9/2/14 2:11 PM

When I started riding D2R2 7-8 years ago, there were few cyclecross bikes. Most people are either on mountain bike with knobby or semi-slick tires. Or they're on touring frame with 28-35 slick road tires.

The next few years, I saw fewer and fewer mtn bikes and more cyclecross bikes.

But the last 2-3 years, I started to see increasing number of mountain bikes again. Upon close inspection, most of them are 29'ers. Majority of riders use knobby tires, though I saw quite a few narrow width knobbies. They seem to be keeping up pretty well.

So let's see what 29'ers are good at and not so good at.

The way I see it:

- disc brake come standard
- 29" wheel rolls just as well as 700C if sporting similar rubber.
- light weight, locked-out forks add a little weight but not a huge penalty any more. Dosen't impact pedal efficiency as bad as older designs.
- many of the 2x10 drivetrains offers good range of gear for the terrain. Often better at the low speed climbing end, if not quite as good at the high speed end.
- While slower on pavement and easy (flat) terrain, there aren't that much of such terrain on D2R2.

What do you all think?

This is just random musing, for a techtalk forum...

9/2/14 2:53 PM

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... 29" wheel rolls just as well as 700C if sporting similar rubber.

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9/2/14 2:58 PM

IMO maybe a disc CX or rigid 29er for folks over 5-9" or so. Although the 29er BB will be a touch high for optimum. Seem like CX bike are now a lot higher BB these days. Grinding no need for that, but plenty benefit of having a low BB, again IMO.

Maybe a Disc CX with a 650B set of wheels. Fit wide higher more volume tires and lower the BB some too. Just gotta pick your geometry carefully maybe?

I also think and learned something with the stiff Aluminum TCX Giant CX I have which fits 38C tires.
big tires brings big comfort. Same 40+ mile trail on 33mm CX Racing Raphs I did not dare go lower that 44/55 lb rode and tracked less than desirably to me.
The 42C Speed conti [really 38 size] same trail, same bike, lower pressure was night and day.

I bombed a 5 mile descent with the 38s in the big ring I had dragged the brakes on with the smaller tires. If speed and comfort are important, and aren't they always?

9/2/14 3:18 PM

We got plenty of CX talks in the other threads.

I'd like to hear what people have to say about 29'er as gravel grinder, as in the thread title.

9/2/14 3:26 PM

Most 29's have a high bottom bracket, very long chainstays, and a slack head angle, leading to a long,high bike, that feels pretty sluggish for road use.

Would it work? yes. Would I enjoy it? No.

YMMV

9/2/14 3:28 PM

29er BB too high as I said, but with a rigid fork with a lower crown to axle length it would quicken up the steering a bit and lower the BB. But if you do not understand the geom and want an off the shelf bike...


BTW, look at both the Giant and Specialized sites. The are both on the adventure/gravel band wagon and have some cool choices..

Specialized even has a steel one, 520 Reynolds I think.

Spesh is the AWOL, and Giant has the x-road series.
Trek and others must be on same wagon by now...

9/2/14 4:24 PM

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Would it work? yes. Would I enjoy it? No.

YMMV

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9/2/14 4:37 PM

I've never ridden a 29er so I can't say much, and I haven't ridden a mountain bike in years (my commuter has flat bars, disks and 26" wheels, but it's not a mtn bike).

The only "advantage" you cite is disks. Assuming you want them (I'm not sold on them), why not just get a cross or gravel bike with them?

I wouldn't want to ride that distance with flat bars, but I'm not a mountain biker.

The fact that people at D2R2 "keep up" on 29ers means nothing. There is a guy who rides a fat bike and is way faster than me. This year a couple on a tandem were faster than me. That's just because they are better riders.

If you had a 29er, I'm sure you could make it work reasonably well. As you know, people ride the event on everything under the sun. Lots of people just retrofit a beater for more rubber and gears. Two of my favorite bikes I saw this year were an '80s Fat Chance, and an old, rusty Romic road frame set up with fenders and wide tires.

But starting from scratch, why a 29er?

9/2/14 5:02 PM

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But starting from scratch, why a 29er?

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9/2/14 5:15 PM

Beats me, I've never ridden one. I got a cross frame and had no problem putting the gears I wanted on it. I just see no reason to use a mtn bike for the ride. But if you want one, go for it.

9/2/14 5:34 PM

Here is a discussion of bikes from the Raid Rockingham site. It is a dirt/gravel ride that is challenging, but less difficult than D2R2. It is sponsored by Independent Fabrications, IMHO a great company that makes all kinds of bikes:

http://raidrockingham.com/tech/

And remember, the best description of bikes for D2R2 is "You don't have the right bike, no matter what bike you have." :)

9/2/14 6:02 PM

I hate to say this, but if you haven't riden one, you can't just brush it off as unsuitable without giving a good arguement as to why.

For those who had 29'ers, it's easier to come to a conclusion based on your own experience, probably easier to back up with understanding of why too.

P.S.
I just saw the other ride. At 50'/mi, it's not even as hard as a typical ROAD ride! Naturally mtn bike don't belong... ;-)

But thanks for the heads up. It's so flat it could be used as a fun early season tune up ride and to work out any equipment kinks. I'll keep that in mind for next year.

9/2/14 6:18 PM

I just asked why you would want to use one, and I still haven't heard an answer that makes sense to me. Gears are easy to set up. You buy a fork you won't use, ride in a position I wouldn't want to, and put on different tires. Whatever. I'm not arguing about anything, go for it. And I've ridden Rockingham, it's plenty difficult for me.

9/2/14 6:59 PM

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And I've ridden Rockingham, it's plenty difficult for me.

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9/2/14 7:12 PM

On the 29'er front:

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I just asked why you would want to use one, and I still haven't heard an answer that makes sense to me.

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9/2/14 8:03 PM

Are you talking about a 29er mt. Bike ?.

The vast majority of those come with front shock forks and do you need that on a really long gravel/dirt ride with pavement thrown in ?. Yes, there are a lot of non-shock bikes, but not as common unless building from a frame.

A shock fork is unnecessary weight, IMO, especially if the alternative is a cross bike with 40mm+ tires at a lower pressure.

9/2/14 8:13 PM

"especially if the alternative is a cross bike with 40mm+ tires at a lower pressure."

+1

9/3/14 5:50 AM

I didn't even consider my 29er for the Dirty Forty, despite it's (currently) better low-end gearing and disc brakes.

- It's 3+ pounds heavier, though I could shave a pound with narrower tires.
- The handling is designed for singletrack, not roads.
- I cannot imagine riding 60-70 road miles with only one hand position; I want road bars.
- The gearing range is actually too wide (biased toward the low end) and as a result, it has big gaps between gears which I don't like on the road.
- Even a locked out suspension fork is less efficient than a rigid fork on roads, plus it accounts for much of the excess weight.

In other words, I'd have to modify it quite a bit to make it work the way I want and it still wouldn't handle as well. Then I'd have to put it all back so I could use it in the woods.

I guess if you were going to have just one bike for both disciplines, either a gravel-specific bike or a 29er (rigid, perhaps?) would be the best compromise, depending on whether you lean toward road or off-road, respectively. A true 'cross bike designed for racing would be the least flexible, but workable option.

9/3/14 4:05 PM

The reason I asked were two fold:

1) Not everybody has a cross bike in their stable. So it becomes a chicken and egg problem for people who find the IDEA of D2R2 (or similar rides) appealing that they have to ride what they have (with minor modification) to get a taste before commiting to build a specific bike in order just to try it for the first time (and HOPE they really do like it 'cause they've now got a new bike!)

Older 26" wheel mtn bikes tend not to give the rider a true taste of the real fun nor the true challenge due to the way those bikes ride (the smaller diameter wheels don't maintain moment well on those many roller coaster sections). I thought 29'ers may bring it closer to what makes the ride fun. Unfortunately, I don't have a niner myself. Or I would have simply jumped on it and see for myself.

2) this is tech talk forum, we frequently theorize on various quirky build configuration that are far out of the box. So I thought this would be something to muse about.

But I guess this is really ROAD bike tech talk forum? Mountain bikes need not apply!

Still, it flushes out one thing I overlooked, flat bar and one hand position. I had forgotten about that part because my hardtail (26" wheel) which I used for commuting and riding with beginners has a set of bar end on it. It doesn't give me a road like position by any stretch of imagination, but does avoid any pressure point issues.

9/3/14 4:26 PM

"But I guess this is really ROAD bike tech talk forum? Mountain bikes need not apply! "

We kind of cover all the bike we all ride/have it seems like.

I would point out that for gravel/adventure use, hybrids have long longish Top tube and tend to have lower BB heights as well. Which is why I grabbed the 2012 Specialized Sirrus frame to make my dedicated ride. They also have more tire clearance than most CX frame/bikes due to folks wanting/riding at least 38C tires 'and' having fenders.

9/3/14 4:38 PM

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I would point out that for gravel/adventure use, hybrids have long longish Top tube and tend to have lower BB heights as well. Which is why I grabbed the 2012 Specialized Sirrus frame to make my dedicated ride. They also have more tire clearance than most CX frame/bikes due to folks wanting/riding at least 38C tires 'and' having fenders.

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9/3/14 4:48 PM

What is not clear about what I said? Be happy to try to be more succinct?

Do you know what a Hybrid bike is ? Comfort bike maybe some call them?

9/3/14 4:53 PM

I don't get the context

9/3/14 5:05 PM

Gravel grinding would be well suited with a hybrid frame. Such as the 2012 Sirrus I and putting together as an example.

Has all the things IMO good for the task.

Low BB, Tire Clearance, Top Tubes tending to be longer than shorter. HTA not as slack as a MYB, and not as steep as a road Geom. So with a short stem and short reach drop bars conducive. Unlikely a hybrid will need a real long stem to accomplish the task.

They also tend to have sloping Top Tube, not good for portage for a CX, but great for off road.

I used my 90s steel trek 730 hybrid for years as my only off road bike. It fit 45C knobbies and with drop bars and barcons it worked for single track to road use with a tire/wheel swap. I also commuted to the LBS on it when I had that job in 2012 wrenching.

9/3/14 7:36 PM

Problem with hybrid is, you can only use the frame, if at all.

Majority of hybrid are stocked with low end wheels/fork/components. Not always the sort you want to ride 60-70 miles of bumpy dirt roads with.

Further, many hybrids frames are made of heavy gauge steel, because that's what the targeted market.

But we've been through the road bike angle. Touring bikes and such had been covered (and used successfully). Hybrids are often heavier than touring frame and has poor quality groupo. I don't see why we need to go there.