Budget Hardtail XC Build USD$1000 - 100% COMPLETED

Discuss light weight issues concerning mountain bikes & parts.

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Erwandy
Posts: 44
Joined: Mon Jul 27, 2015 2:14 pm

by Erwandy

ooo wrote:
Mon Jan 15, 2018 2:43 am
Safer approach is to build heavy bike and work with parts 1 by 1 with test riding between changes - but this is very slow
Your approach is reverse, much faster, probably make sense to wear extra protection for testing period.
If we forget about safety, other downside is that some problems can have a consequences (other problems) and it may be hard to figure out what happened first

I have some concerns was about shifting quality - ultegra shifts slow on mtb cassette, i would not go more than 11-32
and while your bike have testing period, may be you don't need high top speed? you can use 32x11-32 or lower combo

about modification - I am worried about stem. it may be ok for road use with suspension for, but not for offroad use,
in some places suspension fork and air in wheel will be not enough to save it from failing...
Yes you are right on the shifting speed. I did noticed that on that mega range ratio the shifting was not as fast as how it should be. This actually sparked a thought on me to switch to 2X11 11-30 setup instead. I race marathon XC mostly and having 2X11 may work better for me.

As for the gearing ratio, I did the maths based on Sheldon Brown calculator and based on repeated tests on several chainring size and cogs, combined with the factor of crankarm length that I use, here's how it looked like:
Image

* at the top end, with 165mm cranks I have found that I can pedal to racing speed with 32t chainring and 11t cogs. If Strava were to be trusted my personal record was a sustained 35kph average speed over 46kmh of non stop endurance ride on tarmac with MTB - and that done within 1.30 hour. I have developed my riding style to spin more and grind less - so I will suck big time at sprints but the type of races I participated does not depend on bursts of speed. What worries me the most is my climbing ratio. At full strength I can still pedal uphill on steep terrain with 1.6 or even 1.7 ratio. But on long and tiring race, having a 1.5, 1.4 or even 1.3 will help a lot to minimize fatigue

ooo
Posts: 444
Joined: Sat May 21, 2016 12:59 pm

by ooo

with wider 11-32 you can use front derailleur less time - this is real benefit for mtb (and whole reason why 1x is popular)
'

by Weenie


bm0p700f
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by bm0p700f

oops WWism goes bad. Bad luck, good luck it was not serious. So you are just going to have to live with a heavier bike or a maybe a Shimano XT 11-50T cassette. A smaller cassette will be kinder to the RD anyway.

Erwandy
Posts: 44
Joined: Mon Jul 27, 2015 2:14 pm

by Erwandy

bm0p700f wrote:
Wed Jan 17, 2018 7:54 pm
oops WWism goes bad. Bad luck, good luck it was not serious. So you are just going to have to live with a heavier bike or a maybe a Shimano XT 11-50T cassette. A smaller cassette will be kinder to the RD anyway.
Well shit happens :mrgreen:

Yes I have reassessed things up and I will sacrifice adding another 300-400g to attain reliability and comfort with a 2X11 setup instead. Having verly light bike is nice but I need enduring reliability as well. Need to makes sure that I am pedaling to the finish line instead of psuhing my bike hahaha

ooo
Posts: 444
Joined: Sat May 21, 2016 12:59 pm

by ooo

gear calc link - 36-22x11-32 vs 32x11-50 - (on 26"x2.25") single range is 7.2 to 33 km/h, double range is 7.8 to 37 km/h (or same 33 km/h for 32-22x11-32)
'

andrew9
Posts: 39
Joined: Wed Nov 05, 2014 1:01 am
Location: South Australia

by andrew9

Thanks for sharing this awesome build, really enjoying it.
I'm surprised the cassette failed, it must be thinner than it appears in the photos. When you compare it to those SRAM cassettes that are very minimal, but still designed for abuse by heavy riders, I would have thought you would have been fine with your modifications.
I expected the brake lever clamps to fail first, but I do hope that doesn't happen. That hole cut in the stem is also a worry.

I was amused by the person that criticized you for modifying any parts, they must find it annoying having to always pay manufactures a premium to make light parts for them

Erwandy
Posts: 44
Joined: Mon Jul 27, 2015 2:14 pm

by Erwandy

andrew9 wrote:
Thu Jan 18, 2018 6:55 am
Thanks for sharing this awesome build, really enjoying it.
I'm surprised the cassette failed, it must be thinner than it appears in the photos. When you compare it to those SRAM cassettes that are very minimal, but still designed for abuse by heavy riders, I would have thought you would have been fine with your modifications.
I expected the brake lever clamps to fail first, but I do hope that doesn't happen. That hole cut in the stem is also a worry.

I was amused by the person that criticized you for modifying any parts, they must find it annoying having to always pay manufactures a premium to make light parts for them
Well truth be told, I was nervous with the cassette. In person you would see how thin they are. That will be the last of anything resembling that mod that I will do. The biggest mistake was fooling with the rivets - changing them to aluminum was BAD idea lol.

The brake levers are holding good for now.

Erwandy
Posts: 44
Joined: Mon Jul 27, 2015 2:14 pm

by Erwandy

ooo wrote:
Thu Jan 18, 2018 12:59 am
gear calc link - 36-22x11-32 vs 32x11-50 - (on 26"x2.25") single range is 7.2 to 33 km/h, double range is 7.8 to 37 km/h (or same 33 km/h for 32-22x11-32)
Thanks man. Appreciate the calc.

DurianGrey
Posts: 31
Joined: Tue Jun 13, 2017 9:57 pm

by DurianGrey

While I personally wouldn't have the confidence to ride that thing anywhere near as hard as I'd need to to win a race, kudos for reporting the failure and good luck with it.

Does the radiator repairman's time or any of the tools used (I'm guessing you do your own painting) factor in to the cost?

Erwandy
Posts: 44
Joined: Mon Jul 27, 2015 2:14 pm

by Erwandy

DurianGrey wrote:
Thu Jan 18, 2018 4:54 pm
While I personally wouldn't have the confidence to ride that thing anywhere near as hard as I'd need to to win a race, kudos for reporting the failure and good luck with it.

Does the radiator repairman's time or any of the tools used (I'm guessing you do your own painting) factor in to the cost?
Thanks.

I already own the tools since I am a gadget addict as well. The cost for aluminum weld is around $18 is so far

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dgasmd
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Joined: Sun Apr 15, 2007 5:10 am
Location: South Florida

by dgasmd

This is one of the most "baller" threads in a while in this site. You hardly see true weight weenie spirit here anymore. Kudos.

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hjb1000
Posts: 257
Joined: Wed Sep 16, 2009 10:25 am
Location: Australia

by hjb1000

Yes this is a great thread and enjoy the old school WW spirit! Keep it up

mrirocz
Posts: 5
Joined: Thu Feb 08, 2018 1:48 am

by mrirocz

wow...this has to be one of the best threads I have read in a while! You are awesome SIR!

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