Chain Adjustment and Ride Height

[Champ87]

For those not already aware - one characteristic of using an eccentric for chain adjustment is that it will change ride height as the eccentric is rotated. Using my Sprint ST as an example I've attached a GIF file to illustrate this effect. In normal chain adjustment the difference is minor but it could have more effect when changing sprockets without corresponding chain length adjustment. That's not to suggest it's a problem - just be aware that there may be 2 positions that will achieve a given amount of chain slack



This characteristic can be useful. For the Sprint ST (non-ABS versions) rotating the eccentric 180° was quick trick to lower seat height. Of course, the front then needs to be adjusted by sliding the fork tubes through the clamps. Apart from lowering seat height and reducing ground clearance, this change also affected side stand and center stand slightly. This did not apply to my own Sprint ST ABS. On ABS versions rotating the eccentric too far would cause the rear wheel speed sensor to contact the swingarm preventing full 360° rotation.

I'd be interested to hear if it's possible to rotate the SX eccentric a full 360° or even 180°. The SX seat height is just fine for me but, if it's possible, it might be a trick for shorter riders and certainly something we should all be aware of to avoid accidentally changing rear ride height.

[Champ87]

As a follow up I did a little bit of checking on my own bike. The eccentric cannot be rotated the full 360°. There is about 180° of rotation available before something prevents further movement. As the eccentric is rotated the ride height changes by about 16 millimetres (that's 5/8" for the 5% of the human race that doesn't get metric).

I mentioned that flipping the eccentric around was a trick shorter riders could use to lower ride height and seat height on certain single-sided swingarm bikes. Not an option on the H2 SX. I had no need to do that anyway but I like to mess with these things to help understand my bike a bit better.

[Drnick]

Excellent point! Of course you'll need to buy the spanner! THAT DOESN'T come with bike

[Champ87]

Excellent point! Of course you'll need to buy the spanner! THAT DOESN'T come with bike

Yes, toolkit looks like they threw a few pieces under the seat as the bike left the factory. Still, even if they gave you a gold plated adjustment spanner it wouldn't be enough - you'd still need a 10mm hex socket and ratchet to loosen the bolts. Oh, and a torque wrench to tighten it all up.

I'm not too bothered about it: even though my Triumph Sprint tool kit included an adjustment spanner I still used the CNC machined billet aluminum spanner in the pic. Sure, it doesn't adjust any better but it just feels nice to use quality tools.