Thursday, March 25, 2010

Changing from triple to double chainring

Gear ratio table 1: An original setup of triple chainring

Gear ratio table 2: The new setup of double chainring
Prior migrating from triple chainring to double chainring (and lost 9 gear ratio) I did this table for comparison basis.  It turn out that (expectedly) some gear ratios are 'redundant'.  For example, 1 revolution of crank using 32/16 (front chainring over rear cog) will give same output as 22/11, i.e 2 revolution of wheel.  But again, the use 22/11 (smallest chainring to smallest cassette)  combo is not a good choice since it put an extreme sideways load to the chain.

The reasons I am switching from triple to double chainring were :-
1. less shifting for front derailleur
2. I need an extra 44t and 32t chainring to be fitted on idle crankarm for my touring bike.

In deciding on how many teeth I need for middle chainring (apparently become outer), I need to figure out what were those gear ratios I'll be 'losing' and whether that lost will be very much regretted or not.  In this case, in very rare occasion I used 44/11 and 44/12 combination.  This rare occasion was, downhilling tarmac from Genting Sempah back to Hospital Orang Asli in Gombak.  In some other occurrence, I was on shallow knobbie tires on night ride. flat terrain.  Since this setup intentionally for my ultimate MTB bike i.e. Kona, it will not be an issue.

My choice of 36t chainring was due to it is the best number of teeth for my riding style.  At 36/11 (3.27) , it caters top ratio of slightly over 44/14 combination (3.14).

The Installation
It was quite straight forward if you are familiar with installing and removing chainring for cleaning purposes.  However, I need to emphasize that you need a short stack bolt to tie the chainring to the crank arm.  Other things that matter: -
1. The need to readjust (read: lower) the FD's clamp on seatpost.  And it comes with PIA of FD tuning.
2. Protruding bottle cage's tab may obstruct FD's clamp.
3. FD's cage only can gets lower to the point it hits the chainstay.  This cause top of the cage may not have an ideal clearance on largest chainring.
4. Optionally, the chain may be shorten by 1 link to compensate chain slack.
5. And again, FD requires precise, perfect and painstaking adjustment to avoid chain derailed outward (it did happened to me). Alternately, fitting a bash guard may prevent this mishaps.

Tuesday, March 16, 2010

Of the long silence

My P1 broadband was pathetic.  Uploading a resized photo to picasaweb took ages, if it ever made it in a very rare occasion.  So here's my consolidated updates: -

Of new newbie

I bought 13" Proton T-Blaze from BBS for my son who seems hardly earn much height to ride my 16" Scott.  I took him for a ride once at Kepong Metro Park, then FRIM, and lastly a trip to my parent's house, some 15km away from our house.

Of upgrading Proton T-Blaze

Stock 6 speed rear upgraded to 9 speed SRAM X4 gripshift.  V-brake wheelset swapped for a better one from Scott while crankset replaced with Truvativ FiveD.  There you are.. a much better setup for my beloved son.

Of newbie at Kepong Metro Park

He did 3 rounds before I took him for climbing and descending lesson at his chewable size. All seems good and ready for a trail trip in FRIM.

From Newbie skill class

From Newbie skill class

Of newbie at FRIM
On trail, shifting seems a bit harder for him to digest.  Wrong gearing seems his common mistake however he managed to make it to Steroid junction.  I bumped into Pak Adib, Maher (Pak Adib's son), Sufino, and BC Kelolo.  Somehow FRIM was a bit too much for him, for now.

Of newbie on my memory lane
I cycled to my parent's house a number of time, alone.  This time around, I took my newbie along on nice Saturday afternoon.  Even within low vehicular traffic can be challenging for a 10 years old.  I was tailgating and gave instruction from time to time to ensure his safety.  I chose backyard route whenever possible and push the bikes on those 2 to 3 lanes crossings.

Of being beaten by a girl
I was beaten by Azealea.  She did pretty well on recent KLMBH hash at Sungai Buaya, Rawang.  I'm currently motivated on getting back to my fitness level.

Of diarrhea and low blood pressure
I had mild diarrhea and upon checked up by GP, my blood pressure measured at 90/60.  As a result, the GP asked me to keep my exercise not more than 120bpm heart rate.  Kinna devastating shall I keep 120bpm on my cycling workout since at my peak reached 180bpm.  I decided to give it a try quit smoking (again? I lost count of my fail attempts).  A few days later I recovered and did a check on my parent's home BP set, it was on healthy 118/75.  Nice!

Father undergo coronary artery bypass
On 6th March, my beloved father admitted to Hospital Serdang for Coronary Artery Bypass Surgery (CABG).  The surgery on 9th March went well and he's recovering progressively.  Alhamdulillah.
In 1 occasion when I was bathing him, memories as per mother iteration on how much he loves us.  Abah went to the extend sucking our running nose when we didn't know how to blow it our own.  He would just use him decent shoes while we had shoes of twice the cost for raya.  He's the one who put family on top of his personal priority.  I love you Abah.