Converting a 700c Road Bike to 650b ...

[Lovetoclimb]

One of my two steel road bikes was designed to maximize available clearance using standard Campy 11 caliper brakes and 700c wheels. As such I can fit a tire that measures around 31mm wide on a 700 x 23mm wide rim with enough space to be comfortable. I can also squeeze fenders over a 25mm wide tire on the same wheels. This is all under the Campy Athena 11 calipers with the brake shoes brought down as far as they will go.

The wheels I have used on the bike for the last 2+ years are starting to show the abuse from traveling, riding "off pavement" and so on. Since I am considering rebuilding them salvaging the Campy Record hubs, the idea of converting the bike to 650 and possibly fitting say up to a 35mm wide tire crossed my mind. I think the use of long reach brake calipers like the Velo Orange Grand Crus may give me the extra brake reach I need. But what else should I be measuring to determine if it will work? I am hoping I can find a rando friend with 650b wheels to see just how big of a tire I can fit and measure any differences in how the bike relates to the ground.

Anyone else done something like this? 650b seems to be all the rage these days. That supple life is calling out to me!

[weisan]

https://www.bikeman.com/bikeman-blogs/650blog/1771-650b-conversion-guidlines

[kevintice]

I recently converted a Lemond Zurich to 650b, with 38mm tires. Works great. The Grand Cru brakes("medium reach") may not have enough reach as they max out at 57mm. I used the Tektro long reach brakes which have a max reach of 74mm, If I recall correctly. The 650b rim is 584mm diameter as opposed to 622mm of the 700c rim. So use those figures when determining brake reach needed

[Lovetoclimb]

Those Tektro brakes look great too, and less than half the price of the VO brakes!

[Ed-B]

The new version of the Tektro 73mm brake is the R559, it has a latch on the quick release to prevent accidental opening. And you're no longer limited to recessed fitment - you can get these brakes with long mounting shafts for bikes that use hex nut attachments.

I'm pleased that people are still finding that Bikeman 650B conversion guidelines article useful. I wrote it 9 years ago...

Ed.

[mhespenheide]

Funny that you bring this up; I'm debating doing the same with an old Bianchi.

I think I've taken the right measurements that it seems like a good idea...
...now if only there were a decent source of 650b wheels on the used market so that we're not paying custom prices.

[weisan]

Funny that you bring this up; I'm debating doing the same with an old Bianchi.

I think I've taken the right measurements that it seems like a good idea...
...now if only there were a decent source of 650b wheels on the used market so that we're not paying custom prices.

I converted my Bianchi to 650b for commuting. I got a set of wheels built by guy on eBay for $100 shipped, nothing fancy but held up more than 2 years of regular commuting and trail riding.

[93legendti]

I converted my Salsa Casseroll to 650b. I am considering converting my Serotta Concours to 650b...I have a set of nashbar long reach brakes and some Pacenti tires...just need another wheel set from Old Potatoe...;)

[thirdgenbird]

The new version of the Tektro 73mm brake is the R559, it has a latch on the quick release to prevent accidental opening. And you're no longer limited to recessed fitment - you can get these brakes with long mounting shafts for bikes that use hex nut attachments.

I'm pleased that people are still finding that Bikeman 650B conversion guidelines article useful. I wrote it 9 years ago...

Ed.

It's a very well done article. It's made me want to try a conversion on several occasions. Are you associated with bikeman?

[Ed-B]

It's a very well done article. It's made me want to try a conversion on several occasions. Are you associated with bikeman?

Thanks, I tried to cover the essentials for people who might want to try a 650B conversion. This was early in the resurgence of 650B, there wasn't much information out there at the time, and we were getting a lot of questions on the email lists by people who were considering the format.

I live a few miles away from the Bikeman shop, and I know the owner and some of the guys who worked there. I offered to write a few articles for them in exchange for a discount on the bikes and parts that I used. The articles continue to bring web traffic to their site, and I'm still riding the bikes. So I think it has been beneficial for everyone.

[thirdgenbird]

Awesome. I have ordered from them. Great customer service. I ordered a fork and then emailed them first thing the next morning and asked if I could asked them if I could add a star nut. They replied back and said they would toss one in the box free of charge. It's a small thing, but great service.

[93legendti]

Otoh, I've ridden my 650b twice and gotten a flat on the rear both times. Switched out rim tape to velox. Changed brand of inner tubes. Same result. Going to be awhile before I try it again.:crap::crap: Going back to 700c tubeless-haven't had a flat since 4/2012..

[CMiller]

Good article, and from my own experience I'd take a careful look at bottom bracket drop, especially if you can't fit fat fat fat tires in there.

"bottom bracket drop", it's the distance below the axle centerline to the bottom bracket centerline. If you have the geometry tables for your bike, look for a drop figure between 65mm and 72mm. But unless you have the frame geometry tables, you'll need to work with the height that you can measure directly on your bike.

The bottom bracket will come down a bit with 650B tires, you can expect a lowering of about 8mm-10mm converting from 700x23mm tires to 650x38B tires. For reference, the old racing standard for bottom bracket height is 267mm, and that was determined when people rode toe clips and straps on 170mm cranks. It's still a good guideline. So a good 650B conversion candidate will have a bottom bracket height of about 275mm with 23mm 700C tires. More is better, but anything lower than 270 is risky."

I don't pedal through corners on my 650 bikes and the drop makes more of an issue if you aren't able to get something big like a 42 in there.

[stephenmarklay]

So the idea here is to make a more gravel road or comfy bike correct?

[geeter]

Great article Ed. I have been debating doing this for a while.

[mhespenheide]

So the idea here is to make a more gravel road or comfy bike correct?

Yes. If the limiting factor on putting larger tires into your bike is the rear brake bridge and the fork crown, 650b lets you decrease the diameter of the rim and then add back in a bigger tire, getting you back to (roughly) the same overall outer diameter of the rim+tire system. It's a small enough change that you should still be able to keep rim brakes (with a change to medium-reach brakes instead of short-reach) while big enough (in some cases) to add a significantly larger-volume tire.

If the limiting factor stopping you from putting on wider tires is the width of the chainstays, 650b helps a little bit but not too much.

[palincss]

Otoh, I've ridden my 650b twice and gotten a flat on the rear both times. Switched out rim tape to velox. Changed brand of inner tubes. Same result. Going to be awhile before I try it again.:crap::crap: Going back to 700c tubeless-haven't had a flat since 4/2012..

Perhaps you might want to look for and remove the embedded wire or piece of glass, before giving up entirely?

[weisan]

Before Eve ate the apple...

I converted my Salsa Casseroll to 650b. I am considering converting my Serotta Concours to 650b...I have a set of nashbar long reach brakes and some Pacenti tires...just need another wheel set from Old Potatoe...;)

After Adam blamed the woman...

Otoh, I've ridden my 650b twice and gotten a flat on the rear both times. Switched out rim tape to velox. Changed brand of inner tubes. Same result. Going to be awhile before I try it again.:crap::crap: Going back to 700c tubeless-haven't had a flat since 4/2012..

[happycampyer]

After Adam blamed the woman...love the double entendre.

[93legendti]

Perhaps you might want to look for and remove the embedded wire or piece of glass, before giving up entirely?


First time there was a small wire. I removed it. Found the hole in the tube. That was back in December or so. Flat was while on the road.

80 degrees today, so I tried it again. This time flat was on a local trail I've ridden hundred of times. Couldn't find anything on the tire, inside or out. I looked for several minutes running my hand inside and outside the tire. Gave up when I couldn't find a hole in the tube.


Going to take it to the lbs see if the stem hole is the problem. Maybe there is a burr. I will change the rear tire from Hutchinson to Pacenti. Buy more tubes. Then ride my cross bike. :D

[oldpotatoe]

I converted my Salsa Casseroll to 650b. I am considering converting my Serotta Concours to 650b...I have a set of nashbar long reach brakes and some Pacenti tires...just need another wheel set from Old Potatoe...;)

Let me know, Velocity makes some nice 650b rims.

[palincss]

First time there was a small wire. I removed it. Found the hole in the tube. That was back in December or so. Flat was while on the road.

80 degrees today, so I tried it again. This time flat was on a local trail I've ridden hundred of times. Couldn't find anything on the tire, inside or out. I looked for several minutes running my hand inside and outside the tire. Gave up when I couldn't find a hole in the tube.


Going to take it to the lbs see if the stem hole is the problem. Maybe there is a burr. I will change the rear tire from Hutchinson to Pacenti. Buy more tubes. Then ride my cross bike. :D

If you have it ready to hand, you might also try some sealant of the kind used for tubeless. There's a guy on the iBOB list who lives in goathead country who rides flat free on Parigi Roubaix tires (by far, the most fragile, flat-prone tires I've ever used).

[93legendti]

Perhaps you might want to look for and remove the embedded wire or piece of glass, before giving up entirely?

The cut on yesterday's tube was in quite a different position from the first one. Far enough away from the site on the first tube, that whatever it was, it was a different culprit. I suppose it could be bad luck.

[93legendti]

Let me know, Velocity makes some nice 650b rims.

I'd be going a different route. What else you got?

[jc031699]

I am looking for some 650b x 32 tires with a folding bead, in planning for conversion of a Univega Superstrada from 1996. Not nearly as much clearance as the 1980s versions.

There used to be Grand Bois Cypres and Hutchinson tires of this type, but now I can't find anything. Any suggestions?

Thanks-

[Pastashop]

I am looking for some 650b x 32 tires with a folding bead, in planning for conversion of a Univega Superstrada from 1996. Not nearly as much clearance as the 1980s versions.



There used to be Grand Bois Cypres and Hutchinson tires of this type, but now I can't find anything. Any suggestions?



Thanks-



You can get Pari Moto and Gravel King in sub-38 mm size, I believe, and Soma has a model (?) that measure out to less than 38 mm.

I did this once in a Koga Miyata Prologue...

https://uploads.tapatalk-cdn.com/20170415/a6976db50e6a6aa41b62f45f6e421050.jpg

[Geeheeb]

another 650b lemond:

http://i66.tinypic.com/fjggaf.jpg

[ripvanrando]

I converted a Peter Mooney last Fall. Stripped it down and put some older 10 speed dura ace laying around. The hardest part was the wheels. Getting the rims was one hassle. Wrong spoke length. I had not built wheels in a bit and wanted to do it myself.

I shoulda had Old Spud or someone like him just do it for me. I wasted so much of my time.

[oldpotatoe]

I converted a Peter Mooney last Fall. Stripped it down and put some older 10 speed dura ace laying around. The hardest part was the wheels. Getting the rims was one hassle. Wrong spoke length. I had not built wheels in a bit and wanted to do it myself.

I shoulda had Old Spud or someone like him just do it for me. I wasted so much of my time.

YUP!! I'm ready!!

[mhespenheide]

another 650b lemond:

http://i66.tinypic.com/fjggaf.jpg

Geeheeb,

What brakes did you end up using for that Lemond conversion? My Lemond looks about 2mm too long for medium-reach brakes; I'd have to go for true long-reach brakes.

[Geeheeb]

Tektro R539

[azrider]

Posting here as it seems to have the most traction/responses for 650B conversion questions/discussions:

I'm going to try and convert my Dave Scott Centurion to 650b and I "think" i've got everything covered.........except for small gearing issue.

So my question: Will my tricolor 600 rear derailleur be able to tell the difference between a 7 speed hyperglide, as opposed to 7 speed uniglide, which is what's on the 700c wheel currently?

Sorry if that's dumb question.

[cmbicycles]

That derailleur won't know/care about the difference between 7/8/9 as long as the shifter matches the number of cogs. I think uni/hyper is mainly how the cogs engage the cassette body, and a little more ramping of teeth on hyperglide.

[palincss]

So my question: Will my tricolor 600 rear derailleur be able to tell the difference between a 7 speed hyperglide, as opposed to 7 speed uniglide, which is what's on the 700c wheel currently?


When Uniglide went out and Hyperglide came in, I had the LBS use a Dremel to make the Hyperglide cassettes fit on my Uniglide hub. The derailleur didn't notice the difference, although I did: the shifting improved.

[azrider]

That derailleur won't know/care about the difference between 7/8/9 as long as the shifter matches the number of cogs. I think uni/hyper is mainly how the cogs engage the cassette body, and a little more ramping of teeth on hyperglide.

When Uniglide went out and Hyperglide came in, I had the LBS use a Dremel to make the Hyperglide cassettes fit on my Uniglide hub. The derailleur didn't notice the difference, although I did: the shifting improved.

Thank you Thank you.........appreciate the info fellas.