Designing a bike for rough road brevets and light multi-days

[Clean39T]

More long winter days thought experiments ahead..

EDIT :: clarified some thinking based on convos below.

I have a notion that it would be fun to have a bike that could work well with a pair of aerobars, a forward saddle position, and aero wheels for brevets and ultra-distance stuff, light n' fast multi-day tours and the like, with two setup styles depending on whether the terrain is rolling/flattish, or hilly/mountainous. It'd also be my traveling bike.

I'm thinking something with 73STA and 72-73HTA and higher trail (50mm rake to get into the upper 50s trail figure) and longer wheelbase to make things stable. Probably 430 CS, making for around 1040 wheelbase.

The 73-STA for me would mean I would run a 12mm setback post with an SMP Forma/Dynamic when in mountaining mode, and a 0-mm setback post with something like a SMP T-3 saddle when in rolling mode.

I think I'd design the reach to work with a 120mm stem in dirt-road mode and a 100-110mm stem in brevet mode. For me, that's a 590 TT.

Tire clearance would be maximized under TRP 957s - so measured 36-38mm max. Would run 30s in pure road mode, 35-38s in dank chipseal or dirt-road mode.

And of course steel frame/fork - with some specific braze-ons.

What got me thinking about this is: https://redshiftsports.com/pages/switch-aero-system

But then I thought, why not achieve the same thing with normal parts and less weight.....

I suppose I could just mock my Kirk up like this and try it out. But internet ramblings are more accessible on a day where there's a few inches of fresh snow keeping me off the tarmac.

[prototoast]

If you need to switch saddles too, I'd think two seatposts with a stop marked on them would make the most sense. If a single saddle could meet both needs, I'd give the Redshift a try.

[Clean39T]

Originally Posted by prototoast

If you need to switch saddles too, I'd think two seatposts with a stop marked on them would make the most sense. If a single saddle could meet both needs, I'd give the Redshift a try.

I think I would need/want to switch saddles.

I'd probably try this SMP: https://www.sellesmp.com/us_en/t3.html.

I do realize a Grevil would do this, so would an Aspero. The steel addiction is hard to quit..

[pelicanrando]

It's a fun idea. For off road races and events I'd prefer a wider tire and different brakes, but it sounds great for brevets/ultradistance. Would you do dynamo or battery lighting? And would you use bikepacking bags for carrying everything?

[ColonelJLloyd]

I do this with my bike. No ultra-distance stuff, but I like aero bars in the endurance position for centuries and even shorter rides. By endurance position I mean the elbow rests are at a level that keeps my hip angle more or less the same as when I'm riding in the drops. Maybe even split between hoods and drops. This means 30mm risers under the elbow rests, but I'm actually going to increase that a bit this spring.

Anecdotally, using the aero bars means a 1mp on flats (say 18mph vs 17mph), but I do it because it changes my position and rests some neck, back, and shoulder muscles. It takes just a couple minutes to remove or install the bars and nothing else changes including my saddle position.

My bike's geo is pretty much what you describe (73/73, 430 CS, 110mm stem) and steel. Discs make it easier, but heavier.

[BRad704]

I looked hard at that Redshift seatpost when I signed up for a Half IM. Since I don't have a TT bike, it still might be a good option.

The idea for light offroad use would be an interesting option in your build. Are you thinking through custom frame builds? or would something like a Schwinn Le Tour or SuperSport work, since they have clearance for 35-38's already? Fork swap to get your desired rake and trail of course...

[Bici-Sonora]

Originally Posted by Clean39T

More long winter days thought experiments ahead..

I have a notion that it would be fun to have a bike that could work well with a pair of aerobars, a forward saddle position, and aero wheels for brevets and ultra-distance stuff, that could also be used for dirt-road events.

I'm thinking something with 73/72 angles and higher trail (50mm rake to get into the upper 50s trail figure) and longer wheelbase to make things stable. Probably 430 CS, making for around 1040 wheelbase.

The 73-STA for me would mean I would run a 12mm setback post with an SMP Forma/Dynamic when in dirt-road mode, and a 0-mm setback post with something like a Bontrager Hilo saddle when in brevet mode.

I think I'd design the reach to work with a 120mm stem in dirt-road mode and a 100-110mm stem in brevet mode. For me, that's a 590 TT.

Tire clearance would be maximized under TRP 957s - so measured 36-38mm max. Would run 30s in road mode, 35-38s in dirt mode.

And of course steel frame/fork - with some specific braze-ons.

What got me thinking about this is: https://redshiftsports.com/pages/switch-aero-system

But then I thought, why not achieve the same thing with normal parts and less weight.....

I suppose I could just mock my Kirk up like this and try it out. But internet ramblings are more accessible on a day where there's a few inches of fresh snow keeping me off the tarmac.

To get your mechanical trail to mid-50s numbers with a 72 HTA and 35mm tires, you'll need a fork in the 52-55mm offset range--definitely custom steel territory. If you steepen the HTA a little to 72.5 you could do a fork with 50mm offset and get the same trail.

[David in Maine]

Here is an interesting blog post that explores aero bar set-up for ultra rides. My take-away is using a more forward, aggressive saddle placement might compromise the use of the regular road bike hand positions and lead to discomfort on a long brevet.
https://torstenfrank.wordpress.com/2...aerobar-setup/

David

[Clean39T]

Originally Posted by pelicanrando

It's a fun idea. For off road races and events I'd prefer a wider tire and different brakes, but it sounds great for brevets/ultradistance. Would you do dynamo or battery lighting? And would you use bikepacking bags for carrying everything?

I think I would do battery lights.

The off-road races would be ones that include dirt-roads, not singletrack and deep chonk - anything more serious I'd want different geo and a different bike in total.

[fiamme red]

When I read "dirty racing," I was thinking of an elbow in your rival's ribs or a pump in his spokes.

[Clean39T]

Originally Posted by David in Maine

Here is an interesting blog post that explores aero bar set-up for ultra rides. My take-away is using a more forward, aggressive saddle placement might compromise the use of the regular road bike hand positions and lead to discomfort on a long brevet.
https://torstenfrank.wordpress.com/2...aerobar-setup/

David

That's what I'm puzzled over. I'd like aero bars for long lonely roads and keeping the hands happy, but if it comes with too many trade-offs, what's the point? Especially if the bars themselves mess up the handling.. or if they are generally unrideable in strong winds.

[Clean39T]

Originally Posted by fiamme red

When I read "dirty racing," I was thinking of an elbow in your rival's ribs or a pump in his spokes.

That would be racing dirty..

[Clean39T]

Originally Posted by ColonelJLloyd

I do this with my bike. No ultra-distance stuff, but I like aero bars in the endurance position for centuries and even shorter rides. By endurance position I mean the elbow rests are at a level that keeps my hip angle more or less the same as when I'm riding in the drops. Maybe even split between hoods and drops. This means 30mm risers under the elbow rests, but I'm actually going to increase that a bit this spring.

Anecdotally, using the aero bars means a 1mp on flats (say 18mph vs 17mph), but I do it because it changes my position and rests some neck, back, and shoulder muscles. It takes just a couple minutes to remove or install the bars and nothing else changes including my saddle position.

My bike's geo is pretty much what you describe (73/73, 430 CS, 110mm stem) and steel. Discs make it easier, but heavier.

Could you share some pics of your setup? I'd like to see how the aero bars sit on your bars, arm-rests, etc. I think I'd be in a similar place of not going much more acute in my hip angle than when in the drops.

[Clean39T]

Originally Posted by Bici-Sonora

To get your mechanical trail to mid-50s numbers with a 72 HTA and 35mm tires, you'll need a fork in the 52-55mm offset range--definitely custom steel territory. If you steepen the HTA a little to 72.5 you could do a fork with 50mm offset and get the same trail.

Good point. I was looking at front-end geo on the Aspero and Grevil, as well as Caledonia..

Have you ever experimented with aero bars on your longer brevets?

[mhespenheide]

My first concern is that you might later feel limited by a tire clearance of 700c-38mm, even though that feels fat in comparison to your road bikes.

As much as you and I love custom steel and rim brakes, I think this is a very good example of a use-case for disc brakes and having the option to switch to 650b-42mm or even 650b-48mm. (And if you're going to go disc and lose the sweetness of a steel fork with rim brakes, you might as well go carbon for the frame and fork.)

Pairing a wheelset switch with a seatpost and saddle and aerobar switch gets you quite different uses with a single frame and components without significant compromises either direction.

Or you could just add a pair of aerobars on to one of your existing steel bikes and ride brevets with that and then optimize for your dirt events ... but you've bought other dirt-road bikes and then sold them later saying that gravel isn't your thing.