posted January 17, 2008 Share Just checking the installation instructions for my raceface crank and it has options for the 'chainline' like 48,49,and 50 with spacers. so now how do I know what chainline my 2005 Specialized S-works M5 hardtail frame should have? Link to comment Share on other sites More sharing options...
bob_the_builder Posted January 17, 2008 Share F@cking Sheldon brown... I hate hime, do you think he knows JBoringman? Seems to be something to do with double/triple chainring thingy... http://www.sheldonbrown.com/chainline.html Link to comment Share on other sites More sharing options...
NotSoBigBen Posted January 17, 2008 Share Thanks BOB was busy reading there but flippin heck! Will just try to measure the existing 'chainlline' and see if that helps. It seems the chainline is from the middle of the BB to the middle chainring, at least on a triple chainring bike! Lets see tonight ....... Link to comment Share on other sites More sharing options...
bob_the_builder Posted January 17, 2008 Share Ya, look, I've been riding for 22 years now (ok, never MTB, but still..) and this is the first time I've heard of a Chainline... Good luck... Link to comment Share on other sites More sharing options...
NotSoBigBen Posted January 17, 2008 Share Always a curved ball you know! Every other BB I installed just had the spacers for if the BB shell was 68 or 73 MM, easy peasy. Now these okes come with some other complications ........ but guess if I want the bling I'll have to go the 'extra mile' so to speak. Like I said will measure the existing and just make it the same. Link to comment Share on other sites More sharing options...
Guest Big H Posted January 17, 2008 Share BB kyk in die Barnes manual sowel as by die link van Park Tools. http://www.parktool.com/repair/readhowto.asp?id=95 They do not have Raceface in this article but reading may help. Link to comment Share on other sites More sharing options...
Guest Big H Posted January 17, 2008 Share See "Chapter 17 Chainline" in Barnes Manual regarding chainline. Link to comment Share on other sites More sharing options...
NotSoBigBen Posted January 17, 2008 Share Dankie oom, ek's nou by die huis en lees bietjie daaroor in die Barnes. Sal daai CD moet saamdra werk toe (middagete lees!) Link to comment Share on other sites More sharing options...
Johan Bornman Posted January 17, 2008 Share Thanks BOB was busy reading there but flippin heck! Will just try to measure the existing 'chainlline' and see if that helps. It seems the chainline is from the middle of the BB to the middle chainring' date=' at least on a triple chainring bike! Lets see tonight .......[/quote'] Chainline simply refers to how far out the RH crank sits from the BB shell. For perfect chainline on a triple-chainring bike, it is easy. You put the chain on the middle chainring and on the middle sprocket at the back. The chain should then be perfectly straight when viewed head-on. If it is not, use or remove the supplied spacers to get that right. On a double-chainring bike it is a bit more difficult, although the priniciple is the same. Also, 9-speed and 7-speed bikes make your job easier, since there is a defininte middle sprocket. On older bikes with non-adjustable chainlines, you have to fit a different BB with a longer or shorter right axle stub. That's why it pays to first remove your BB and then get an exact replacement. Bike shops often just give you a BB if you ask for one. It could render the chainline out by a considerable margin. Link to comment Share on other sites More sharing options...
NotSoBigBen Posted January 18, 2008 Share Thanks JB, that together with what I've read now makes sense to me! So last night I measured the existing setup at 48mm so will just check tonight by putting middle chainring and middle cassette ring and if it's straight I'm sorted. If not I have an opportunity now to get it right and lets see if it improves the shifting or anything? Just as an aside I always wondered how exactly to adjust the 'B-screw' correctly, any insight? As I now understand it is to adjust the distance between the 'upper' pulley wheel and the cassette for the best shifting performance and not to 'take up slack in the chain' as some dufus told me once! According to SRAM for the MTB's it should be at about 6mm, is it the same for Shimano and also for roadbike or are there different tolerances so to speak? I never worried about it just high, low and cable tension but guess there's more to it than that! Link to comment Share on other sites More sharing options...
Johan Bornman Posted January 18, 2008 Share Thanks JB' date=' that together with what I've read now makes sense to me! So last night I measured the existing setup at 48mm so will just check tonight by putting middle chainring and middle cassette ring and if it's straight I'm sorted. If not I have an opportunity now to get it right and lets see if it improves the shifting or anything? Just as an aside I always wondered how exactly to adjust the 'B-screw' correctly, any insight? As I now understand it is to adjust the distance between the 'upper' pulley wheel and the cassette for the best shifting performance and not to 'take up slack in the chain' as some dufus told me once! According to SRAM for the MTB's it should be at about 6mm, is it the same for Shimano and also for roadbike or are there different tolerances so to speak? I never worried about it just high, low and cable tension but guess there's more to it than that![/quote'] The B-screw is the least important setting on the bike, provided you've always just left it as it was. Essentially, it varies the distance between the upper pulley and the underneath of the smallest sprocket, where the two are at their closest. As you shift towards larger sprockets, the distance automatically increases. Adjust it only if the pulley and the sprockets actually touch. Up to six mm is ok, but this is not critical. If it shifts, it shifts, and the B-screw can't improve shifting. If the gap between the upper pulley and smallest sprocket is too large, it will have the effect of a retarded shift, simply because you now have a lot of sideways flexible chain in there that must be moved over to the next sprocket. Typically you'd fiddle with the B-screw if you suddenly move from a cassette with an 11-tooth high gear to one with a 14-tooth and you can hear some unhealthy griding in there. Link to comment Share on other sites More sharing options...
ewep Posted January 18, 2008 Share BB, gonna hijack your thread here!!! Johan, I read in a brochure about some or the other "special lubrication" that's added in the cable housing of road bike. Does this help at all or is it a gimmick? Link to comment Share on other sites More sharing options...
NotSoBigBen Posted January 18, 2008 Share ' date=' provided you've always just left it as it was[/quote'] Now therein perhaps lies the crux of the matter ......................... Etwerp get you're own thread dufus ..... I'm busy with important technical discussion here that you will not be able to follow anyway Link to comment Share on other sites More sharing options...
Thug Posted January 18, 2008 Share Etwerp get you're own thread dufus ..... I'm busy with important technical discussion here that you will not be able to follow anyway (unless you start talking about Pies) Link to comment Share on other sites More sharing options...
Guest Big H Posted January 18, 2008 Share BB' date=' gonna hijack your thread here!!! Johan, I read in a brochure about some or the other "special lubrication" that's added in the cable housing of road bike. Does this help at all or is it a gimmick?[/quote'] Jy wil seker nou weer 'n rede he om KY Jelly wat soos strawberries proe te koop jou e-pervert!!!!!!! Link to comment Share on other sites More sharing options...
Johan Bornman Posted January 18, 2008 Share BB' date=' gonna hijack your thread here!!! Johan, I read in a brochure about some or the other "special lubrication" that's added in the cable housing of road bike. Does this help at all or is it a gimmick?[/quote'] It doesn't help and is far worse than a gimmick. Completely dry is better. Grease in a cable only works as long as you can keep the grease clean. Anyone who has ever ridden in dusty and muddy conditions will know that the dirt very quickly works itself up to 150 mm into the cable ends from each opening. At the brakes this is usually at the levers and at the calipers, but if the brake cable is exposed anywhere on the frame, you'll have an additional intrusion at those two extra exposed ends as well. The constant to and fro of braking and gear changes works the dirt much further into the cable than the cable's absolute movement from changing or braking. If you have grease in there, it creates a bigger mess. Further, grease quickly emulsifies. An emulsion is a mixture of two liquids in such a way that the smallest molecule is completely encapsulated into the bigger molecule. In the case of grease, you have a large hydrocarbon molecule that readily swallows the smaller water molecule. Now you have water that cannot evaporate but still do all the damage that water does, as is evident from bearings with just a drop of water in the grease. All greases emulsify with enough "massaging" in the presense of water. Cables have another problem inherent in their design. Since they're not smooth like wire, but shaped like a bluntly-serrated saw blade, it is difficult to keep it clean by way of a rubber seal. No seal can assume the shape of the cable and maintain its integrity as the helical cable slides over the seal and effectivy morphs its shape with each cable actuation. Some cable manufacutrers have attempted to solve this problem with just such a seal, but unfortunately chose the worst seal for the job - an O-ring. An O-ring is a poor seal for any two sliding surfaces. If you examine the cross section of an O-ring, the reason will be evident. It simply encourages dirt to slide underneath it due to the angle at which the two surfaces meet. Look at your front shock and you'll see that it has a wiper seal angled upwards. Now imagine if that was an O-ring in there. I notice that BBB has attempted to put a wiper seal in its ferrules. However the cable shape is still the fundemental turd in the water can. Finally, the best way to keep a cable free reasonably free of dirt is to isolate the ends from the elements with a ferrule that has a double end closure. By that I mean a ferrule with an end closure (the part with the little hole in for the cable to slide through) as well as another one 5mm further down the line. This creates a no-man's land zone between the inner cable and where it enters the outer cable. Ideally this no-man's land has to be larger than the travel of either the brake or gear mechanism that it serves. It creates a very long ferrule that confuses many people. However, it is the best solution and better than grease (no matter what fancy name they give it) and O-rings. Road bikes generally don't need any fancy cables but MTBs certainly do. In my view the extended ferrule with a built-in isolation zone is the best solution yet. Far better will be a plastic-coated cable with wiper seals and an isolation zone in the ferrule. Grease has no place here. Johan Bornman2008-01-19 02:24:54 Link to comment Share on other sites More sharing options...
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