Road bike vs. recumbent comparison

[Balor]

Biggest problem with flat tires on a bent is the fact you're not able to glance down and see your tires to see if they are low.

Why not, you can sit up and see for yourself? It is equivalent to engaging an aero brake, though .

I did have a slow leak like that on front tire recently - I've noticed suspicious 'vagueness' looked down and saw it being 'squished'.
Turns out I have like a 2mm cut and my sealant nearly dried out, so I had to install a tube.
New sealant fixed it right away.

Since my front tire is 2x presure than the rear, rear tire still have plenty of sealant.

 

[ed72]

I've gone to latex tubes with sealant. I had found in the past that such an arrangement will slow the leakage rate compared to non-sealed butyl combinations. I have not had a flat in months since. I'll probably get one today.

 

[paco1961]

Have posted this before but add again - Mr Toughie tire liners. A small weight penalty for a huge amount of added confidence. I won’t ride without them - DF or bent.

 

[Balor]

I've gone to latex tubes with sealant. I had found in the past that such an arrangement will slow the leakage rate compared to non-sealed butyl combinations. I have not had a flat in months since. I'll probably get one today.

I've installed G-one tires (27.5, 40mm, there are 30mm 700c available) and they are basically "UST" - hold air with no sealant! I've added sealant just in case anyway, of course. Feel very fast and comfortable! (No definitive tests as of yet).

I think it might be a very good option for Vendetta equipped with disk brakes - they are about as high as 23mm wide 700c tire, unless width is also an issue.

 

[ed72]

I've installed G-one tires (27.5, 40mm, there are 30mm 700c available) and they are basically "UST" - hold air with no sealant! I've added sealant just in case anyway, of course. Feel very fast and comfortable! (No definitive tests as of yet).

I think it might be a very good option for Vendetta equipped with disk brakes - they are about as high as 23mm wide 700c tire, unless width is also an issue.

Is that 559? They are out already? Marcel Graber won TABR on those tires but they were prototypes then. Should be fast especially on poor pavement but nothing but suspension will help on your roads. I suspect they will corner really well, too......let us know.

I just put the fast skinny tires onto my bent for this weekend's race down in Washington, NC. The Midlantic 12/24.....can't decide which race to do. I brought a bungee cord to latch onto Larry's V20 if I do the 104 mile race but looking at the videos of past races, the DF riders looked really squirrely. The bents would obviously have to take corners very wide (and slow), so, the DF riders would pass in the corner after sucking the bent rider's wheels nonstop. I am not sure there is much to do about such a performance difference other than to string them out in the pain cave during a cross wind to atone for their errors in judgement although I can't blame them. I have a corner on training route that I used to use to test the adhesion of new tires mounted to my DF. So, I know that corner well. I could take it at close to 30 mph on the right tires on my upright but 22 mph is as fast as I can take it on my bent. Coupled with lower peak power is a bad mix. The relaxed pace of a 12 hour might be better plus I can listen Andrea's jokes for 12 hours, she must have at least 252 chicken jokes

 

[Balor]

27.5 - 650B 40mm, that is. Schwalbe seemed to abandoned 26" (559) format so far as nigh-zoot tires are concerned.
I've bought a 100$ wheelset from China for that purpose - seems very nice for the price.
Again, they are exactly as high as 700c 23mm tires, and I can, if barely fit them into my bent.

They feel surprisingly stiff btw (when you try to bend it around before you install it), but Schwalbe compounds are the real deal.

 

[Balor]

I have a corner on training route that I used to use to test the adhesion of new tires mounted to my DF. So, I know that corner well. I could take it at close to 30 mph on the right tires on my upright but 22 mph is as fast as I can take it on my bent.

That's... strange. Same tires? What could be the difference? Different weight distribution? How EXACTLY did you test that limit - by fitting DH armor? You cannot know what is enough unless you've known what is too much?

Theoretically, a bent with slightly forward weight bias should corner better than DF, because correcting for rear wheel sliding is easier than correcting for front wheel slide, especially on a bent.
Shouldn't your CHR have forward-shifted weight distribution as well? It has a long wheelbase.

 

[RojoRacing]

That's... strange. Same tires? What could be the difference? Different weight distribution? How EXACTLY did you test that limit - by fitting DH armor? You cannot know what is enough unless you've known what is too much?

Theoretically, a bent with slightly forward weight bias should corner better than DF, because correcting for rear wheel sliding is easier than correcting for front wheel slide, especially on a bent.
Shouldn't your CHR have forward-shifted weight distribution as well? It has a long wheelbase.

as a retired professional DF racer of sorts I've saved and not saved dozens of front and rear slides. One thing I can say for sure is that trying to save the same caliber of slide on a bent is 300% less likely. If you were still able to save it on a bent you can be sure the correction arch to get you back on course is twice as big which normally means you're no longer on the road.

Center of gravity values on paper say the bent is fast in a corner but that's only a small part of the equation for cornering fast.

 

[ed72]

That's... strange. Same tires? What could be the difference? Different weight distribution? How EXACTLY did you test that limit - by fitting DH armor? You cannot know what is enough unless you've known what is too much?

Theoretically, a bent with slightly forward weight bias should corTner better than DF, because correcting for rear wheel sliding is easier than correcting for front wheel slide, especially on a bent.
Shouldn't your CHR have forward-shifted weight distribution as well? It has a long wheelbase.

Longer wheelbase is one significant difference (much bigger arc). The ability to absorb bumpy roads being another. Front end geometry is another but these are quick off the top of my head. I have spent so many hours watching Sebring and MidLantic Century race videos where uprights and bents compete comingled that the cornering speed differential is so obvious. I just rode Saturday's race course in my car and a couple 120 degree turns onto narrow roads will require starting in the opposing lane, hitting the apex perfectly, and then using a touch of the oncoming traffic lane......would doable but tough on a crit/road bike (DF). I am on a 54 inch wheelbase bike.....my road bikes are around 39 inches. I test by riding progressively faster and faster. It is chip seal with bumps. On the bent, you get kind of a skidding action. On corners with a large radius (not sharp) and on very good roads, I suppose there is no difference but I don't ride on such roads and thus, a little bias. Same tires.....25 mm GP4Ksii. Putting 35 mm tires onto the road bike would be grossly unfair comparison. Apples to apples. Weight is 50/50 for the M5. I don't know what my custom road bike is.....one design criteria was no wheelies when climbing 20 degree slopes......so maybe 60/40 or maybe 55/45 when on the TT bars.

 

[Balor]

Yea, makes total sense on both accounts. You need to be much more careful on a bent, and unless you, indeed, equip DH armor and willing to take a spill, you need to leave a much greater error margin for a possible slide due to a, say, road irregularity that you'll be able to correct for on DF easily and on a bent - not at all.

 

[Balor]

By the way, Rohorn equipped his motobent with a small degree of rear wheel steering for exactly that reason - 'correcting for long wheelbase'.
It would actually make a bent with a large front weight bias easier to control, too - makes steering not as "overly sensitive", though latter can be a bonus if you can handle that.

 

[bladderhead]

Rear wheel steering would require a linkage. Heavy, complicated and prone to coming loose. Am I right?

 

[Balor]

Rear wheel steering would require a linkage. Heavy, complicated and prone to coming loose. Am I right?

Well, complicated yes, heavy - depends, coming loose - not if you know what you are doing, as with any remote steering. In my case, I'm way 'past saving' on weight front and hence 'give or take a few pounds' don't matter much to me .
I've been contemplating RWS because could not turn around on a narrow 1.5 lane bridge I use as turnaround point on my training loop, but I now can on my new bent, and I'm certainly would not be racing crits so I'll likely pass for now. Plus, making it suspended would be even harder and I'm not willing to part with suspension just yet, I'm loving it way too much. Bents need at least a couple of inches of suspension to equal *rigid* DF bikes to when it comes to dealing with bumps.

 

[Osiris]

It's not just you. There are numerous posts here concerning front flat wipeouts. Most people are shocked but the sudden loss of control as I was. Second flat I managed to stay up although I was only going about 15 mph uphill. On the other hand some people say how easy mbb is to self correct after a slide and when a flat occurs they just slow to a stop. Personally I don't see it. Just wondering if anyone has had bad experience flatting in rear wheel drive such as bacchetta front or rear.

I've never had a flat on any bent other than the V20, and of course it had to be the front tire. Coincidentally, just that morning I had read a post on another forum talking about how quickly a Cruzbike will crash should the front tire flat. I was lucky that in my case it happened near the top of a steep hill, so I wasn't going more than 10 mph. Still, it took all the effort I could muster not to crash. I've had several front tire flats on my DF's over the years, and never experienced any significant loss of control as a result. In one case, I rode the bike half a mile back to the parking lot on a completely deflated tire.

 

[Gary123]

My record was 8 miles on a front flat in the dark on an old Raleigh. Must have been a pretty tight fitting tire. Don't think I could have done that on a vendetta. I'm not knocking the cruzbike but people should be aware of front flat wipeouts.

 

[Balor]

That's not limited to Cruzbikes per se - any MBB (ok, mine being somewhat of an exception ), *especially* French designs that rely on massive trail for stabilizing extremely floppy frond end are particularly affected, or any bent with significant recline for that matter.
Being able to sit bolt upright and steer by body English greatly helps - if you can manage that in time.

 

[bladderhead]

Maybe it depends on which tyres you have. None of my recent pinch flats have caused me to fall off. (The replacements for these ******* Rubino have not been delivered yet.) I used to have Continental Contact on my Grasshopper. They were so stiff, getting them on or off was a terrible fight. I rode miles on a flat. Did not notice. The tyre was so stiff it almost kept its shape.

 

[Gary123]

You're probably right I was running Conti 4000s which are very thin and fast. A tight fitting thicker tire would be more likely to keep control.

 

[Osiris]

That's not limited to Cruzbikes per se - any MBB ...

Yes, while the comment was specifically about a Cruzbike, the problem may a more general one which applies to all MBB designs. As a result of my near crash, I took off the stock wheels and put on a set of tubeless wheels and tubeless Hutchinson tires filled with sealant. That at least restores some measure of confidence when riding the Vendetta on public roads, where you're likely to suffer a puncture.

 

[ed72]

That's not limited to Cruzbikes per se - any MBB (ok, mine being somewhat of an exception ), *especially* French designs that rely on massive trail for stabilizing extremely floppy frond end are particularly affected, or any bent with significant recline for that matter.
Being able to sit bolt upright and steer by body English greatly helps - if you can manage that in time.

I can vouch for that. This front flat on ice feeling can be experienced in all its glory on other bents. I hit a nasty little but deep pothole lurking in the shadows. Immediate front flat. In fact the impact was so great, my rear wheel left the ground. Having grown up riding my bikes on frozen ponds in the North, I could keep it upright but zero steering. The road was sharply off camber and angled to the left, where I wound up in a 2-3 foot deep ditch next to a colonial era graveyard. The poor souls were covering their ears by the time I was done. So, I can confirm a rear drive, reclined bent is a handful with a front tire blowout. Certainly running tubulars would minimize this effect but I was thinking it could also be (perhaps?) mitigated with a different rim width/depth. Some of the new rims are so wide that there is no sidewall or more importantly tread to "cover" the rim bead edge. In effect, the width of the entire casing is taken up by the rim well. Well? Is this plausible?