Picture is worth 1000 words. Here is a normal frame (540mm top tube) sized down to a XS (500mm top tube). Trail is the key factor to determine bike handling. Its going to be hard to get a small frame not to have a large "trail" without smaller wheels.
In this case, anything 520 or lower top tube length gets 650b wheels.
And - I have friends your size that had custom built frames to get smaller wheels in order to avoid toe overlap.
I don't disagree w/what has been said re 650b wheels. Many mtn bike manufacturers and some gravel bike manufacturers, such as OPEN, are making frames that allow for either or both. With mtn bikes, it allows a 27.5+ tire in the 2.6" to 2.8" range compared to 2.30" or so w/a 29" tire. Similarly for gravel bikes.
That said, the need in this instance is partly based on the type of riding that is intended which I don't think was specified. The original post mentioned "wider" tires but didn't specify how wide. This could mean anything from 30 or 32mm up to say 47mm or larger. Accordingly, a 650b may not be required. In addition, her current Ridley has an approx. a 52.5cm top tube so that some of the compromises mentioned for very small frames may not apply.
Finally, what is being left out of the discussion is fork rake. Trail is a function of head tube angle, tire diameter and fork rake. In my opinion, the biggest problem is that frame manufacturers design only one fork and generally it's to fit a larger frame. They then use this fork for all their frames. But as the head tube angle decreases to prevent toe overlap on the smaller frames the trail increases to unacceptable lengths. The problem could easily be solve by having a larger fork rake on the smaller frames which would both decrease trail and increase toe clearance.
An example is the geometry of the OPEN U.P. The smallest frame would be my size based on top tube length. But the head tube angle on this frame is much smaller than even the next size up w/the same fork rake. I wrote Vroomen to ask about the handling as I was concerned about the trail number. I got sort of a vague answer which was disappointing from such a high end designer.
DrSpoke wrote:I don't disagree w/what has been said re 650b wheels. Many mtn bike manufacturers and some gravel bike manufacturers, such as OPEN, are making frames that allow for either or both. With mtn bikes, it allows a 27.5+ tire in the 2.6" to 2.8" range compared to 2.30" or so w/a 29" tire. Similarly for gravel bikes.
I love this idea myself, and my next bike will be designed to fit both 650bX50-ish and 700cX38-ish. I envision two wheelsets, one with fat, 650b, somewhat nobby gravel tires and the other with fast, plump 34ish 700c tires. Versatile!
DrSpoke wrote:Finally, what is being left out of the discussion is fork rake. Trail is a function of head tube angle, tire diameter and fork rake. In my opinion, the biggest problem is that frame manufacturers design only one fork and generally it's to fit a larger frame. They then use this fork for all their frames. But as the head tube angle decreases to prevent toe overlap on the smaller frames the trail increases to unacceptable lengths. The problem could easily be solve by having a larger fork rake on the smaller frames which would both decrease trail and increase toe clearance.
An example is the geometry of the OPEN U.P. The smallest frame would be my size based on top tube length. But the head tube angle on this frame is much smaller than even the next size up w/the same fork rake. I wrote Vroomen to ask about the handling as I was concerned about the trail number. I got sort of a vague answer which was disappointing from such a high end designer.
Great example! I didn't refer to fork rake specifically, but the "compromised to fit 700c" front end geometry of the Open U.P. you mention here is the sort of geometry compromise I meant to imply. It's not necessarily bad, and it might handle and fit fine, but with smaller diameter wheels, it just isn't necessary to tweak the geometry of smaller frames as much...
I'm not a big advocate of 650b on gravel bikes as I don't feel the need for it at my size. But they are a nice option for others depending on size, expected trail conditions and/or other bike options available. And I am considering, and will likely end up with, a set for my new mtn bike as I went small @ 2.1" for the 29er set and thinking of going big on a 27.5 wheelset.
Wow, so much to consider. I'm honestly not sure how wide I need my tires to be. In PA we have a lot of loose gravel and there are some light singletrack trails through fields that I would ride on. Otherwise, I have a mountain and a road bike, so would probably defer to them for the extremes. I'm going to try to pop into the LBS tomorrow to talk to them about the Ridley X-Trail and they also sell Scott and Kona.
bethlikesbikes wrote:Wow, so much to consider. I'm honestly not sure how wide I need my tires to be. In PA we have a lot of loose gravel and there are some light singletrack trails through fields that I would ride on. Otherwise, I have a mountain and a road bike, so would probably defer to them for the extremes. I'm going to try to pop into the LBS tomorrow to talk to them about the Ridley X-Trail and they also sell Scott and Kona.
bethlikesbikes I live here in Pa. and have done 2 Pa. gravel rides. No I probably don't need that for Pa(40 mm tire). but if you are ever going to or thinking about going to the MidWest to ride you probably should consider a bike that can fit a 40 mm tire. A mt. bike would work some on the extremes but not your road bike. I will give you an example on a Pa. ride. On the Maple City Century at Honesdale. Lots of riders were riding their roadie bikes with probably 28 mm tires. They really had to pick and choose their lines especially when they were in the rough stuff and also going downhill they had to go slow. At my end with my gravel bike I could let it rip and not really worry about picking my lines. I thought maybe that is what you were getting a gravel bike for to ride in any kind of terrain. I also know the more money you can afford to spend upfront in the beginning as long as the bike fits you the less you will have to spend later on with upgrades.
Based on your budget, I think Ridley X-trail fits the bill.
\nHow tall are you and what’s your inseam?
\nI think you should look at the reach measurement, not necessarily the top tube.
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\nI’m 6’ tall with 33” inseam, and I ride a medium size frame with a 120mm stem.
\nMy daughter is 5’7” with almost the same inseam, and she rides a XS Fuji with a 70mm stem with a 30mm spacer under it.
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\nRidley does run big in terms of the stack height, as I can’t get the handlebar low enough but that might be beneficial to you. I got the bike for gravel/trail riding as well as riding in the snow and ice (with studded winter tires).
\nI find the bike to be fun to ride, stiff and generally pretty good but not great.
\nTo me that’s to be expected based on the low price tag of the bike.
\nMy guess is that it might be due to the entire frame (?) being made out of HM Modules carbon fiber.
\nHaving said that, I think the type of tire, size and air pressure may have a bigger affect on the ride.
\nI also think that the tubeless tire will make a big difference.
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\nKeep your eyes on the funky sizing with the smaller size frames though, as the XXS frame has a longer reach than the XS frame.
\nIf you are comfortable with Fenix, You may want to get a X-trail with the same reach measurement.
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I'm a happy (biased) Jamis Renegade owner, so I'll throw that in with the suggestions. I use it for everything. The bike is stable, fast, and comfortable, and it has handled gravel abuse with aplomb. It combines a longer wheelbase with fairly aggressive steering geometry.
The Renegade has multiple fork sizes to pair well with different frame sizes, keeping handling consistent. The stack and reach of the size 51 seem like they might be on the money for you, given the lower BB compared to your Fenix. You may be able to find a 2017 Renegade Expert or Elite in your size on clearance. The Elite especially is a really great spec right of the box. For 2018 they added the Escapade, which is a very nice steel Ultegra spec. It's not as light as the carbon models, but it's not a pig either.
![[Inflite-CF-SLX-_667]](https://www.cyclinside.it/web/wp-content/uploads/2017/08/Inflite-CF-SLX-_667.jpg)
