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Old 11-29-2018, 06:17 PM
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Wayne77 Wayne77 is offline
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Join Date: Dec 2004
Location: SLC, Utah
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Another frame geo thread...working around a bike with short trail

Some of you might have seen the PSA about the crazy good deal going on right now for the XSogn (by Rawland). So I'm looking at that bike hoping I can make it work for my wife who I'm hoping to get into gravel riding. She doesn't like roadbikes & narrow tires and the "pressure" she feels to go fast (that's not coming from me...I think she's putting that pressure on herself). Also, she hates riding in traffic so I'm hoping a more relaxed / outdoorsy / cushy tire kind of vibe would be just what she needs. Anyway, I digress...

One strike against the XSogn is that it only comes in 3 sizes. Therefore I'm looking at both the "56" and the "59" for my wife. I'm pretty well versed in the stack and reach she needs for a proper fit, and therefore I know what concessions need to be made between each of these sizes when ideally I think my wife needs something in between.

With her current road bike her bars need to come up about 2cm. She's fits the classic short torso/long legs female profile so I don't think her bars need to come forward too much, but a cm further out is probably ok. Let me stress however that this thread isn't primarily about fit, I just need to figure out what handling impacts we'll deal with between the two very different sizes, especially since the stem is where we'd have to make some adjustments. On paper the handling impacts of a longer wheelbase are pretty obvious but its not that simple. Here's the catch - both bikes have a shorter than average trail (32mm). With the short trail a constant, and stem length being the variable, I'm wondering how the handling on a short trail bike will change with varying reach and stem lengths. Not only am I trying to understand how a short trail affects handling of this bike across the sizes, I'm also wondering whether stem length and or front center will either increase or decrease the impacts of that short trail.

**Note that currently she is riding a frame with reach of 37.6cm and stack of 56cm, and as mentioned she has 3cm of spacers, a positive rise stem, and her bars tilted up more than normal to get the hoods to where she wants. She's 5'9", seat height is 71.5cm. Current frame is a 55cm. I think ideally she should be on a 56cm road bike. Also I want to get her bars back to a reasonable tilt so she can reach the brake levers easier when in the drops. Current saddle tip to bar length is 50.5cm, saddle setback 6.5cm**

**I used an online frame calculator to derive the resulting measurements below**

Option 1: 56cm XSogn - same stack (56xm), slightly longer reach (39.3cm), ~2.5cm shorter trail) The Xsogn also has a 73.5 (vs 73) STA so that possibly makes it feel a little longer than a typical 56cm frame. If we go with this option, I think the extra reach is ok but we'd need one or 2cm more spacers under the stem to get the hoods where they need to be. And I'd probably need another to accommodate for the lower hood height occurring when we rotate her bars back down. Basically it seems like this frame is about the right length but the stack is still 2-3cm lower than I'd like.

Option 2: 59cm XSogn - Accommodate for a longer reach than normal for a bike her size by using a 2cm shorter stem / stack is 3cm higher (59cm vs 56cm) than her road bike...again a short trail of 32mm).. Certainly a 59 would normally be out of the question for someone needing a 56. That said my wife currently has a 9cm stem, so using a 70mm brings the bars back so the saddle to bar distance is a reasonable 52cm (currently she has 50.5cm and I think she could probably use an additional 1cm of reach as is)

My gut tells me that option B...even with a shorter stem to create a comparable cockpit length, will feel way to long due not only to the longer front center but also due to the short trail. Is this correct? In a nutshell how would a 58-59cm bike with a 70mm stem and short 32mm trail handle? Would wheel flop be an issue with the short trail? I imagine the short stem and lighter weight rider will pull weight off the front wheel...and that's last thing you would want to on a bike with really short trail correct? Or is it better to move your weight back on a long bike with a short trail?

Sorry for the really long post... As the dust settles, it seems like its a choice between two less than ideal situations: smaller bike that is long enough but too short, or a long bike with a short stem that may handle really poorly.

(All this obviously means it may not be a wise purchase...I know that's the default answer here, but lets set that aside just to keep the discussion focused on trail, handling, how it relates to longer vs short frames, etc):

If any of you are still awake I'd love to hear your thoughts!

Last edited by Wayne77; 11-29-2018 at 06:30 PM.
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