Two chaps came to see me recently for Bike Sizing exercises. The first chap was considering buying two bikes, an MTB and a touring bike. He was about 175cm tall, with slightly longish arms and legs but still fell very squarely into the 54cm size category of the touring bike he was after.

The second chap came in a few hours later and was confused. He was keen on a Canyon road bike, but being an internet retailer, had no opportunity to go and sit on one somewhere. He was 178cm tall (5’10″) and had been putting his dimensions into the Canyon website size calculator. The reason he was confused was that the calculator kept telling him he was a 53, whereas his instincts (and mine) said 56.

He thought he may have been doing the measurements incorrectly, so I did them for him, and sure enough, the website suggested 53. But I could now see why,  he had extremely short arms for his height and simulating the 53 geometry with my jig confirmed he needed that size.

Comparing the two chap’s dimensions afterwards, the arms of the shorter 1st customer were a full 6″ (15cm) longer than  the 2nd!

A chap came in for a fitting last week with a lovely 1990′s steel framed ‘ten speed racer’. It was spotless and had obviously been very well looked after. The non indexed 5 speed shifters were on the downtube and it had a quill stem. I had been thinking about how bike design had changed over recent years and to see this bike ‘close up’ confirmed the conclusions I had come to.

You may think that the single biggest influence affecting bike geometry was the increased use of carbon fibre, but in my opinion, road bike design in the last 20 years has been changed the most by the movement of the shifters from downtube to hoods, coupled with the increasing number of gears.

When the shifters were on the downtubes, we had our hands on the bars tops and drops, moving to the ‘hooks’ when braking or climbing. With the shifters in the hoods, and more frequent gears changes, we prefer our hands to be on the hoods for a much larger proportion of the time.

When riding on the ‘hooks’ this customer’s hands were very uncomfortable, not surprising really given the wrist posture and white knuckles

The trouble with just putting the shifters into the hoods was that for a lot of people they were too far away, especially as the ‘reach’ of the bars was typically at least 100mm if not more. This is why we have seen the increased use of ‘compact’ bars with both shorter reach and drop as well as better designed shifters that attempt to spread loads over the whole palms. The position of the shifter has also altered, when they first came out, they tended to reflect the old ‘hooks’ position with sharp angles between bar top and hood skirt. Unfortunately, some people still set them up this way and their hands hurt. Fortunately, most manufacturers now ensure a smooth transition from bar to hood, optimising hand comfort. We have also seen an increase in ‘Sportive’ geometry with shorter top tubes and longer head tubes, but again this is just allowing us to ride on the hoods whereas we used to be on the bar tops.

Mike

BikeDynamics.co.uk

Many people buy their bikes on the internet, which may save a few pounds, but  means you can’t always at least sit on the bike before buying it. This can still be reasonably safe though if the manufacturer uses ‘conventional’ sizing practices and the customer has a good idea what size he is.

A customer came in last week with his new Ribble ‘Stealth’. As soon as he came through the door I thought ‘this bike looks big’. When asking him what size it was, he said its a 52, which would normally be appropriate given he is about 5’6″ (168cm). I thought maybe the bike just looked bigger than it was really and we started the fitting. It soon became apparent though that it was far too big for him.

Looking at the Ribble website, the 52 Stealth was the second biggest in the range and more equivalent to conventional 56 / 58. The 52 referred to the size of the seat tube on the sloping frame. Funny sizing like this is just about ok if it follows through your entire range of bikes, but Ribble seems to have different sizing conventions depending upon the model. My Ribble Sportive Racing is classed by them as a 52 and fits my 5′”7 frame just fine. So, a big ‘Thankyou’ to Ribble for their ambiguous sizing. Ths customer was left with the only sensible choice of sending it back or selling it. I couldn’t charge him for the full fitting so lost out too.

This is a more traditional knee pain case study.

Jill W came to see me with anterior knee pain. She is about 5’4″ and was on a women specific Specialized Dolce. My first instinct was to check the crank lengths, but was pleased to find they were 165mm. From my earlier post you may imagine that I was fully expecting to see 170mm’s. Jill has an approx. 5mm leg length difference and it was the longer left leg that was giving her the most trouble.

Measuring the fully extended  right knee angle gave a result of 140 degrees, which is towards the bottom end of the expected range for a bloke. I would expect Jill’s much looser hamstrings to be able to stretch much further than this and sure enough, we were able to put her saddle up 26mm before introducing any negative effects at all. The cleats were also placed asymmetrically a couple of mm each side of the nominal to help minimise the leg length difference. Front knee pain is due to the tightness of the knee angle over the top of the stroke, so I am always keen to see this angle in excess of 70 degrees. The left was still below 69 degrees though, and as the saddle could not go any higher, questioned whether even shorter cranks were more suitable. As 160mm cranks are quite rare, we though it worth trying the new set up as is. As you will see from the quote below – she was fine.

“I  have returned from 3 days cycling around Cheshire, originally chosen for lack of hills due to concerns about my knees. I need not have worried. I sailed through with almost no discomfort so much so that I decided to climb The Cloud, near Congleton, just to celebrate the fact that I knew it would not be a strain on my knees.”

You may well have noted that I have numerous pages on my site talking about the interaction between cyclist and bike, but very little on the key contact point which is the saddle. I hope to improve on this later this year and have formed some thoughts on the subject. The main conclusion is that saddles are very very personal and once you have found one that works for you – keep it and fit it on all your bikes. Some of my customers talk about garages and sheds full of discarded saddles they have tried over the years.

Here are a few considerations for now.

If ever swapping a saddle, don’t assume the new one will put you into the same place. I measure hip position before swapping a saddle and often find that the effective height and fore-aft location can change by +/- 10mm.

You will sit further forwards on a wide saddle and further back on a narrow one. Assessing sit bone width on foam pads is a good start, but I get a better idea of how suitable a saddle width is for a customer by seeing where they sit on it and how far back or forward on its rails it needs to be to get them in the right place.

A recent customer could not work out why a more ‘comfortable’ saddle he had bought made his hands hurt. The saddle was heavily padded and wide, so he sat further forwards on it, shifting weight onto his hands. We needed to use a seat-post wiith  more set-back, but got him into a position where both the saddle and his hands were good.

As a Bike Fitter, I quite like people presenting themselves with knee pain because as a rule, it is usually straightforward enough to track down the root cause and resolve it. Cleats holding the foot in an unnatural angle and  a low saddle are the usual culprits, but high saddles are also reasonable frequent.  A recent customer John W, came along complaining of posterior knee pain which is normally due to tendonitis of the hamstring attachment points and often due to the saddle being too high. If anything though, his saddle was too low and I wanted to put him up 2-3mm. His cleats were also well located with plenty of float either side of the nominal foot posture. There was an additional clue in that the pain was towards the outer rear of the knee which can indicate Popliteal tendonitis. The popliteal muscle is involved in unlocking the knee when running or walking and also rotates the femur relative to the tibia. Essentially, if the cleats allow too much rotatation of the tibia, the popliteal tendon is having to work too hard and becomes inflamed. The solution here was to swap his floating cleat for a fixed one, something I am normally loathe to do, but fortunately in this case it worked fine and John is now cycling pain free.

I’m fairly sure this will be the first of many blogs on the subject of crank lengths.

There is a perceived wisdom amongst many cyclists that there is no difference between 170mm and 175mm, so ride whatever comes on their bike. This may be true if you are 6 foot tall but for many shorter people (such as myself) this is a dangerous misconception. Researching crank lengths when I first set the business up a few years ago, I came to the conclusion that even 170mm cranks may be too long for my stumpy little legs (79cm inseam) swapped them for 165mm and loved them. I spin more easily and climb better because my legs are not too squashed up over the top of the stroke. The problem is that many manufacturer’s now fit 172.5mm as standard across a large proportion of their range, even as small as 53′s, 54′s  and S/M’s. They state that people are a lot taller these days, but I know that I’ve not grown at all in the last 20 years!

It only takes for a realtively short person to be sold a bike 1/2 to 1 size too big for them to get a big mismatch between leg length and crank size. On a purely selfish basis, this is good business for me as I see a lot of customers in this situation struggling with knee, hip and back problems. They are not always impressed though when I tell them their cranks are too long. This then creates tension with their local bike shop when they go in asking for a swap. The shops are not at fault because they are selling what the manufacturer’s specify, so either stomach the cost or tell the customer I’m talking rubbish and there is no difference anyway.

I’m generating evidence at the moment to see which manufacturer’s are the biggest culprits. Anything American seem to be the worst so far but I’ve also seen a shocking case of a 5’4″ girl riding a UK brand bike with  175mm cranks!

Mike

The job satisfaction with getting people set up properly on their bikes is normally quite high, but it went through the roof when I saw a chap called Chris Hartley. He is in his mid 50′s and time trialled all his life. Going under an hour for a 25 mile had always eluded him though and he suspected it was never going to happen now. Chris came to see me because he was struggling with hip position, never comfortable and suffering from hip pain. To cut a long story short, his saddle was too low and his 172.5mm cranks far too long for his 5’7″ stature.  His hip angle was very tight and no doubt contributing to his discomfort in this area. The key changes were to get his saddle up and forwards and swap him onto to 165mm cranks. Other changes to the front end were relatively minor.

The signs were looking good when he reported a 10 mile pb a couple of weeks later. Then this e-mail came through

“Mike, For the second time I am able to report another Life time personnel best! After 32 years of trying, I have done it. E2/25 59 min 30 sec (2 min 28 sec off my all time PB) Despite a gusty tail wind to the turn there were several sheltered stretches on the way back. It was at about 17 miles I suddenly realised that my dream was about to come true. I was on my best bike with a disc wheel this time but I had copied the other bikes setup as closely as possible. And yes before you ask I used 165mm cranks.”

Chris credits the positional changes, medical treatment on his hip and the support of people around him for the improvement. I’m delighted to have have been part of that team.

Hello All

Just getting going with blogging.

The intention is to share ‘interesting’ bike fitting experiences with everybody on a reasonably frequent basis. Even though I’ve been a full time Bike Fitter for three years, I’m still frequently presented with new and interesting people and problems. I’ll start with a few case histories from the last couple of years, then share the new stuff as it come through.

Mike@BikeDynamics