I took a different approach to a seat, but I was unsuccessful as the seat was too wide in the middle and therefore uncomfortable. The basic idea was to have it where most the pressure would have to be in the back and there would be a large opening in the front so all the sensitive bits would be free. The front part extended out to create a handle as well.
Here are some pics from May when I was building it, though I never took any final pics of it.
This is the core made of cardboard before I laid the composite over it:
This one is part way in the layup process and shows some of the shape:
I might have to make another attempt on this sometime.
I agree whole-heartedly with both of you (Ken and Harper). I have to keep the pressure up to at least 40 psi or cornering feels like running in a pool while wearing flippers. I also noticed that for some reason, the tire deflates pretty fast. One morning it was 20 psi (and I’d only filled it up a week or two beforehand). I only like low tire pressure when riding on rainy sidewalks – it’s still hard to turn, but there’s more tire holding the ground, so it might be safer (actually, I’m not sure about that).
I wonder if the w-i-d-e KH 700c rim would improve the handling of the Big Apple tire? The KH 700c rim is 30.8 mm wide inside and 38.0 mm wide outside width. It’s the same width as the KH XC 24" rim. It might be worth it to rebuild the Schlumpf wheel with a KH rim if the KH rim handles better.
I’ve ridden many road miles on my KH29 outfitted with the BA2.35. At high pressure, it handles amazingly well, allowing incredible leaning turns which feel like I’m riding my own personal roller coaster.
yeah, I’m agreeing here with the high pressure sentiment. After I put some more air in the thing, and raised the seat and started pedalling with my toes, the kh29 was a dream to spin up to fast speeds. I didn’t find it helped much when I let some pressure out for offroading either - it seems to be a tire that likes to be nice and full.
Uh,…your welcome? I am sure you didn’t mean for that line to sound derogatory and I am glad you are experimenting, but I think I better make some clarifications lest some may be misled.
Ken didn’t buy a complete seat or one of my molded air cushions. He bought one of my DeRail CF seat bases, and a Gemcrest low profile leather cover (with my retaining wire bead), and a DeathGrip handle. I also sent him a dual density foam cushion that I had never tested but I thought might help him with his flat seat buildup. It has (or had) a center relief groove. We had an email discussion about his flat-seat desires.
My DeRail bases are considerably less curved than a Gemcrest CF base, so I’m not sure what you are reffering to on the concavity but would like to know.
I build my RoadRelief saddles with low curvature, but usually not completely flat. I adjust the curve using closed cell foam wedges under the molded air cushion. You can achieve any surface shape on any base using this method. Seat and component pics
Keep us posted on your high speed antics, Ken! (and your seat surgeries)
Ken, your first experiments are really interesting. Sounds like the future. I can’t wait to try it out in Laos. But it sounds like the seatpost is not very adjustable…too bad they are 25.4 as well.
Anyway, that is AWESOME that you were riding at full Coker speed on your very first ride (and while sick too)! I think you’re right - get used to it so you can run shorter cranks and it will blow the Coker away. But I hear you on the crank dilemma - in order to go touring, you actually do have to be able to climb hills.
Hi Scott- sorry I didn’t mean to mislead anyone- your seat foam is certainly less curved than the most, and I was using a miyata carbon seatbase. What I did was shave off the back and front of the foam, so that it’s thickest on the most curved part of the miyata base (the centre). Therefore, it’s even flatter now. The aim was a completely flat seat, but I think it’s limited by the sort of seatbase you’re using. I think your seatbases are even flatter than the miyatas. And I love cutting things up so please don’t take offence
Hmm…more pressure on the Big Apple- sounds like a plan.
Hi David, I’ve got the 125mm cranks on- but on the hyperdrive mode it takes a lot more effort to ride up steep hills. I wasn’t able to ride up a hill that I normally would with a Coker/110’s.
On the other hand, switching down to 125mm/29" and you feel almost undergeared going up the same hill. If only you could switch from say 1:1.55 to 1:1.2 or something like that.
I’ve changed the pedals over to Snafus- quite a large and stable platform, although a tad heavy. In terms of the spokes- I prefer all my wheels to be built up by my LBS anyway (the mechanic is top notch), so will take it in and rebuild with some double butted spokes. Having loose spokes just gives me an excuse to get it done sooner:) .
I went for another quick ride to Makara Beach. After pumping the Big Apple tyre up hard, it certainly felt less squirelly.
Distance 17km each way:
Time to the Beach 41:20 (battling a headwind)
Return total: 1hr:30:12 (?did that headwind change direction?)
My impressions are that it is significantly easier to cruise at a slightly greater speed than a Coker, but anything over 25km/hr takes much more effort. Especially on the lumpy roads where I live- each bump has more potential to throw you off.
It is possible to spin the cranks as fast as on a Coker, but it’s so much twitchier that you have to concentrate much harder. That’s why there is actually not as big a time difference between a 36" Coker and 46" Schlumpf in Overdrive mode on my current circuit as you would expect. Also, on some uphills where I would have ridden on my Coker- I had to struggle with on the Schlumpf. I couldn’t ride up a 10% grade without going very very slowly and wobbling all over the road and falling off eventually. In the end I flicked over th 29" mode and it seemed to work fine.
I think I will put on shorter cranks to try and make the Schlumpf more stable. Longer cranks increase leverage on both ends. On your end you have more power, but when you hit a bump the axle has more leverage on your foot and can throw you off more.
I guess as always it’s a case of picking the right gear for what you are riding. To optimise efficiency, you need to use the gear with the greatest overlap to your terrain. So in terms of terrain this is what I would pick for different grades (all with 125mm cranks):
>10% downhill: Schlumpf 1:1 mode
5-10% dowhill: Coker 36" or 46" Schlumpf Overdrive mode
0-5%: Sclumpf 46" Overdrive
0-3%: Sclumpf 46" Overdrive
3-5%: Coker or 46" Schlumpf tied
5-10%: Coker
10% or greater: Sclumpf 29’er 1:1
That’s based on a rough estimate, but I think that for flat and slight inclines, a 36" gear is undergeared, and that is where the Schlumpf has it’s advantage. Of course, you have two gears to choose from, but I only changed it a couple of times during my ride, because I haven’t got the hang of on the fly shifting yet (it’s my third ride).
Those downhill preferences probably assume that you don’t have a
brake. If you do, I’d guess that the Schlumpf in geared mode would
rule on all downhills, as well as on the flat and on uphills up to
about 4%.
That means that the Schlumpf is always preferred, except for the
uphills between 5 and 10 percent, because the gear step between 1:1
and 1:1.55 is so large that the Coker fills the niche.
My Schlumpf 29’er should arrive this month. I can hardly wait.
Meanwhile, all reviews and stories are perused!
Klaas Bil - Newsgroup Addict
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Possibly, I think it’s still faster to spin a small gear fast downhill than to use a brake to try and slow down a heavy Coker wheel or a Schlumpf in 46" geared mode. I reckon you’d have more control spinning fast than using a brake.
Thinking about it again, I reckon the cut off should be more like 5-8%, but it is a continuum, and specific to my style of riding, my prefered cadence, and 125mm cranks. But there are so many variables: For example, I reckon changing cranks down to 110mm would give a more efficient spread of gearing- a 29’er/125mm feels a little undergeared on 5-8% grades, a 46"/125mm slightly overgeared. 29’er/110 could be just right. Therefore everything 5% or steeper I’d flick into 29", anything between 10% down and 5% up I’d use a 46" Schlumpf. Alternatively, you could stick 150mm cranks on the Schlumpf and ride it in 46" mode on just about anything, without bothering to change gears at all. But that’s not why we buy something with gears is it :)?
NB: above are just my guesstimates. I’d be interested to hear your opinion if you have the time to experiment with your inclinometer .
My guni is out of commission for the next few days. I’ve had to resort to riding my Coker (with 125s) on my commutes for the last fortnight.
And it wasn’t so bad! I knew that the downhills and flats would be considerably slower (I’m not sure HOW slow bc my Coker’s cycle computer is clearly way off, but I think my max speed on the Coker is no more than 16 mph due to the large crank size. Maybe they are 140s?
Anyway, as Ken has noted, there are areas where the Coker definitely rules. My commute is divided almost evenly bw bike path and sidewalk. The sidewalk riding requires weaving among pedestrians at times. There are also the potent lures of sign posts, hydrants, and other obstacles to ride around. Here the Coker allows for much greater control (despite the additional height of the rider). I have also developed techniques, like resting one leg against the wheel, that aid in still-standing at street lights. And then on the uphill sidewalks, the Coker is much better because of the long cranks and the smaller wheel (compared with the 46" guni). I’ve tried switching down to 1:1 on the Schlumpf on those uphill sidewalks, and it’s ok, but there is a sacrifice in speed at times, depending on the block.
But when I get to the bike path, riding the Coker makes me feel like I’m
riding a 26". It feels SO SLOW.
Like Ken, I have a breakdown of ideal riding size. If only I had a cycle team (the Tour de Stone) to keep up with me>
REALLY steep downhills: 29" guni
Steep downhills: Coker
Crowded sidewalks: 29" guni or Coker
Steep uphills: Coker or 46" guni (depending on how steep)
REALLY steep uphills: 29" guni
Everything else: 46" guni
I’ve fiddled around with Excel a bit and produced the attached graph that shows exactly that: it is a continuum. This is based on your earlier numbers.
But I would need LONG roads that have various grades, and I don’t have those here. Every climb is short, except the ones of 0 %.
Can you believe that I ordered a brake on my Guni?
Hmmm…got me thinking. I wonder what would happen to those curves with shorter cranks (say 110mm?). I would guess that it will steepen both the Schlumph 1:1 and 1:1.55 curves, but there will be a greater difference between the two at either end- essentially a wider gear differential (ie it would steepen the 1:1.55 more than the 1:1).
Interesting.
BTW, I found that less effort is needed to slow down the wheel even at 46" mode, simply because the wheel is so much lighter and has less momentum at any given speed.
I am sure you didn’t mean for that line to sound derogatory and I am glad you are experimenting, but I think I better make some clarifications lest some may be misled.
.