Category Archives: Guides

Choosing the correct size road bike – Geometry Explained

Choosing the correct size road bike can be a challenge to say the least. There is a huge variety of sizes on the market due to new aesthetically pleasing (and structurally improving) tube shapes and modern styling which makes it all the more confusing. To add to that, not all bikes are measured the same way, so it is crucial to consider the overall geometry of the bike before buying.

Frames can be grouped into 3 main categories; traditional, semi-compact and compact.

Traditional frames (sometimes classed as 50/50 geometry) use a horizontal toptube. This tube will be similar in length to the seat-tube. A formula can be used to help select the correct size frame:

  • inside leg measurement (cm ) x 0.69

It is very important to select the correct traditional frame size because the bike has minimal stand-over height. You want to be able to clear the top tube by an inch or two when standing over the frame.

Our Winter/Audax and the 7005 CX are the traditional bikes in our range.

Ribble Cycles Winter Audax Bike

Semi-Compact frames
have a slight slope to the toptube. This achieves a touch more stand-over clearance and also allows more seatpillar to show. Unfortunately there isn’t a clear cut calculation to work out the correct size because the degree of slope of the toptube can vary, however, to give a rough estimate the following formula is often used:

  • inside leg measurement (cm) x 0.64

The correct size is normally determined by a combination of your height and inside leg measurement. If unsure about the size it is always best to ask the experts as they will know about the specific frame in greater detail.

Our semi-compact frames include the Ultralite Racing, 7005SL, Reynolds 525 Steel, Azzurro, Gran Fondo, Sportive 365, Alloy Sportive bikes and the HF83.

Ribble Cycles HF83

Compact frames
are the last style on the market which are characterised by an even steeper toptube slope. Again, the toptube slope can vary massively so a special formula won’t be accurate. A specific height guide will apply to each model. The compact design allows for smaller triangles to be used which increases the strength /stiffness of the frame, improves the manoeuvrability , handling and also shaves off a bit of weight. Another great feature about compact frames is the ability to incorporate taller headtubes compared to traditional frames. Additional height gives a more upright riding position for comfort, however still maintains a stiff and responsive ride without compromising the stand-over clearance.

The Evo-Pro Carbon, Sportive Racing and R872 frames have compact geometry.

Ribble Cycles Sportive Racing

How do I choose the correct toptube and headtube Length?

The length of the toptube is the most important measurement to consider when choosing a bike. Frame geometries will always give an effective toptube length (C measurement in the image below) which is the horizontal distance from the centre of the headtube to the centre of the seatpillar. This is a much more accurate number to use because it eliminates the differing toptube slopes that frames have.

It is also important to consider is the length of the headtube (F measurement). Generally, the shorter the headtube, the more race orientated and aerodynamic the riding position will be. Taller headtubes relax the riding position and achieves a more upright setup. This is well suited to distance events, training rides and leisure riding; basically it’s less competition focused!

Ribble Cycles Geometry

There is a good chart below which gives recommendations for the rider’s height:

Rider Height Effective Toptube Estimate (cm)
5’0″ – 5’3″ 49 – 51 (XS)
5’3″ – 5’6″ 52 – 53 (S)
5’6″ – 5’9″ 54 – 55 (M)
5’9″ – 6’0″ 56 – 58 (L)
6’0″ – 6’3″ 58 – 60 (XL)
6’3″ – 6’6″ 60 – 63 (XXL)

All that’s left to do is set the saddle height, adjust the bar and saddle angle so it is comfortable and to your own preference.

If you then wished to optimize the fit yet further to iron out all the little imperfections a bike fit will be in order. A professional bike fitter will adjust and tweak your setup to further increase your efficiency, eliminate the chance of injury and in the long run, make you ride faster!

Gear hangers – What are they – And why do they break?

We have a few emails regarding gear hangers breaking/snapping a year, sometimes within weeks of receiving the bike usually after a few months/years of riding. Gear hangers are not a part that is usually covered under warranty and unless this the result of a crash then having them snap on you can generally be avoided. So for those people who are not sure what these are, or those who are buying their first bike and want to avoid the inconvenience of this, and a gear hanger breaking mid ride is pretty inconvenient, here is all the information I have on them and how to preserve their life as long as possible.

How they fit and what they do!

Gear hangers, or replaceable dropouts as they are otherwise known, are designed to be replaceable. They are usually made of alloy and will break under extreme stress in order to save your frame from being damaged. This can be the result of a crash, mis-shift or most usually simply being in the wrong gear when the chain and derailleur are under the most load either when the road goes upwards sharply or setting off from a standing/stationary start.

All the hangers for our bikes are of the cast alloy type and attach to the frame using either one, two or in some cases three countersunk bolts. The mech itself then attaches to the hanger. There are many different types of hangers and you usually find that each model of frame will have a specific one unique to it. This can sometimes change year by year, which doesn’t make things easy when trying to source a replacement.

 Ribble Cycles Gear HangerHere is a gear hanger in action – blink and you’ll miss it!

Why do they break and how to avoid it! (Overshifting)

As previously mentioned hangers are made from a soft metal designed to break under extreme stress, this may sound a bit strange, but the reasons for this are to protect the more expensive parts of the bike firstly the rear derailleur and then frame, they are if you like the ‘weakest link’ on a bike’s drivetrain. A broken rear mech, although dependent on which one, can be relatively expensive and a bit annoying. It is nothing however compared to the cost of replacing the frame.

There are a few reasons why they break aside from crashes, which are usually pretty much unavoidable. The most common on new bikes is usually however down to rider error. Either being in the wrong gear combination for the terrain or when starting off, i.e. the big ring on the chainset paired with the biggest sprocket on the cassette, or trying to change gear when the load on the chain and gears is at its greatest on steep inclines.

Other reasons can be an incorrectly fitted or worn chain, a chain that is too short for the chainset/cassette combination fitted, debris in the chain or derailleur and incorrectly set up gears can also cause undue stress on the hangers.

Dos and Don’ts!

Do keep your chain well maintained. Clean and lube regularly. The same goes for your derailleur, cassette and chainset.

Do check your chain regularly for stiff links or possible bent links.

Do ensure that after fitting any new parts to the bikes drivetrain that you check the gears are correctly set up – reset and adjust if necessary.

And lastly Do make sure that you are in the right gear for starting off and climbing, always start off in the small/inner ring at the front, and ensure you are in a suitable gear combination before the road ramps up on a steep climb.

Hopefully then your hanger will last as long as you have the frame and you won’t have to try and limp home if one does snap on you!

On Bike Refuelling

Before heading out on a ride there are a few nutrition fail safes you might want to consider.

Cycling - Hydration

For shorter rides of less than 90 minutes it is probable that your body will be well enough fuelled, that is as long as you have eaten well prior to the ride. In general a high carbohydrate meal with a medium to low Glycemic Index (porridge and/or eggs with rye bread are good examples) 2-3 hours before the ride followed by a snack such as a banana, High 5 energy bar, small flapjack/cake or a handful of Powerbar Sport Energize Shots 30-45 minutes before you start should suffice.
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