agobel

Hello all, thanks for taking the time to answer my questions. I'm revitalizing my 87 Stumpjumper as a sort of hybrid errand bike, and I'd appreciate your input on the fit of the tires specifically. I've started with some used wheels from eBay.

Front wheel is an STX-RC Parallax hub laced to a Mavic X222 rim. Rear wheel also has an STX-RC hub and Sun CR-18 rim. The Mavic rim is labeled 559 x 17, which I think means 17mm inner diameter. They look really close in size, so it seems safe to assume the CR-18 has an 18mm inner diameter by its name; it's not actually labeled.

I have only two spare 26" slicks currently - very basic Kenda 26 x 1.95's. The side of the tires read, "TO FIT HB-575 RIM", which I don't understand at all. I pumped one up on the front wheel and even though it fits uniformly, it just looks odd to me. I've never had MTB rims this narrow, so I have no idea if this amount of bulge is acceptable or safe. So, that's the first question. Could this tire choice be unsafe or over-stress me or the rims?

Secondly, would 1.5" tires be safer for these wheels, bulge less, or ride noticeably faster? There are several sets of 1.5" slicks within my price range on eBay. I'm reserving as much money as possible for the rest of the build, so I would prefer size-specific advice over your favorite tire. Budget slick suggestions (like my Kendas at <$20 per) would also be appreciated.

Thanks very much for your input and advice!

Lastly, the tube I was using was an Avenir 26 x 1.95-2.125. If the tire technically "fits," it has to be at the very top of the range size-wise for this rim. Does a slightly oversized tube matter in my experiment or application? I would obviously get smaller ones if I went all the way down to 1.5".

Jeff Wills

559 is the bead seat diameter of the rim (in millimeters)- you have the common "mountain bike" size wheels. 17 is the inside width (in millimeters) of the rim- fairly narrow, but not unusual.

The tires fit without blowing off the rim, so you're past the first hurdle. 1.95" (50mm or so) is a smidgen wide for that rim, IMO, but not excessively so. If you're OK with them, run 'em until they fall off.

A "faster" option would be narrow slicks: 1.25" (32mm). Usually these accept higher pressure- up to 100 psi. I had a set of Tioga City Slickers on my old Fisher mountain bike- it made a very nice commuter.

Tubes don't matter unless they're so big they prevent the tire from seating properly.

rekmeyata

Actually tube wise it's better to have a size smaller then the tire. For example, if you had a 700c X 28 tire you would use a tube that's a 700c 19 to 23. It makes for installing tires easier due to the smaller tube allowing more room to get the tire on and beaded, and provides a lighter tube. BUT, a larger tube then the tire will allow the tube to be thicker thus a tad less prone to punctures, but more difficult to put on.

LesterOfPuppets

Those tires fit fine. Looks like it says 559 in parentheses before the 26x1.95 on the tire sidewall. I've run 2.1" on Sun CR-18s before. Just gotta keep the tires firm so they don't fold over in the turns and you'll be fine.

EDIT: 50 PSI should be adequate.

Burton

The rims will accept any tire that will clear your frame. Tube size is better as close as possible to the tire size. Rubber is porous and a smaller tube will be streached more and lose air faster over a week.

Tire size isn`t the only thing to look at. Tire profile counts for just as much and profiles for offroad and asphalt are very different. For asphalt you want a round profile - for offroad a flat profile offerrs better grip.

The other thing tire size affects is your gearing. Going to a skinny tire may in theory be faster, but it also reduces your wheel diameter and with a small main chainring - your top speed may be limited. I run round profile slicks with a minimum 2in size in the street.

rekmeyata

I forgot to mention, one of my MTB's has the Kwenda Qwest tire on the rear and it's a hard wearing highly puncture resistant tire. I use it not only off and on the road but also on the trainer (after cleaning the tire first of course) for the last 4 years, and that tire simply takes a long time to wear, in fact it still looks good.

Jeff Wills

26 x 1.25" slicks, $10 each:
https://www.nashbar.com/bikes/Product...1_10000_202472

LesterOfPuppets

I picked up the Performance version of one of those last weekend. Performance calls it the Forte Slick City. I'm 75% sure they're the same tire.

Looks like they have an online only 10% off for the rest of today. I almost splurged on a Ritchey Tom Slick for $5 more, but I'm glad I didn't because this tire rolls and corners GREAT for $10.

I would definitely notice their perkiness on the road compared to your current tires. I can feel the difference over my Michelin Country Rock 1.75". The Country Rocks are MUCH better on non-paved surfaces however.

agobel

Thanks kindly for the very helpful input, folks. I'm pleasantly surprised at the values on Nashbar and Performance. Makes me think I've been overly eBay-biased. Currently considering https://www.nashbar.com/bikes/Product...l#ReviewHeader and https://www.nashbar.com/bikes/Product...1_10000_202472.

The more I consider the tires, the less I feel like I know. In addition to the grocery store, this bike will take me to my favorite fishing hole, as well as a rail trail. I've attached a picture of the fishing trail. As for the rail trail, I assume you know what gravel looks like. Like anyone building a go-anywhere bike, I want the best traction off road and speed on road. I don't really want a combination tread as per Mr. Sheldon Brown, "The usual design is to have a smooth ridge down the center of the tread, with knobs on the sides... In practice, combination-tread tires don't work all that well. They do OK in dirt, but they're pretty lousy on pavement... If you mostly ride on pavement, but also do a fair amount of dirt, a combination tire on the front may be a good choice for you, with a road tire on the back."

Only thing is these sort of combination treads or even tiny-knob mountain treads seem rare in 1.5". Would a tread as light as the above link have any advantage over a slick on packed dirt or grass?

Thanks again.

LesterOfPuppets

Yeah, it's tough to decide which surface to plan for more in cases like these. I've actually had some continuous tread in the middle knobs on the outside tires that weren't bad, they were 1.95" though.

I rather like the Serfas Drifter 1.5" tires I have. Quite nice on the street and not too shabby on mellow trails. I currently have two of my MTBs set up with Michelin Country Rock 1.75" in front and Serfas Drifters on the back. That's my favorite dirt/road combo of the tires I have.

Serfas Drifter front and back is a really nice setup too. The Drifters grip the road better than the Country Rocks, IMO, but I got the Country Rocks for really cheap - $12. Drifters and Country Rocks are approximate equals in the dirt, slight nod to the Country rocks in some dirt conditions. Country Rocks seem a tad lighter despite their larger size, never weighed them though.

Drifter

Country Rock

Sheldon was mostly right about combo tires, but I still like them. I have a feeling he wrote that at a time when most of them sucked or was just thinking about all the sucky ones he's ridden. There are some that aren't bad though. The best option of course is to buy a separate wheelset and have one shod with slicks and one with knobbies.

LesterOfPuppets

Here's a pic of my Mongoose with Serfas Drifters 1.5" front and rear. Mounted on a Sun Zero Degree Lite front and a Specialized XL-21 in back - the narrowest MTB rim I've ever owned. It measures just a hair over 15mm on the interior and you can see that it does bulge a bit. That's really no concern unless you run low PSI, though. That depends on the tire also. The Drifters have relatively stiff sidewalls, likely less stiff than your current tires but stiffer than Michelin Country Rock and Panaracer Fire XC.


Grey Goose by Lester Of Puppets, on Flickr

agobel

Also looking at https://www.nashbar.com/bikes/Product...1_10000_202472. Would a tread so subtle make any difference in traction or puncture resistance over packed dirt and some small rocks? Thanks again all. Trigger approaching pulled, but on what...?

LesterOfPuppets

Those remind me of the Avocet Cross, but maybe a little lamer.

agobel

Budget didn't permit the combination tread up front this time, which I would have preferred. I think these will be great on the road, flat, packed dirt trails & some gravel though. Thanks all for your input. I ended up going with this baby tread 1.5" up front https://www.nashbar.com/bikes/Product...1_10000_202472 and this uber slick 1.25" in the back https://www.nashbar.com/bikes/Product...l#ReviewHeader.

I'm assuming that front tread will offer absolutely no grip, but I've heard of slick fanatics riding bolder trails than mine. This was also incentivizing as I seem to experience wrist fatigue easily:

Wider Front, Narrower Rear
"A wider front tire makes sense in many applications, however, when handling and ride comfort are considered. A wider tire will generally provide better cornering traction than a narrower one, assuming appropriate inflation pressure. A wider tire also provides superior shock absorbency. I personally prefer a slightly wider tire in front, since I suffer from some wrist discomfort on occasion."

- Sheldon Brown

MitchL

https://https://www.google.com/imgres?...JJGtgQeMqKWPAw
I have been trying to wrap my head around rim/tire sizes and I'm going crazy. So if you could help expain this, that'd be great. Shouldn't the bead seat diameter be close to the rim diameter. Based on SB's pic. https://www.google.com/imgres?imgurl=...JJGtgQeMqKWPAw . 559 mm is way smaller than 26".

What does the inside rim width tell you about the tires that will fit. Does knowing the outside rim width help with anything?

Thanks

agobel

"The rim's diameter will generally be 6-8 mm larger than the Bead Seat Diameter, depending on how high the rim flanges stick up above the bottom of the rim channel." - Sheldon Brown

So, yes, it is, but I think you may be over-complicating the compatibility question. Bead seat diameter refers to the part of the rim where the metal rings inside the tire (bead) situate upon inflation. This larger number is going to be the same in all compatible tires for your wheel. It's used to get you into the right family of tire. Jeff said I have 559mm BSD wheels - this is the same on all mountain bike wheels we refer to as 26" wheels. If you have 26" cruiser wheels, for example, like on an old 3 speed, or old 27" road bike wheels, the BSD will be different. Sheldon's chart right below the graphic you posted makes this easy to understand: https://sheldonbrown.com/rim-sizing.html.

I started this thread for advice on how much breathing room I have in selecting a 559mm tire for a 16-17mm WIDE rim. The consensus was that there's a large range of safe and appropriate widths depending on terrain and preference. Sheldon's handiest visual aid for this range can be found at https://sheldonbrown.com/tire-sizing.html#wtb. Just scroll up slightly.

Does that make sense?

MitchL

That makes more sense now. Thanks for the help.