Stem Length

[upandover]

Hi,

My new road bike is a little long for me (it was a great deal) The height is fine, it's just the stretch, slightly uncomfortable over longer distances.

I'd like to replace the 120mm stem, with a shorter one. I'm thinking 90mm. Would this change seriously affect the handling?

Thanks
Steve

 

[Garz]

Not really, if you get more comfort it has to be worth the change!

 

[jimboalee]

Stem length is Reach - (Toptube L + 25mm).

Toptube L is the HORIZONTAL theoretical distance.
25mm is the rearward offset of the Aheadset.

Reach is dependent on the height of your Sternal Notch, your Height and your Arm Length multiplied by a your Seated Height Ratio.

Unfortunately for me, the toptube of my SWorks and a 110mm stem is 3mm too short. As I can't be arsed to buy a 113mm stem, I'll have to put up with the discomfort.

 

[grimpeur]

A lot of people make the mistake of thinking they are reaching too far to the bars when in reality they are not reaching far enough.

See this advice:
http://www.hewittbikefitting.co.uk/index.php?page=Advice

 

[e-rider]

if it's only slighty too long on longer rides then I would change to a 100 or 110mm. Going from 120 to 90 is a big jump!

Perhaps you just need to raise the height rather than shortening the stem - have you tried flipping the stem upside down?

 

[Gerry Attrick]

if it's only slighty too long on longer rides then I would change to a 100 or 110mm. Going from 120 to 90 is a big jump!

Perhaps you just need to raise the height rather than shortening the stem - have you tried flipping the stem upside down?

Yeah, I would agree with that. A small change in stem length makes a tremendous difference to the feel of the bike. I wouldn't shorten the stem by more than 10mm at a time, and then riding the bike for a week or so before making the next change. It may also pay benefit by experimenting with the saddle height. Remember that the raising of the saddle also lengthens the effective top tube length.

 

[upandover]

Thanks guys for the advice.

I may have low-balled the discomfort. I'm much happier sitting about an inch back from the hoods, and spend most of my time there. I'll have a go at flipping the stem, and then consider a less-short replacement. I've also swapped saddles, with one which I think will put me slightly further forward, (without compromising my position to much).

In terms of replacing it and trying for a week, wouldn't that mean buying three stems, or would you expect your bike-shop to swap them if it wasn't right?

Cheers
Steve

 

[Gerry Attrick]

IMHO, it depends. If you bought the bike from the dealer you are purchasing the stem from, then I would expect he would allow you to try different stems free of charge until you are happy. If you bought the bike elsewhere, well.......you pay?

 

[upandover]

If figured. The bike was second hand, so...

 

[02GF74]

how tall are you and what is you trouser inside leg?

is bike road bike or mountain? if hybrid, then forget it, dunno about those.

what is bike top tube length when measured hosizontally, from centre of head tube to seat tube or seat post if sloping.

I'll be able to tell you* if your bike is too big or not.

* NB I am not a bike fitter but know what is right & recommended for me so can work it out - plus see frame size recommendation on specialized site.

 

[ttcycle]

Just as an add on to the OP - I've just used the fit calculator on one of the websites and it's come up with two stem lengths that are inbetween the standards. Would be useful to have some feedback as to whether a shorter or longer stem is better.

The options are:

More aerodynamic positioning = 10.2-10.8cm
More comfort less aero = 9.1-9.7cm

More inclined for the comfort fit but the standard stem lengths I can choose are:
9cm, 10 cm, 11cm or 12cm

Which one is the best for comfort in terms of reach?

Thanks

 

[jimboalee]

The mass producers of roadrace bikes size their frames around 'average' dimesional ratio men.

My SWorks 54cm is sized around a bloke who is 172cm tall and has 'average' skeletal ratios.

The top tube length is decided by using a 100mm stem as std, and any variation from 'average' can be accomodated by changing the stem length.

A 10mm difference in stem length might result in a 1 degree difference in Lumbar vertebrae angle. Sod all really and your body will adapt to accommodate.

If you have any queeries about this, consider the difference in lower back angle between riding on the tops and riding in the 'tuck' on the drops.
After riding for a half hour on the drops, returning to the hoods feels like you are sat bolt upright and in a totally inappropriate position for a roadrace bike. Returning to the tops feels like a dutch upright

My suggestion ( and you don't have to take any notice of it ) is to fit a 100mm stem.

 

[jimboalee]

Just as a sideline, I had a bike once which was 3" too small for me. I fitted a 'long series' seat pin and a Cinelli 150mm ( 6" ) reach stem.

Why did Cinelli make such a stem if 100mm was std ????

The bike's handling was extremely dosile, as the handlebars were moved sideways to steer rather than twisting around the headtube, coupled with a quite shallow head angle.
The bike could be ridden with one finger on the bars quite confidently and it made a superb long distance cruiser. Its shallow seat angle helped too.

By 1970s standards, it looked MUCH TOO small, but it wouldn't look out of place in 2009.

 

[ttcycle]

Ah jimboalee...just saw this - finally decided on 9cm stemlength as that's the usual set up on the bikes I have/had. I'm sure it will be fine - I can get another stem if it turns out to be the wrong option but thanks