25 or 30mm

davidof

I want to upgrade my sons wheels to tubeless. I'm looking at DTSwiss 1900 Spline as they are within the budget. I'm now looking at internal rim width, 25 or 30mm? Cat 2 or Cat 4 wheels? Son is 55kg, mainly cross country use, some drops and steps.

Any thoughts?

steve_sordy

For that type of use at your son's weight, I would go for the narrower internal rim width. It will reduce weight and make his acceleration a bit snappier. I am assuming here that he will not be having the wider tyres that we are seeing now on quite ordinary bikes. If the rim is too narrow for the tyre it makes it adopt a balloon shape and it can squirm, or even roll off the tyre completely! Too wide and the tyre can lose grip on the corners and may come off the rim under hard cornering. In either case the tyre will not have the profile the designers had in mind. Fortunately the tyre/rim combo can have quite a wide range.

Almost ten years ago I rode in the French Alps for a week with 19mm rims and I didn't have any problems with the wheels. I was no gung-ho hero, but it redefined what "steep and rocky" meant for me. The fashion for wider and wider rims along with the wider and wider tyres sure has taken off. I used to ride everywhere (BPW, Peaks etc) on my 27.5 x 2.2, and I'm at a riding weight of 92kg (14.5 stone)! But my current bike came with 29 x 2.6 and 30mm internal rim width!

The link below is to a WTB website on tyre and rim widths. It will show you the range of tyre widths that are optimal for various rim widths. Page down to the second chart.

https://www.wtb.com/pages/tire-rim-fit-chart

Without looking it up I don't know what cat 2 or cat 4 means.

steve_sordy

The other thing that occurred to me when I re-read your OP. My previous answer was aimed at the post title (25 or 30mm?) But you start off by saying that you want to go tubeless. You can convert a rim to tubeless very easily. You do not need to buy new wheels. Google "Stans tubeless conversion kit"

You may not even have to buy a kit. Ask a separate question on here to get more advice.

davidof

My son has a felt with 21mm internal rim width and 2.35" tires. I converted the wheels to tubeless and all was ok for 6 months but the rear started to leak. I checked and the rim tape had started to come unstuck.

I've now retaped 5 times, with different tapes, and never got rid of the leak - it is obviously going into the hollow section of the rim and escaping via either spoke holes or the valve. Inspecting the tape there is no obvious place this is happening. I have fluid in the tires.

As he dinged the rear I was thinking of upgrading the wheels.

steve_sordy

What a nuisance that can be! Have you tried several layers of rim tape? Have you tried various sealants? Yes! is probably the answer.

One solution that I know will work is to use Gorilla tape as rim tape. I used to be an enormous fan of Gorilla tape. It was recommended to me by a bike shop. It is cheap, looks great and it works! What more could you want? I used it on seven different bikes before I had a problem. The problem came when I had difficulty fitting a tight tyre. Subsequently I could not get it off. Long story short, the glue from the Gorilla tape had spread and glued the tyre to the rim. I entertained a bike forum for a week with that story. It was so unpleasant and time consuming to get everything sorted out and the bike up and running again that I will no longer use Gorilla tape. But it WILL seal leaky rims.

davidof

Thanks Steve, I'm going to try with T-Rex tape, which is similar to Gorilla but I can't find Gorilla in France. I tried Duct tape but it is no good.

People report good results with T-Rex and I can buy 25mm width.

I think the issue is the rims have a very deep U channel for the spokes and this makes the seal imperfect but that is a guess as I haven't identified where they are leaking.

mully79

if you have a deep narrow channel use electrical insulation tape.
Go around the middle, pull it tight to help push into the channel then go around one side then the other then back to the middle.

Worth a rub of sand paper over the spoke holes in case there is a burr that keeps cutting the tape.

davidof

mully79 said:

if you have a deep narrow channel use electrical insulation tape.
Go around the middle, pull it tight to help push into the channel then go around one side then the other then back to the middle.

Worth a rub of sand paper over the spoke holes in case there is a burr that keeps cutting the tape.

Yes that's a good idea and I will try it too and the idea about checking burrs is good too.
Many thanks everyone.

davidof

Thanks for all the advice which I took on board.

This is what I did to solve the problem
1. retaped with 25mm TRex tape. The rims with a deep center groove proved tricky with standard tubeless tape to get a good seal
2. used a Mucoff valve - there are options to give you a better seal than cheapo conical tubeless valves and I would reccommend if you are having issues despite the cost
3. used a thinner tubelss sealant, in my case Joe's.