Thursday, 29 May 2014

Shimano Chain - Quality Comparison

Shimano Chain - Quality Comparison - Intro

I have recently worn out a HG53 9 speed chain on my commuter bike. It lasted about 2 years in country lane conditions. It has been kept clean compared to the average MTB chain, but with a good life span of 2 years I was wondering how the more expensive chain differ.

Shimano Chain - Quality Comparison - Grades

In 9 speed there are 3 grades of chain available:

HG53 - Labelled with Altus, Acera & Tigra on the Packet
HG73 - Labelled Deore, LX & 105 on the Packet
HG93 - Labelled XT, Saint and Ultegra

Below left to right XT, LX, Acera

Shimano Chain - Quality Comparison - Visual

So I have now tried all three types I have a new HG93, a new HG73, and a used HG53 pictured below for comparison. There is little difference between the HG73 and HG53, but the HG93 clearly has a superior finish. It looks good, I wonder whether it will last longer?

Below left to right XT, LX, Acera 

Shimano Chain - Quality Comparison - Stock Photos



HG - 73

Shimano Chain - Quality Comparison - Which one to Choose

I would probably opt for the HG 93 or the HG 53 I would pick from the cheapest or the best, the middle ground seems to offer little in the way of improvements over the budget chain.

Thursday, 15 May 2014

Wheel Building - Part 1 - Choosing Bits

Wheel Building - Part 1 - Choosing Bits - Intro

I have by trial and error built numerous wheel for my own personal use. Building your own wheels is very satisfying, and is surprisingly easy. But you will require patience.Key to this first chapter is the Edd Spoke Calculator. When choosing your rim, and particularly your hub, life will be a lot easier if you choose parts that are listed on Edd.

Wheel Building - Part 1 - Choosing Bits - Rims

Choosing rims is a matter of preference but also function. For example very wide rims may cause problems, particularly with rim brakes. For a hassle free experience try and match the width of rim you are replacing. But for the follwoing type of bike choose the folwwoing widths.

Racer - 13mm - 15mm
Hybrid - 15 - 19mm
MTB - 19mm - 27mm

The other dimension to look out for is the ERD (Effective Rim Diameter) which is the diameter of the rim from the inside. Its easy to measure, if you have a rim already.

Rims come with different numbers of holes. 36 is my favorite.

Wheel Building - Part 1 - Choosing Bits - Hubs

Choosing hub is largely preference but be careful to get the right width of hub. The Over lock dimension. Of course if you are replacing a hub, then try and match the existing.

Buy a branded hub, which has measurements in the listing;

  1. Left Flange & Right Flange (on most hubs these will be the same, but not always).
  2. Centre to left flange & centre to right flange ( these will often be different on disc hubs and cassette hubs)
 The above measurements are not critical if you are building from scratch and the world is you oyster. Choose away.

Wheel Building - Part 1 - Choosing Bits  - Spokes

When the going gets tough. Cheat.  Use the Edd spoke calculator to work out your spoke length.

You can select your hub and rim type if they are listed, or enetr your own measurements, using the green buttons.

To the left of screen there are some choices.
  1. Number of spokes. Thats easy. Count the holes. 
  2. Crosses. Pick 3 for anything larger than 16" or 2 cross for anything smaller. More crosses makes for a strong wheel. 
So hopefully you will now have all of your bits in the post. Most spokes come with nipples (the bits that screw on the ends) but some don't. For utility riding get 14 gauge stainless spokes. Butted spokes are fine if you have the money.

Spokes have around 8mm of thread on the ends and that allows for some error in spoke length.It also means that you can somtimes re-use spokes (yes it fine I have done it repeatedly) from an old wheel. For example a hub with a similar flange width could be reused with a rim and spoke combo. In fact if you re really stubborn you can get spokes to work in some very unexpected scenarios. See one of my first wheel builds.

Aiming for Functional turned out Funky !
Sunlight and Daylight Assessment

Wednesday, 14 May 2014

Dimensions for Shimano DH-F7 Dynamo Hubs (DH-703-SB & DH-702)

Dimensions for Shimano DH-F7 Dynamo Hubs - Intro

I have just spect about 1 hour looking for dimesions for any of the following hubs:

  • DH-703-SB - Brompton Hub
  • DH-702 - Capreo Narrow Front Dynohub
Both of these hubs have narrow OLDs for folding bikes and the likes.

Dimensions for Shimano DH-F7 Dynamo Hubs - Dimensions

Left Flange  = 74mm
Right Flange = 74mm

Centre to Left Flange = 19.7mm
Centre to Right Flange = 20.8mm

OLD = 74mm

Edd spoke calculator has dimension logged for the DH-703-SB, but not for the for the DH-702.

If you are build a ETRTO 349 wheel for a Brompton then, many retailers will sell a spoke pack to fit your chosen dynamo. 

For a 305 ETRTO wheel, best use the spoke calculator. I calculated 125.7mm spokes based on 28 spokes at 2 cross.

I would have much preferred to use a DH-702 (Capreo Dynohub) as they are cheaper, but you try finding a 24 hole 305 rim!! Not easy. You can't even buy un-drilled rims of that size.

Sunlight and Daylight Assessment

Thursday, 8 May 2014

Converting Bike from Single Speed to Three (3) Speed

Converting from Bike Single Speed to Three (3) Speed - Intro

I have a cheap folding bike (Giant Conway) a purchased 2 years ago which is single speed, as I live in a hilly area, I spend most of the time either coasting or pushing the thing up hills. I may as well use a scooter. There is no gear hanger, and the rear drop out spacing is narrow, so I opted to replace the exist hub with a sturmey archer 3 speed. A failed attempt at gearing using a mountain bike hub can be viewed here.

Converting from Bike Single Speed to Three (3) Speed - Wheel Build

This is the first 16" (305) wheel I have built, and it was 2 cross, 28 spoker. The 2 cross lacing confused me for a while. I used stainless 14 gauge spokes from SJS.

Converting from Bike Single Speed to Three (3) Speed - Ratios / Range

The original bike had a 14 tooth sprocket which was too high-a-gear uphill and too low down hill, so I assumed that keeping the sprocket the same size on migrating would give good gearing. But no.

Sheldon brown recommends adjusting gearing so as to use the top gear as you normal gear, keeping the two the gears for inclines / climbing. And this worked out right. I didn't have any sprockets, but a free alternative was to swap chainsets. The original was 46 tooth, and I dropped to 38! Which is about right.I was surprised how much smaller I had to go.

The MTB chainset used, is a shimano one, with 170mm crank arms, and is just the job. Why do they use such short crank arms on folding bikes?

Converting from Bike Single Speed to Three (3) Speed - Conclusion

Swapping to 3 speed?

Use Sheldon's Gear Calculator  my original set-up gave 3.5 meters of development.

After Installing the 3 speed hub this changed to:

4.7 meters is too high for practical use, so by decreasing the chain ring size I got:

If I had chosen the correct sprocket size I should have chosen 17 teeth (16 or 18).

So there we are, Happy tinkering.

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Thursday, 1 May 2014

Chainsaw Cuts in a Curve? Why?

Chainsaw Cuts in a Curve? Why? - Intro

I have an old Husqvarana or Husky 136, which is fine for my needs. I was cutting like a dream until the end of last week, when it strated to cut in a curve, jamming the bar after a few inches of cutting. The saw was freshly sharpened and the bar was straight, so why had this suddenly happened.

Chainsaw Cuts in a Curve? Why? - Cause

At the time I thought I must have hit a stone or something so I immediately resharpened the saw, this did not help so I sharpened it again. Odviously I was hacked off, and in a rush and had no vice to hold the bar.

The result was that I filed down the left hand cutters more than the right hand ones.

The below picture shows the result, you have to look hard, but the right hand cutters are consistently longer than the left hand cutters. With a larger gap between the depth gauge and the cutter edge a shorter cutter will cut a longer piece of wood. If all of your short cutter are on one side then the saw will cut to that side. If you look at the difference between cutter C and D below, you will see what I mean. Cutters G and H are obviously different lengths also.

Chainsaw Cuts in a Curve? Why? - Solution

Guess what more sharpening. but only the long cutters. This was my first time thinking about cutter length and after 5 - 6 file strokes over the longer cutters the saw was back to cutting well again. The moral of this storey is keep an eye on you cutter length.

I guess a good thing to have would be some measuring callipers, as this would take out the guess work, but the M1 Eye Ball did an OK job in my case.

Happy Chopping.

Sunlight and Daylight Assessment