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ContiClassicAttack actual dimensions

2319 Views 36 Replies 7 Participants Last post by  crazypj
I am building a cafe racer with a combination fork brace/fender mount/caliper hanger. I need to know tire dimensions/clearances to complete this part of the project, but don't want to actually purchase the tires until the project is closer to completion, so the tires are fresh. (I've been "working" on this bike for nigh on 30 years, and it might be a couple more years before it's actually ready for tires.) Since no tire company other than Avon seems to publish actual measurements of their tires, I was hoping someone here could take a couple of measurements for me. The bike has an 18 x 2.15 Sun rim on the front. At this point, I am considering the 90/90 R 18 ContiClassicAttack and the Michelin 100/90-18 Pilot Activ. If anyone out there has either of these tires and can measure the actual overall diameter and width, I would greatly appreciate it. Thanks.
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Thank you all for your replies. One of the reasons I am considering the ContiClassicAttack is because radials don't grow as much at speed as do bias-ply tires. The main reason, though, is that they are supposedly the best-handling of all tires narrow enough for older bikes, at least according to the March 2017 issue of the German magazine Motorrad Classic. Here are their test comparison results with point scores:
8th place, 156/250 -- Avon Road Rider
7th place, 167/250 -- Pirelli Sport Demon
6th place, 174/250 -- Metzler Sportek Klassik
4th place, 200/250 -- Bridgestone Battlax BT45
4th place, 200/250 -- Continental ContiGo!
3rd place, 201/250 -- Dunlop Arrowmax Streetsmart
2nd place, 204/250 -- Michelin Pilot Activ
1st place, 224/250 -- Conti RoadAttack 2 CR/ClassicAttack

(The 1st place RoadAttack happens to be in their "CR" DOT-approved race compoind, so it's a bit of a ringer.) The narrowest front RoadAttack, 100/90-18, requires a minimum rim width of 2.50", which is why I was looking at the 90/90-18 ClassicAttack. Thank you very much, JCW, for the PDF of the Conti catalog. As I assume you discovered, it is no longer on Continental's website and is much more comprehensive than the catalog currently posted. It is a tad confusing, however, in that they show the 90/90 as also requiring a 2.50 minimum rim width whereas their 110/90-18 is seemingly suitable for a 2.15" rim - go figure. Incidentally, they show the centrifigul growth as a mere 7mm on the 90/90, so that's good. I'm obviously going to have to read more in the Conti catalog before making any decisions.

I was definitely incorrect about Avon being the sole company that lists actual tire dimensions, since I discovered that Bridgestone also does so, and that Conti once did. That said, it's obvious that the manufacturers generally don't cater to custom builders, who need to know exact dimensions of all sorts of things. I haven't added anything to my build thread in years, but anyone who cares to take a look at it can google "T140 cafe project, cont. britbike".

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Why would you build a bike with tire clearance so tight that you are committed to one specific brand of tire? If you plan for it to be functional, that tire may not be available when it comes time to replace them. Or, if this is not a functional build (not really something this crowd has much appreciation for) buy the tire you like the look of, and build the bike around it! It won’t matter because the tires never wear out in a Pipeburn build....
Actually, I am aiming for a .5-.75" clearance, just not a 1-1.5" gap. That way, I can build for the tire that is best (why would I do that if the bike isn't intended to be "functional"), and future owners can still - within generous limitts - change up as they wish. BTW, though their premium price might hold them back, I expect this new, narrow strain of radials to be the future of reto-bike rubber. You are right on, 8ball, about the tires never wearing out. Due to medical problems, I haven't been able to ride since 2004. I wouldn't expect the next owner to ride it on anything buy lovely Sundays, either. But I built my first cafe racer (low bars, pipe, seat and tank, extended swingarm) in 1968, and spent nearly 45 years in the motorcycle business, so I'm kinda in the habit of doing this. I will admit this bike has become a bit of an albatross by this time, but I am bound and determined to make it the best T140 cafe racer it can be. And it's well on its way.
The 90/90r18 conti classic attacks fit a 1.85 to 2.5 inch rim.
I'm not sure where or how you are reading the fitment chart...

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30 year build???? And I thought I was a bad procrastinator
I was looking at page 283, which shows acceptable rims for the 90/90 R 18 Classic Attack to be 2.50 and 2.75. What page did you copy above? And yes, a 30 year build is ridiculous, but that's my life.
That would be terrific, JCW. Nothing beats an actual measurement. BTW, the ContGo is a bias ply, and so doesn't need as wide a rim as a radial. That said, there is a video on youtube of a guy who was mounting 100/80-18 RoadAttacks F & R on a Ducati single road racer (I googled conti roadattack). It had 2.15 rims F & R, which is apparently the widest rim size allowed in his Vintage racing class.
I notice that all of the measurements in the PDF catalog you sent for the 90/90 ClassicAttack and the 100/90 RoadAttack are identical. That can't be right. My guess is the the 90/90 is, in fact, smaller in every dimension. Your ruler will rule!
I am sure you are right, JCW, but I am hoping the ClassicAttack is a bit wider than the ContiGo, even though their nominal sizes are the same. Thanks for checking.
Thank you for that, JCW! I've been delving deeper into Conti's catalogs. In your 2015 catalog and elsewhere, they say acceptable rims for the 100/90 R 18 RoadAttack 2 CR were 2.50 and 2.75. But now, in some of their catalogs, they say that the same size RoadAttack 3 CR can be fitted to a 2.15 rim. I emailed their technical department to try to clear up the confusion. I don't really expect a reply, but we'll see.
Yeah, I'm liking that 2.15 is the pick of the litter, but suspicious of that way wide range. Even if their tires are the hot lick, I'm not sure we can really trust Conti's specs!
Hi Crazypj. Yes, tires vary a lot from their nominal sizes, which is why I've been so frustrated by Continental's rather screwy spec sheets. Fortunately, JCW has a 90/90 R 18 ClassicAttack and was able to measure the width for me. As it turns out, that tire is pretty darn close, at 91.5mm wide. One of the benefits of the Conti's radial construction is that radials don't gow much at speed, but I'm figuruing on leaving a good 1/2" on top, just in case. BTW, if you are reading this JCW, did you happen to measure the overall diameter of that tire?
Please don't go to any trouble on this. Just eyeballing a ruler or tape through the center (axle) will be close enough. Amazon lists the size (for shipping purposes) as 24" x 24". If the diameter is that small, it will not work for me. I am hoping for something in the 25-25.5" range. Thanks, guys.
Thank you very much for getting that measurement, JCW. Sounds like a hassle. That OD is a bit small for this bike, I think, which makes the 100/90 R 18 RoadAttack the best choice for me. So far as putting my opening query on the racing forum, dirtchecken, the tires in question are, from what I understand, more common on the track (at least for track days) than they are on the street. I needed an answer to the question, and sure enough, JCW was here to answer it.
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