NeoY2k

Hi,


As my Alloy w carbon fork "Randonneur" Cyfac (Audax bike) w 25mm GP4K tires was way too flexy for loaded touring (to the point of being pretty dangerous actually), I built myself up a new bike - keeping the road bike for unloaded or lightly loaded riding.


So I built a bike based on an alloy Kona Dr Dew 2007 frame I had lying around, paired with the 2012 (I think) Dew Deluxe alloy fork (Kona P2 Hybrid alloy 700c), for a setup very similar to a Kona Rove, or Kona Dew Drop of old. Which all are pretty much the same bike, at least it seemed to me. I am running 32mm Conti GP 5000s.


Sure, it solved the flexiness problems: no more speed wobbles, feels very safe riding loaded.


However, this bike is the harshest thing I have ever ridden. Every chip in the pavement seems to want to destroy my wrists and elbows. Riding the bike loaded with its 4 panniers, it yields some give and gets somewhat less painful. I spent about a week on the road with it, was happy to have carbon bars, staying in the drops provided some suspension and some relief, still, I can't see myself for weeks on end on this bike.


I am puzzled as I always considered that frame and fork compliance were distant seconds to tire width and can't find why it is so brutal. Kona Roves I briefly tried didn't seem any special and they should pretty much be the same bike.


What could be the causes for this problem?

I might consider larger tires, but as 32mm are harsh... GravelKings 40s or Vittoria Voyager Hypers 40s might be larger, but only to some extent, and Conti GP 5K are pretty supple tires, so I doubt there's much more to harness from this way...

I might consider a Redshift suspension stem, but it seems a bit gimmicky... and expensive.

I might consider changing the fork, but 410mm disc forks with rack eyelets aren't common (surlys are 390mm). To my knowledge, this bikes wants 410mm forks, but I might be wrong, anyone having more infos on this frame?


Thanks,

Nicolas (Puzzled)

trailangel

Brooks Conquest or Flyer sprung saddle:
https://www.brooksengland.com/en_us/...s/flyer-3.html
https://www.brooksengland.com/en_us/...onquest-1.html

NeoY2k

Rear end's fine thanks (And I'm not in love with Brooks saddles, though I thoroughly worn a B17 on a previous touring bike).
Front is where the problem is.

bikeaddiction1

How high is your tire pressure? I weigh 180 lbs and I would not run a 32 mm tire at over 70 - 80 psi for perfectly smooth pavement and at least 10 psi lower for mixed surfaces.

NeoY2k

I inflated them at about 70 PSI for loaded touring (5kPa), so it seems about right.
Worried about dropping it too much further because of the added weight re pinch flats (80kg rider + 12kg bike + 17 kg luggage + 2kg water = about 110kg total weight)

fietsbob

there you go, its the 100 psi tires because they're thin, you have to do that..

Probably just HTFU, it is what it is.. gel pads under the tape may help..

I cannot guess if you have clearance for a 40 tire, DIY on the measurement..
larger volume tires use a lower PSI as a result..







..

AnkleWork

Not sure what you mean. Even 100mm tires would also be wider "only to some extent."

Anyway, consider using the widest practical tires. They tend to have lower rolling resistance and aerodynamics hardly matter. For a more comfortable ride on any tire size, set pressure carefully.

NeoY2k

Hmm actually the bike in question in this topic is not the 25mm one, which oddly enough, is less jarring than the new 32mm bike. And that is very much what puzzles me.

NeoY2k

Well 32mms contis GP5K measures true at 32mm on my R460db rims and are a high TPI/supple casing.
So going 40mm with the harder casing associated with might not yield that much of a different.
Or might it?

40mm would fit fine. I don't think any larger would.

Cyclist0108

Get a stopshock stem. They are a wee bit heavy, but definitely work.

Also, let some air out of your tires, try Compass tires as wide as you can put in the frame, etc.

NeoY2k

So you got one and like it? They don't develop play with time?
It is one of the options I consider, but they are expensive and suspensions stems of the past did have an ill fate

fietsbob

Yes, at the high end there are the Rene Herse tires supple casings , for a more compliant ride..

NeoY2k

Though the fundamental and pretty much theoretical question is: how can a frameset make that much of a difference in comfort when its geo is pretty much what you were expecting and that almost similar bikes did not show signs of harshness.
The Sutra was also sold with 32mm tires. Didn't felt the same - though only riding them round the block.

AnkleWork

That's not theoretical; it's empirical. You'll have to measure it.

NeoY2k

Sure, measuring it would provide data.
Though one thing that steers my curiosity toward the frame geo is the measurement I get. I double checked, and I get strange results.

I measured a 73 to 74° head tube angle for what is supposed to be a 71° hta bike.
STA measures at 75° for what is supposed to be a 73,5° sta bike.

My other road audax bike measures at 72° hta which sounds right.

However the fork I fitted it 410mm ac. Could not find the actual info on the fork needed for the 2007 Dr Dew, but I'm not aware of a ie 440-450mm P2 fork...

Handling is not especially wonky, but what I might be feeling might be a messed up geo.

NeoY2k

So, same feelings.
And as puzzled about how a 25mm bike could, thanks to its frame, soak up what 38mm tires could not...

Cyclist0108

It has been fine so far. I use it on a drop-bar mountain bike with a rigid fork.

79pmooney

I keep hearing on this forum that tire size and pressure are everything. I've been riding a long time and just don't buy it. My experience - fork stiffness makes a big to huge difference. Now I haven't ridden CF anything so I cannot comment on CF forks. I do know that on Cycle Oregon, every time we come to harsh chipseal, those of us riding steel and ti bikes have to hit the brakes to stay clear of the carbon bike riders who have just slowed down. (My two ti bikes both have steel forks.)

Of my 5 steel forked bikes, one is a cushy magic carpet - the old Raleigh Competition with almost fishing rod diameter Reynolds 531 fork blades with big bends. My Peter Mooney is a lot stiffer but less stiff than the forks Peter originally made for it. Good on chip seal and decent on rougher. My two ti bike forks are roughly the same as the Mooney except that ti, even using almost the same fork, is wonderful on rough roads. My '83 Trek, probably a lower end 400 something series with heavier tubing, is a real step less comfortable on poor surfaces.

Tire quality means (again in my experience) as much as tire width and pressure. The silk tubulars we raced 40 years ago were wonderful! (Probably 21c though no one measured them.) Our bigger cotton training tires with less pressure, good, but not wonderful. (23-25c?) All the clinchers I've riddine since were a real step down, getting better as I started putting the $70 best Vittorias on my good bikes. Then those bikes got the new Graphene Vittoria G+ 28c tires. Wow! A breakthrough for comfort as big as going to a titanium bicycle.

One trend that I suspect is hurting comfort - disc brakes that require stronger, stiffer forks and frames. I don't know this; just speculating. I have observed that with steel forks, stiffer means less hand comfort. Same holds true for stiffer handlebars, though again, I limit my comments to aluminum and steel.


As all this relates to chipseal and the like - when I got my first ti bike, I found myself seeking out the worst pavement simply because it was so much fun to ride over. Has to discipline myself so I wouldn't be killing tires and wheels. When I went to the 28c Vittoria G+ tires, same thing. That old Raleigh was so much fun riding really rough washboard gravel I spent a grand paying a local frame builder to assure it was string enough to do what was so much fun.

Ben

NeoY2k

Ordered a shockstop stem. Will give you my review.

Though I am now pretty confident I messed up the bike geo, fitting a wrong fork, and maybe that a 74° head angle - on a burly straight fork - makes things worse with vibration traveling straight up. Though how much or wether it actually has this effect, I don't know.

Wether touring on a 74° hta bike makes any sense.. The fork having modest rake (45mm), the resulting bike still has a lot of perceived trail, actually I find it has excessive wheel flop.

Or it might be the combination of low rake and steep hangle that doesn't make much sense, because when computing it I end up with 53mm trail which is low. With a 71° this bike should have had 71mm trail. Strange how low trail feels like excessive trail...

fronesis

EDIT:

I had originally suggested your pressures were too high, but now I see how much weight you are carrying overall, and 70psi for that much weight is NOT too high.

Maybe the aluminum fork is the culprit.

squirtdad

It is not just the tires, The frame is the basis for everything. The wheels and tires come next, but can't overcome a harsh frame. Wheels also make a difference single gauge vs double, etc and then of course the tires

Ride is a sum of the whole

if for your weight the frame and fork is too robust (like a 52 cm frame made from SLX not SL) it will be harsh. Fork design and flex is huge, straight legs may not be be as compliant as needed

frame material can make a difference alloy vs carbon vs steel

not a lot of help I know but some input for your theoretical quesstion

TiHabanero

I am inclined to focus on the fit of the bike, ie, forward weight bias onto the hands, wrists, elbows. I wonder if the fit is a bit more scrunched and the bars slightly lower than previous bike.

Racing Dan

From my experience you need to put some cushioning between yourself and the road. > Lower air pressure, thicker bar tape, gloves?, seat and pants, ect ... else you may sit in a position with too much weight on your hands for you to be comfortable. > Move seat back, raise and move bar closer.

NeoY2k

Actually re: fit, the new bike has the exact same stack as the previous one. Reach, with a 90mm stem, is 8mm longer and I felt cramped. I switched to a 110mm stem and compensating with one less spacer, so the reach is 30mm longer than the older bike. While it felt way better on day rides, after the second day on road it felt too long.

Though with its steeper angles the weight distribution is more forward so that has to be taken into consideration too.

I wanted a more relaxed bike vs the precedent, and actually felt that way with more reach.

But the bike actually felt harsher with the 90mm stem than with the 110mm stem...

This bike really challenges my assumptions.

Re: cushioning: 32mm tires @70 psi for a 110kg rolling weight, thick fizik tape with gel inserts, gore mitts, carbon bars, Arione/SMP saddle, gore shorts... How it is so harsh despite all this cushioning is beyond me.

Koyote

My new bike keeps telling me "You're old, and slow, and you smell bad."

Now that's an overly harsh bike.