forteh

You couldnt be further from the truth Typically on refurb jobs youre designing equipment to fit a 30-70 year old concrete tank, alot are in imperial measurements and nearly every one is different. The concept and design is usually the same but each one is different. That tank from seafield is one of the largest rotating half bridge scrapers in europe, 55m diameter tank and almost 4 meters deep, tis a lot of shit I was working on it for 18 months and Im pretty proud to say that it worked very well and thames water are very happy with it. It sucks sludge from the bottom of the tank and sends it off to the sludge processing plant elsewhere on the site - capable of 72litres per second when cranked up

In this instance only cosmosexpress, we have very little need for a dedicated fea package at work (its all heavy engineering and typically based on emperical designs + theyre too tight to pay for it ) but its usefull for checking simple brackets and fabrications The joys of having an engineering suite available to mess about for hobbies

On a side note I had a quick play on solidworks last night and have one V brake arm designed, need to run it through FEA some more and tweak the design, then do the bearings and pivot

I designed this Id show you the cad drawings but theres 330 meg of them and I really cant be arsed For anyone in edinburgh its the sewage works at seafield

Disk has nothing to do with the rim, aslong as you have a disk hub and tabs on your frame/forks then you can use a disk

Another no-vote for hope skewers, may well be ok in a rear vertical dropout but with a front disk it just cannot hold it. Ive got a stock deore skewer holding my king disgotech hub on without any problems I tried some of the bolt through 'security' things, the allen heads are made form a soft form of cheese though so good luck ever trying to tighten them up properly, they also need an odd bastardised size allen key (between 4 and 5mm). Any tensioner will do but best if you have a sprung one, in my experience the ones you just bolt up are less than useless

Erm, the same number of teeth as your 4th sprocket perhaps?

Highrollers are one of the favourite tyres By standard I presume you mean the maxxpro 60a compound? Stick with highrollers but get the 42a super tacky or 40a slow reezy and youll be sorted. If you want really sticky go for the tryall tyres but theyre expensive and wear out pretty quick, grips well though

Spokes too tight I reckon

I got my rear king discotech (like the classic but with the option of putting a disk adaptor on there) built onto a viz rim from ben travis for 160 quid

This is a hope hose? There are no olives, its a proper hydraulic connection, if youve split the hose then you need to get the end refitted. If your lbs hasnt repaired the hose then your local hope dealer should be able to do it or talk nicely to hope and they should do it it for you; give them a ring and check its possible to refit the ends (pretty sure it is). Have you tried repeatedly pumping the lever? If the pads arent moving then the bleed is still f**ked and the hose could well be leaking air into the system. If the pads are hitting the disk but its not working then your pads are likely contaminated with oil, when the hose split the oil more than likely tracked down it and ran straight into the pads - throughly degrease the disk and you will probably need new pads aswell if theyve been badly contaminated. Try burning the pads off over a gas ring and see if that helps, I would guess you need new pads though. Sounds as though youve part stripped the TPA or something similar, not sure how the new model TPA works though. Get a replacement metal TPA wheel from tarty and see if its better. Its always more advisable to reset the pads rather than use loads of TPA adjustment The steerer tube is likely to be made from a stiffer, more resilient material to resist bending, the legs are likely to be springier to aid with front wheel moves like hoks and taps, also to absorp some impacts. Theres no need to have a weld if there is sufficient material to support a decent interference fit. Pushfit + glue is more than strong enough (testimony to that is the fact that your forks broke somewhere else) and it avoids the problem with the welding HAZ (Heat Affected Zone) which puts large stress raisers into the material

Any mech will run like a tensioner, just shorten the chain more until it pulls the mech out straight

You know more than me on the metalugic side, we only really touched on the subject at uni and it was so long ago Ive forgotten most of it Forging forces the material into a specific shape, with good design this can form a better material grain flow in order to relieve any stress during use. Bit of info on forging and material grain flow However naturally you cant make any shape with a forging (unless you forge it multiple times but I suspect annealing would have to take place between operations thus making it far more expensive) so forging your billet to the approximate size and shape before machining gives a far better grain flow If you imagine a round rolled bar has all the grain flow in one direction, if you wanted to form a rivet out of that bar you could simply machine the shank out of the bar (much material waste) but the only material area holding the head onto the shank would be the same diameter of the shank. If you were to forge the head on (by twatting it with a large hammer basically) the material is plastically deformed and squashed into the head shape, the means that the grain flows longitudinally along the shank and out in a radial pattern at the point where the head and shank meet. This grain flow is continued all the way through the material and forms a far stronger piece. I could well be wrong about working 7075 and tempering, it was a bit of a summation by my part The material on the middleburns I got from tarty, you can tell that they are forged to shape from inspection (got 2 pairs here to look at) - for the cost of them I dont think you could machine them to look how they do, the shape just seems too organic. Obviously I could well be wrong but Id happily bet a tenner that theyre forged to size and shape

I would go with a tensioner that is sprung at the very least, theres no reason why you cant use your rear mech to act as a tensioner, all you need to do is adjust the hi and lo screws until the mesh is inline with the chain Its heavier than a dedicated tensioner but works better than an unsprung tensioner imho.

Dzien dobra Inur Sorry I had to, polish lodger Im not too familiar with the suitablilty for forging of 7075 as opposed 6061 but 7075 is a far higher grade of material and in its annealed state appears to be stronger than heat treated 6061. In T6 condition 7075 is almost 40% stronger in shear than 6061 T6 Some 6061 info Some 7075 info Im betting that the 7075 echo cranks are machined from plain billet, if they were forged and then machined they would be far superior A bit more research - middleburns are forged from 7075 and then heat treated to T6 before machining, probably explains why you dont get as many failing as deng cranks; the forging makes it a much stronger component, also explains some of the price difference too. edit: hubs are very easy to forge, rims are extruded and frames are fabrications, nearly everything else on a bike can be forged. Forging can be fully automated, aslong as you have material going into one side it will produce forgings falling out the other side

Yeah thats the sensible solution in reality Afterall you can just get a new rear sprocket for a few quid if you fancy a change.

I know a man that can manually machine down to tenth of a thou (thats 0.00254 mm in modern money) Cant do it with the speed of a cnc machine though I would guess that all of the deng products are machined from plain billets (which have been forged) but how many of his products are actually forged into shape in order to give the correct grain structure that gives forgings their strength? Are the machined deng cranks (gu/zoo/czar/adamant/echo) machined from a crank shaped forging (presumably taken from the forged echo cranks?) or are they machined from plain square billet? Material specs quoted on tarty would seem to indicate that theyre not the same.

Ok so Ive got an 8spd xt cassette not xtr :$ The rings are 11/13/15/17/20/22/23/26/30, the 30t one has a slight kink in it but you wont be using that one anyways. The 17t and upwards are mounted on the alloy carrier, the carrier body where it fits onto the freehub is 25mm wide, the rest of the space can be made up using other chainrings and/or spacers Yours if you want it, comes with all of the rings and the correct lockring - not quite got the gear ratios you were after though

Its not just limited to trials or even NMC, go have a look through CRC and see how often the phrases cnc and strong come up in the same sentence Its like the 05 echo cnc rims, how do you think any drilled/punched rims are made, blimey it was a cnc machine Yes it can look pretty (although imho most of the machining on dengs frames is pretty rough) and can create a light, stronger component if its designed correctly to minimise stress raisers.

I graduated 7 years ago, besides which why should they have an opinion on why the bicycle industry has a cnc fetish

I know what cnc means, I have a degree in mechanical engineering I meant why is the industry fasinated with the process and why do they claim it makes things stronger?

Ill check the number of teeth on the xtr cassette I have and post back here, it should fit without a problem, you might just need to fiddle about with spacers (Ive got some spare you can have). As I said you can have it for postage costs which shouldnt be more than 5 GBP

What is the fascination within the bicycle industry (particularly in trials) with the notion that because something has been made using a cnc machine that it is automatically stronger and a better product? Forging a component makes it far stronger, I just dont get this who cnc thing Certainly the use of a cnc machining makes mass produced repeatabilty cheap and practical and has its uses particularly with deep pocketing and the like but it doesnt means its actually any good. Sorry personal rant over, discuss....

You would need to buy some square taper front free wheel cranks, an 18t screw-on chainwheel, an 18t bashguard and possibly a longer bottom bracket to make sure the chainwheel clears the frame.

I would keep the cranks, bash and ring that you have now and sort out the rear end as its easier to change the ratios that way. The xt cassette has the 1st 5/6 rings mounted on an aluminium carrier that slips onto the cassette, you may not need the extra spacers to tighten it up. If you measure the width of your current cassette Ill compare it to my spare one to see how well they match Thinking about it, it might be an xtr cassette, either way it would cost you about 5 quid postage to greece