Tiagra vs ultegra crank arm weight

Discuss light weight issues concerning road bikes & parts.
Post Reply
fattywilliams
Posts: 27
Joined: Wed Apr 10, 2019 6:43 pm

by fattywilliams

Have tiagra crankset on my training bike it weighs 910g thought this could a place to save weight quite cheaply as it a trainer I'm not looking to spend much money atall seen that the ultegra cranksets are quite bit lighter almost 300g but keep seeing the arms themselves really cheap with no chainrings on ebay would I be able to put my 4700 rings on a 6800 crank arm and how much weight will I actaully save or is most the saving in the rings?

Sent from my VTR-L09 using Tapatalk


alcatraz
Posts: 1917
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

If you do upgrade get the original rings. Ultegra and Dura-ace use hollow chainrings.

As for losing weight maybe check for any 24mm crank. Maybe 2nd hand fsa sl-k or sram red gxp + adapter or maybe even the chinese ful carbon cranks that can be had very cheap.

Shimano cranks shift very well. Ultegra is a hard group to beat when it comes to overall performance.

If you are a true weightweenie at heart and like an upgrade project maybe start looking for old sram red 10s components. They are very light and being 10s you can get them a lot cheaper.

by Weenie


User avatar
silvalis
Posts: 603
Joined: Mon Sep 07, 2015 1:02 am
Location: Aus

by silvalis

197g for a 6800 left arm 170mm
148g for 50/34
~330g right arm + bolts

Tiagra 50/34 rings are about 250g

Punctuation would be nice.
Chasse patate

fattywilliams
Posts: 27
Joined: Wed Apr 10, 2019 6:43 pm

by fattywilliams

alcatraz wrote:If you do upgrade get the original rings. Ultegra and Dura-ace use hollow chainrings.

As for losing weight maybe check for any 24mm crank. Maybe 2nd hand fsa sl-k or sram red gxp + adapter or maybe even the chinese ful carbon cranks that can be had very cheap.

Shimano cranks shift very well. Ultegra is a hard group to beat when it comes to overall performance.

If you are a true weightweenie at heart and like an upgrade project maybe start looking for old sram red 10s components. They are very light and being 10s you can get them a lot cheaper.
I was thinking about this to be honest with you I am a fan of sram so I'm gunna keep eye on the deals I can pick up I don't really wanna change my bb to a gxp did you say there's a adapter to make it work with a shimano BB? Presumably some kind of shim? Is this not likely to encourage creaking

Sent from my VTR-L09 using Tapatalk


alcatraz
Posts: 1917
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Don't worry about wasting a bottom bracket. The standard ones are dirt cheap.

It's best not to convert gxp to shimano because gxp cranks don't have a preload mechanism so you will end up with a small amount of float on your chainrings. It will affect your shifting performance negatively.

I've managed to get it work very well with a conversion kit but it's not worth the hassle of saving 10-15usd or whatever a new bb costs.

It's my understanding that creaking doesn't occur between spindle and bearing but between bearing and frame.

fattywilliams
Posts: 27
Joined: Wed Apr 10, 2019 6:43 pm

by fattywilliams

alcatraz wrote:Don't worry about wasting a bottom bracket. The standard ones are dirt cheap.

It's best not to convert gxp to shimano because gxp cranks don't have a preload mechanism so you will end up with a small amount of float on your chainrings. It will affect your shifting performance negatively.

I've managed to get it work very well with a conversion kit but it's not worth the hassle of saving 10-15usd or whatever a new bb costs.

It's my understanding that creaking doesn't occur between spindle and bearing but between bearing and frame.
Appreciate what your saying but I have bought a decent 386 thread together bb for my shimano crankset so don't really wanna be binning that off already

Sent from my VTR-L09 using Tapatalk


TheKaiser
Posts: 619
Joined: Thu Sep 05, 2013 3:29 pm

by TheKaiser

fattywilliams wrote: ↑
Fri May 03, 2019 11:24 am
alcatraz wrote:Don't worry about wasting a bottom bracket. The standard ones are dirt cheap.

It's best not to convert gxp to shimano because gxp cranks don't have a preload mechanism so you will end up with a small amount of float on your chainrings. It will affect your shifting performance negatively.

I've managed to get it work very well with a conversion kit but it's not worth the hassle of saving 10-15usd or whatever a new bb costs.

It's my understanding that creaking doesn't occur between spindle and bearing but between bearing and frame.
Appreciate what your saying but I have bought a decent 386 thread together bb for my shimano crankset so don't really wanna be binning that off already

Sent from my VTR-L09 using Tapatalk
If you already have a nice BB that you're attached to (no pun intended) then the adaptors for Sram BBs usually consist of a top hat looking reducer that will fill the gap between the 22mm portion of the spindle and the 24mm Shimano bearing ID. As Alcatraz said, you don't have a good preload mechanism with that setup, so you need to shim and/or use a wavey washer to take up the space and prevent lateral play or over preloading the BB bearing. That often requires some experimentation. If your BB company has a good customer service department, perhaps check with them to see if they offer anything, or even if they can send you a smaller ID bearing to swap into the BB unit. Otherwise, try searching on here for "GXP crank in Shimano BB conversion" or something of that nature. It has been discussed quite a bit.

by Weenie


fattywilliams
Posts: 27
Joined: Wed Apr 10, 2019 6:43 pm

by fattywilliams

So I've manage to pick a up a 6750 crankset 172.5mm 50-34 haven't collected it yet anyone know a weight for it I search online and keep getting weight including the bottom bracket

Sent from my VTR-L09 using Tapatalk


Post Reply
  • Similar Topics
    Replies
    Views
    Last post