CR18 Rims, 28 & 36 holes, 74 mm hubs, etc., etc.
For reasons that I will explain, I would like to rebuild the rear wheel of my Dahon Boardwalk to make use of one of the several 32- or 36-hole Shimano freehubs that I have lying around. This will allow me to have a tougher wheel, to convert from 6 to 7 (or 8) speeds, to have a somewhat wider gear range than the (older) stock Boardwalk and to generally benefit from the advantages of the freehub design.
The catch is that the stock Boardwalk has a 28-spoke rear wheel, and I don't have a 28-spoke hub shell "in stock." Even if I did, at 170 lbs., riding bumpy NYC streets and carrying all sorts of luggage, I'd rather have 32 or, better yet, 36 spokes in the rear wheel (unless someone could convince me that 28 is enough).
My Boardwalk came with Weinmann rims (not sure of the exact model but it ends in "19"), which is a very basic, mid-width, single-wall alloy rim. My thought was to convert to Sun CR-18 rims, which I have used in other applications (larger wheels) and I like very much. While these are narrower that the Weinmanns, they should be plenty strong, esp. in the 406 diameter. These also have the advantage of being offered in 28- and 36-hole drillings. The 28-hole drilling is important, because the front wheel is based on a 74mm Dahon hub with 28 holes.
Assuming that I want to match front and rear rims, it seems that my options are:
a. Obtain 28-hole and 36-hole CR-18 rims, swapping the front rims and building a new rear wheel on a 36-hole freehub
b. Obtain a 28-hole freehub and use it in relacing the existing rear wheel
c. Obtain a new 74mm front hub drilled 32 or 36, thus freeing me up to obtain the best deal on any quality 32-or 36-hole rim set
d. Do nothing or simply replace the 14-28 freewheel with a wider range 7-speed freewheel
Although it's not the simplest or cheapest, as the above suggests, I am leaning toward option (a). On that note, does anyone know of a web-based vendor who offers the CR-18 in 20x1.5 in. (406 ETRTO) with both the 28 and 36 drillings?
Option (b) might be OK if I can be convinced that 28-spoke wheels are reliable for day-in, day-out commuting (this bike is fairly new to me, but so far, so good).
Option (c) seems less likely, but I would be curious to know of the options in 74mm hubs (other than the Panatour, which I don't foresee buying).
Option (d) may be the short to mid-term solution, as I have several freewheels lying around.
Your thoughts would be appreciated.
I am using a shimano megarange 11- 34 freewheel on a boardwalk.I have had the derailluer adjusted but still have a hard time getting the chain up onto the 34t cog. The 94 inch top gear is very nice though. I mostly ride my other folders though since i have too many bikes and it is fairly flat here. If you replace the freewheel with a 7 cog unit space the right side out with a washer .You should aso change to a 7 speed gripshift if you want full use of the gears.You could also get a custom 6 speed freewheel from Loose screws bicycle small parts. and avoid changing the gripshift.
Last edited by James H Haury; 05-16-05 at 04:01 PM.
If you think a 406mm 28H rim is hard to find, try finding a good 349mm 28H rim!
Originally Posted by ETRTO 520
However, here's one, though it is skinny:
Sun, 20x1-1/8, M13, 28-Hole, Black Alloy Rim
There's also a matching 36H version of this same Sun M13 rim, but I don't know anything about its quality. Caveat emptor.
Thanks to James and Spambait11 for your follow up.
I do have an 11-34 t. Megarange freewheel lying around and will probably install it until I can sort out the freehub/rim quandry. The freewheel should work without a hitch: I already installed a long cage rear derailleur and a bar-end (bar-con) shifter (on drop bars), so I won't face derailleur- or shifter-capacity issues. I'm not a big fan of the 26 to 34 t. jump on that freewheel, however.
As regards the Sun M13 rim, I wouldn't mind using it and the price is right, but, unfortunately, 20 x 1 3/8 does not equal 20 x 1.5/1.75. These are two distinct wheel sizes (ETRTO 451 and ETRTO 406, respectively). I prefer ETRTO 451 to ETRTO 406, but, alas, they won't fit on the Boardwalk.
Although, based on their websites, the rim manufacturers seem to make a good mix of ETRTO 406 and 451 rims (and other sizes) with a fair range of drillings (28 - 48) (see, for example, the Sun Ringle site), actually finding these from web-based vendors is a different story ....
Check loose screws ,their custom freewheels are about 40 bucks .The disadvantage is that you cannot get an 11 top cog with their custom freewheels another possibility is to contact Gaerlan custom bicyces and see what they will do.They are located out in Sqaw valley Ca. http:www.gaerlan.com They are currently out of the shop on a bike tour till the 24th .I just checked but they will email back and forth to discuss your needs. I worked with them before on a roller kit.
Last edited by James H Haury; 05-17-05 at 02:48 PM.
Ah, that makes sense. It's the same kind of distinction between an ETRTO 349mm rim vs. 305mm.
Originally Posted by ETRTO 520
Good news: Here's a source for a 406mm Sun CR18 28H rim; Bad news: You have to buy from the U.K. though I have heard people have had good response and service from them:
St. John's Cycles
Gaerlan is great to buy various parts from. But the last time I asked him whether he could secure me a particular rim, he didn't seem to want to. You might also want to email Zach Kaplan - he seems able to get most things stateside.
Thanks, Spambait11, for chasing down the link to St. John's Cycles in Bridgwater, Somerset, UK. It seems a shame to order oversees for such a simple item, but absent a domestic source, it may be the best solution. In fact, although I live in Brooklyn, NY USA, it looks like I'll be in the UK at some point late in the approaching summer. Perhaps a side trip to scenic Somerset would be in order ...
In the short term, I'll switch to a 7-speed, wide-range freewheel.
In the medium term, I am going to look for a 36- (or 32-) hole generic replacement rim that has more or less the same characteristics of the Dahon's stock Weinmann TM19 rims. I will then build up a replacement rear wheel based on a 7-speed freehub, and run unmatched front and rear wheels until further notice (no big deal for me ...)
In the long term, I'll swap over to Sun CR-18 rims with a 28-hole rim in the front and a 36-hole rim in the rear. To that end, to repeat, if anyone knows of a domestic bike parts vendor who stocks the CR-18 20 x 1.5 (ETRTO 406) in both 28- and 36-hole drillings, please let me know. Thanks.
Check with Yellow jersey bicycle in madison wis, and Harris cyclery in West Newton Mass first.
American Classic is the manufacturer of the 74mm front hub on the Helios SL's Rolf wheels. You can probably source a hub from them directly.
BikePartsUSA has CR18s in 36H in both 20x1 3/8 and 20x1.5, it looks to me... but no 32-hole or 28-hole versions.