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wyrd bið ful ãræd
1,725 Posts
Discussion Starter · #1 ·
I am 1.77m (5'10") with 0.84m (33") inseam and I ride an ARC in size M. Have been doing so for the last 4 years. But lately I feel as though my lower back is starting to ache. Age is catching up on me too, but I also have a FS which do not give me that same pain in the lower back ... :rolleyes:

Here's the geometry.
- effective top tube length 23.5" (close enough to what is on the Yeti webste)
- stem 10°up, 90mm, flat bar
- effective top tube length 23"
- stem 0°, 70mm, riser bar

My seat position on the FS is lower than the handlebars, whereas, in the ARC, it is almost level.

I have to also mention that the ARC is now a road bike for me, for the last 2 years, and I am using 700C rims and because I am using 28mm road tyres, the actual diameter of the wheels is no different to when I was using off-road tyres in a 26" rim, if you get what I mean. AND, quite important I feel, is that the fork that I am using on my ARC has an A2C length of 440mm as opposed to the 470mm specified by YETI. Contributing factor?

Should I try out an ARC in size SMALL then, which has an effective top tube length at 22.5"? as on the last couple of rides I have noticed that when I am just crusing along, with my palms flat on the bar, I feel as though I am reaching forward slightly, which may contribute the ache in the lower back.

Do any of your guys also have a 'real' road bike? Is the effective top tube length shorter on a road bike than on your mtb? Is it just me or when I see roadies, they do tend to seem to be a bit cramped up in the bike frame? Maybe as they do NOT need the additional cockpit space that mtbs need?

Who is John Galt?
1,771 Posts
I am 6' and ride a large size ARC, can't see going any smaller. Maybe that's your problem, you aren't stretched out enough? But I've got to say the lower back pain is most likely caused by the hardtail, I get the crud beat out of me on my ARC though it's getting better now that I'm getting some hardtail skills and not depending on the 575s suspension to run over everything, LOL. Since you are on the road that's not going to be as big a problem but few roads are perfect. I do have a road bike, it's an Orbea Onix and I'm a 54 cm if that helps any. Only time I get lower back pain is when I haven't ridden in awhile. I've got my ARC set up with the bars almost level with the saddle, with a riser bar and three spacers under the bar.

722 Posts
I'm just about 6ft and tried a Large ARC, and a Medium, and I thought the medium was better for me, however if I was a fraction taller I'd want a Large.

My Father has a small, and its way to tiny, if your inside leg is like mine at 32", yo uwill need a mega long seat post!

Probably look at different bar stem set up for a bit more comfort.

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