Dick Whittington Posted April 9, 2008 Share Posted April 9, 2008 ... well they say there is a fine line ❗ Having bought a Sigma BC-1606L bike computer, I just wasn’t happy with the placement of the magnet and pick up. The ideal placement of one was always a compromise for the other. So, whilst standing on the shoulders of giants like Miles and Strangely, I decided to go back to the drawing board and see if there was another way. The magnet is design to be fitted to a bicycle spoke so I though why not use that fixing rather than discarding it. So what I did was to buy 3 bicycle wheel spokes, cut them to a length slightly shorter than the diameter of the brake disc. Then I inserted the spokes in the ventilation slots 120 degrees apart with a slight bend to ensure they are secure. Then I tied them together with zip ties and clipped the magnet on. “Hey Presto” the magnet sits in front of the pickup and everything works beautifully – for now! See picture here Now this may not be a good idea in the long run: 1. The spokes are stiff and hard. If they come out or brake things could go a bit “Pete Tong”. This is why there are three of them zip tied together with paint marks where they touch the hub to show if any movement has occurred (visible in picture). They are difficult to move (need to use a screwdriver on the ends) because the inside of the vents are not machined. 2. They may heat up too much and melt the magnet attachment and zip ties, but the contact is minimal. 3. They may create hot spots in the disc, but they don’t block the vents and the contact is minimal. Anyway I think I’ll monitor it closely for a while. 🙅🏻♂️ Dick And all I ask is a fast car and a momo to steer her by Link to comment Share on other sites More sharing options...
ECR Posted April 9, 2008 Share Posted April 9, 2008 Well done .... (I think ....) Good to try something new. Link to comment Share on other sites More sharing options...
alextangent Posted April 9, 2008 Share Posted April 9, 2008 Insanity! If the spokes come adrift at speed it could puncture or even rip the tyre sidewall. Link to comment Share on other sites More sharing options...
tiddy1 Posted April 9, 2008 Share Posted April 9, 2008 Why don't you just glue the magnet to the head of the bolt which holds teh disc in place, then make a small bracket from a piece of 1mm aluminium slipped between the uprignt and the steering arm. very neat and out of the way. If you want better response add a second magnet on the opposite bolt. Worked fine for me Simon Link to comment Share on other sites More sharing options...
susser Posted April 9, 2008 Share Posted April 9, 2008 And nothing too potentially damaging is being introduced to the wheel area. Those spokes are secure because of their "hardness" but are also a hazard for the same reason. I would lock them together with wire; even a paper clip bit of wire would be more suitable than a zip tie IMHO. Link to comment Share on other sites More sharing options...
Dick Whittington Posted April 9, 2008 Author Share Posted April 9, 2008 Alex: Yes my worry exactly; seems a little over-engineered, but that's me all over. Simon: I've not seen a custom mount for the pick up before. Got a picture? susser: Yes I thought a blob of aradite at each crossover should do the trick. Dick And all I ask is a fast car and a momo to steer her by Link to comment Share on other sites More sharing options...
Chris Cardwell Posted April 9, 2008 Share Posted April 9, 2008 The simplicity is amazing Link to comment Share on other sites More sharing options...
Dickie Normuss Posted April 9, 2008 Share Posted April 9, 2008 I'm not convinced of it's integrity at speed. Centrifugal force can be quite extreme 😳 VX HPC - Loud and proud here Watch out, whatever hits the fan will not be distributed evenly Link to comment Share on other sites More sharing options...
Jason Plato Posted April 10, 2008 Share Posted April 10, 2008 spoke aero screen eye 😔 Taffia rear gunner Link to comment Share on other sites More sharing options...
david nelson Posted April 10, 2008 Share Posted April 10, 2008 Just bond it to the bolt head. Thats what i have done and it works. Nice idea but think its a bit ott. next time you are thinking about it think what happens if it fails? David Link to comment Share on other sites More sharing options...
Area Representative Paul Richards Posted April 10, 2008 Area Representative Share Posted April 10, 2008 I've tried various methods of attaching the magnet, but in my experience the best solution is to araldite the magnet to the drive shaft (De dion cars only) and fix pickup to a bracket on diff. Wires then all hidden in transmission tunnel etc. I've run this for 4 years now and no problems. Paul Richards Area Representative - L.A.D.S. (Lancashire and District Sevens) LADS Website Growing old is compulsory - Growing up is optional Link to comment Share on other sites More sharing options...
Jason Plato Posted April 10, 2008 Share Posted April 10, 2008 bit tricky to read when wheelspinning in 4th gear tho Paul 😬 Taffia rear gunner Link to comment Share on other sites More sharing options...
Area Representative Paul Richards Posted April 11, 2008 Area Representative Share Posted April 11, 2008 If I get wheelspin in 4th gear I'd be too busy to look at the speedo. I'd also be too busy to look at a speedo reading 'o' if I was at speed with front wheels locked. Advantage of fixing to drive shaft is that everything is neat and out of sight. Paul Richards Area Representative - L.A.D.S. (Lancashire and District Sevens) LADS Website Growing old is compulsory - Growing up is optional Link to comment Share on other sites More sharing options...
susser Posted April 11, 2008 Share Posted April 11, 2008 "Centrifugal force can be quite extreme " Omega squared x radius (Omega being rotational velocity in Radians per second) Can be quite alarming when you work it out. Result is Newtons Link to comment Share on other sites More sharing options...
JamesZ Posted April 11, 2008 Share Posted April 11, 2008 Susser, isnt that just the acceleration? Surely you need a mass factor in there? Link to comment Share on other sites More sharing options...
susser Posted April 11, 2008 Share Posted April 11, 2008 Well yes it is. If you use a mass of 1 then you get an answer in Newtons. Divide that by 9.81 and you get a "gravity multiplication". In other words how many times heavier the object is; Because it's only the Omega squared that is exponential. As I see it. Link to comment Share on other sites More sharing options...
Sheds Moderator Posted April 11, 2008 Share Posted April 11, 2008 Impressive bodgery but still bodgery IMO . A better solution is to make a bracket to hang the sender and glue a magnet onto a driveshaft or the back of a front hub, depending on whether you wish to measure front or rear wheel speed. Keep the spokes on bikes where they belong. Link to comment Share on other sites More sharing options...
Myles Posted April 11, 2008 Share Posted April 11, 2008 Umm - I take it that you looked at my site and then climbed the North wall of the Eiger instead... here All you need is a haberdashery magnet and some epoxy... Credit to Mav here - I used to epoxy a magnet to the wheel rim - but this was a pain in the arse for more reasons than I can be bothered to type at this time of night... 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Alcester Racing 7s Ecosse™ 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
Mark w Posted April 12, 2008 Share Posted April 12, 2008 just bond it on with araldite , worked fine for me and a neater solution too. Link to comment Share on other sites More sharing options...
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