One size small frame with one size longer stem vs larger frame with smaller stem?

Anyone who has ridden both these set ups - what difference do you feel in handling, comfort, weight distribution? The larger frame will not have any spacers and smaller frame will have a couple. Lastly, do you think it’s easier to go down spacers if reach is reduced by say using same size stem?

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Over steering vs. under steering I‘d say - sort of a physics question- right :thinking:

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Id just pay for a bike fit…

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So good timing on this, as I am literally in the middle of dealing with it.

My current bike (Canyon Aeroad, small) is probably just a wee bit small for me, mostly because I cut the steerer tube too short ( totally on me, no one else). I either needed a slightly longer stem (running a 120 now) or to come up a cm or so.

I ended up moving up one size on two different options (yes, that means I am buying two bikes….N+1 is for rookies. :crazy_face:). Trek Emonda in a 56 and Giant TCR in a ML.

When I test rode the Emonda, the fit was all wonky and I left the store because I could not figure out if the bike was too bike or not. There was a ton of spacers, the HB were too wide and I probably needed the shorter seat mast. (I had it bottomed out and it was just a few mm too high still).

I measured the HT height from the ground before I left the shop (83cm to top of HT) and then compared it to my bike at home (83 cm to the bottom of my stem). There is a mandatory spacer that is required for the internal cable routing on the Emonda, and since I wanted to come up a bit with my stem, I figured it should be OK. Asked the shop to remove all the spacers and slam the stem for me. Went in last night to ride it again and it was a completely different bike. HB were still too wide, but I was in the ballpark. Pulled the trigger on it and brought it home. Still need to dial in the stem length once I get narrower bars.

The Giant has the exact same stack, so I will just plan on slamming that stem as well.

So I will go from having a long stem (120) with some spacers (~2cm) to having a shorter, slammed stem (100-110). I don’t expect any major differences in handling since my overall position will be the same. The newer bikes may feel a bit more stable / less twitchy, but nothing significant. As long as your stem lengths remain within a reasonable fit range (~100-120) and your overall position is roughly the same, any differences will likely get lost among the general differences in the bike.

If you go from a very long stem (+120) to a very short stem (<90), then you’ll likely see some handling differences.

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I would say at speed it is unlikely to make a huge difference.

At lower speed a larger frame with smaller stem feels more agile. It might be counterintuitive because the wheelbase is slightly longer but a shorter stem gives you a more direct leverage. This is the reason I prefer a 100mm stem on a gravel bike while I tend to prefer 110 or 120 on my road bikes.

I had 2 bikes where I had replicated the same fit, contact points where at the same distance ± 3mm but one bike had a smaller frame and longer stem and the other one had a bigger frame and shorter stem. There werer 2cm of difference between the stem lengths. I would mostly feel the difference when going from the bigger frame/shorter stem to the shorter frame/longer stem when pedaling out of the saddle and putting more weight on the handlebar. It would felt slightly weird. That feeling would disappear after 5 minutes of riding. It never happened when going from the smaller frame/ longer stem to the bigger frame / shorter stem so I attributed it to the stem length. I ultimately sold the bike with the longer stem as it was a gravel bike and it felt less at home out of the road.

Also take into account that stem manufacturers don’t necessarily make their stem at the exact advertised length. Tolerances can be sometimes up to ±5mm. You could buy 2 stems from 2 different manufacturers and end up with a 110mm stem that actually measure 113mm and an advertized 120mm stem that actually measure 117mm!

Test rides the bikes if you can. The bike I eventually sold was purchased online after a call with the LBS fitter who convinced me to go one size shorter (ML). In hindsight it was a bad decision as I had done my own calculations based on a bikefit I did several years ago, my previous bikes, 3 decades of experience and my own preferences and had decided initially for an L. think I am pretty sure they had the ML already in inventory and they pushed to get rid of it.

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One other thing to do is look at Geometrygeeks.bike…you can compare different sizes of bikes / models side by side and know exactly where the geometry differences are…greatly simplifies selecting the appropriate size stem and spacer situation.

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GG is great and I use it a lot. But I found 99Spokes is handy since it also adds a graphic overlay between the frames and wheels to get a better idea of the impact of the differences. I know there are other sites that have similar tools, but they require more work than the 99S version that is automatic (assuming they have the bikes you are considering).

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https://www.bikegeo.net/ lets you put in different lengths for stems, different spacer stacks etc and you can compare the different fits. The other website that works well for this is Frame Comparison

But to answer the question, most bikes will handle just fine with stem lengths between 90-120. You’d notice a difference switching back to back between the 2 extremes, sure, but the bike would likely be perfectly rideable with both.
In the same way, I’d be surprised if a size 54+110 stem handled materially differently to a 56+100 with everything else kept the same. I’ve run 110, 100 and 90mm stems on the same bike before now and it didn’t affect the handling in any noticeable way.

Tbh if your proportions are in the middle of the bell curve you can probably get your contact points relative to the bb in the same place in 3 different sizes of the same bike, assuming the style/general geometry is a good match for you.

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I think it depends a bit on other body proportions, your preferred fit, and your riding style.

For example, I have sized down in order to get more saddle set back and longer stem. I have a short torso with a decent amount of upper body mass. Going smaller allows me to move my center of mass backward, taking weight off my hands & neck, without ending up overly stretched out.

The OP hasn’t said what a longer and a shorter stem mean. So it’s all relative.

Handling depends on the combination of trail, stem lenght and handlebar width. (Plus wheelbase, BB height, and weight distribution, but I leave these elements out of the equasion for now.)

In large sizes going down a cm or even two may(!) not make that much difference. But for the smallest frame sizes, going from 90mm to 80mm can make a relax steering bike rather twitchy for it’s purpose. Therefore you often see that the smallest size has a geometry with a lot more trail if it is standard equipped with a 80mm or even shorter stem.

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That frustrates the heck out of me. I even have 2 stems from the SAME manufacturer and stem angle which vary by 3mm. The tolerances are terrible in this industry for so many manufacturers.

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I have a Syncros stem in my parts box that is labelled 110. It is at least 120mm!

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I totally agree with that. A professional bike fit is a must otherwise you won’t be using the bike properly no matter what the frame size and will get injured.
I tend to prefer a smaller size for the road and the larger for MTB.
I’m 168cm (5’4"). On the road I use a size XS or S (49) and MTB typically size M.
Typically long seat tube and stem.
BTW - if you look at the pros they usually ride the smaller bikes.

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Not necessarily…if he has a fit that he is happy with, he doesn’t need to go see a professional fitter to figure out how to adapt it to a different frame.

See my example above…my fit is good, but I needed to make a couple of small tweaks. A quick trip to Geometry Geeks and I knew I could adapt my position to the larger size frames I was considering.

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As a rider myself doesn’t fit ‘standard’ bikes of today (S, M, ML, L, XL) this system of bike fit is totally frustrating as it really only serves the manufacturer to save costs. What also makes this more awkward for me is the slack head angle many manufactures use today. I typically us a 72.5-73 degree STA and a 73-73.5 HTA.

I would lean to the larger frame and smaller stem but with the current awful sizing system this can leave you on a bike that aesthetically looks a too big for you.

Go custom if you know what fits you and can afford it or search elsewhere for a bike that does fit you correctly.

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I have a few bikes of varying sizes, though they are set up almost identical in riding position.

My two extremes are a large steel frame, traditional geo, 58cm top tube (my first bike sold to me on the basis of being 184cm tall) and a small 2007 Canyon Ultimate AL, 53.5cm TT (bought as a frame 2nd hand and sold to me as medium). 1st bike fit on the Canyon told it was too small and would never work. Comparisons between those two are not really valid as the front end is higher (only by two cms), but both are very rideable by me.

Best comparison is a medium 2017 Canyon Ultimate AL, 55.5cm TT (the last of the Canyon Ultimate ALs). The difference between the 2007 S and 2017 M, is stem is flipped on the S, the S has 1cm longer stem (110mm compared to 100mm) and 1cm longer reach bars, that is all, everything else in identical. I prefer the S when racing, particularly on technical circuits as I prefer (or have far more experience with) having more weight over the front wheel. Training rides it does not matter.

Yup my miss. I have a 110 on the 56 frame and I was thinking of going 120 with a 54.

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Unfortunately in my country road biking is the rarest of rare sports. So no access to a professional bike fit. No access to trying out bike frames as well.

I’m 168 cm. (5’6’’). I have a long torso and short legs. I bought a 49cm specialized Roubaix and put a 110mm stem. The seat post is also set back. I gotta say that I love the way this bike fits. I later purchased a small 51cm Cerverlo Áspero and it’s great (they don’t make a smaller frame) but it is a less agile more stable feel. Certainly some of this is due to frame geometry but I’m a fan of slightly small vs. slightly big.

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Thanks. Also I feel a 110 stem is that wee bit more twitchy coupled with the steep head tube angle of the one size larger frame. Smaller frames tend to have slacker head tube angle and I will pair this with 120. Let’s see. Inclined more to the smaller frame with some spacers and 120 stem.