Useful Info from CRMO BMX and Skateboard Mail Order Store UK
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Useful Information Charts
- What gear ratio do I need?
- What Bottom Bracket do I have?
- What length spoke do I need?
- Can you build my wheels for me?
- What size T Shirt do I need?
- What size Gloves Do I need?
- What size Helmet do I need?
- What length Frame do I need?
- Why do I keep getting punctures?
- How do I get my new grips on?
- Is this DVD suitable for my 10 year old?
- Can I take my gyro system off and run a single cable?
What gear ratio do I need?
A standard BMX gear that is commonly accepted as the correct ratio is 44 on the front and 16 on the back but now with the cassette hubs you can have a much larger range off sizes so here a quick guide to keep the correct ratio but utilize the smaller cogs available. Remember the smaller you go on the rear the more pressure it puts on the driver and chain. We prefer only going to 10 tooth as it uses bigger bearings in the drivers.
| Front | Rear |
|---|---|
| 23T | 8T |
| 25T | 9T |
| 28T | 10T |
| 30T | 11T |
| 33T | 12T |
| 36T | 13T |
| 39T | 14T |
| 42T | 15T |
| 44T | 16T |
What Bottom Bracket do I have?
There are now 4 different types of Bottom bracket used on BMX frames these are USA, Mid, Spanish and Euro. The easiest way to decide which you have is to measure the out side diameter of the bottom bracket shell the measurements are as follows.
USA = 57mm
MID = 45mm
SPANISH = 42mm
EURO = 40mm With thread CRMOLY FRAME
EURO = 43mm With thread ALUMINIUM FRAME
Please note that these dimensions outside diameter’s and may vary from frame to frame as different manufactures use different thickness of materials but it is a rough guide. And the hole that goes through the bearings comes in different sizes to 19.05mm =3/4 inch 20mm on some complete bikes and 22mm
What length spoke do I need?
There are many different lengths of spokes that are available and many different lacing patterns so getting the correct spoke is vital. There are a number of different spoke calculation charts on the web one of the best is www.dtswiss.com this can look a bit confusing so if you are not sure just give us a call on 01462 650740 and ask to speak to one of our wheel builders and they will be able to advise you as to the correct length.
Can you build my wheels for me?
We have a full workshop facility at our warehouse and with a team of experienced wheel builders we can pretty much do any combination that you want, If you already have a hub or rim then feel free to send it in for re-lacing or truing just call us on 01462 650740 to check stock availability and pricing. This normally is a 2-4 day service to build a pair of wheels. Also depends on the time of year.
What size T Shirt do I need?
| Small | Medium | Large | XLarge | |
|---|---|---|---|---|
| Chest (cm) | 87cm aprox 34 inch | 98cm aprox 38 inch | 108cm aprox 42.5 inch | 120cm aprox 47 inch |
| Shoulders (cm) | 44cm aprox 17 inch | 46cm aprox 18 inch | 47cm aprox 18.5 inch | 57cm aprox 22.5 inch |
| Under arm to bottom (cm) | 43cm aprox 16 inch | 44cm aprox 17 inch | 47cm aprox 18.5 inch | 48cm aprox 18.5 inch |
Please note that manufacturers t shirts do vary so this is only a guide and if when you get your t shirt it is the wrong size don’t blame the guide!
What size Gloves Do I need?
| Size | Across The Palm (cm) | From wrist to top of middle finger (cm) |
|---|---|---|
| 3 Youth Xsmall | 7.5 | 17 |
| 4 Youth Small | 8 | 17.5 |
| 5 Youth Medium | 8.5 | 18 |
| 6 Youth Large | 9 | 19 |
| 7 Xsmall | 9.5 | 19.5 |
| 8 Small | 10 | 20 |
| 9 Medium | 10 | 20.5 |
| 10 Large | 10 | 21 |
| 11 XLarge | 10.5 | 22 |
| 12 XXLarge | 10.5 | 22.5 |
Please note that manufacturers gloves do vary so this is only a guide and if when you get your gloves they are wrong size don’t blame the guide!
What size Helmet do I need?
| Make | Youth | Small | Medium | Large | Xlarge |
|---|---|---|---|---|---|
| Protec | 53-54 | 55-57 | 57-58 | 59-60 | |
| TSG | 54-57 | 57-60 | |||
| Fly Racing | 55-56 | 57-58 | 59-60 | 60-62 | |
| Bell | 51-54 | 54-56 | 58-63 | ||
| Capix | 54 | 56 | 58 | 60 | |
| California Pro | 50-52 | 54-56 | 56-58 | 60 |
Conversion 25.4mm to 1 inch so 56cm helmet is 560mm divided by 25.4 = 22.04 inches
All dimensions are in cm and to get the size that you need you measure round the circumference of your head. This is only a guide to sizes as different helmets do have different fits so please be aware that it is always best to try helmets before you buy.
What length Frame do I need?
There are many different frame sizes to choose from but as a guide people that ride Flatland tend to prefer a shorter top tube frame 18” to 19.5” top tube, people that ride ramps tend to go for 19.5 to 20.5 top tube and people that ride dirt tend to go a little longer from 20.5 to 21.25. These are only guides but the height of the rider plays a major part in choosing the correct frame. If the frame is too long then manuals and other tricks are harder to do and if it is to short then you find you bang your knees on the bars and the bike feels very twitchy. If you are unsure about this then please call us to get some advice before you buy as there is nothing worse than a nice new frame and the first time you ride it you realise its not right for you.
Why do I keep getting punctures?
There are a number of factors that could cause punctures the obvious one is things sticking into the tyre glass thorns etc so check the inside of the tyre thoroughly. If you get what is known as a snake bite or pinch flats this is two holes on opposite sides of the tubes then the tyre is not inflated hard enough for general street riding you should be inflating to around 60 psi plus but if you have tyre that can take more then it is a good idea to run them harder. If you are running one of the new style rims like the Demolition Zero or Primo Balance rim that has holes in the second skin of the rim then a good rim tape is vital if you can not get one of these then electrical / duct tape works really well.
How do I get my new grips on?
The best way to fit grips is with hair spray just a small squirt up the grip and then slide it on and leave it for a few hours, the cheaper the better with hair spray as the cheap ones tend to be more sticky. Or put grips in hot water to make soft then slide on you may have to wait overnight for them to fully dry out. Do not use WD40 or GT85 or other lubricating sprays as these don’t fully dry out and your grips will never be fixed solid.
Is this DVD suitable for my 10 year old?
If we are aware that a film contains scenes or language of an adult nature then we will state that in the description. However, we would recommend that if you are unsure it would be a good idea for you to watch it first to vet it for your child. Most of the DVD are clean but some do contain swearing and crash scenes where open wounds may be shown, so please be cautious.
Can I take my gyro system off and run a single cable?
The answer is yes but it is easier on some bikes than others. If you have a cable with a lower 2 into 1 cable then it is easier as you already have the cable stop, the hanger and straddle cable that you need. If you have separate twin lower cables then you will need to buy a straddle bridge and a straddle bridge cable. If you are unsure about this then please call us on 01462 650740 and speak to one of our mechanics who will be able to help you.