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2008 Scott CR1 Tire and Gearing Questions

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2008 Scott CR1 Tire and Gearing Questions

Old 05-05-20, 10:34 PM
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busygizmo
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2008 Scott CR1 Tire and Gearing Questions

Hey all,


I have a 2008 Scott CR1 that I've been happy with over the years. I probably average 1K miles a year so it's not high mileage. I've been looking the last couple of years at getting something newer mainly for lower gearing and wider tires. Recent furlough and the reality that my job isn't likely to return any time soon means that I'm looking to upgrade my current bike.


I ride a lot on Vashon Island near Seattle, if you get off the main highway it's essentially country roads with little traffic and lots of hills. The problem is that the roads are rough in places, often chipseal, and the climbs can be steep, 13%-20% with one supposedly hitting 28% for a short section. I end up grinding out of the saddle in my lowest gear for many of these climbs. I switched to a compact double several years ago but still with a 11-25 cogset it would be better with a 27 or 28 in the rear. The components are 6600 Ultegra that say you can only get a 27 tooth max cog but am wondering if anyone has experience with a 28 tooth cog? I was looking at upgrading to 11 speed but then would also have to deal with the freehub spacing so figure I'll deal with just upgrading the cogset and eventually replace the bike later.


I'd also like wider tires than the Conti GP4000 23mm I have now. The width doesn't look like an issue but the rear brake bridge only clears the current tire by about 2mm. Anyone used 25mm Conti's on an older Scott CR1? Alternatively is there a more comfortable tire that is similar in quality to the Conti's? I've read good things about the Specialized Turbo Cotton tires that come in 24mm but am not sure about durability and how they handle occasional rain. Wheels are Mavic Ksyrium Elite, outside with 19mm.


Thanks.
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Old 05-05-20, 11:45 PM
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You're likely not going to do a ton better with tires on the current bike. 2mm is already flying pretty close to the sun on clearance, and GP4000 are already a reasonably supple tire. Latex tubes might not be a bad thing to try, if you're not already using them.
What pressures are you running and what's your bike+rider weight? If you're not currently getting pinch flats, it might not hurt to try lowering the PSI.

The Puget Sound islands do seem love laying down chunky chipseal.

For gearing range, if your derailleur has inadequate cog capacity or wrap, a simple solution might be to throw a Shimano 9-speed MTB derailleur on the bike: they have the same actuation ratio as pre-2015 Shimano 10-speed road derailleurs. Something like an Alivio RD-T4000 would probably work fine with your shifters and a Shimano 10-speed cassette.
That said, max cog capacity for rear derailleurs is often a fuzzy metric, and the reality depends somewhat on the derailleur hanger geometry for the particular bike. So Shimano tends to err low on their estimates for max cog. A 50-34 combined with an 11-28 cassette is going beyond the reasonable chain wrap of an RD-6600, though.

Last edited by HTupolev; 05-05-20 at 11:48 PM.
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Old 05-06-20, 02:58 PM
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Originally Posted by HTupolev View Post
You're likely not going to do a ton better with tires on the current bike. 2mm is already flying pretty close to the sun on clearance, and GP4000 are already a reasonably supple tire. Latex tubes might not be a bad thing to try, if you're not already using them.
What pressures are you running and what's your bike+rider weight? If you're not currently getting pinch flats, it might not hurt to try lowering the PSI.

The Puget Sound islands do seem love laying down chunky chipseal.

For gearing range, if your derailleur has inadequate cog capacity or wrap, a simple solution might be to throw a Shimano 9-speed MTB derailleur on the bike: they have the same actuation ratio as pre-2015 Shimano 10-speed road derailleurs. Something like an Alivio RD-T4000 would probably work fine with your shifters and a Shimano 10-speed cassette.
That said, max cog capacity for rear derailleurs is often a fuzzy metric, and the reality depends somewhat on the derailleur hanger geometry for the particular bike. So Shimano tends to err low on their estimates for max cog. A 50-34 combined with an 11-28 cassette is going beyond the reasonable chain wrap of an RD-6600, though.
I suspected as much, it's too bad so many older frames had such narrow tire clearance. I have an older steel frame I haven't ridden in years and was looking to see if wider tires would fit but it is even narrower at the chain stays.

I may have to go with the MTB derailleur although I've seen that there was a 6600 Ultegra made with larger capacity. I'll probably switch the cogset at least to a 11-27 when the current one wears out and if it doesn't work I'll have to swap out the derailleur too. As a general rule I'm pretty cognizant of avoiding cross-chaining so I'm not super worried about max capacity but wouldn't want the jockey pulley rubbing the largest cog.

Currently I'm at 184 pounds which is heavier than I's like to be by 20 pounds so losing that would help with climbing issues although I'll never be a lightweight. I've been running the tires a little lower than in the past (~90psi) and haven't had any issues so far. I was thinking about even trying a little lower over time to see what happens, especially if I can shed a few pounds now that I have plenty of time to ride. I would like to try latex tubes, need to shop around for a set. I had bad luck with these many years ago so have been reluctant to try again and currently have a large stock of Conti butyl tubes.

Thanks for the feedback.
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Old 06-28-20, 05:57 PM
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FWIW I was able to fit 700x25 Gatorskins borrowed from someone else's bike onto the Scott so I ordered some Conti GP 5K at that size and they fit almost exactly like the GP 4K 700x23's. Tried some 700x28 Gatorskins and they rub on the back brake bridge so there is the limit.

My bike is going in for an overhaul at my local shop and while there they are going to install a larger cassette, they seem to think an 11-32 will work. I only asked if they could fit an 11-28 and they said the bigger one will fit. We'll see.
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Old 06-29-20, 08:08 AM
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Originally Posted by busygizmo View Post
FWIW I was able to fit 700x25 Gatorskins borrowed from someone else's bike onto the Scott so I ordered some Conti GP 5K at that size and they fit almost exactly like the GP 4K 700x23's. Tried some 700x28 Gatorskins and they rub on the back brake bridge so there is the limit.

My bike is going in for an overhaul at my local shop and while there they are going to install a larger cassette, they seem to think an 11-32 will work. I only asked if they could fit an 11-28 and they said the bigger one will fit. We'll see.
FWIW, I also ride a CR1 (great bike, 2014). My only knock on it is the narrow tire clearance. Mine came with 25s on the stock set of wheels, and they rolled fine (Vittoria). I bought some Conti GP4000 25s, and put them on a set of Boyd wheels (wider rim profile), and they rubbed. Went back to 23s, which flare out closer to 25s on the Boyds. It all depends on the tire/rim combo you use. I would say also to check your chainstays after a couple of rides. They may roll smooth on a stand, but that doesn't count for the flex you get while riding on the road.

As far as gearing goes. My prior road bike was set up with a 12-27 in the back (Ultergra 6600), and a 50/34 compact in the front. You can do some pretty good climbing on that. If you are looking to do a wider range 10 speed cassette, SRAM makes a 12-32 cassette, which is what I'm currently running. You can switch out your RD for a Shimano 105 series 5700 GS derailleur which will by default handle the 32 tooth cassette, and can be found online new right now for less than $50. You can also install a Mircoshift RD, which has a large capacity as well. Otherwise the CR1 frames are still light, stiff, and both climb and accelerate well. Good luck!
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Old 08-03-20, 05:19 PM
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Originally Posted by Plainsman View Post
FWIW, I also ride a CR1 (great bike, 2014). My only knock on it is the narrow tire clearance. Mine came with 25s on the stock set of wheels, and they rolled fine (Vittoria). I bought some Conti GP4000 25s, and put them on a set of Boyd wheels (wider rim profile), and they rubbed. Went back to 23s, which flare out closer to 25s on the Boyds. It all depends on the tire/rim combo you use. I would say also to check your chainstays after a couple of rides. They may roll smooth on a stand, but that doesn't count for the flex you get while riding on the road.

As far as gearing goes. My prior road bike was set up with a 12-27 in the back (Ultergra 6600), and a 50/34 compact in the front. You can do some pretty good climbing on that. If you are looking to do a wider range 10 speed cassette, SRAM makes a 12-32 cassette, which is what I'm currently running. You can switch out your RD for a Shimano 105 series 5700 GS derailleur which will by default handle the 32 tooth cassette, and can be found online new right now for less than $50. You can also install a Mircoshift RD, which has a large capacity as well. Otherwise the CR1 frames are still light, stiff, and both climb and accelerate well. Good luck!
Thanks for the feedback.

Another follow up: got the bike back after a full overhaul, all cables, brake pads, headset bearings, chain and cassette replaced.
The shifting is much improved as is the braking between the new cables and kool stop brake pads.

They installed an 11-32 Shimano, probably a Tiagra. It shifts well and there doesn’t seem to be any issues using the 32t with the standard 6600 rear derailleur. I’ve been hitting more of the hills on Vashon Island and was able to pedal seated on many of the sections I’ve previously only been able to grind out standing up. The 32t is probably a bit overkill but the shop couldn’t get an Ultegra 11-28 until September.

We rose the Ride the Hurricane in Port Angeles over the weekend and there were a few sections where spinning a 28t cog was preferable to the 25t even though it rarely gets above 7%. The only negative was my fiancé’s electronic shifting stopped working so she had to do the whole 18 mile climb in a 21t cog.

Upshot is that the gearing works and at least GP5000’s fit in 25s. I still really enjoy riding this bike although the styling is a bit dated.
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