Johan Bornman

Guys, particularly those of you from Cape Town, I've made an announcements regarding courses there in the events section. Those of you who contacted me individually, I'll send you the announcement by reply of mail. Regards

Cape Town: I am no longer going to bring the regular Yellow Saddle DIY Repair and Maintenance Course, Wheelbuilding Course or Fork Service Workshop to Cape Town. A bunch of factors contributed to this decision. I’ll be frank. My Johannesburg business is now a sizeable concern that needs more and more of my time and a course hosted in Cape Town requires a disproportionate amount of time for the same or less profit. For example, a course in Jhb requires 3 days of my time. One for prep and admin and two for the course itself. The same course in Cape Town requires 6 days. Plus travel, plus accommodation. A second factor is the increasing sophistication of the content. In Jhb, it is presented in a dedicated workshop-studio equipped with vices, compressed air, oil baths, ultrasonic cleaners, individual workstands, tools, machine tools and a backup of stock to cover all eventualities. To pack all of that into a box and ship it to Cape Town is not possible. I have to dumb-down in order to accommodate and I swallow hard on that concept. Thirdly, I’m changing my business to an IP-based one. In other words, I want to sell my IP instead of selling me, applying it. A fourth factor is the sales lead time. I find it much longer with Cape Townians. You guys roll each penny around until it’s shiny before spending it. However, you only tell me at the last minute whether you’re going to spend or not. This makes all the travel arrangements precarious. Where does this leave you? Either you travel to Johannesburg for your education or you play impresario. Impresario? I’m prepared to work in Cape Town if say a club, organises a course with me as the presenter. The club comes up with a budget and marketing plan, do all sales, book the venue, organise the catering, prints the literature (probably mine with their branding) and hire me as the presenter. The club/individual could and should, turn a profit and everyone’s happy. If the impresario is ambitious they could squeeze in three revenue streams: 1) Wheelbuilding course. This one is held during the week just before or just after the weekend maintenance course. This one would be aimed at workshop mechanics and freelancers. 2) Following that on say, the Friday afternoon, we squeeze in a Fork Service workshop and 3) the weekend Repair and Maintenance Course during the weekend – open to DIYers. I’m sad it had to change but I have to be pragmatic. Thanks for all the support. I’ve planted the seed. Let’s see what happens.

Long out of warranty.

Thanks to R who alerted me to this. To the owner of this thread, Grant, lets look a the facts. It took me a while to piece this together since yo do have the habit of coming back three months after having a job done, then claiming you've done no riding and thus the problem was never gone. That may be so. But at least give me the courtesy of responding quicker so that the issue is still fresh in my mind. Lets refer to the report from the Magura agent. 1) They noticed (just as one does in passing), that the wrong oil was used on a completely clean and disassembled fork. This is a pretty remarkable power of observation and would require access to a tribology laboratory, enough residual oil on the parts and of course direct evidence of oil damage. Oil doesn't damage parts in the way they suggest. Most unprofessional and a cheap shot. I suggest they tell us what oil was used in their opinion. 2) I agree that the damper should be replace and I'll get to that reason in due course. 3) In my opinion, the bushings are not worn. They are stained, as this type of nylon does, but not worn. Actually, it isn't my opinion. I micc'd them in the fore-aft and laeral positions and the difference is absolutely minimal. I'd like to compare my measurements with theirs. I thus dismiss this as a cheap shot with no apparent purpose. My response to Grant was that the report was absolute rubbish and I think it should be clear why I say that. Back to the fork. Grant's original damper broke. The folowing two pictures the break. Here I've separated the top part of the damper. What you see there is a neat, precision break at the crimping. The damper is manufacturered by inserting a machined piece into an aluminium tube and then crimped. The crimping is a weak point since the damper, under lockout resists force in the direction of the black part. Repeated strain fatigued the paper-thin crimp and it separated. Have another look. The break is so neat that you won't believe it should be one part but the two grey parts should be joined. I replaced his damper with a scrap one. Not optimal, due to the scratches and dents. As can be seen in this photo. And this one However, it was an attempt to help Grant. The fix worked for a while but eventually enough oil leaked past the dents in the alu to prevent the damper from working properly. Eventually, all the oil settled in the bottom of the fork and pops the seals. I showed Grant this but sometimes it is better not to explain things to some people. They think just because something was "serviced" it is now immune to all ills. A note on Magura forks. All forks, and I suppose, everything in life, as drawbacks.The magura's aluminium compression ring is follly. It isn't good practice to allow a sliding element like this to be made from aluminium. There's good reason why every single, (read all others) fork companies make their compression rids from hard-chromed steel. Secondly, that crimping proces is dodgy. They should consider epoxy, which will not weaken the structure that much. I can only do so much for someone. If they don't want to report problems promptly, they don't do anyone any favours. Gant failed to mention that I dropped everything else I'm doing and helped him immediately - each time. No que, no wait. More I don't want to do.

Someone, not you of course but Fritz in your local, assaulted the lockring with too much torque. You have a problem but it must come off. Use more force. Put the wheel upright on the floor in front of you and lean it back against your knees. Bend over it and install the whip on the leftand the cassette cracker on teh right. The two levers should make a V shape pointing towards the floor. Now use your weight to press down. Should you have to bounce, to it carefully because either of the two tools may twist and fold. The BBB cracker is well designed and won't slip out but don't be tempted to use a large shifting spanner on it as it will collapse. Good luck and curse the installer. It doesn't have to be very tight at all. I don't recommend removing the freewheel with the cassette on. If anything goes wrong and you cannot get it all back (although it shouldn't), you are in deeper trouble because if the freewheel is not fitted, you cannot remove the cassette at all. Next. And this goes for ANY bicycle part. Use ordinary grease. Bicycles don't require special grease. Period. You have more problems. That hub is of rubbish design. Should you have to replace the inboard bearing on the hub itself, you require a special tool that DT Swiss in its wisdom had designed by a fairy. The tool is too weak to remove the ratchet ring. Other than the poor design, poor seals and poor installation, service is straight forward.

Don't go by the stated size. For instance, I have a 37 on my Open Pro rims and they actually only measure 29mm across. Tyre manufacturers are notorious for overstating the tyre size and we have the weight weenies with their cocaine scales to blame. Bike magazines regularly do a tyre shoot-out and one of the features of this useless test is to weight the tyres and compare them in tables. Tyre companies respond by overstating the size so that their tyres will look good in a particular size category. A couple of years ago an obscure American tyre manufacturer, Avocet, blew the whistle on this practice and said that it will, with immediate effect, stop the practice and adjust all its tyre sizes. 25s suddenly became 23s etc etc. If you want to try a Citiride, choose an outrageous size and try. You may be pleasantly surprised.

There is no way that a 47 will fit a road bike, if that is what you have. Mine is a 37 and just-just clears a road bike, but then I have long-reach brakes and a little bit more clearance between wheel and fork. If yoiu're in Jhb, you're welcome to try my wheel and see if it fits.

Continental City Rider - the widest your bike can handle. I recently did a loaded tour of 900km with those. Half the route was on tar, half of dirt.

I'll forgive you if you overlook my poor grammar.

Nonsense? More like misunderstanding in where the gears are located. But thanks pointing it out so friendly.

Shocks are measured in stroke and extended length. Those look like inch sizes. Translated into civilizees, it becomes a 184mm x 44.5mm. This is a longish shock with a longish travel. Your internet trawl says you can fit up to a 200mm x 63mm. Put your bike in a stand and remove thel rear wheel and at least one of the shock mounts. Now have someone hold the back triangle for you whilst you guide him/her, using a ruler, up tot he 200mm point. Look for any frame part that bottoms out or hits something else. If nothing comes in the way of that much opening of the rear triangle, you can go ahead. You will have to increase the new shock's travel proportionally to the new length. This realationship may or may not be linear, depending on the path the shock mounting pionts move, but a few measurements with the help of our assistant will tell you the truth. Measure twice, then drink beer.

Welcome to your first evern (and hopefully last) Atom freewheel. You're on the right path - the axle comes out first but now you need the Atom tool. If you swing by, I'll allow you to touch my Atom tool.

No

Have done so plenty of times here search. Double butted and durable in the same sentence should bring it up.

You will have to put a new kit in that brake. At least on the lever side. Yu may even need a new reservoir cap bellows too. The rubber in Hayes brakes turns to jelly after a couple of years and a simple bleed won't do the job. I have the spares in stock and I'm close to you. Contact me if you need help. johanatyellowsaddledotceeodotzeda

Yes. A 29er wheel moves forward 2280mm with every revolution. If you turn the crank in your 39/26 gear once, your bike goes forward 3420mm If yo turn the crank in your 40/28 gear once, your bike goes forward 3257mm. Thus, the 39/26 gearing is 5% harder than the 40/28 setup. If you're a glass-half-full type of person you would put it differently: the 39/26 gearing is 5% faster.

The clearance between the highest tooth on the large chainring and the lowest point on the derailer should be 1mm. In your case it is about 10mm. Those bike shops are to blame. That orange sticker on there is the remnants of a transparent tab that Shimano fits to new derailers to help the mechanic find the sweet spot. It is transparent and marked at the 1mm mark so that it is easy to set up. There are four adjustment positions that are important on a front derailer: 1) Low Limit 2) High Limit 3) Parallel with chainrings 4) Height above chainrings.

You also need to know this: They are stronger but build weaker wheels. Stronger is not always stronger.

I like those indicators. I'll rather glance down to my handlebar than try and squint backwords through a pair of multifocal glasses to see a blurry cassette. The latter spells accident. However, as easy as they to remove, they're bloody difficult to put together after you've opened them to clean inside. Tiny springs with mystery recesses and tiny little plastic bits that require watchmaker fingers. I just sukkel to get it right. I blame it on the lack of educational toys - especially that ball-shaped one where you have to press a star-shaped thingy through a star-shaped hole and a square one through a square hole. As much as I like these indicators, I don't have one on my singlespeed.

There is a tool available. It is an expensive tool that's not typically a DIY tool. It is a right/left hand tap and special insert sleeves. Once the crank is stripped, there's not enough meat in there for a chasing only and it thus has to have a new sleeve fitted.

The lilttle blue sticker is Columbus Steel sticker. Columbus is Italian. Good luck in communicating with them. Try one of the British suppliers of bike tubing. They send stickers with each tubeset you buy from them, perhaps they will sell you one. The Mavic one...why bother advertising for them? Less is more.

I think they'll charge you the same to de-chrome or chrome. Chroming is cheap, do it.

One more thing. When purchasing bearings, be a snob. Never ever under any circumstances buy a bearing made in India or China. I'm not saying they are all rubbish, but I haven't seen a good one yet. And one last, last thing. Freehub body bearings are kinda special. There's usually two of them in there and they have considerable drag - enough to let the freehub not "free" perfectly and push the chain forward. This is not a fault, just a matter of bearing spec. Cartridge bearings can have super tight seals and lots of grease, or soft, poofter seals with very little grease inside. You actually want the latter.Better is not always better.

It takes 4 x 6091 bearings. However, not all 6091s are created equal and on the Powertap it matters. The two bearings in the freehub are separated by a stupid soft aluminium spacer. It is so soft that it may even be Lithium, not aluminium (chuck water on and see what happens). Therein lies the problem. if the bearing's inside race isn't exacty as thick as the spacer, the spacer will deform around it and effectively become shorter, allowing the two bearings to drift and assume the wrong preload and; deform enough to "flow" over the race into the plastic seal and jam the whole kaboodle. Many standard 6091 bearings have a stepped design on the inside race's outside cirumference which has to do with the seal design. Bearings that don't work here include Enduro. Therefore I suggest you take a sample to the bearing shop and inspect the replacements for compatibility. Don't let them tell you it is only the ID, OD and thickness that counts. In this case there is more. Further, PowerTap uses a generic freehub that I've seen on many other wheels. I can't remember right now which, but it is very common. This freehub is of poor quality in the alu version (a steel version also exists that performs better). The quality shows in the pawl cavity wear. The cavities where the pawls live wear backwards, deforming the seat and messing up the pawl performance. The way to check for wear is to remove the freehub body, remove the pawl springs, clean it properly. Now lay the pawl flat into its recess and see if it fits perfectly. If the recess is longer than the pawl itself, replace the body.

Take it to an electroplater and let them take it off for you. The process is the reverse of chroming. However, the electroplater has to be exta careful since the steel can easily be compromised by too much current and too long in the bath. I've had one such job destroyed, but several done successfully. Just inspect the fork well after the job and look for deep pits that indicate the problem. Are there any metallurgists on here? I wonder if the Cr in the CroMo can actually be leeched out by such a process?