Andje wrote:Anyway, I'm going to 11/12 JRH spokes and a 21 inch moto rim and DOT rated rear tire.
I've been down that road. It has some bumps... but It's probably worth it (why do I say "probably?" because I've only been up to about 1/5th your speed on this bike/these wheels!)
Here are some thoughts from the experience:
1) Starting with the hub - I wanted a NuVinci, so that meant there would be a top end to the strain I could put on the hub flange. This ultimately meant 13GA JRH spokes with oversized nipples (and washers, because the oversized spoke nipples were still too small). Link: viewtopic.php?f=6&t=37207&start=60#p589891
. I know your drive is different, but spoke flange strength might still be a consideration.
2) I didn't shop for rims and tires at the same time. So, I convinced myself to buy 21" rims and 2.5" tires. Too bad I bought the rims before realizing that 2.5" tires were impossible to find. 2.75" tires not too available either. I went with 3" tires, since that was the smallest I could find. This made for a really tight fit:
Presently, I have like 1mm clearance on each side of the chain stays. That's plenty-good, as the rim is solid and the wheel is true - but it's really really close.
Bottom line - look into 21", 20" and 19" rims, and shop for tires at the same time. Don't buy till you have a combo you like.
( Don't let the pic below fool you, in that picture I have spacers on the axle widening the rear.)
3) Radius: Noting that my custom dropouts push the rear axle back 3" and down 1", the 21" rim and 3" tire works fine radius wise. Looks like it would work with the standard dropouts, actually. IIRC, your dropouts push the axel back about 2"?
If you want me to take any measurements for clearance sake, let me know.
4) Again, without long term and high speed tests, take this with a grain of salt - but...
If you buy a tubeless motorcycle or scooter tire, stick with tubeless technology all the way. I have a tube mounted in a tubeless wheel in the rear - had to have it installed professionally, and per the mechanic it was an SOB. The front is pure tubeless, using "Stan's Tubeless" fluid and rim tape. The wheel went together much easier - installed by the same shop/mechanic.
Link: http://www.endless-sphere.com/forums/vi ... 15#p587532