How crucial is matching ERD when replacing a rim but keeping the same spokes?
Flat spotted my E13 27.5 TRS rim today. I've dinged them a few times but now the tyre won't seal so it's probably terminal.
Not massively keen on E13 stuff in general (seems poorly made) so keen to swap out for a different rim.
ERD on the TRS rim is 561mm, so I figure a rim with anything up to 565mm will be ok?
Currently looking at XM481 or EX471
That'll depend on how long the existing spokes protrude from the nipple inside the rim. Personally I'd look for a closer match, but you may be lucky.
'Freespoke' has a reasonable list of erd values, as does the wtb website
XM481 is 563, so 1mm per spoke extra, should be fine with that, but will you be using PHR washers with the rims?
I wouldn't quite trust the erd measurment on e13 rims.
I did a rim swap from xm421 (563) to TRS+ ("561") plus washers and the spokes were a good 3mm shorter than I'd have liked.
DT erd's include the phr washers.. or at least the DT calc factors it in.
I have 3 x 32h e13 rims that i keep meaning to send back to CRC (6069 hookless version I believe)
You can manage the ERD to a limited extent by using longer nipples for larger ERD rim or washers/double square/internal nipples for smaller ERD rim.
Thanks all 🙂
Not sure what PHR washers are- will do some googling.
I was originally planning to use the same spokes and nipples
Washers spread load around holes instead of eyelets . They come free with Dt swiss rims, well they did with mine from CRC.
Spokes from here are only 25p each plus postage so £8 for 32 +post
spokes
Spank spike race erd is 558, mavic 830 are 559, spokes will be 1mm longer than ideal but should work, you could use Sapim HM washers on the spank rim to add 1.4mm to the erd.
+2mm should be OK IME as long as the spokes are long enough for the rim you have.
You may also be able to straighten your rim out with an adjustable spanner (Matron)
Had you got long out of the TRS rim beforehand?
I've been running four of them for about 18 months and rate them quite highly. Only managed to kill one, and that took a number of heavy, square-edged hits.
Saying that, I did get them cheap and they are hard to find now. So if they were pricey I'd definitely move to DT instead.
You may also be able to straighten your rim out with an adjustable spanner (Matron)
Yea I tried that but weirdly the flat spot is on the rim bed. Seems like the rock hit the rim sidewall at a perfect angle to depress a 10mm section of rim bed, which means there’s a fairly large gap under the tyre bead. Never seen this before! Might seal with a load of sealant but that always makes me nervous
I did that to a rim luckily it sealed. Thought about building it up a little with bits of tape, or even taking back to round with car body filler.
"which means there’s a fairly large gap under the tyre bead"
I had exactly this on an i29.
It would seal tubeless but any pressure on the sideall at that point and the air just hissed out.
I might try putting some gorilla tape on the gap and retape the rim over it with TESA tape...
If you start trying to compensate for short spokes by using long nips, make sure they're brass.
Because this:
https://www.wheelfanatyk.com/blog/wheel-building-tip-no-9-succeed-with-alu-nipples/
It is crucial to have spokes that are sufficiently long so that they engage into threads in the broader head of the nipple and thereby prevent nipple failure at the "neck" or shoulder point as discussed in the wheel fanatyk blog link above. It's quite common for nipples to fail here when spokes are too short. Brass nipples take longer to fail but they still crack eventually. For that reason, using a longer nipple to bridge to a spoke that is too short is a bodge that you may or may not get away with.
Obviously any risk does not always manifest as an actual failure but you have to determine if you are willing to bear the risk - where will you be when the nipple fails?
It is a little less bad to have a spoke that is slightly long as long as you can still tighten the nipples enough to achieve good tension.
If the current spokes protrude beyond their nipples then you will have a little margin to go with a larger ERD. If the current state is that the spoke end is just reaching the slot or below it then you have very little margin for using a larger ERD rim.
I just had to rebuild a wheel because of a spoke length miscalculation - I changed the hub from the one originally intended and it left them just a little short. It seemed more sensible to me to spend another 8 quid on spokes now rather than have it fail and do the same thing later.
Thanks Alex, really helpful!