Road bike sizing

70 Votes here (click stars to vote)

The most important thing when purchasing a bike is to get the bike frame size and setup right - otherwise you will find you ache on longer rides, and lose enthusiasm for cycling very quickly.

Riding the most expensive bike in the world will not be fun if it is the wrong size for you. As a quick starting point to getting your bike setup right:

- With your feet 20 cm apart measure the distance from the crotch to the floor (you will need some help here!) Advice: find a big hardback book and push it up between your legs, while the other edge of the book is held square against a wall. Make a pencil mark on the wall at the top of the book, then measure from the floor to the mark (repeat three times for an average). Not very elegant but pretty accurate.

- Multiply this measurement by 0.67

That should be a good estimate of the frame size from the centre of the bottom bracket - the part where the pedal arms (cranks) join the bike frame - to the top of the seat post (the part where the saddle enters the frame).

Some bikes have a different geometry (eg sloping top bar) and will be measured differently - your shop or online supplier will make this clear.

(note: this is not the same as setting the correct saddle height for your bike - see below.)

Having bought the correct size bike (use the bike sizing chart here for added confidence) , there is a lot of flexibility for making further adjustments. The saddle height and position is much the most important adjustment to make.

First, make sure your saddle is horizontal. Use a spirit level if necessary. Although some cyclists prefer a saddle that slopes slightly to the front or the rear, this should be a conscious decision following experimentation, not an accidental misalignment.

Now adjust the saddle height so that your legs are almost but not quite straight when they are on the pedals at the bottom of the turn. You might prefer to start with the saddle a little lower at first, while you gain confidence, and then raise it 2mm each week until it is at the right height.

Detailed advice: setting a bike saddle height

There are many formulas and guidelines for setting the exact height and position of the saddle - none of these are perfect because we are all different sizes and shapes. I think the best advice for initially setting a bike saddle height is to multiply your inside-leg (to the floor) measurement by 0.883 and set the saddle height to be this measurement - measure from the bottom bracket to the top of the saddle, straight up the seat tube.

As a check, your heel should now only just reach the pedals when they are in the 'straight down' position. The saddle position might need slight further tweaking but it should be in a pretty good 'starting position'.

If you find you have pain at the front of your knees you should try raising the saddle a little, but for pain at the back of your knees you should decrease the saddle height.

Saddle back and forth position

Now you need to set the 'back and forth' position of the saddle. Typically this results in the saddle being pushed back almost as far as it will go. To check, sit on the bike with a plumbline to hand. Now with your foot on the pedal, which should be in horizontal position, the plumbline dropped from your knee should be in line with the axle of the pedal.

Your bike setup will now be pretty close to how it should be. Don't be afraid to try different positions and setups, but keep a note of the initial setup used so that you can quickly return to the 'original' settings.

34 Comments

Dai makes this comment

Monday, 14 June 2010

Thanks a sensible and informative bit about sizing, not so difficult after all eh!. I'm new to this sport, so what should be the ideal position for the handlebars for max efficiency etc. I'm working on whatever is comfortable since no 2 people I see have a similar setup

2012 here I come
Admin makes this comment

Wednesday, 16 June 2010

Max efficiency and most comfortable are rarely the same thing so you are looking for a compromise, with comfort taking priority - also handlebars are less easy to quickly adjust than sadddles. If you are already comfortable and the handlebars are a few centimetres below the saddle I wouldn't change too much, and if you do, change things very slowly - the pros might have saddles 15+cm higher than the handlebars but they didn't start off like that on day 1.
Ben makes this comment

Wednesday, 04 August 2010

I know that you have talked about the correect size bike but I once heard that when you sit on your seat both sets of toes should be able to touch the floor, is this correct. As when i did my working out with the book in my groin, i got 54 and the two bikes i've been looking at are sold as either 47 or 55. Which would you advise please?
Admin makes this comment

Friday, 06 August 2010

Hi Ben, There's a big difference between 47 and 55. Probably you need the 55 but because some bikes are measured differently it's not possible to be 100% sure at a distance - either go in the shop and sit on one, it will be obvious which is right for you - or if it's online, sites like evanscycles have quite detailed sizing guides to make sure you get the right size for that particular model of bike.
Kev makes this comment

Tuesday, 24 August 2010

I want to get into road cycling and am thinking of buying a Trek 1.1 bike that you recomended as a entry level bike.

I am 6"4" and calculated I would need a 25 inch frame. Evans cycles stock it in a 62 cm frame which is only slightly less than 25 inches. Even better its on offer for £419.00

Do you suggest that I take a chance and buy it? Also is crank sizing a big factor in getting the right fit?

Great site by the way, really usefull stuff!
Admin makes this comment

Thursday, 26 August 2010

Hi Kev, sounds like a great deal. Evans have a '28 day returns with full refund' policy so in any case there shouldn't be too much risk involved. Also Trek bikes have to be collected from your nearest store (not posted to your house) so they can check it is set up right for you.
Crank sizing is not a big factor in getting the right size bike.
Kev makes this comment

Thursday, 26 August 2010

Ok thanks so much for the advice, I think I'll go for it.
Admin makes this comment

Friday, 27 August 2010

Looking forward to hearing how it goes Kev, good luck with the bike.
Alun Jones-Davies makes this comment

Sunday, 12 September 2010

Thanks for the excellent guide to set up my new bike. Just got a new Trek 1.1 compact and it's superb.

Just one question: Will I get used to the pain of sitting on a racing saddle? Will bike shorts with padding help? Sorry thats two questions...!

Regards Al.
Admin makes this comment

Friday, 17 September 2010

Alun, Sounds like one question to me and the answer is yes - riding with (padded) cycling shorts will get rid of the pain completely. Indispensable for us mere mortals.
earbyphil makes this comment

Sunday, 03 October 2010

I read your guide, and thanks. I also opted for the Evans Trek 1.1 as my first road bike and am enjoying it. No real aches and pains so very happy.
june makes this comment

Friday, 15 October 2010

do you eventually get used to the ache from the saddle?
Admin makes this comment

Saturday, 16 October 2010

Hi June, yes you do! Some saddles just don't work for some people, some women prefer women-specific saddles, and padded cycling shorts are highly recommended if you're not wearing them already but generally you should get used to the saddle very quickly. I do know peple who also use a gel type cover for their saddles although it won't usually be necessary if the saddle and shorts are OK.
spencer robinson makes this comment

Friday, 24 December 2010

Hi There.

Can you advise me on bike sizes. Im looking at purchacing a specilized tarmac.I currently ride a langster 56". Im 5ft 11" and have 32" inside leg and seem to have a long back and have suffered with back problems on long rides. I have been to 2 dealers one recomends a 56 and the other a 58 which has left me a bit unsure of what to order.

hope you can advise

regards

Spencer
Admin makes this comment

Monday, 27 December 2010

Hi Spencer, you're almost certainly between the two - 32" leg would usually be 56, but with a longer back the other shop perhaps think there is a good case for getting the 58..(I'm 6'1", 33" inside leg and a 58 is just right for me).
Take a look also at the Evans Cycles online sizing chart (see the menu at the bottom of their home page to find it)
Carl makes this comment

Tuesday, 01 February 2011

I think am a weird shape! I MTB and have 2 bikes at the moment..my Bionicon is a full sized M (18") and is very roomy across the top tube with a standard stand over which is a bit tight...I have a 29.5 inside leg but am just over 5'10 but I also use a Krave hardtail that I made for my wife which is a 14" frame..I use a long seatpost and slightly longer stem to give me more room..I want to get a roadie for winter use and have been offered a 48cm Focus but I can't get to try it, it's too far away and I don't have enough time to get there. I want to know if a 48cm will be just to small? 48cm is a lot longer than the Krave but not that much shorter than the Bionicon.. Does the BB to seatpost length have a direct correlation with the top tube..as I think a bike that small would possibly cramp me up too much? Thanks
Lee Halsall makes this comment

Tuesday, 01 February 2011

After returning to cycling a few years ago on my mountain bike,I have bought and restored an old racer. After a few rides covering 20 miles at 13 mph,on mixed hilly and flat terrain, I find that its my lower back that aches,and not my thighs, as on my mtb. I suppose at 58 I should expect a lot more muscle pain than when I was younger, but I am quite light and reasonably fit from the mtb,which I ride almost exclusively on single tracks here in north east Scotland.
So is it likely that I have some part of my bike set up wrong,or just different muscles in use because of the different cycle geometry/gearing.
Mike makes this comment

Monday, 07 February 2011

Hi Spencer,

I'm new to road bikes, I'm 180cm tall and bought a 58 frame which I now believe to be too big as another shop recommend a 56.
Is there an easy way to make it more suitable for my size, ive bought a shorter handle bar stem that seems to help (ive had the bike 3 months so it cant be returned)
Admin makes this comment

Saturday, 26 February 2011

Unfortunately because we are all different shapes and sizes and bikes are often different geometries I can't comment on specific size problems - although a 48 sounds too small for someone 5'10, and somewhere between 56 and 58 will usually be about right for someone 180cm...
Re back pain, some discomfort is normal on changing from an MTB to a road bike but if its persistent it could be that the size isn't quite right - having a handlebar too low relative to the saddle can be quite rough on us older folk, might be the handlebar should be a bit higher to start with at least
Rob Preston makes this comment

Thursday, 17 March 2011

I'm buying a Specialized Allez 16 at the end of the month and was recommended a 56cm frame by most bike shops (I'm 5ft 11 with 32in inside leg) but sitting on this size frame it just didn't feel "right"...

However I popped into my local branch of Evans last night and had a chat with the friendly staff, mentioned my concerns about a 56 frame and asked if a 54 frame might be more suitable...

After double checking my height/inside leg I hopped onto a 54cm frame and with the saddle set correctly and using Evans' measuring process (knee angle etc...) it was confirmed that actually a 54cm frame would be fine for me.

More importantly, it felt far more comfortable for me, I felt more "at home" on this size frame.

The point I am making is that despite what friendly bike shop staff and other experts tell you, don't ignore your own instincts and don't be afraid to ask questions!

Half an hour is all it took for me to confirm my suspicions that my body shape is slightly different to others, and I'm now looking forward to many years of comfortable riding on my new Spesh!!!
wes makes this comment

Tuesday, 05 April 2011

thinking of riding again after total knee replacement,but can only bend my knee 90 degrees,will seat height and bike size help.
Admin makes this comment

Saturday, 09 April 2011

Hi Wes, have you tried cycling yet? I'm no expert in knee replacements but it seems to me the saddle will have to be the right height for your leg length, regardless of the knee replacement - if you try having the saddle higher so your knee doesn't bend so much you will get other muscle problems instead, as well as being very inefficient for cycling with a saddle too high.
Helen makes this comment

Thursday, 19 May 2011

Your sizing chart doesn't cater for me!
I'm a weenie 5'1", 29" inside leg, size 4 feet. What size would you reccomend? And don't say a kids' bike!
Admin makes this comment

Friday, 20 May 2011

Hi Helen,
If you look at the evans sizing chart: see bottom of this page under 'Bike sizing' you will see there is a section for 'womens road bike sizing' which for heights of 4'10" - 5'1" and suggests a frame about 44cm - 46cm (or 47-49 for a hybrid bike frame)
Inside leg 29" sounds quite long for height 5'1" but what do I know, I'm no tailor - if it is you might need a slightly larger frame.
Good luck!
David makes this comment

Wednesday, 29 June 2011

Hi, I am looking to buy a road bike, and according to the formula above I should be buying a 50cm frame. However, my local retailer assures me adamantly that I need at least a 54cm frame...who do I believe? The last thing I want is to buy a bicycle that is the wrong size, and that is a large difference to be choosing between.

Thanks.
Admin makes this comment

Thursday, 30 June 2011

Hi David, there are a couple of possibilities eg as mentioned above, some bikes have a different geometry (eg sloping top bar) and will be measured differently; you measured wrong; the shop has made a mistake (my first bike was too small because the shop 'tricked' me into buying an old stock bike they couldn't shift (I don't go there any more...)
Try the evans cycles sizing chart mentioned in the response to helen above, or get an opinion from a second bike shop
David makes this comment

Thursday, 30 June 2011

Thanks for your help - I am 167cm tall with a 75cm inseam, but I am only 16 years old so I'm planning to grow a few centimetres in the next couple of years. According to Evans, a 54cm frame would fit - the bicycle that I'm looking at has a traditional frame.

The only problem is that my local retailer doesn't have any road bikes at all in stock; I can't put my leg over one to try it out roughly for size.

Thanks anyway.
Paul Sculthorpe makes this comment

Monday, 15 August 2011

I've just read your article on bike sizing and I'm quite relieved! I'm 42, 6ft, 97kgs, and I started riding in Feb this year and have neever altered the bike setting as I always thought it was cofortable, however now that I'm riding more often and for longer distances the setup has become an issue. I recently complete Manchester to Blackpool 60 mile ride in a respectable 3hrs 26mins but suffered with a sore right knee. Yesterday I did 51 miles and again the sore knee returned! A friend at work mentioned the seat height and hence here I am reading your article. I'm relieved to know that I'm likely to cure the knee by raising the saddle, so I'll be trying it on my next ride. I have the Manchester 100 mile in Sept and that will make it a much more pleasant experience. Thanks
steve makes this comment

Saturday, 10 September 2011

I ordered my first road bike over the internet a couple of weeks ago. I picked a 56cm frame because for my height, 5' 11" with a 32" inside leg, all the charts i had seen recommended this size.
When I picked the bike up it looked too big but I took it home anyway. However, I just couldn't get comfy on it. I felt far too stretched out and all my weight seemed to be on my hands. The seat also had to be set low.
I took it back to the shop and tried the next size down and it was mucj better. It turns out that Boardman bikes have much longer top tubes than other makes. Luckily the shop let me swap or I would have made a very expensive mistake.
O
Chris makes this comment

Thursday, 15 September 2011

Hi, I've just purchased a new Pinarello FP2 from Wiggle but im now abit concerned I may have order the wrong size! I have ordered a 59 frame and im a whisker under 6'1" with an inside leg of 33". Please could someone advise? Thanks!
Admin makes this comment

Friday, 16 September 2011

Hi Chris, 58 - 59 are usually the right size for you (except if the bike has an unusual shape with a sloping top bar which can change the measurements) and the 57cm would almost certainly be too small.
What makes you think it might be too big?
davtherav makes this comment

Sunday, 02 October 2011

Thank you so much for your advice. My set up was way out, I wondered why I had pain at the back of my knee my saddle was 2cm too high!
Crawford makes this comment

Wednesday, 12 October 2011

Hello, i have just bought my first road bike recently. i have a mountain bike but i dont consider mountain-biking to be the sort of cycling for me. the question i wanted to ask was how do you look after and maintain a road-bike? apart from replacing brake pads and lubing chain (obviously) what else do you have to do to keep it in top-form.
Admin makes this comment

Thursday, 13 October 2011

Hi Crawford, I have to admit that personally I do little except change the brake pads (very rare) and tyres, get the gears professionally re-adjusted once a year because the shop always seem to do it better than me (sometimes the chain needs replacing at the same time).
Every month or so I flick all the spokes to check none have become loose (it's a pain when a wheel becomes misaligned, and much easier to sort out if you catch any problems early).
If I've got a quiet afternoon I might clean the bike and lubricate the chain, but not very often.
I do obsess about tyre pressures though and check that each time I'm going out.