650b frame vs. 650b Conversion??

[Tom Norton]

I know this may be subjective but how much of a difference would there be between the above mentioned frames? Ride quality,feel,etc..

[Joseph Kopera]

I'm by far not the expert here, but from what I've gathered it really depends on the particular bikes you're comparing, and, I agree, can be quite subjective on what kind of ride quality you're looking for and to which use you're going to put the bike.

Those things aside, it also largely depends on changing the wheel size alters the geometry of a particular frame: trail, BB drop, seat stay and chain stay width to fit larger tires, etc... can alter both handling, quality, safety for better or for worse, or a mix of the two.  

That being said, there are a number of frames that have been popular for 650b conversions-- early 1980's Treks 600 series and Fuji's seem to be favorites. There are particular Raleigh's as well (others can expound more on this).  I converted an `83 Trek 613 and am in love with the thing.  I'm also really like my Soma GR.  Both bikes serve different purposes in my fleet and handle very differently, but they're also rather different bikes as well, even with the conversion.

Cheers,

Joe 

Western Mass.

[Murray Love]

In terms of ride quality, feel, it depends, about which more below. But some practical considerations:

Converted bikes are likely to have mid- to high-trail geometry, which, when added to the pneumatic trail of wide 650B tires, can result in less than optimal handling with a front load. If you don't often carry a front load, this may be a non-issue: my converted Specialized Sequoia handles just fine.

The BB drop is also important. Frames with >75mm BB drop may be prone to pedal strike depending on tire width. Most older road frames have less drop than this, so the issue doesn't arise. But when I temporarily converted my Kogswell P (80mm drop), I had pedal strike on several occasions with 38mm tires.

Tire clearance may be an issue with some converted road frames, and likely won't be on a well-designed 650B-specific frame. I had to dimple the chainstays (badly) on my 531 mystery bike to get tire clearance for 38mm tires, and it won't take anything much larger than that. On the other hand, my Sequoia has ample clearance for maybe up to 42mm tires.

Finally, most conversions are of older road frames, and these tend to have horizontal dropouts, which are more difficult to make play well with fenders, especially when clearances are tight or chainstays are short.

But when we speak of ride quality or feel, we're often talking about variables like tubing thickness and length, which have to be evaluated on a case-by-case basis. Most production and semi-production 650B frames use relatively thickwall OS tubing, which are often far stiffer than the tubing on older road frames. Some people are content with this, I hate it. It's a matter of taste.

Murray

Victoria, BC

On Mon, Jan 23, 2017 at 2:17 PM, Joseph Kopera <joeyk...@gmail.com> wrote:

I'm by far not the expert here, but from what I've gathered it really depends on the particular bike, and, I agree, can be quite subjective and largely depends on how going to 650b alters the geometry of a particular frame: trail, BB drop, seat stay and chain stay width to fit larger tires, etc...

That being said, there are a number of frame that have been popular for 650b conversions-- early 1980's Treks 600 series and Fuji's seem to be winners, in my book.  I converted an `83 Trek 613 and love it.

Cheers,

Joe 

Western Mass.

On Monday, January 23, 2017 at 4:57:37 PM UTC-5, Tom Norton wrote:

I know this may be subjective but how much of a difference would there be between the above mentioned frames? Ride quality,feel,etc..

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[Steve Frey]

The replies above from Joseph and Murray are right on the mark. It really depends on the specific 700c frame you're talking about converting and the specific 650b frame you're comparing it to. 

For example, I own a Rawland Stag, a bike that was designed specifically for 650b wheels, and I also own a 1982 Trek 614 that I've modified to run 650b wheels. With the same 42mm tires on both bikes, the two are more similar than they are different. The Rawland has a slightly lower bottom bracket (yes, lower), and has a little less trail than the Trek (37mm vs. 46mm). The difference in BB height isn't enough to notice. I do notice the difference in trail, but it's the sort of thing that I notice in the first minute on each bike and then it disappears. Though the two bikes handle differently, I think both handle intuitively and I'm comfortable on both bikes with and without front loads in all kinds of conditions. Overall, with 650b x 42mm tires on both bikes I prefer the Trek, but it's for mostly subjective reasons. 

I think the only generalization you could make is that it's usually going to be easier to build up a purpose built 650b frame with 650b wheels. With my Rawland, building the bike from a bare frame was almost as simple as, buy some parts, bolt them on the frame, and you're done. With the Trek it required some work. It was a fun project and I really enjoyed it, but I had to spend quite a bit of time tweaking and fussing with things to get it to all go together correctly. In the end I think it was completely worth the effort, but others might not agree.

Steve

[somervillebikes]

I'd echo a lot of what Murray said.

Lots of 1980s Japanese production bikes make great candidates for conversion, with ample clearance for 42mm tires and adequately high BBs. Trail can be an issue, as most production '80s frames were built with mid- to high-trail geometries. If you can find a good candidate, and the bike has the ride and feel that you like, I'd say go for it.

I converted a few bikes to 650B before buying a bike designed from the ground up for 650b (Rawland Stag). The purpose-built 650B Stag surpassed the conversion in terms of overall feel and balance, but it also had its issues (an overly stout fork being the biggest issue).   Then my next bike was a 650B custom (a Jeff Lyon L'Avecaise), and that again surpassed the Rawland because the design parameters were now in the control of me and my builder.

Despite the shortcomings of conversions, they can still be a lot of fun. And my 1984 Shogun tourer 650B conversion is still one of my favorite around-town bikes, its' now on revision 3 since conversion (townie edition):

Anton

velolumino.com

  

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[Nick Favicchio]

I'm exceedingly prejudice, but I recommend old Motobecane Grand Jubile or Grand Record.

They were 27" until the late 70's. 27" means more room for everything. 610 centerpulls just barely reach a 650 rim.

More interestingly, 74° ht and 55mm fork offset + 650b x 42mm = 40mm trail. 70's bike boom bikes means the fork and ht angles vary but my Grand Jubile came this way and I'm pretty sure it's not the only one. Looks like others I've seen but catalogs from bitd show some bikes with 55mm offset and some with 40mm offset and seemingly at random.

Quality too is typically solid, generally better than Peugeots and Raleighs imo but paint can hide all sorts of stuff.

My experience having an old 531 bike randofied was super positive. It taught me a lot over 5k or so miles and when the time came for a custom, I knew what I wanted.

[Tom Norton]

The frame I am considering is my 1984 Miyata 610. I have already switched from 27" to 700c and am running 35mm tires. It is my favorite bike right now. Wondering if I do consider going to 650b I will have to have the canti posts relocated.

I did convert my 1983 Schwinn Super le Tour to 650b and really enjoy it also. Wondering if I should just start looking for a dedicated 650b frame.

On Monday, January 23, 2017 at 4:57:37 PM UTC-5, Tom Norton wrote:

[somervillebikes]

You will almost certainly need to have the canti posts relocated-- especially going from 27" to 650B. My Shogun was 27" and there was no canti in the world that would have worked with the existing studs. I had new ones put on, as well as some other bits and pieces.

Anton

velolumino.com

[David Cummings]

I have done three 650b conversions and a couple 27" to 700c conversions (so ease and amazing what 4mm smaller diameter can gain you in tire sizes!).  Lots of great guidance here already. 

You mentioned frames and ride quality.  You have two bike designed to be a bit stiffer than the average road bikes of their day.  If you took a frame with lighter tubing from the same era, you might experience something different.  Without going too far down the "planing" rabbit hole, frame material will make a difference in your ride quality.  I would try a 650b conversion of a bike that was more along the lines of a lightweight sport tourer, rather than a touring bike such as those you already own.  You may decide to hold off on repositioning the canti studs after such an exercise.  

If you do decide to go with your current 610 and move the canti studs, you will need a repaint.  Might as well go whole hog and make sure the bike has enough braze ons and properly spaced fender mounts in the rear triangle.  

Cheers,

David

[Tom Norton]

David,
You mentioned"light sport tourer". What bikes would fall into that category?

[Philip Kim]

Hard to say since there are many different bikes, and many variables make up the ride. But here are experiences with some 650b bikes I've had.

650b converted Trek 400 Elance (I believe there's a similar Frek in the current BQ)--- 531 Reynolds tubing, converted very nicely with Tektro 559's. Could only fit 650bx38 with fenders. The frame was one of the more lively frames I've pedaled. Could easily ride long distances without getting tired. Handling was awkward with front load. Felt more noodle-y when loaded with camping load (front and rear load). If you got a custom low-trail fork probably could all front load and it would probably smooth it out. I've never done it, so I wouldn't know. Tektro 559's didn't perform well for me even with Kool Stop Salmon.

I got a Winter Cycles-made Box Dog Pelican. It was fairly easy to build up, and everything almost lined up nice building it up, but it's a semi-production frame. A bit more stable than my 650b conversion while keeping most of the lively ride of the Trek 400 conversion. A lot more extras than the Trek - fork dyno wiring, brazeons, and cantis are always nice. This is with my gf now as I'm getting a custom from Norther Cycles soon.

On Monday, January 23, 2017 at 4:57:37 PM UTC-5, Tom Norton wrote:

[David Cummings]

A short definition of a "sport tourer" would be a do-anything bike - it's in between a dedicated touring bike and a racing bike. Lots of mid-level bikes from the 70's and early 80's fall into this category: light frame, slightly relaxed geometry, eyelets for racks. Comfortable for riding all day long, a good credit card tourer.

There's a good thread over on BF with examples: http://www.bikeforums.net/classic-vintage/1044414-show-your-classic-sports-touring-bicycle.html?styleid=4

Right off the bat, you will see a Trek 610 given as an example. A 620 would NOT qualify.

In Miyata-speak, I could consider the 710 to be a sport-tourer (they call it semi-pro). The 610 is just a step below the 1000 (considered by many to be one the best full touring bikes ever made).

Cheers,
David

[William Harrison]

The 1983 Trek 620 is very much still a sport tourer.  The 620 didn't become a heavier touring bike until 84. 

[Ken Freeman]

I think the main difference  in the 84 620 cep' maybe for brakes is the long chainstays variant.  But I don't think the tubing gauges became any heavier in the 1984 620.  The 720s were also not particularly high-gauge.  And the 610 was not particularly light, with its 10 7 10 downtube.

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Ken Freeman
Ann Arbor, MI USA

[David Cummings]

I guess I was thinking of the later model touring Teks with canti's. Do you have any other suggestions to more clearly elucidate the difference between a dedicated touring bike and a sport tourer?

[Les Lammers]

Maybe this will help: http://www.bikeman.com/bikeman-blogs/650blog/1771-650b-conversion-guidlines

[Jim Bronson]

My older Rivendell that I converted was already an excellent riding and handling bike, and running 650B made it even smoother.  The handling seems unaffected to me.  I don't ever run a front load, due to prior negative experiences doing so when I was running 700c.

That said I do have the issue with the pedal strikes if I am not careful.  I can also only fit 38mm tires, and the horizontal dropouts with fenders make it a bit of a chore to change a flat on the back.

I need to get it repainted, I will probably have the chainstays dimpled when I do so it will be able to fit 42s with fenders.

All this said - I would like to get a purpose built custom 650B Rando bike one of these days in the Constructeur style with hidden wiring and so forth.  

I tried a V1 65cm Soma GR and it just wasn't big enough for me.  I haven't tried a V2 65 which I hear are bigger, but I am somewhat skeptical.  I'm super tall, just kind of comes with the territory.  I don't think there's a stock bike out there that is an ideal solution, so it will have to be a custom something or another.

Jim

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