Educate me on rim widths

[Overkill]

I'm currently spec'ing some wheels, and I'm trying to figure out what rim width to choose.

I was looking at two rims in particular; the RD (with cut-outs) which is 80mm, and the large marge lite's at 65mm. Other than increasing the footprint by 4-5mm using the 80mm rims, what else am I missing?

I'll be running a nate on the back and a bud on the front.

PS - I did try the FAQ thread, but I didn't see this addressed.

[vikb]

If you want to run a 5" tire I'd go with the 80mm rims to get a better tire profile and sidewall support. The 4" tire would work fine on either rim.

[bdundee]

I find with a wider rim lower pressures feel more stable.

[Overkill]

When you guys use terms like better sidewall suport and more stable, are you referring to the tire folding over? I've experienced this feeling in cyclocross at low pressures on narrow rims compared to wider rims.

[impalapower]

If you want to run a 5" tire I'd go with the 80mm rims to get a better tire profile and sidewall support. The 4" tire would work fine on either rim.

And if 100mm rims were applied to a 5" tire, would the sidewall support get even better yet?

[mikesee]

I'm currently spec'ing some wheels, and I'm trying to figure out what rim width to choose.

I was looking at two rims in particular; the RD (with cut-outs) which is 80mm, and the large marge lite's at 65mm. Other than increasing the footprint by 4-5mm using the 80mm rims, what else am I missing?

I'll be running a nate on the back and a bud on the front.

PS - I did try the FAQ thread, but I didn't see this addressed.

Need lots more info to give any kind of real recommendation.

Your height/weight?

Where and how (and for how long, and how often) you'll ride this bike?

% of dirt vs. snow?

Carrying any kind of load?

etc... etc...

[Overkill]

Ah, an experienced wheel builder - my lucky day!

To answer your questions:

I'm 5'8 and 145 pounds and will be riding this bike 90% snow and 10% dirt trails. I have no plans to be loading it up with extra weight for touring. I'm a competitive racer looking to ride all year and have some fun.

I'll likely be riding this bike 3 times per week during the winter and very little if any during the rest of the year. I'll be riding on trails and a local railway track (not in service) that had been walked on and snowshoed on.

I'd like to keep the bike light which is why I was wondering if it made much difference between the two rims. The Marge lites would be 3/4 pound lighter.

I'm interested to hear your thoughts.

[bdundee]

Another option which I have done 4 times now is buy unholy RD's and drill them out with 1.5" holes. Saves some cash and saves about 100g over the drilled stock RD's. Don't quote me but I think I ended up around 770g when it was all said and done.

[vikb]

When you guys use terms like better sidewall suport and more stable, are you referring to the tire folding over? I've experienced this feeling in cyclocross at low pressures on narrow rims compared to wider rims.

If you cut a cross section of a really wide tire on a narrow rim it looks like a lightbulb and when you push it sideways [cornering or steering] it can flex easily. As you use a wider rim that profile changes to look more like an upside down "U". The tire doesn't flex sideways as much with a wider rim.

I moved to a wider rim on my MTB with 2.4" tires this summer and noticed a significant improvement in steering precision compared to the same tire on a narrower rim. I'm much more confident descending techy fast sections now because I can place the bike exactly where I want it to go.

I'll be paying more attention to the tire width vs. rim width when I buy new wheel components for my MTBs.

[mikesee]

Two more questions:

Which frame/fork?

Where do you live--i.e. what kind and quantity of snowfall do you see in a week/month/season?

I ask because Colorado or Utah light and dry varies drastically from Sierra cement, Anchorage melt-freeze, or Michigan muck. See?

[Overkill]

I'll be using a 907 frame (170mm rear) and a carver o'beast fork.

I live in Quebec Canada, just outside of Ottawa. We receive about 100 inches of snow per season that stays on the ground from December to march. It's quite cold here, so our snow is normally dry. We likely see close to 5 to 10 inches per week.

It you step off the trail, You'll be up to your waist in snow!

[mikesee]

I'll be using a 907 frame (170mm rear) and a carver o'beast fork.

I live in Quebec Canada, just outside of Ottawa. We receive about 100 inches of snow per season that stays on the ground from December to march. It's quite cold here, so our snow is normally dry. We likely see close to 5 to 10 inches per week.

It you step off the trail, You'll be up to your waist in snow!

Given all that you've written, RD's are probably overkill. If I were in your shoes, and assuming that you can fit a 4.8" tire in the rear of your frame, I'd pick the Marge Lite's. You're light enough that you don't need an 80mm rim, and your snow has enough moisture content that it's going to pack together pretty well.

If you like being the first one out (freshies!) after a storm, get a Bud tire for up front, and either a Nate or a Lou out back. If you tend to wait til things have been packed in by others, you'll likely be happiest with a BFL up front and Husker Du out back.

Good luck,

MC

[duggus]

From what I've read on here the Lou won't fit on a 170 rear 907. The Nate/Bud would be perfect, which is what you were looking at from your first post. I also think Surly recommends at least the 80mm rim to run their 4.8" tires... so you could go Rolling Darryl/Bud front, Marge Lite/Nate rear. Or just both as Rolling Darryl's.

Keep in mind you say you want to ride this nearly exclusively in snow... wider is better in snow.

[FoldersUnite]

What bike store are you using? I'm from Ottawa too and the stores don't tend to sell many fat bikes.

[Overkill]

Thanks for the great info guys. Yeah, my plan has been bud up front and Nate in the back.

I've only demoed a bike a couple of times (in the snow), and I can see myself more of a "freshie" as you call them - so it appears I was on the right track as far as tire selection goes.

It sounds like I can go either way on the rims which is nice to know. That may be a good compromise having the 80mm on the front and 65mm on the back.

Thanks for all the info guys, I've learned a lot - especially from mike. Cheers.

[Overkill]

Tall Tree Cycles in westboro. Talk to Will, Thom, Brad, or Grant. There is lots of inventory flowing in this week, so I'd pop in there in case certain items go fast.

[gcappy]

From what I've read on here the Lou won't fit on a 170 rear 907. The Nate/Bud would be perfect, which is what you were looking at from your first post. I also think Surly recommends at least the 80mm rim to run their 4.8" tires... so you could go Rolling Darryl/Bud front, Marge Lite/Nate rear. Or just both as Rolling Darryl's.

Keep in mind you say you want to ride this nearly exclusively in snow... wider is better in snow.

This is correct. Lou will NOT fit on a 100 mm rim on a 9-0-7 170 centered frame. The BFL's just make it.