Stem lengths for a TCR - bike fit advice

Discuss light weight issues concerning road bikes & parts.
devonbiker
Posts: 70
Joined: Wed May 30, 2018 1:26 pm

by devonbiker

After some bike fit advice please.

I've been riding my Giant TCR Advanced Pro 1 for a year. I am 5'11" with an in-seam of 33cm. I was sized for the ML size and instantly swapped the 110mm stem that came with the bike for a 100mm one so I could gradually get used to racing geometry (coming from a Defy). Over the last year I have also gradually lowered the stem and now feel pretty comfrotable. The saddle is roughly 5mm from the extreme forward position and I have it tilted forward about -1 degrees. I can sometimes see the front wheel hub in front of the handlebars when my hands are on the hoods and want to push on. I use the bike mainly for training / fitness and like to ride fast.

I'm now thninking of putting the 110mm stem back on and possibly putting the saddle position to the most forward position, or should I stick with the same stem and just leave it as it is? I'm thinking this might give me slightly less twitchy descending and get my back slightly lower for a more aero position?

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by Weenie


cyclenutnz
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by cyclenutnz

If you feel like you have twitchy steering it's probably from having the saddle too far forward. If you want to stretch out move the saddle back first
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zefs
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by zefs

Why change the position if you are comfortable? You can use the drops for a more aggressive position or the hoods with arms parallel to the ground.
I wouldn't worry about seeing the freehub as it's just a ballpark method, if you rotate the pelvis forward that extends the spine and you can see the freehub but it doesn't mean the reach is off.

My guess is for training purposes you wouldn't gain much by going to the 110mm stem and saddle 5mm forward (the saddle will also become less flexible when pushed all the way on the rails, which may cause more pressure as well).

Rudi
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by Rudi

I'm kind of with cyclenutnz on this. A 100mm stem isn't really short enough (generally) to be giving you twitchy handling. zefs advice is good also - you don't want to end up in that Schleck scenario where the front end was so low and far away he couldn't ride in the drops (truth or myth I don't know).

I'd say if you still have the 110mm then why not play about and see what feels better. For me i'd probably put it on and leave the saddle where it is to start with and see how that feels.
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GothicCastle
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by GothicCastle

At 5’11”, you could ride either an M or an M/L TCR. Depending on your proportions, one or the other might be a better fit (there is only a little more than 1cm difference in reach).

I’d suggest using the saddle setback to get yourself positioned over the bottom bracket correctly, then figure out a bar/stem combo that makes you comfortable.

devonbiker
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by devonbiker

GothicCastle wrote:
Wed May 15, 2019 4:46 pm
At 5’11”, you could ride either an M or an M/L TCR. Depending on your proportions, one or the other might be a better fit (there is only a little more than 1cm difference in reach).

I’d suggest using the saddle setback to get yourself positioned over the bottom bracket correctly, then figure out a bar/stem combo that makes you comfortable.
What I have noticed is that slamming the stem to only 17.5mm of spacers beneath compared to having all the spacers (45mm) beneath has made me feel like I could do with being slightly more streched out, although that is partly due to my body slowly getting accustomed to the racing bike position. So going back to the 110mm stem may be a natural progression of this adaptation process.

Like other people have said it's probaby not good to adjust saddle fore-aft to change reach as this will affect pedal stroke efficiency. About 5m off most forward position feels about right and that was the default factory position. I've also added a -1 degree saddle tilt.

zefs
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by zefs

That difference in stack height gives about 8mm extra reach (assuming -6 stem). Also the drops are always closer compared to the hoods, so maybe that is the reason you feel the need for extra reach.

DJT21
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by DJT21

You might find going longer and lower at the front necessitates a slightly lower saddle. It really depends upon where your saddle is now, and if it's already too high.

dim
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by dim

everyone is guessing .... have a proper bike fit where they connect you to a computer and also set your cleats properly ...
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Js2
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by Js2

Proper bike fit is definitely the way to go. Ofcourse your fit will change in time so you can adjust accordingly after, but have a good baseline to start with. Weight distribution affects handling like cyclenutz pointed out. Saddle setback and height should be set first in relation to your bottom bracket before playing around with different stem length. It is not a good to compensate with saddle forward just to run 110 - 120 stem.

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Lewn777
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by Lewn777

There's no real right or wrong answer here. I'm about the same dimensions as you.
A longer stem like 12mm will make you more aero as will slamming the stem and using a -17 stem. Also this set up looks way cool and super pro.

However a 100mm stem will make you less aero as will a -6 stem and the bike more twitchy, but I find this combo better for climbing as being more upright can be a bit better for cardio.

Slam the seat max forward for best power transfer but slam it back for best aero.

For me the sweet spot on my bike (yours may differ) is 11cm stem -17, fully slammed with seat medium rear. If I ride the hoods and look directly down I like the bar/stem to obscure the front hub.

However my bike is on the smaller side compared to yours. If your bike was my bike (and this is just an educated guess) I'd run a -17 degree stem, fully slammed 100mm or 110mm and the saddle 1cm from fully rear.

icantaffordcycling
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by icantaffordcycling

Lewn777 wrote:
Fri May 17, 2019 2:47 am
Slam the seat max forward for best power transfer but slam it back for best aero.
Please stop spreading misinformation. Your anecdote about your personal position does not add to this conversation. Go make a post on Instagram flexing your slammed stem and leave op alone. I suggest tagging the @slamthatstem account and using the hashtag #slamthatslem for the most clout. /s

OP please don't "slam" your saddle forward or backward but rather view the back end of your bike and front end of your bike independently. Therefore do not use saddle positioning to compensate for reach. Also, do not worry about making your bike too twitchy or too slow in the handling department. As long as you stay in a reasonable length (somewhere between 80mm - 130mm) your body will adapt to the feeling of the bike fairly quickly. It doesn't matter how twitchy or stable your bike is in that reasonable range if you are uncomfortable and unable to focus on taking the correct line while descending or cornering anyways. Going back to fore-aft position. "The fore-aft position is important because it affects how different muscle groups are activated through your pedal stroke as well as how much pressure is put on your knees. Generally speaking, if you move your saddle backward, you will increase hamstring engagement and if you move your saddle forwards, you will put more load on your quads." Using the plumb bob method will get you in the right ballpark.

In regards to aerodynamics: note that although lower and narrower is almost always better, being more stretched out does not always have the same effect in aero gains. As others have said, we can only guess what is going on, I would suggest that you get a performance oriented bike fit as you seem to be looking for aero gains.
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Lewn777
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by Lewn777

icantaffordcycling wrote:
Fri May 17, 2019 3:46 am
Lewn777 wrote:
Fri May 17, 2019 2:47 am
Slam the seat max forward for best power transfer but slam it back for best aero.
Please stop spreading misinformation. Your anecdote about your personal position does not add to this conversation. Go make a post on Instagram flexing your slammed stem and leave op alone. I suggest tagging the @slamthatstem account and using the hashtag #slamthatslem for the most clout. /s

OP please don't "slam" your saddle forward or backward but rather view the back end of your bike and front end of your bike independently. Therefore do not use saddle positioning to compensate for reach. Also, do not worry about making your bike too twitchy or too slow in the handling department. As long as you stay in a reasonable length (somewhere between 80mm - 130mm) your body will adapt to the feeling of the bike fairly quickly. It doesn't matter how twitchy or stable your bike is in that reasonable range if you are uncomfortable and unable to focus on taking the correct line while descending or cornering anyways. Going back to fore-aft position. "The fore-aft position is important because it affects how different muscle groups are activated through your pedal stroke as well as how much pressure is put on your knees. Generally speaking, if you move your saddle backward, you will increase hamstring engagement and if you move your saddle forwards, you will put more load on your quads." Using the plumb bob method will get you in the right ballpark.

In regards to aerodynamics: note that although lower and narrower is almost always better, being more stretched out does not always have the same effect in aero gains. As others have said, we can only guess what is going on, I would suggest that you get a performance oriented bike fit as you seem to be looking for aero gains.
You attack me, but never have I seen a more pointless and petty post.

Everyone has already seen the information you're regurgitating and almost seem to be cutting and pasting from Sheldon Brown and various other places x1000 for the last 20 years. There's like 5 GCN videos with this stuff and 5 different presenters presenting it, everyone's seen it, get over yourself and get some riding experience.

Somewhere between 80-130mm stem hat the heck? That's like pick a random stem!
Short stems make your bike twitchy and long ones slow down the handling, so someone choosing between 100-110mm your post does NOTHING to help them with such a wide range. He'll end up on his face if he uses an 80mm stem and find his handling very slow and hunched foreward with 130mm, but your go-to informational website didn't tell you that.

Pros often run their seats far back in the peleton because it's more aero, they also run far more forward for power as with TT bikes. It's a simple will known observation.

It might horrify you to find out I'm far more experienced and than you on two wheels.

Please, by all means write your opinion (not that there's any point becuase you can find it in 0.000004 seconds with a search engine). But please refrain from attacking other people's opinions, or we're going to be in flame wars until one of us gets banned.
Last edited by Lewn777 on Fri May 17, 2019 5:49 am, edited 1 time in total.

icantaffordcycling
Posts: 432
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by icantaffordcycling

Agreed. You were cycling when I was in the womb. Here is your cookie. But saying that slamming your saddle back is more aero is so so wrong. Taking a quick look at any tt bike or triathlon bike you will see that people slamming their saddles forward to open their hip angles allowing them get more aero.

The difference between my post and yours is that you offered a personal annecdote showing your position while I explained the basic rules of bike fitting. Yes I used the internet as a source. That internet twaddle happens to be correct and your 'internet twaddle' is incorrect.

The only thing that horrifies me is that someone as expierenced as you can't back up their own point and resorts to a personal attacks.
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by Weenie


icantaffordcycling
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by icantaffordcycling

Lewn777 wrote:
Fri May 17, 2019 5:20 am
Somewhere between 80-130mm stem hat the heck? That's like picking a random stem!
Pros often run their seats far back in the peloton because it's more aero, they also run far more forward for power as with TT bikes. It's a simple will known observation.
Please, by all means, write your opinion (not that there's any point because you can find it in 0.000004 seconds with a search engine). But please refrain from attacking other people's opinions, or we're going to be in flame wars until one of us gets banned.
1. My point was that adapting between a reasonably sized stem which I believe to be between 80-130 to facilitate a better bike fit is worth the small change in handling.
2. Pros run their seats far back because they size down in frames in order to get lower headtubes. If you read my post I explain that getting lower is always more aerodynamic. Shorter headtubes are lower which is why they choose smaller frames. The trade-off with smaller frames is not enough to reach which they facilitate with pushing their saddles back. I am guessing that OP is not a pro and does not spend 8 hours a day on his bike during the offseason to change the muscle groups that he can use while cycling. They run their saddles forward on TT bikes to open their hip angle allowing them to get more aero.
3. OP please take everything that I said with a grain of salt and instead double check it using "internet twaddle" from fitters that fit pro bikes for a living. I did not attack you, I simply asked you to refrain from posting incorrect information.

Similarly to what I had to do yesterday. I am done wasting my time arguing with you.
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