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Road stem change - get me in the ballpark(8 posts)

Road stem change - get me in the ballparktreeman
Sep 27, 2002 5:38 AM
Hi everyone,

It's interesting how many different bike fit theories exist and how divergent they are. Until I learn more, I could use some opinions to get me in the ballpark. I bought a like new, 10 year old Giant road bike this summer and have enjoyed my return to biking after a twenty five year hiatus.

The bike is a 50 cm and I estimated that I need a 52 cm. So, I have pushed the seat about as far back as it will go ( and made other adjustments), but I get a bit of lower back pain after 15 miles and thought the 65mm stem might be a bit too short.

Most posts indicate that a 110 mm stem (plus or minus) is common on a properly sized bike. So, where do I start? It is a quill stem and I wish not to put much money into this bike because I will likely buy a new one in the next two years. I also like the higher bars philosophy of Rivendell and Sheldon Brown.

What do you think - 9, 10, or 11 mm?

Thank you.
65 is definatly too short...Steve_0
Sep 27, 2002 6:05 AM
especially if you think your frame is to small to begin with. How are you measuring? TYPICALLy (not always) a stem is measured from center post to center clamp. 65 sounds like (maybe) a mis-measurement?

In any case, find someone who is willing to work with you. Rivendell will accept returns w/out scratches....itll cost you some extra shipping, but you cant put a price on comfort.

I use a tecnomic deluxe, which will certainly guarantee your bars high enough. Your LBS may even have some old stems laying around to try. Some even have an 'adjustable' stem you can borrow for a month to 'tweak' occasionally to determine your optimal length.

Personally, Id order a 10 or 11 Technomic for starters, be careful not to scratch it in case its not quite right.
You never indicated any of your measurements...Quack
Sep 27, 2002 6:17 AM
If you do indeed need a 52cm C-T frame, I would probably go with the 10cm stem. A 52 would likely have a top tube about 1cm longer than a 50, and being that you slid your seat back as far as it would go, I would throw in another 3cm to get you back out over your pedals again. So add 4cm to 6.5 cm and you get 10.5cm. If you have good flexibility in your back, you may want to go with an 11cm stem but being that you were suffering back pain, you probably want to go a bit shorter and go with the 10.

By the way, taking my advice is pretty risky compared to going to a small high-end LBS and paying them $50 to get the fit right the first time. Look for a shop that deals Italian bikes and you will probably have good luck.

or your hobbies/interest and 'turn-offs'. nm.Steve_0
Sep 27, 2002 6:24 AM
Good one. I am so naive, I thought this was a bike site. (nm)Quack
Sep 27, 2002 6:28 AM
Thanks! and some answers to your questionstreeman
Sep 27, 2002 7:17 AM
Treeman refers to both my profession and the amount of hair on my back.

Traded my 1973 Gitane with sew ups for a chainsaw in '77. The saw was not nearly as enjoyable.

My measurements? About 42 -38 - 40? 5" 7" , "Cycling inseam" about 30 inches. 46 years young and re-born now that kids are leaving the nest.

Yes, the current stem is 65 cm reach, center to center.

My hobbies: model railroading (also a bunch of cracked, anal compusive guys), and once again - biking!
For startersGregJ
Sep 27, 2002 7:29 AM
The saddle fore-aft adjustment is for positioning your body properly over the pedals, not for compensating for top tube or stem length. I think you should go to your local shop and ask that a knowledgeable employee put you on a trainer and analyse your position. Or you could do more research on fit and do it yourself. Back pain could be due to a number of reasons, saddle height, saddle tilt, fore-aft adjustment, or reach, or something completely unrelated to fit at all. Quill stems are pretty cheap and it would be well worth the investment to get this right.
Sep 27, 2002 11:26 AM
Don't try and compensate for a frame that's too small by moving the seat back. The seat should be adjusted to where your knee is properly aligned with the pedals.

Without seeing you on a bike, guessing what stem you need is impossible.