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Thought experiment: 700c to 650A

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Thought experiment: 700c to 650A

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Old 06-14-18, 06:19 PM
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Thought experiment: 700c to 650A

Have any of you ever converted a 700c bike to 650A?

Consider it sort of a thought experiment... going from 700c to 650b (584mm) is fairly common, but I haven't run across much information or anyone's tale of converting to 590mm.

I'm kind of wondering how brake reach would be affected for direct-mount center-pulls...
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Old 06-14-18, 06:32 PM
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700C = 622mm diameter 650A = 590mm radial difference = 16mm -- can your brake calipers handle that much additional pad drop?

Alternatively, do you want to try some form of drop bolt mounting?
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Old 06-14-18, 06:41 PM
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I have done that, but I consider it an exceptional case. This was on a bike that could take a variety of wheel sizes; I started with 27", went to 700c, and then went to 650A. This is an English bike with 32 spokes on the grind wheel and 40 on the rear.🆒

The main reason you wouldn't do this is: the rim options in 650a are limited (anything you like as long as it's CR18) and the tire options are almost as bad (panaracer Col de la Vie is your best bet). Those are fine options if they suit you. I understand better options are available in Japan... do you live in Japan?

another advantage to 650a is that the aforementioned CR18 rims are available in both 32h and 40h drilling, perfect for an older English bike. Like mine. Few rims are available in both those options.

650b rims and tires can be expensive, but there are very high quality options. 650b tires can be found in a wide variety of widths. For high millage bikes, this may make a lot of sense.

In theory, 650a is fine. In practice, I find 650b more attractive.
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Old 06-14-18, 06:43 PM
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Don't mistake me: when I said "thought experiment," I meant it; I intended this is purely hypothetical discussion. No parts, no frame, no anything bought. I'm just curious about the possibilities.

Originally Posted by rhm View Post
I understand better options are available in Japan... do you live in Japan?
I can only wish: it would make practicing Japanese a lot easier.

Residency in Japan is quite difficult, as your employer has to constantly vouch for your visa status; if you get fired or quit, you have 3 months to leave the country. Like Switzerland, permanent residency & immigration is almost impossible (without marrying a Japanese national) & can take decades.

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Old 06-14-18, 06:45 PM
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I think @ThermionicScott did that, but was dissatisfied and converted to 650b afterward. Has a detailed thread about his Bianchi.
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Old 06-14-18, 09:56 PM
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Old 06-14-18, 11:06 PM
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So here you have two actual experiments, not thought experiments. I would think the question has been asked and answered.
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Old 06-15-18, 03:02 AM
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I've done it, and made a thread about it. Theoretically there's nothing wrong with it, it's easy, but the selection is one rim and a couple tires. Ultimately the Panaracer col de la vie is a lackluster tire if you're after any performance, and mine never measured much more than 35mm, meaning you'd be better off with 27" to 700x32-35 conversion, or a 650b conversion with quality tires.
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Old 06-15-18, 04:49 AM
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Originally Posted by rhm View Post
The main reason you wouldn't do this is: the rim options in 650a are limited (anything you like as long as it's CR18) and the tire options are almost as bad (panaracer Col de la Vie is your best bet). Those are fine options if they suit you. I understand better options are available in Japan... do you live in Japan?
I'm not advocating a 650A conversion by any means -- the choices in tires in 650B itself would be enough to close the case -- but shopping for parts from Japan isn't as difficult as you might think. Grand Bois' shopping site when viewed with Chrome set to translate into English is quite easy to navigate, and purchasing from them is little different from buying from a US or British vendor. Here's what Grand Bois has for 650A rims:


Of course, shipping cost for a rim might be a problem...
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Old 06-15-18, 05:08 AM
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I’ve bought rims and tires directly from Gran Bois, and shipping wasn’t terribly costly, but that depends on yen-usd relationship at the time, of course.
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Old 06-15-18, 05:48 AM
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Originally Posted by gugie View Post
So here you have two actual experiments, not thought experiments. I would think the question has been asked and answered.
This is bike forums. We never stop talking about the same stuff over and over again, right?
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Old 06-15-18, 07:38 AM
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Originally Posted by bikemig View Post
This is bike forums. We never stop talking about the same stuff over and over again, right?
Has Grant Petersen, Jan Heine/Compass, or correct tire inflation been mentioned yet?
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Old 06-15-18, 07:50 AM
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i've done it and as was said before there are two problems. cr18 rims while good in every other size are too large in 650a and there arent many decent tires. the ones that are decent flat very easily. by the way i used tektro long reach brakes and they worked really well.
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Old 06-15-18, 08:45 AM
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Originally Posted by nlerner View Post
Has Grant Petersen, Jan Heine/Compass, or correct tire inflation been mentioned yet?
Or why not Brooks saddles & the superiority of Proofide over other brands of exactly the same stuff?

Originally Posted by 52telecaster View Post
... By the way I used Tektro long reach brakes and they worked really well.
Yeah- Tektro's 556/559 'Bigmouth' calipers definitely have the reach for a conversion to 650b (584mm); I did that myself on a bike I've long since sold in favor of riding actual 650b frames. But I haven't found much (if anything, aside from @John E's mention of drop bolts) that would help anyone facilitate a conversion to a smaller wheels size on a frame originally built for cantis or direct-mount center-pulls.

That's kinda what got me wondering: the canti braze-ons can't be raised or lowered, so how would someone use a smaller wheel size, if the initial brake-reach remains fixed? Shorter canti arms? Drop bolts? Or maybe a wheel size that isn't so much of a jump as from 700c to 650b?

-
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Old 06-15-18, 09:03 AM
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Now that department store MTBs with 650B wheels are thing, there are cheap rims available in the 650B size. I've found a mismatched pair at the local co-op, 36/32h... they were disc wheels but the rim sidewalls have a brake wear indicator so I am gonna use them as a cheap way to try the kool-aid. The co-op supplier's catalogue lists a generic 650B rim for sale and it looks a bit like a rhyno-lite so if nothing else it should take a beating. That 650B rim is the same price as their generic 650A so price-wise it's kind of a wash at the low-end now, at least for me.
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Old 06-15-18, 09:47 AM
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Originally Posted by bikemig View Post
This is bike forums. We never stop talking about the same stuff over and over again, right?
Yeah, but thought experiments generate zero pictures.

Pics or it didn't happen...

;-)
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Old 06-15-18, 10:15 AM
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Originally Posted by nlerner View Post
Has Grant Petersen, Jan Heine/Compass, or correct tire inflation been mentioned yet?
It's a little depressing that we haven't had a good chain lube thread on BF for a while . . . . ah, the good old days.

Originally Posted by gugie View Post
Yeah, but thought experiments generate zero pictures.

Pics or it didn't happen...

;-)
Just think of this as a non-bikeporn thread safe for kiddies.
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Old 06-15-18, 11:17 AM
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Originally Posted by bikemig View Post
It's a little depressing that we haven't had a good chain lube thread on BF for a while . . . .
Yah, I think my chain-lubing technique has changed at least three or four times since we've had one, in fact. That's three or four missed chances to tell you guys you're doing it all wrong and only I know the One True Path
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Old 06-15-18, 11:21 AM
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Originally Posted by Lascauxcaveman View Post
Yah, I think my chain-lubing technique has changed at least three or four times since we've had one, in fact. That's three or four missed chances to tell you guys you're doing it all wrong and only I know the One True Path
If you don't put up some pics of your new chain lubing techniques, @gugie will be sorely disappointed!
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Old 06-15-18, 11:30 AM
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Originally Posted by bikemig View Post
If you don't put up some pics of your new chain lubing techniques, @gugie will be sorely disappointed!
I think the time has come for a new C&V chain lube thread. If you don't start one, I will.
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Old 06-15-18, 12:23 PM
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Originally Posted by noobinsf View Post
I think @ThermionicScott did that, but was dissatisfied and converted to 650b afterward. Has a detailed thread about his Bianchi.
Originally Posted by noobinsf View Post
You found it! I feel like I'm going to hurt a very nice Japanese person's feelings whenever I say (or think) it, but the Col de la Vie's just didn't make me happy. To this day, I'm still not sure if they were as slow as they felt, but it just seemed like I was working harder than I should have to by the end of a day's riding. They are well-made tires on par with Panaracer's other mid-level skinwall tires, I think it's just the choice of tread. I've still got the wheels I built, and the tires I rode from Paris to Brest and back. Maybe I should sell them to someone else thinking of doing the same thing...
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Old 08-13-18, 11:13 AM
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I was just think ing doing this conversion too.

Because I am use a small frame and like to pedal with the arch of the foot...so I am not happy with toe-overlap on 700C...the smaller 650A would be perfect solution for shorter riders!

I.e., 16mm more for the toe clearance.

16mm = (622-590) / 2
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Old 08-13-18, 03:52 PM
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You only get 16mm more clearance if the tire size doesn't change. Most 650A tires are 35-38mm, which gets you a wheel that is the same diameter as a 700x23C.
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Originally Posted by chandltp View Post
There's no such thing as too far.. just lack of time
Originally Posted by noglider
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Old 08-15-18, 03:43 PM
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Originally Posted by DIMcyclist View Post
Residency in Japan is quite difficult, as your employer has to constantly vouch for your visa status; if you get fired or quit, you have 3 months to leave the country. Like Switzerland, permanent residency & immigration is almost impossible (without marrying a Japanese national) & can take decades.

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You don't need to reside in Japan to buy from Japan. You can order from Grand Bois in Japan with virtually no more difficulty than ordering from any US online supplier. CYCLES GRAND BOIS ? ?????(CyclesGrandBois web-shop) is their shopping site. Use Chrome and it'll translate into English. Placing items in your shopping basket and checking out are almost identical to what you're used to, with one exception: after you place the order, you wait until Grand Bois sends you a PayPal invoice that will include the shipping charge. Pay with PayPal as normal, and it takes care of the currency conversion. Items come in the mail via Japan Post about as fast as from any US source.
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