# Fit Question (stem length)



## bigsky

Newby here so bear with me,

My LBS took all sorts of measurements, and my 58cm Windsor Knight was set up pretty well by me initially, but they suggested I switch the stem (100mm) to a shorter one (80mm). Most of my initial set up was based on stuff I'd read or watched on youtube. Concerning stem length, is sighting the front hub from riding position a good way to get a proper fit, or is it just a guide? In other words, when I look down from riding position now, my bars do not block the hub, but are behind due to the shorter stem.

I feel a little bit round in my back when in this new set up, but the LBS said that being too stretched out would cause back pain on the long rides. I only got one short ride outside before the new set up (MT is just thawing out) and that's all I have to compare it to. 

I won't get back to the LBS till next week, so I figured I'd throw it out here for suggestions. Thanks in advance.


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## rocco

bigsky said:


> Newby here so bear with me,
> 
> My LBS took all sorts of measurements, and my 58cm Windsor Knight was set up pretty well by me initially, but they suggested I switch the stem (100mm) to a shorter one (80mm). Most of my initial set up was based on stuff I'd read or watched on youtube. Concerning stem length, is sighting the front hub from riding position a good way to get a proper fit, or is *it just a guide*? In other words, when I look down from riding position now, my bars do not block the hub, but are behind due to the shorter stem.
> 
> *I feel a little bit round in my back when in this new set up*, but the LBS said that being too stretched out would cause back pain on the long rides. I only got one short ride outside before the new set up (MT is just thawing out) and that's all I have to compare it to.
> 
> I won't get back to the LBS till next week, so I figured I'd throw it out here for suggestions. Thanks in advance.



It's just a guide but I also think it's a very good one. You certainly don't want your front hub to be completely in unobstructed view in front or behind your bars when you have your hands on the tops of your bars. Your back should be a flat as possible. 

It's impossible to say for sure without more dimensional information about you and your bike plus good images or video of you riding your bike but I suspect the 80mm stem is too short. I also suspect your frame is too big for you (not certain but highly likely). 

I'd be leery of just taking this LBS's word on fitting unless they have a good local reputation for doing quality professional fittings... can they provide references? 

Here is a good basic guide for you.


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## Mike T.

bigsky said:


> they suggested I switch the stem (100mm) to a shorter one (80mm).
> I feel a little bit round in my back when in this new set up, but the LBS said that being too stretched out would cause back pain on the long rides.


What a minefield. As a back pain sufferer for decades (deteriorating disc) I, last year, went to a shorter stem and flipped it over to give a shorter, more upright position. It didn't help at all.

This year I've been working with a physiotherapist who video taped me riding rollers (VERY informative!) and took still pics. She wanted me to go to a lower and more stretched position so as to flatten the back and put the bend where it should be - at the hip joint and not curved along its whole length like my shorter, upright position had me doing.

I was using 100mm stems (2 bikes) flipped up and she wanted me to go to 130mm flipped down as she liked the pics where I slid my hands forward on the hoods and flattened my back. I rode like this on the road for a couple of weeks while the stems were coming mailorder.

After about three or four rides the new position (gripping forward on the hoods) felt normal and riding on the normal grip position felt too short. Then the stems arrived. My position now feels SO natural as she says it takes a few rides for the new position to "imprint". There is no way I could go back to an upright short position now. I know I'm way more aerodynamic and maybe this has something to do with being 5 minutes faster over 30 miles from the same ride last March.

So be very careful about any "expert" who tells you that "being too stretched out would cause back pain on the long rides". Look at the pros bikes - they all use 130mm stems that are as low as the frame will allow and they ride 150 miles.

I've no idea what is right for you and no-one can compare themselves to others or diagnose others, especially through the internet. But stem changes are quite easy and not too expensive ($142 for my two new Thomson stems).

By the way - an 80mm stem on a 58cm frame doesn't sound right at all - not to mention that it will look silly. Either the frame is too big or the stem way too small. My frames are 54cm and the stems 130mm.

Check out this site for a fit starter. And remember, ANYTHING you read is just someone else's opinion -
http://bikedynamics.co.uk/index.html

Have fun!


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## tom_h

bigsky said:


> ... Concerning stem length, is sighting the front hub from riding position a good way to get a proper fit, or is it just a guide? In other words, when I look down from riding position now, my bars do not block the hub, but are behind due to the shorter stem....


It's a rough rule of thumb that will get most fit cyclists, of "typical" body proportions, within about +/-15mm of a correct tube top plus stem length. 

Given the variations in handlebar reach & drop, head tube angle, fork rake, etc, the "block the hub" method can only be a rough guide. 

It seems to hold true on both my bikes when I am in the drops, but I consider it incidental to a good comfortable fit.


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## tom_h

Mike T. said:


> ...Look at the pros bikes - they all use 130mm stems that are as low as the frame will allow and they ride 150 miles....


yeah, but they are all super-fit, flexible guys, mostly in their 20s and a few in their 30s ;-)

Many are riding with their backs nearly horizontal even when on the hoods (eg, Andy Schleck) ... many of us couldn't handle that for extended periods.


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## Mike T.

tom_h said:


> yeah, but they are all super-fit, flexible guys, mostly in their 20s and a few in their 30s ;-)
> Many are riding with their backs nearly horizontal even when on the hoods (eg, Andy Schleck) ... many of us couldn't handle that for extended periods.


I'm 62 and my physiotherapist looked at my side profile video and still pics and suggested a longer & lower stem from my 100mm one (I'm 5' 8" with a 54cm frame/55cm TT) and I'm nothing special in age, flexibility or size. I thought for decades that a longer, lower position would make my chronic back ache worse. But I was wrong. I'm doing two hour rides at 18mph average and my backache, while not cured by the longer stems, is certainly no worse.


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