Let's talk about tubulars

Discuss light weight issues concerning mountain bikes & parts.

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eliflap-scalpel
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by eliflap-scalpel

jooo wrote:This is one of the open mold tubulars (29er - from Eliflap's blog). They seem to be available from a few different places:
Image
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i am using them since few months ...

very satisfied ....
http://eliflap.it/

njee20
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by njee20

I see Light Bicycle are now doing 320g tub rims here, which are interesting.

Has anyone tried using wider road tub rims on a mountain bike? Flirting with the idea of something like these, reckon you'd fold one in half the first sign of a bit of air or a rock?

Geoff
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by Geoff

It has definitely been done, but why? Today, we have several MTB tubular rim options.

The problem is not necessarily the strength of the rim, but the width and the profile of the rim bed. With a modern MTB tubular, you need a wider rim with a radius that matches the tire in order to get a good glue job.

njee20
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by njee20

It has definitely been done, but why? Today, we have several MTB tubular rim options.


Because they're $127 for a 250g rim, so lighter than Enve, Innolite, etc, on par with AX-Lightness, but about 1/6 the price... Never seen another open mould tub rim <300g - as I said, the LB ones are 320g, Eliflap's ones up there ^^ are 380g.

23mm width seemed relatively wide, I did wonder if you'd have enough surface area to get a decent bond, MTB tub tape looks to be 25mm, so you'd be on the border I reckon, I'd not want to go too wide on the tyres.

Geoff
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by Geoff

That would probably fall under the category of 'false economies'. You will not get anywhere near the performance with a rim not designed for the purpose.

Before there were MTB tubular wheels, people were experimenting with 650c rims and custom tubulars. As soon as the concept was proven-out and rims became available, it didn't make any sense to take the risk. In my basement, I have a set of old(er), 650c Zipp 404s that I got off a Tri-gal that I was preparing to build-up for my MTB Frankenbike. Fortunately, I didn't have to build them, as MTB tubular-specific rims became available.

You are not only looking at the width of the basetape, you need to be aware of the radius of the curvature for the basetape to maximize the contact surface for the glue.

njee20
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by njee20

Mmm, which was my thought. Thing is that there's no weight saving with all the other open mould rims (indeed Eliflap's are heavier than my LB clinchers) and I'm not prepared to spend AX Lightness money, so it seems a pretty pointless exercise. Shame.

Geoff
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by Geoff

Well, lighter weight is not really the best reason for running tubulars for MTB. For me, principal reason for tubulars is so that you can run lower tire pressures with a lower risk of either pinch flats, in the case of clinchers, or the risk of burping, if using tubeless. The concept is similar to the use of tubulars at lower pressures for 'cross.

mentok
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by mentok

Geoff, how often do you ding your tubular rims on the ground? I feel like that's going to be one of the big advantages for me - i'll be able to run lower pressures which on a tubeless clincher would have resulted in too many dings of rim on ground/rock. i don't think this will be as much of a problem with the tubular rims because the rims themselves don't have as tall a profile nor are they as fragile if they do happen to touch the ground meaning lower pressures are still safe.

i think i run the pressures that i do to prevent dinging rims on the ground, as much as a i do to prevent burping. I weigh about 2x"geoffs" though, so there's that...

Geoff
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by Geoff

That's easy: never!

Now, I will say that at least part of the reason is that I am not a 'DH-type' guy. Really, I run the MTB more as a fun, recreational tool to get a break from the road (or when there is too much ice and snow on the road). Accordingly, where there is a choice of descents, I'm not the guy pitching over the top of the rock garden...

njee20
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by njee20

So why bother with heavy and expensive tubs? Serious question. I run 20-25psi in tubeless, never wanted to run less, and never burped a tyre.

For me, unless there was a weight saving I'd not bother with tubs.

bm0p700f
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by bm0p700f

The light bicycle 320g tub rims should be delivered to me soon I am getting 28H drilling which I will lace to Miche 966 hubs build weight I expect to be 1370g and they should be very stiff.

I have also got the ambrosia tubular rims for 29er MTB's and they are 370g 32H drilling though but they do a 28H version.

So now I will have two 29er tubular wheelset with some Geax Saguro 29er tubs as I like them.

weeni
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by weeni

bm0p700f wrote:I have 26" setup currently for racing. XTR hubs on Geax rims and geax saguro tyres which quite frankly are brilliant. I run them at 30 psi and the grip is endless almost. The off camber grip is good too when going through ruts, roots e.t.c. The ride quality is superb also I no longer get blister forming on my hands in a race. The tyres are quite heavy though and are only 2.0" wide. I have not flatted them yet in 7 races. I carry Geax pitstop with me just in case.

If you did a 28 spoke DT Swiss 240 build with the straight pull hubs and chinese carbon rims it would be 1500g in weight but it would be very stiff. I have some lightweight (1350g) alloy clincher 26" wheels using DT Swiss 350 rims and they are abit on the flexible side.

A DT swiss build on chinese carbon rim or FRM carbon tubular rims if I could afford them would be my choice.



iplay now provide 27.5er carbon tubular rims 280g, 29er tubular rim 380g. very stiffness.

you can contact bella@xmiplay.cn
web: www.xmcarbonspeed.com
Email: bellajian@foxmail.com
Skype: bellajian1988

mentok
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by mentok

@bmp: how'd you go with those LB rims? were they these ones?
http://www.light-bicycle.com/tubular-mt ... DsojfmUdS0

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hjb1000
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by hjb1000

I just bought a pair of Remerx tubular rims to try. I'm still on 26 inch, and the rims weigh about 375g each, which isn't bad at all. The Ambrosio's I had before were a more porky 440g. I will see how they build up.

bm0p700f
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by bm0p700f

Well I have raced on them twice and rode on them a few more times and the rims are good. They are very stiff and because of that they have remained true. Given the mud that is about now I have to ditch the tubs for a tubeless set up (better tyre choice) but I will be back on them in the new year unless those geax suguaros actually turn up. Been waiting far too long.

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