road bike frame size?

gerrylombard

Hi. I'm looking at buying a used road bike on the assumption I'll get more bike for my money. The choice of frame size is a bit limited. According to the guides, I should be looking for a 58cm frame (I'm just over 6'0"). Is it a bad idea to use a shorter frame, say 55cm, with the saddle raised up? Also is there a recommendation for the distance from the front of the saddle to the handlebars? Thanks. G

Smithzer

I am just 6Ft and I have a 56, so a 58 would be ideal for you. I would bring the bike down to my LBS and get properly set up for it. It could save a lot of time and pain

Lumen

gerrylombard wrote: »

According to the guides, I should be looking for a 58cm frame (I'm just over 6'0"). Is it a bad idea to use a shorter frame, say 55cm, with the saddle raised up?

It's a bad idea to use a frame that's the wrong size. You can obviously fix the saddle height, but that does nothing for the reach or for the drop (to the handlebars). Smaller frames have shorter top tubes and head tubes.

You can use a longer stem to fix the reach, add spacers and flip the stem to reduce drop, but it'll look a bit odd and the handling will likely be more twitchy.

That said, lots of 6ft riders use 56cm frames, so 55cm might not be far off.

gerrylombard wrote: »

Also is there a recommendation for the distance from the front of the saddle to the handlebars?

There are various rules of thumb and charts, which depends on various body measurements.

I've used this before, and it's as good as any.

Nothing beats being fitted in person by someone who knows what they're doing, but this is a used bike which makes it harder.

Idleater

What I learned from my recent bikefit excursion, If you are flexible and have strong back and shoulder muscles you will be more likely to be able to support your upper body at the higher drop from the extended seat post, lower bars with less discomfort at the neck/ across the shoulders.

I am neither strong nor flexible, so 1.80m/5'11" equates to 57cm frame in my chosen manufacturer.

gerrylombard

Thanks for the tips. Will I get a bikefit in any bike shop?

My LBS has some trade-ins for sale, so that might be the best place to buy. I'll find out more about them, and will ask your opinions on them. G

bmacg

Its important to remember that frame size refers to the length of the top tube, not the length of the seat tube as sometimes supposed. This is the critical measurement on a frame, as its the most difficult to adjust afterwards, (you can easily raise or lower the seat post to change the reach from saddle to pedals). The only way to compensate for a top tube that's the wrong length is to move the saddle fore or aft, but this range is limited by the need to have the saddle properly centered over the pedals, or to buy a different-sized stem, but this can be expensive, and too-short a stem can result in very twitchy steering.
There are no hard and fast rules. Some riders prefer a longer top tube, which results in them stretching further to reach the handlebars, and thus having a flatter, more aerodynamic profile. Others, (like me, who may be a bit older and less flexible), prefer a slighlty shorter top tube, resulting in a more relaxed and upright riding position, but less aerodynamic.
The best advice is to go to a bike shop that offers a fitting service. If you're going to lash out several hundred quid for a good road bike it'll be money well spent. Besides, once you get the measurements correct, you'll always know what to buy for future reference.
BTW, as a rule of thumb one tried and tested way of judging the correct length for your tube is to place your elbow against the leading edge of your saddle and extend your forearm along the length of the top tube, fingers extended. The tips of your fingers should stop about an inch or inch and a half short of the handlebars.

gerrylombard

Thanks for this.

I've just looked at two bikes in my local, Joe's Bike Shop, O'Connell Avenue, Limerick - a GIANT Defy, less than a year old, and a TREK 1200, which is older (I gather it's the forerunner to the TREK 1.2). Both are offered at €550.00. The GIANT has basic Shimano equipment on it, the TREK has Shimano Tiagra. Joe thinks the TREK is a better brand, lighter frame, and the equipment is better. What do you think? I'll try them out tomorrow.

BTW, my knees have been giving me trouble since last Sept, swelling and hard to fold up. My GP wondered if my present bike (a trusty old Paganini steel, 55cm seat tube height) is set up incorrectly for me. I'm over 50 so I'm more tortoise than hare! Gerry

bmacg

To a degree its a matter of personal choice. I'd be inclined towards the Trek though. They're a great brand and pretty bomb-proof. I've a five year old Trek 1000 as my winter bike, and its proved a very trusty steed. Everything on it is of standard dimensions, (seat tube diameter, BB size etc), so its very upgradeable. If I remember correctly the 1200 has Tiagra deraileurs, but a bontrager crankset and bottom bracket. All pretty good stuff for a first bike.
As for the knee trouble, that's not uncommon when starting out, and is often down to incorrect saddle position or height. At this time of the year it could also be inflamation due to cold, if you cycle without adequate protection on your knees. If it happens in mild weather though, its probably the saddle.
Correct saddle position and height is a hotly debated topic, but I found when starting out that it was best to begin with the commonly accepted setting for both, then tweak it as I got more experience and confidence.
The commonly accepted method for setting saddle fore and aft position is the KOPS (knee over pedal spindle) approach.
Place your bike in a stand or get someone to hold it, then sit on it with your normal riding shoes, and feet in your normal position on the pedals. With the pedals set at exactly 3 and nine o'clock, (ie both parallell to the ground), drop a plumb line (any weight on a piece of string), from the front of your knee directly down. The string should pass exactly through the ball of your foot and then through the pedal axle. Move the saddle back or forward until you get it in this position.
As for height, the saddle should be set so that at maximum extension, ie with the pedal at the very bottom of the stroke, your leg is almost, but not fully, extended. A good way of checking is to straighten your leg, your bum should just about lift off the saddle, but no more.
Another good rule of thumb is to set the saddle height so you can just rest your heel on the pedal at the bottom of the stroke. Your heel should just be able to reach the pedal without having to rock your hips.
The golden rule when trying to sort out any ache is to make small changes to only one setting. Even a tiny change can have a noticeable effect. Try it at the new setting for a few rides, then adjust if it hasn't worked out. If you change more than one thing at as time, (eg both saddle height and fore and aft), you'll have no way of knowing which was the culprit if the new setting doesn't work out.
If you're buying from a good bike shop, see if they'll do a fitting for you. A half an hour could save you a load of grief later on.
Happy cycling.:)