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Old 02-16-06, 05:22 PM   #1
Trocadile
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Who has switched tires on their Downtube?

Hi - I'm new to the forum and to folders. I've been riding a 2005 Downtube VIII FS for a couple weeks and enjoying it quite a bit while I work on tweaking it. I'm curious about how different tires might affect its performance. The 1.75 Kendas it comes with seem like decent all-purpose tires and have handled the gravel, mud and ice I sometimes go through pretty well, but I'm hoping I can have my cake and eat it too by finding some tires that are still decent on rough tracks but quicker on the smooth stuff. Any suggestions? I'm interested especially in tires like the 1.5 Marathons and Primo Comet Kevlars, but would be glad to hear from anybody who's changed about why they did and how the new tires compared to the stock ones in terms of performance and comfort. Thanks for any feedback
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Old 02-16-06, 06:52 PM   #2
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Quote:
Originally Posted by Trocadile
Hi - I'm new to the forum and to folders. I've been riding a 2005 Downtube VIII FS for a couple weeks and enjoying it quite a bit while I work on tweaking it. I'm curious about how different tires might affect its performance. The 1.75 Kendas it comes with seem like decent all-purpose tires and have handled the gravel, mud and ice I sometimes go through pretty well, but I'm hoping I can have my cake and eat it too by finding some tires that are still decent on rough tracks but quicker on the smooth stuff. Any suggestions? I'm interested especially in tires like the 1.5 Marathons and Primo Comet Kevlars, but would be glad to hear from anybody who's changed about why they did and how the new tires compared to the stock ones in terms of performance and comfort. Thanks for any feedback
Welcome Trocadile! I left the stock all purpose Kenda 1.75 on the front as I also travel bad roads and added a Slime Liner .. I recycled the Kenda Kwest 100psi 1.50 from my Xootr/Swift ( I went to Rolfs and Stelvios on that bike) and the slick went to the rear and I now have a spare for front and rear for the Downtube ...in addition, I changed out the FS's rear wheel for an Alex16 with Shimano Redband 8spd hub to lose the derailleur, gain the benefits of a straight chainline and to have a greater gear range .... this combination works great for me on and off asphalt and seems to be a fine compromise for the multi-terrain uses I put this bike through..

Bruce
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Old 02-16-06, 08:21 PM   #3
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got 1.25 100psi slicks on my girlfriend's DTVIII-FS05. A lot faster than before, not sure how it would behave in rough terrain (her bike is for flat asfalt only).

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Old 02-16-06, 11:11 PM   #4
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Quote:
Originally Posted by BruceMetras
...in addition, I changed out the FS's rear wheel for an Alex16 with Shimano Redband 8spd hub to lose the derailleur, gain the benefits of a straight chainline and to have a greater gear range .... this combination works great for me on and off asphalt and seems to be a fine compromise for the multi-terrain uses I put this bike through..

Bruce
How does the low gear on the internal gear Shimano compare to the stock gearing on the Downtube FS?
I live in the hills.
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Old 02-17-06, 01:50 AM   #5
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I am thinking of changing the tire on my Downtube VIII FS. Thinking of Schwalbe Big Apple or Marathon Plus. These are good tires. However, I cannot decide. I am looking for grip before comfort and of course, least rolling resistance is nice.

Any suggestions is most appreicated.
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Old 02-17-06, 09:37 AM   #6
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I changed the tires on my DT VIII FS to Primo Comet Kevlars. It makes riding on-raod so much easier. I have also taken it on hard-packed gravel paths with some loose gravel on top and/or some light mud. They are ok for that, but I don't think they are good for real off-road, loose gravel roads/paths, deeper mud, or snow/ice.I run mine at the max. tire pressure, so maybe for the rougher stuff, lowering the tire pressure might help.
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Old 02-17-06, 10:19 AM   #7
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Originally Posted by hbob
How does the low gear on the internal gear Shimano compare to the stock gearing on the Downtube FS?
I live in the hills.
Hbob
That's one of the beauties of the hubgear ... you can easily tailor your gear range by just replacing the rear sprocket.. The stock Downtube runs 46 11/28 drivetrain(254%) giving you approximately 32 to 81 gear inches.. The new Shimano 8spd hub has a 307% gear range.. if you wanted to keep the top 81 gear inch figure using the Shimano, your low would be 26 gear inches... if you wanted a lower range, you could change the rear sprocket to say a 21t and would have a low around 21 gear inches.. hub sprockets are cheap and available from vendors like Sheldons.

Bruce
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Old 02-23-06, 11:46 AM   #8
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Originally Posted by BruceMetras
Welcome Trocadile! I left the stock all purpose Kenda 1.75 on the front as I also travel bad roads and added a Slime Liner .. I recycled the Kenda Kwest 100psi 1.50 from my Xootr/Swift ( I went to Rolfs and Stelvios on that bike) and the slick went to the rear and I now have a spare for front and rear for the Downtube ...in addition, I changed out the FS's rear wheel for an Alex16 with Shimano Redband 8spd hub to lose the derailleur, gain the benefits of a straight chainline and to have a greater gear range .... this combination works great for me on and off asphalt and seems to be a fine compromise for the multi-terrain uses I put this bike through..

Bruce
Bruce, Did you have to change the dropout or did the Shimano hub fit fine on the stock bike?
I know you need a horizontal dropout to adjust the chain tension.
HBob
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Old 02-23-06, 12:35 PM   #9
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Originally Posted by hbob
Bruce, Did you have to change the dropout or did the Shimano hub fit fine on the stock bike?
I know you need a horizontal dropout to adjust the chain tension.
HBob
I have an 05 Downtube FS and it has horizontal dropouts.. I think the 06 FS will have a vertical dropout... some of the 06 hardtail Downtubes will come with a hub gear, so I would guess those would have horizontal ones... the chain tension on the FS will be a compromise if you're not using a spring loaded add-on tensioner to compensate for the change in chain tension due to the working rear suspension. On mine, I loaded/bottomed the suspension, set the tension and simply ignore the chain slack when I'm not on the bike. So far, I'm not dropping the chain on my rides.

Bruce
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Old 02-23-06, 01:42 PM   #10
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Quote:
Originally Posted by BruceMetras
.. the chain tension on the FS will be a compromise if you're not using a spring loaded add-on tensioner to compensate for the change in chain tension due to the working rear suspension. On mine, I loaded/bottomed the suspension, set the tension and simply ignore the chain slack when I'm not on the bike. So far, I'm not dropping the chain on my rides.

Bruce
Bruce, Great recommendation for the solution. Thanks. I am on the fence about the Nexus 7 and 8.
I am much more in to up-hill ability than overall range and speed downhill, so I would control that with my hub gear.
Did you get the shimano grip shift?
HBob
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Old 02-23-06, 02:28 PM   #11
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Quote:
Originally Posted by hbob
Bruce, Great recommendation for the solution. Thanks. I am on the fence about the Nexus 7 and 8.
I am much more in to up-hill ability than overall range and speed downhill, so I would control that with my hub gear.
Did you get the shimano grip shift?
HBob
Bob, if you're on the fence, definately get the new Nexus RedBand 8spd hub as it is one of their flagship hubs and is supposed to be the most efficient of their lot .. I got mine Here. I'm sure there are other places selling them, I just happen to like the outfit. It is said that the Shimano twist grip is the only one to work with the new Shimano 8spd, so that's what I'm using and have yet to try any other shifter arrangement.

Bruce
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Old 02-24-06, 04:11 PM   #12
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Originally Posted by BruceMetras
Bob, if you're on the fence, definately get the new Nexus RedBand 8spd hub as it is one of their flagship hubs and is supposed to be the most efficient of their lot .. I got mine Here. I'm sure there are other places selling them, I just happen to like the outfit. It is said that the Shimano twist grip is the only one to work with the new Shimano 8spd, so that's what I'm using and have yet to try any other shifter arrangement.

Bruce
I am going for the Nexus 8 Hub,but am considering the coaster brake model. What do you think of that.
Should the gearing be as good, or does coaster compromise other parts? How do you like the wheel and tire
you chose. I am leaning towards a Big Apple or Marathon tire.
Did you have the wheel,hub assembled by the online dealer or locally? What should that cost?
Hbob
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Old 02-24-06, 08:14 PM   #13
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Originally Posted by hbob
I am going for the Nexus 8 Hub,but am considering the coaster brake model. What do you think of that.
Should the gearing be as good, or does coaster compromise other parts? How do you like the wheel and tire
you chose. I am leaning towards a Big Apple or Marathon tire.
Did you have the wheel,hub assembled by the online dealer or locally? What should that cost?
Hbob
I didn't know there was a coaster brake option with the Deluxe 8 hub... even if there is, I personally wouldn't go that route. My reasoning would be the stock brakes on the FS work pretty well.. mounting the brake torque arm on the FS might be awkward... the front brake provides most of the stopping power, especially on downhills where your weight bias is more forward.. adds another level of weight to an already heavy wheel... those are my immediate thoughts, although others with more experience with coaster brakes might have completely other ideas..

I like the Alex 16 wheel and have built two of them with the Shimano 8spd hub... one for the Downtube FS and one for my Dahon Jetstream XP.. I like the high pressure Kenda slick on the DT, but it is there only because I recycled it from my Xootr/Swift... I'm running a 20x1.75 Avocet slick on the XP front and rear and feel they are a super tire, comfortable and low rolling resistance. The Big Apple or Marathon tires are also excellent choices.. I built both of the wheels myself (my first attempts) so don't know what a dealer would charge.. I'm sure others on this forum know what to expect.

Bruce
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Old 03-04-06, 11:40 PM   #14
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Quote:
Originally Posted by BruceMetras
I have an 05 Downtube FS and it has horizontal dropouts.. I think the 06 FS will have a vertical dropout... some of the 06 hardtail Downtubes will come with a hub gear, so I would guess those would have horizontal ones... the chain tension on the FS will be a compromise if you're not using a spring loaded add-on tensioner to compensate for the change in chain tension due to the working rear suspension. On mine, I loaded/bottomed the suspension, set the tension and simply ignore the chain slack when I'm not on the bike. So far, I'm not dropping the chain on my rides.

Bruce
Bruce, Have you been able to get those picture yet? I am looking at the Nexus Hub with the coaster
brake but I am not sure how the brake arm would attach to the full suspension model. Also, my bike
shop is recommending that I keep the derailleur on as a chain tensioner, or add one. Has your chain stayed
tight with the rear suspension? They are worried chain might come off when I get off or hit a bump.
Please let me know how it is working for you and please post those photos.
Hbob.
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Old 03-05-06, 12:06 AM   #15
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A few things to note in planning your Nexus8 conversion:

http://bike.shimano.com/catalog/cycl...ucts/group.jsp

A. Make sure you order the 'Premium' model (SG-8R25), the so called 'Red Band' ... it's newer, better, and weighs less than the others (1.5kg/3.4lb) versus 1.75kg/3.85lb. http://sheldonbrown.com/harris/shimano-nexus.html

B. The coaster brake model (SG-8C20) weights the most (hub/brake 1.99kg/4.38lb), compared to the V-brake model (SG-8R25-VS) at (1.5kg/3.4lb). The Premium hub and V-brake save a full .5kg/1.1lb.

C. Several factory hub gear installations (Brompton and Birdy folders for example) include a small chain tensioner ... and no need for a derailleur.

D. There are but two choices for shifters, both Shimano Nexus:

+ Twist Shift (SL-8S20)
+ 3-finger shift and Brake lever (rapidfire)
+ no option for a stand-alone rapidfire shifter

Hope this helps!
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Old 03-05-06, 12:46 AM   #16
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Coaster brake on a bike that has more gears than 3 never made sense to me. Weight increase, slightly oddball parts as non coaster hubs and their brake assemblies are fairly rare, the ability to coast is very nice on a an all purpose/broad gear range bike etc.

As for Marathon + or Big Apple. Definately the Big Apple. The Marathon is suppossed to be bulletproof but i have heard the ride characteristics are a let down. A bit slow, sidewalls are too hard (not so comfy) and it tends to 'run into itself into cracks and gaps on the road surface'. I heard this from a very experienced world tourer that gave them a very fair trial.

The Big Apple's are by no means not durable and their puncture proofing is good.

Also the wider one is very comfy yet still pretty fast.

I don't own a redband but since i talked to member Wav. i also think it may be the best route. The redband is only a bit more expensive than the normal version yet more efficient and lighter. With this hub you will have all the benefits of hub gears and (very) closely approach the efficiency of ders. Now if only Shimano sold spare parts for hubs rather than entire units of parts and their hubs were easy to service,.. than i'd buy a redband too. But i am picky about these things. Seems like the redband would be an excellent choice if you want to ride it for at least 5 to 10 years rather than the 15 to 30 that i look for in a hub. Still, i may just take the risk one day.
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Old 03-05-06, 10:31 AM   #17
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Quote:
Originally Posted by hbob
Bruce, Have you been able to get those picture yet? I am looking at the Nexus Hub with the coaster
brake but I am not sure how the brake arm would attach to the full suspension model. Also, my bike
shop is recommending that I keep the derailleur on as a chain tensioner, or add one. Has your chain stayed
tight with the rear suspension? They are worried chain might come off when I get off or hit a bump.
Please let me know how it is working for you and please post those photos.
Hbob.
Hi Hbob, not sure which pics you're speaking of, but I have posted in the recent past a few of my DT FS conversion (Nexus Redband hub - no coaster brake).. Here's One . This shows Powergrips installed on the stock folding pedals as well as the Shimano hub. It also shows the slack in the chain that I run.. The chain tightens up when my weight is on the bike.. So far, I have not dropped a chain in my day to day use which includes dirt trails and broken asphalt.. I don't launch the bike frequently, but I do ride off curbs almost daily (sorry Yan!) . If I found that the chain did derail in my normal riding, I would add one of many devices available to take up the slack or a roller kit or similiar found on This Page . A derailleur would be my last option as I went to lengths to get rid of it for ground clearance etc., although it would work and is the least costly as you already have one.

Bruce
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Old 03-05-06, 11:00 AM   #18
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Bruce, Thanks for the photo. That is what I was looking for. Are those the stock cables?
I am pretty sure I will go without the coaster brake for simplicity. I am replacing my cables
as I am around salt water a lot. I am ordering Power Grips today! when I rebuild my hub I am
going to put on a Marathon Plus tire. I bought two Downtubes and I ride every day, so I
can still ride one while the other is on the stand.
Hbob
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