Tuesday, 24 November 2015

Fix a Cracked Steel Bike Frame

Fix a Cracked Steel Bike Frame - Intro and Disclaimer


This is the first time I have done this. I'm just throwing it out there (USA) offering it up for scrutiny (UK).

It seems to have worked OK but then it may fail and kill me so please consider this before you choose to use any of the below information. That is your choice.


Fix a Cracked Steel Bike Frame - Causes


Having think about the cause is important.

The crack may have been caused by corrosion of the tubing, or a crash or large impact. Perhaps a seat post extended too far out of the seat tube, perhaps an overloaded rack.


A cracked steel frame - Crack is around 8mm in length.

You need to figure out which one an acute trauma will likley mend up OK, if not too serious. But chronic problems such as corrosion may not respond well after fixing.

The crack I have is located under the crimped portion of the chain stay. Apparently this is an inherently weak part of the frame. So I am attempting a rapier.


Fix a Cracked Steel Bike Frame - Method


I have a welder, but have heard that heating up chromoly beyond a certain point weakens it. So I am opting for silver solder. This is not a soilder really but a type of low temperatur brazing which can be down with a normal household blow torch running propane or MAP gas.

I have asked the good citizens of google plus for advice on this one and had some good answers. Post is here. Thanks to +Scott Anderson  +Andy Tong , +Derek Haggerty +David Saul +Seb K and +simon russell-roberts for your answers.

So a 55% silver solder is quite expensive costing around £7 / $12 for  two small rods, buy from ebay with the correct flux. The flux has be be the right stuff.

You will need to clean up the crack and the area around it very well, I used a spinning wire brush thing on a drill. Remember the metal on the frame will be thin so don'y go mad.

Apparently you can use acid based cleaners to get the metal really clean, although some say its OK just to brush.

Once the crack and area around it are clean, prepare the flux. Mix it up like toothpaste and then apply it on the area where you want solder (filler) to go. If the flux is messy the filler will be messy.

For a patch I used the link from a bicycle chain. This (I think) is quite good as it allows you to feed the rod in to the center of the patch (through the two holes). And I should imagine that the plate from a chain has a very high tensile strength. Others may know better (please comment).

Holding the patch in place is tricky but once the flux has been melted it should hold it in place fairly well. Heat up the work, until it is glowing a little, then apply the silver braze / solder rod to the hot metal. It should melt and run in to the joint and beneath the patch very quickly.

If the filler is not taking to the areas where you want it too dip the end of the rod in the powdered flux and try again, it may be that you need more flux.

When finished there should be no gaps, and the filler should be ramped up around  the edge of the patch, and the inside of the holes (if you have any).

Results below. Sorry about blurry photos.




Fix a Cracked Steel Bike Frame - Result


Well time will tell.

I have painted over this with basic metal paint. I think the soldering will hold, I have tested the strength of silver solder on other objects and it is very high. The only questions are whether the patch is big enough, and whether the frame is not internally corroded.

If this crack were in the main triangle or the (gulp) head tube, I would not attempt a mend.


Environmental Consultants London

DIY Long Tail EBike - Chapter 4

DIY Long Tail EBike - Chapter 4 - The Final Chapter


So its been a while since I posted chapter 3. Its one thing to build a long tail cargo bike or long tail cargo e-bike, but whether it works or not . . well that takes a few months to find out.

Below are described the "few" teething problems and remedies that I have stumbled upon over the last few months. Also a few fatal flaws in the concept . . .

DIY Long Tail EBike - Chapter 4 - Drive Train

You will see chapter 3 that that I have a flip flop set up (more of a flop flop set up really) with the electric motor on one side and the pedals on the other. 

Chain Tugs and a Large Rear Sprocket - Essential

I found that the gearing for the motor was too high, and it was not running at a high enough RPM on hills, so I have added a 24 tooth free wheel (ebay), to lower the top speed and increase torque. You might consider going a bit bigger. Head over to TNC Scooter Parts to find all sorts of handy sprockets etc. Just be sure to get the right gauge!

The next niggle was that the ultra strong loctite used on the non-reversed threads was not strong enough. So I have had to opt for epoxy there. 

Last drive drain mod was to add some tug-nuts / chain tensioners on the slot drop outs as the rear wheel kept moving, this is understandable as you are imputing nearly twice the load (you pedaling and the motor). It also helps with tensioning the chain correctly.

Reversing the drive side of the bike i.e. chainset and sprocket (for pedals) on left hand side of bike. Is . . . problematic. Not only is the sprocket thread now the wrong way around, but also the pedals.  

Most of the problems I have had with this bike. In fact 99% of them could have been avoided by using a hub motor. USE A HUB MOTOR!

DIY Long Tail E-Bike - Chapter 4 - Lights

Hah! The headlight is serious overkill. Splashes light all over the place. So I had to add in a smaller side light so I could switch the headlight off when cars were approaching. 

Monster Headlight / Sensible Side Light . . .
Introducing this side light meant using a switch. To toggle between them. Ebay again held the answer. The switch is an engine kill switch for a quad bike of similar.

Switch for Side Light and (more importantly) "Captain Shakry" Squeaky Hooter Thing

DIY Long Tail EBike - Chapter 4 -Seating

Unless you want your kids to fall off on to the road, then they will need some handles. I have arranged this by using some rope threaded through some 15mm water pipe, and then hole drilled in deck to fasten with a big knot. All very technical.  

Some padding is a nice touch too. Find some bubble wrap or foam and wrap in cloth, then use a staple guhn to attach to the wooden deck.

Handles for passengers. Quite . . . handy. Sorry

DIY Long Tail EBike - Chapter 4 - Useability

I am sorry to say this bike will not get used very much. Here is why:

  1. Wrong Frame. If you base a cargo bike a on a BMX it will start out not very ride-able. After all BMX bikes are not meant to be ridden long distances. The rear drop spacing are not likley to accept a hub for gears. 
  2. Complex Drive System. The choice of drive system. A hub motor would allow you to have some gears, and maintain a normal right hand side drive setup at the rear. Sooooo much easier.
  3. Not Powerful enough. In the UK the 250W power limit is too low. What is the point. I get sweaty riding this bike, and it has a limited range probably about 15 miles. My "normal" cargo bike will go all day if I am supplied with pies. 
  4. It is heavy. It must weigh 40 kg without a rider or cargo, so you can only really turn it around whilst rolling it (you can pick the front end up and swing around but this requires a large turning circle).
  5. It is noisy. Wrrrrrrrrr. I like to be able to talk to my kids as we wizz along the country lanes. This is somewhat spoiled with the noise from the electric motor. 
  6. No Luggage to Fit. The wide rear deck, and short distance to foot rests means that panniers will not fit.EDIT: You could add a bicycle side car, for luggage space.

DIY Long Tail EBike - Chapter 4 - Hints for Prospective Tinkerers

1 - For the love of crumb cake. Please use a hub motor on the front wheel.

EDIT: Or move your chain drive motor to the front wheel, it is a lot easier, especially on a BMX!

2 - Even with a BMX Frame, you could still have 3 widely spaced gears by using a 3 ring chainset (with shifter and front mech) up front. Mount a rear derailleur for chain tension only. I was planning to do this and may do in the future. 

3 - Use an MTB Frame

4- Use the online calculator to work out if you can build a bike with useful range. 

5- If you are not using a hub motor. Then really pay attention to the chain and sprocket gauges.

NOT FINISHED - FURTHER "IMPROVEMENTS".

I moved the motor on to the front wheel in the end. - Front wheel chain driven ebike.

I also tried a side car for a time. - Thorpy's guide to bicycle side cars.

DIY Long Tail EBike - Chapter 4 -  Two Years On

It is around 2 years now since I completed this long tail e bike, and I have been improving it over that time so as to make it as good as possible. 

"Nearly Finished"
So what has been attempted.

Cushion on Rear Seat 

This was made with some foam, and black fabric, which I then used a staple gun to attach the wood deck at the rear. 

Lights

This took a while to get right, choosing an e bike headlight is tricky just because there are so many options. For a short time, I fitted a very bright light, but you do not really need this. A 3W LED head lamp is probably sufficient. 

A rear light can be found on ebay for not much money. LED lights are preferable. 

Speed 

I only have one gear on this bike, and that has caused a minor problem in that is is difficult to match you motor speed with your pedal speed. I have successfully used a 3 speed switch , to slow the motor to match pedal speed.

Of course setting you gearing correctly is important. For 15mph speed I have opted for 46 teeth front chain ring, and 14 tooth rear freewheel. 

Tires

The smoother the tire the less energy will be wasted, if on roads, so unless you are going off road a lot then opt for a semi slick tire. These provide a smooth center ridge, and so knobbles on the side, this is important as if you do ride a heavily laden bike on a side slope, if it slips you will have to be very strong to stop it.

On this longtail e bike bike both the rear and front tires are difficult to remove, if you get a puncture. I have installed so tire slime, and it has worked very well, I have not had a puncture since!

Luggage

If the rear seat is taken up with children, then where do you put all of the bags and stuff? Well upfront would be the obvious answer. I managed to fit a front rack. Steco do some good cargo racks, which would do the job well. 


Friday, 6 November 2015

Thorpy's Guide to Balloon Bike Tyres

Thorpy's Guide to Balloon Bike Tyres - Intro


The tyres that you put on you bicycle can make a huge difference to how it performs and feels when you are riding it. Balloon bike is a term introduced by Schwalbe (a company that manufactures tyres), to describe high volume tires with a bouncy feel, which usually have a shallow tread being intended for on majority road use.

Balloon Bike Tyres - Not Just Schwalbe


There are a number of offerings from Schwalbe if you fancy a pair of balloon bike tyres, but other companies are now also starting make to high volume semi slick tyres that give a similar effect, some of which I have listed below.

Fitting Balloon Bike Tyres


All of the below tyres bar 1, are 2.35" or 60mm tyres. Above this is unlikely they will fit in a standard MTB frame. It is important to note that the final width of the tyre will change dependent on the width of the rim on to which it is fitted. 

Choice of Inner Tubes for Balloon Bike Tyres


It is worth noting that is probably worth using a wide inner tubes with all of the below tires, as a general inner tube will be stretched very thin when using a high volume tire and increase the chance of punctures.

Thorpy's Guide to Balloon Bike Tyres - Schwalbe Big Apple 


I first roade these in the 50mm (2") size, and there were a very good practical tyre. However, I have since been running a set of 2.35" Abig Apples, which are superb. They have virtually no tread, and are lovely of tarmac / asphalt.



When compared to normal MTB tires or even touring tires (such as the Marathon Mondial) they seem to almost push the bike along, they have so little resistance. You can cut 5 minutes off of a 45 minutes journey, whilst applying the same effect, and the comfort is much increased.

The big apples with the newer tread design, have an endurance compound rubber, which sits very nicely on the road. A lesser compound which is available on "active line" Schwalbe tyres is not so good, but still perfectly adequate.

2.35" Big Apples are available with a race guard puncture protection, which is OK against most things except thorns, which will punch straight through it.  "Green guard" would offer more protection but is only available in 2.00" and 2.15" variants.

I have run 2" (inch) balloon bike tires and whilst these would be OK for a light rider, always go for a 2.35" (60mm tyre) if you can fit them in your frame, the balloon effect is much more pronounced.

Thorpy's Guide to Balloon Bike Tyres - Fat Frank

 

The fat frank can be had quite cheaply online. It offers the main advantage of having the Kevlar protection belts that has been replaced by "race guard" in the newer big apple tyres. Having tried these tyres for that exacting reason, I found them not to offer better protection against thorns, which will go straight through the kevlar belt.



The main disadvantages are that it has a little too much tread for on road use, and that is uses schwalbes SBC rubber compound. The result is a squirmy feeling tire, that has too little tread for off road use, and too much for on road. 

Thorpy's Guide to Balloon Bike Tyres - Big Ben

This is similar to the big apple in every way except for the tread pattern. 

At this point it is worth noting that 55mm Big Ben tyres, and Big Apple tyres are available with "green guard" which is a super tough puncture protection layer within the tyre. I have owned two sets of tyre with green guard (Marathon and Energizer) and have found that it creates a "dead" feeling when riding the bike. Of course this could because I am imagining things. . .



Thorpy's Guide to Balloon Bike Tyres - Supermoto

The supermoto tyre is in apperance exactly the same as the Big apples. However, as it is design for racing etc. it has been lightened up, by removing the puncture protection belt, and uses a kevlar bead.

The one reason why I would like to try these out is becuase they use a "pacestar compound" which is suppoosed to be super gripping, aznd genrally lovely to ride on.

These supermoto ballon bikes tyres are very expensive compared to other offerings.

Thorpy's Guide to Balloon Bike Tyres - Michelin Pilot Sport

So these are not a ballon bike tyre because that is schwalbe brand, but there are high volume and semi slick with a puncture protection belt. Below image from www.cynut.com  .


I have never run these tyres but I am very tempted to try them if I can find them on sale at a good price. There is a review by a chap who has used these Michelin Pilot Sport Tyres here.

Thorpy's Guide to Balloon Bike Tyres - Hutchinson Low Rider


The Hutchinson Low Rider Rigid Tyre has an imposing profile ideal for beach-cruiser bikes. 



The Hutchinson Low Rider tyre in 2.35 is designed for urban/city use. It's ultra-wide cross-section makes it the ideal tyre for a beach cruiser. The large size provides great riding comfort and a unique look. + 33 TPI carcass for faultless reliability and sturdiness  + Reflex: reflective strips on the sidewalls for increased visibility at night + Unique look Weight (manufacturer): 990 g 

Thorpy's Guide to Balloon Bike Tyres - Maxxis Hookworm


These are really a street BMX type tire but function well (so I've heard) as a cargo bike or commuter tyre.  These are BIG, at 2.5" it is unlikely these will fit in a standard frame. Although you may be lucky.

These do not have any puncture protection which is a major disadvantage, although running these with sealant would get around that problem.

Blurb: Urban assault! 26 x 2.5 Inch (61-559 ISO). Bead-to-bead slick tread with wavy water channels. Large air volume for comfort under abuse. Lightweight single ply casing. 60a durometer rubber for long life. Wire Bead. 1250 grams. 65 PSI Max.

Thorpy's Guide to Balloon Bike Tyres - Schwalbe Crazy Bob

This description provided courtesy of Matt.
 
Essentially dirt jump/skate park kind of tire it has a stiffened sidewall and rim-to-rim tread, and overall a higher weight capacity than the same size in either Big Apple or Big Ben. No puncture protection belt, but with Stan's sealant in the tubes I've had no issues with mine for several hundred miles now. 



I believe they're grippier feeling and the stiffened sidewall actually helps improve the feel. I think Big Apples felt a little slower, maybe because the sidewall was a bit too flexy. Nominal size is 26x2.35 but mine (on 39mm wide rims), blow out to a massive 2.50!