I have been a avid cyclist and home mechanic for many years, but like most people, i only really took a passing interest in road bike fit. That was until i cycled across the USA last year. 8 hours a day in the saddle forced me to look alot more deeply into exacty how to make your bike fit you for comfort and performance. This guide is the result of my research and experience and is meant to provide you with starting point for road bike fit.
Before you adjust anything it’s a good idea to check you have the correct crank length – with this defined as the distance between the centre of the crank axel to the centre of the pedal axel. There has been extensive research in this area with the upshot of this resulting in this formula...... crank length should be 21.5% of your inside leg measurement.
The best way to do this accurately is to lean up with you back flat against a wall in your cycling shorts with bare feet slightly apart and get a friend to slide a clipboard or hardback book squarely up the wall until it reaches your crotch - it should be pushed up firmly but without been too uncomfortable. Measure the distance from the top of the clipboard or book to the floor – and that’s you inseam measurement. Weight and riding style also has some bearing so if you are lighter or prefer a fairly high cadence then round down to the nearest size crank and if you are heavier and tend to push bigger gears with a slower cadence then round up to a bigger crank.
Best done on a turbo trainer, but not essential.
Assuming you have the correct crank size you can then set saddle height. Simple physics dictates that to get the most efficient use of power from your legs the saddle height should be set as high as possible – but crucially without getting any rocking in your hips when cycling along. for most people this usually means having a 20-30 degrees bend in your leg when the crank arm is at six o’clock and the balls of your feet are directly over the pedal axles (i.e when you are clipped in, or toe-strapped in). Now if you want to get very scientific about this you can get a friend to take a photo of you square on and then measure your leg angle on the photo with a protractor. An easier and less scientific way to do this just judge a slight bend in the leg by eye. The best way to check for hip rocking is to get a friend to watch you from behind whilst peddling, or if you don't have any friends you can put some loose change in your back pocket - if your hips are rocking your will be able to hear it! This should give you a good basic starting point for saddle height – further fine-tuning can be done when other adjustments have been made.
The seat angle should be set flat – as simple as that. If you find that you have to tip the seat forward to relieve that pain in the arse then you have a problem with the seat and you really need to look at trying something else. Furthermore if you do tilt the seat forward this will result in unnecessary energy being expended pushing back on the bars to stop yourself sliding forward and it can also lead locked arms and hunched and tensed shoulders – all of which results in unnecessary pain in the arms or hands or both. The exception to this rule is for short time-tialling. Alot of time trialist have to seat tilted slightly forward with the idea that it gives them a little more power (at the expense of comfort)
To set the seat angle simple make sure your bike is on flat ground, place something flat on the seat like a plank of wood or a hardback book and use a spirit level to check that its flat.
SADDLE FOR AND AFT
This is probably the most important part of your bike set up because it determines how your weight is distributed on the bike and the angle of lean of your back – both of which affect comfort and performance greatly.A good starting point is still the knee over the pedal axel rule. To do you need to drop a plumb line from your tibial tuberosity (which to you and me is the bony bit just below your knee cap) when the crank arm is in the 3’oclock position. The line should dissect the pedal axel. Now at this point I will say that this rule, although used by many bike fitting systems, should not be taken as gospel but only used as a basic starting point.
Note: Cyclist who tend to climb in the saddle tend to have the saddle set slightly back as this allows them to use their glute muscles more efficiently.
Virtually all the evidence is agreed on the fact that handlebar width should be equal to shoulder width. Too small and this can give the steering a twitchy feel, too large and this increases your frontal area and drag as well as putting strain on your shoulder blades and neck. Measuring is simple enough, just get a friend to measure the width of your shoulders (try to measre from the edge of the bone rather than the edge of the muscle). Obviously, you can’t adjust the width of your handlebars so if you yours do differ wildly it would be worth investing in some bars that fit you.
Note: If coming from MTBing to road cycling then you may want to try a slightly wider bar to reduce nervous steering feel
Handlebar height is once again dictated by your preference of comfort or performance. For my trip across the states I had the bars set the same height as the seat and this served me very well – with no back or neck ache at all, even on the 100 plus mile days. For faster shorter day rides you should be having the bars around 2 or 3 inches below the saddle - which I find is a good compromise for performance without sacrificing too much comfort.
The main aim when adjusting your handlebar rotation is to achieve as straight a line as possible between the lower arm and the hand whether riding on the hoods or the drops. Again, the aim here is to reduce stress and muscle tension in the wrists. In most circumstances this will result in the bar end pointing somewhere near the rear axel.
Note: Campag and Shimano hoods have slightly different angles - which will affect the handlebar rotation adjustment
The final, and often overlooked part of bike set up is cleat adjustment both fore and aft and shoe angle . Evidence shows that the best position for efficient power transfer is to have the ball of your foot directly over the pedal axel. When you are sat on the bike and clipped in the ball of your foot forms a protrusion in your shoe – just line this up with the pedal axel. With regards to foot angle position you are aiming for the shoe to be exactly parallel to the frame - a good way to visualise this is to draw an imaginary straight line, which runs through the middle of the foot, knee, and hip. This should ensure there is no lateral knee rotation through the pedal stroke, which is a common cause of knee injuries.
..so that’s the rudiments of road bike set up. Which is intended to give you a good basic starting point only. The most important point to remember though is that none of this stuff is a hard and fast rule. Fine-tuning from this point can only be achieved though experimentation and finer adjustments and will all depend on where your priorities lie between comfort and performance.
I hope you found this guide useful. If you did please take a couple of seconds to vote below. Thankyou.