Stem length on custom frame

Discuss light weight issues concerning road bikes & parts.
steventran
Posts: 174
Joined: Sat Mar 19, 2011 7:31 pm

by steventran

I'm getting a custom frame built and I'm trying to decide on stem length as I develop the geometry.

Assuming I can adjust everything else to get the stack, reach, and trail within an acceptable range, which of the following would look the most aesthetically balanced?

-555mm effective top tube with 100mm stem
-550mm effective top tube with 100mm stem
-545mm effective top tube with 110mm stem
-540mm effective top tube with 110mm stem

Thanks!

DJT21
Posts: 318
Joined: Sun Mar 27, 2011 7:35 pm

by DJT21

You give your numbers to the bike builder and they determine the correct length stem. There's quite a difference between a 540mm top tube and a 555mm top tube!

by Weenie


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pdlpsher1
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Location: CO

by pdlpsher1

Besides aesthetics, the TT and stem lengths are based on several factors including toe-overlap and the trail. Assuming you can get trail and toe-overlap to remain constant, I'd pick 540mm TT and 110mm stem. My custom bike has 540mm TT and 120mm stem. Hope this helps.

Broady
Posts: 385
Joined: Thu Jan 03, 2013 5:02 pm

by Broady

Yeah I went from 560 / 110 to 545 / 120 on my custom and it feels / looks perfect.

Does your builder not require you to go for a fit?

Catagory6
Posts: 405
Joined: Thu Feb 09, 2017 2:36 am

by Catagory6

dont forget about handle bar reach
theres a big diff between 70mm and 85mm too

steventran
Posts: 174
Joined: Sat Mar 19, 2011 7:31 pm

by steventran

I have been fitted, but building around my handlebar stack and reach still leaves a lot of room for modifying things for handling and aesthetics.

The seat tube angle and the stem are the reasons for the large range in effective top tubes.

It seems the consensus is that a 110mm stem would look better than a 100mm stem on a custom geometry frame with a top tube longer than 540mm, fit and handling being roughly equal.

Thanks everyone!


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onemanpeloton
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Location: Edinburgh, UK

by onemanpeloton

this is an interesting question. I've often wondered, if stem length is generally changed to alter the handling characteristics, why do smaller bikes come with shorter stems? Why isnt, for example, the reach of the frame adjusted in such a way that a 50cm frame and a 60cm both use a 100mm stem (and therefore presumably have the same handling characteristics)
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pdlpsher1
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Location: CO

by pdlpsher1

Smaller frames have a toe-overlap issue. Also there are two current trends not helping with toe-overlap, namely running wide/tall tires and a rearward cleat position. I run 28mm tires, have a rearward clear position, and have a $500 pair of shoes, haha. And yes I have toe-overlap and I have to be extremely careful about it so my shoes won’t get ruined. Often you’ll see smaller bikes come with 90mm stems so that the TT can be lengthened to reduce toe-overlap. Larger frames aren’t limited by toe-overlap so they can use longer stems to keep the wheelbase short.


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steventran
Posts: 174
Joined: Sat Mar 19, 2011 7:31 pm

by steventran

Perhaps I should ask the question this way:

Would a 100mm stem look too small on a frame with a 550mm or 555mm effective top tube?

I'm not going for a pro look, just a balanced look. Again, I can keep my handlebar stack and reach constant. The ground trail will be within a range I'm okay with.

biwa
Posts: 152
Joined: Fri Sep 21, 2018 8:39 pm

by biwa

steventran wrote:
Thu Jul 18, 2019 5:58 pm
Would a 100mm stem look too small on a frame with a 550mm or 555mm effective top tube?
No if you're riding the bike, nobody will notice. Maybe if the bike stands still, to someone who's used to the pro look.

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pdlpsher1
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Location: CO

by pdlpsher1

The pros are now on 140-150mm stems. Your 100-110mm will look short. Funny that you say you don’t care about the pro look but ask if your stem will look Ok


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steventran
Posts: 174
Joined: Sat Mar 19, 2011 7:31 pm

by steventran

To be honest, I do like to look at my bikes when I'm not riding them, and it bothers me when something looks a little out of balance to me. This is why I'm going custom.

FWIW, I think pro bikes look exaggerated. I'm looking to design a frame around my fit that has a nice visual balance once built up as a complete bike, but I don't care about having a lot of seat post showing, a ton of saddle to bar drop, a slammed stem, etc.
Last edited by steventran on Thu Jul 18, 2019 7:10 pm, edited 1 time in total.

MoPho
Posts: 549
Joined: Sun Jul 10, 2011 7:48 pm
Location: NorCal/SoCal

by MoPho

pdlpsher1 wrote:
Thu Jul 18, 2019 5:21 pm
Smaller frames have a toe-overlap issue. Also there are two current trends not helping with toe-overlap, namely running wide/tall tires and a rearward cleat position. I run 28mm tires, have a rearward clear position, and have a $500 pair of shoes, haha. And yes I have toe-overlap and I have to be extremely careful about it so my shoes won’t get ruined. Often you’ll see smaller bikes come with 90mm stems so that the TT can be lengthened to reduce toe-overlap. Larger frames aren’t limited by toe-overlap so they can use longer stems to keep the wheelbase short.

Besides when making a U-turn or doing a trackstand, why is toe overlap an issue? :noidea:



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pdlpsher1
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Location: CO

by pdlpsher1

I agree. I’m not into the Pro look either even if I can ride a bike with a 150mm stem. I would go for the 110mm stem if I were you. As you get older you might lose flexibility and revert back to a 100mm stem.


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by Weenie


steventran
Posts: 174
Joined: Sat Mar 19, 2011 7:31 pm

by steventran

Pedaling up tight switchbacks has been an issue for me. Going slow and getting your foot/wheel caught is not fun. This obviously won't be an issue for people who don't ride them.
MoPho wrote:
Thu Jul 18, 2019 7:06 pm
pdlpsher1 wrote:
Thu Jul 18, 2019 5:21 pm
Smaller frames have a toe-overlap issue. Also there are two current trends not helping with toe-overlap, namely running wide/tall tires and a rearward cleat position. I run 28mm tires, have a rearward clear position, and have a $500 pair of shoes, haha. And yes I have toe-overlap and I have to be extremely careful about it so my shoes won’t get ruined. Often you’ll see smaller bikes come with 90mm stems so that the TT can be lengthened to reduce toe-overlap. Larger frames aren’t limited by toe-overlap so they can use longer stems to keep the wheelbase short.

Besides when making a U-turn or doing a trackstand, why is toe overlap an issue? :noidea:



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