Geometry analysis of my frame?

7 replies · 308 views

protohype
32 posts
#1Aug 13, 2019, 1:31 PM
Hey there- I’ve been riding this size L Rawland xSogn (link to geometry) since the fall and it’s been a really good bike. I’ve used it primarily as a commuter with a front rack and basket, but when the weather cleared up this spring, I switched it to gravel duty, as my first dedicated “gravel” bike.

It sports a low-trail front end that works really well with a rack/basket + load and seems overall pretty decent on the steep logging roads I ride here in Oregon. I run 650b x 48mm Juniper Ridge knobbies.

As much as I wish I were more of an expert, I don’t really know how to analyze geometry and compare it to other bikes in a way that makes sense, and because I don’t have any experience on other similar bikes, it’s hard to understand this stuff.

I’d like to know how this bike’s geo compares to some of the best cutting edge gravel bikes. For example, climbing prowess, handling on descents, stack/reach trends, etc.

The xSogn a nice bike, but I’ve been contemplating a frame/fork upgrade for a couple of reasons. The first is that I feel somewhat stretched out even with the short, stock 70mm stem. It also shipped with a fairly low pre-cut steerer so my adjustment options are limited. This situation is fine on the road but I think I’d be happier with the bars a little closer in and higher as I feel pretty vulnerable on some of the bumpy descents with the bars so low/forward.

My secondary concern is that the frame/fork is really heavy. I’ve upgraded a lot of the parts to save weight but I know I’ll never get where I want to be with this stout-tubed production Taiwanese frame. I’m considering looking into a Ti or Carbon upgrade at some point to swap these parts onto, (returning the Rawland to the excellent commuter that it is), and I’d like to be more educated in that search.

So, any geo-nerds out there willing to advise me on what looks good/bad on the Rawland and what to look for in an upgrade?

Just to reiterate- I like to ride fast and comfortable for long distances. I ride a Roubaix (endurance geo) as my only road bike and don’t want/need road-race geo on this bike. Looking for all day comfort and less sketchy descending with still nimble climbing. Terrain is rarely flat with lots of steeps. Thanks in advance for any advice!
0
ljsmith
762 posts
#2Aug 13, 2019, 2:24 PM▲ Top
There are a few numbers that stick out as undesirable for a gravel bike, at least for me. The Rawland is designed to fit massive tires, which aren’t needed for gravel, so the frame geometry just isn’t optimal as a gravel grinder. The head tube angle is 73, it’s a number you’d see on a race frame, which makes for a very twitchy bike, but the curved fork slows it down quite a bit. I’m guessing they paired the steep head tube with a extremely curved fork to eliminate toe overlap. But it’s going to increase the wheelbase and really make the bike handle slow. The head tube length of 117 in the size 56 (my size) is very low (making Stack low at 560). To get in my preferred gravel position I’d need a ton of spacers. Last is the chainstay length of 450. Chainstays that long make the bike very stable but make the bike handle and respond like a bus. The chainstays paired with the fork in a size 56 give a 1064 wheelbase, that is massive (at least for a gravel bike). It will be really stable, but just not a lot of fun if you’re doing anything but riding in a flat straight line.

For me I would want a head angle around 70-71. Stack 585 or greater in a 56. Chainstays 430 or less. Most dedicated gravel frames meet these numbers.
3
drwelby
531 posts
#3Aug 13, 2019, 3:00 PM
ljsmith wrote:The head tube angle is 73, it’s a number you’d see on a race frame, which makes for a very twitchy bike, but the curved fork slows it down quite a bit. I’m guessing they paired the steep head tube with a extremely curved fork to eliminate toe overlap.

Nope, it's a low trail bike, the curved fork speeds it up to compensate for a handlebar bag. You're trading off stability from trail's self-centering for stability from a mass damper (the handlebar bag and rack).

You really can't make comparisons, they're two different animals. And the low trail bike really needs the handlebar bag on there to work, it's a key part of the whole system.

I've put in thousands of miles on low trail bikes with fat tires on gravel. They work fine. They do handle differently - there's no lean steer so they don't fishtail or tankslap in loose conditions. I don't like the way they handle on singletrack. But on gravel roads they go exactly where you point them, and the bike never fights you.

But again, you have to run them with some kind of handlebar bag or they are going to handle poorly.
2
protohype
32 posts
#4Aug 13, 2019, 3:25 PM
drwelby wrote:

But again, you have to run them with some kind of handlebar bag or they are going to handle poorly.

I agree with this assessment for the most part. The bike really accels with the front rack/basket and my lunch on board. Without the load, the handling is far too light. I have managed to get used to it but it’s not ideal for gravel logging roads.
0
drwelby
531 posts
#5Aug 13, 2019, 4:28 PM
You're kind of committed with that bike - keep the front rack on it and get a rando front bag like the Swift Ozette or Velo Orange Randonneur. Then all your stuff (snacks, jacket, tools) goes in the bag.

You could also try narrower handlebars - that might make the bike feel less stretched out. Low trail bike usually work better with narrower bars anyway.

If you want a different bike then you probably want to mess around with something like https://www.bikegeocalc.com.

Enter your Rawland as best you can, and then compare the fit with what you'd get with other models. Just look at the contact points, don't worry about the handling.
0
chas
1,305 posts
#6Aug 15, 2019, 8:50 AM
Crazy fork there. 70mm offset. Wow.
One simple solution that would make the bike more stable and lighter would be to put a good normal fork on there. Say something with a 45mm offset.
That would bring your trail up from 32 to a much more reasonable 58mm.
0
protohype
32 posts
#7Aug 15, 2019, 11:59 AM
chas wrote:Crazy fork there. 70mm offset. Wow.
One simple solution that would make the bike more stable and lighter would be to put a good normal fork on there.

That’s a possibility, but I really like how the bike rides as a commuter with a front load. The low trail is magic for that application. Plus the whole bike was designed around that geo so I think it would be a crime to break it up!

So far I’ve determined I want a shorter wheelbase and a higher stack, possibly shorter reach. A new fork probably woudn’t be able to address all of those concerns.
0
drwelby
531 posts
#8Aug 15, 2019, 12:11 PM
I'd almost say that Rawland is too small - you have almost 2" of spacers and your bars are still several inches below your saddle. You definitely want more stack, but also consider that as you swing your arms upwards your hands move forwards, so you probably don't need less reach.
1

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