[ck42]

Just got him a spanky new IBEX Alpine 320k. It's a 20" bike. He LOVES it. But, as usual, I'm already seeing that some sort of drivetrain upgrade is needed. Looks like the other components are decent considering the price of the bike.

Currently fitted with a 21 spd system (7 in rear - 3 up front) as follows:

Derailleurs - Shimano Acera
Shifters - Shimano RevoShift grip-twist shifters
7-speed rear cassette (unknown)
Cranks - Sunrace M50 crankset (152mm)

I figure that any *real* upgrade will have to be to an 8spd system which is perfectly fine (don't want to mess with 9spd for him tho)

I was thinking of something like a SRAM X-7 setup with an XT cassette (SRAM making decent cassettes lately?). Also not sure of a front derailleur for an upgrade.

Would definately like to hear suggestions/comments tho!

 

[ibexbikes]

IBEX Advice

The derailleurs on the IBEX Alpine 320K are 8-spd type, but the 7-spd arrangement was dictated by the shifters we chose. On our 24" Alpine 440K we use Shimano Alivio Rapidfire shifters. We've heard nothing but good things back on how quickly older kids on these have taken to the trigger shifting. However, we figured the younger ones, most likely on their first geared bike, were better off with twist shifters so the 20" model got Revo's. Nevertheless, if your young rider is far enough along, you might think about going to those Alivio Rapidfires on the 20" bike. For reasonably priced stuff they're OK. I don't know much about SRAM drivetrains, so I'll leave it to others better able to advise you on those.

Anyway, change the cassette to an 8-spd unit; install 8-spd shifters and you're good-to-go.... XT might be overkill, even if you can still find NOS 8-spd. You do not necessarily need to change derailleurs, chain or crankset. BTW, that Sunrace crankset is the best triple we could find with 152mm crankarms... and one of the only ones in that size with alloy arms! It may not be up there with the high-end 9-spd stuff, but it's pretty darn nice for a 20" bike. You're going to have a very tough time locating anything else as good with appropriate crankarm length.

If you want to upgrade the front derailleur you should probably look into NOS 8-spd XT from a few years ago. The highest level 8-spd F/D from Shimano's current line-up is Alivio... one step up from the Acera, but the difference is hardly worth noting. According to Shimano, 8-spd and 9-sp F/D's are not interchangeable... probably due to cage widths. If you use a 9-spd F/D with 7/8-spd chain you may have excessive rub.

You can use a 9-spd rear derailleur without any problem... the shifters dictate the shift gate and the stop limits are within range.

Now, not to be too overbearing, but here's an idea for you... buy one of our Alpine 440K's, move the shifters and derailleurs over to the 320K until he outgrows the 20" bike and then move them back to the 440K when he's ready to move up to the bigger bike. That way, you've got the better drivetrain of the 440K on his 320K, but you haven't wasted anything because the larger bike can be made ready to go again in one afternoon when he's outgrown the 320K!

Best regards,
Jack
IBEX Bicycles

 

[ck42]

Jack,

Thanks for the great feedback!

I neglected to state, after re-reading my original post, that the drivetrain problems are related to the front derailleur. I've gone thru and re-adjusted it (wasn't off by much anyway) but it just needs to work a little better, For the time being, I've put it on the middle ring and told him not to change it. No problems so far with the rear derailleur.

I only mentioned the rear der. bacause of the usual upgrade 'snowball' effect. ie, 8 spd system needs 8 spd chain, which requires 8 spd cassette, which requires....so on. and so on.

Anyway...I think that just installing an XT front der. would take care of things for now.

I agree with the decision you made regarding the twisters for the 20" bike though. Twisters are a little more intuitive for beginning riders. Even after he has another year or two of trail experience, I'll let HIM decide if he wants to try triggers. As a matter of fact, I'm getting ready to try triggers myself for the first time (started on twisters and liked them - but just curious about triggers).

I'm still amazed though at the *amount* of bike I got for the price! Normally, this sort of price range puts you into a bike with MANY components that don't even have brand names...the Al rims and cranks (and Kalloy components) seem to be a great choice for a low cost-good performance setup. I couldn't be happier with the bike (and neither could my son!) considering the price range it falls under! Great job on the 320K Jack!

...oh, and the front fork springs are loosening up a little (with my help ) but they're still way too stiff for him to even move them. I suspect I'll be needing a new blade for my hacksaw in the near future.