Tag Archives: chain conversion

Daytona 675 track gearing & 520 chain conversion

520-rear-49The 520 chain conversion on my Daytona 675 came about because I wanted to change the bike’s gearing to get faster drive out of corners. Although this isn’t necessarily that important on the road it is pretty useful on the track.

While the sprocket changes would produce the gearing change I desired, switching to a 520 chain (from the standard 525 chain) at the same time would also allow for bigger choice of sprockets, and lighter ones too. Less weight in the rear sprocket and chain means less rotational mass which helps make direction changes a little easier and faster.

The standard chain and sprocket setup on the Triumph Daytona 675 (for 2006-2012 models) is a 116 link 525 chain with a 16 tooth front/gearbox sprocket and a 47 tooth rear sprocket. Most people who want the same improved drive recommend going down 1 tooth on the front and up 2 on the rear, so that you end up with a 15 tooth front and 49 tooth rear.

The table below gives you an indication of the gearing changes you can achieve by changing either the front or rear sprocket or both together.

Front Rear Ratio Torque Speed
15T 47T 3.13 +6.3% -6.3%
15T 48T 3.20 +8.2% -8.2%
15T 49T 3.27 +10.1% -10.1%
15T 50T 3.33 +11.9% -11.9%
15T 51T 3.40 +13.6% -13.6%
16T 45T 2.81 -4.4% +4.4%
16T 46T 2.88 -2.2% +2.2%
16T 47T 2.94
16T 48T 3.00 +2.1% -2.1%
16T 49T 3.06 +4.1% -4.1%

The baseline (standard) gearing for the Daytona 675 is 16/47. In gearing changes, the tradeoff is between torque and speed. In 3rd gear at 12750RPM the Daytona on standard gearing will reach 110mph (178kph), while at the same RPM it can (in theory) reach 152mph (245kph) in top or sixth gear. Using a 15/49 gearing, top speed in 3rd is reduced to 100mph (160kph) and 137mph (220kph) in sixth gear.

front-sprocketI decided to go with a pair of Renthal sprockets; a lightweight 15 tooth steel sprocket for the front and a light but hardened 49 tooth anodised gold alloy sprocket for the rear.

rear-sprocketAlthough worried about using an alloy rear sprocket I was assured that the rear will last as long as the chain and front.

There are various chains available on the market, but motorcycle mechanics that I’ve spoken with rate the DID chains over Tsubaki and others. A product description for the DID VX-GB chain that I ended up chosing describes it as follows:

VX-GB Series Chains have superior strength to withstand the tremendous horsepower of current high performance motorcycles. A patented low friction X-Ring is used for maximum performance. D.I.D VX-GB X-Ring chains feature gold side plates and reduces friction by twisting between the side plates instead of being squashed. Normal O-Rings and other makers’ modified O-Rings have squashed points that increase friction. The twisting resilience of the X-Ring’s four sections greatly increases its sealing performance. This keeps the dirt out and the lubrication in much better than any other O-Ring. X-Rings have the greatest wear resistance of any other type of O-Ring or Non-O-Ring chain

When ordering the chain, the sales rep was surprised that I didn’t select the race version of the chain, the DID Road Race X Ring Gold Drive Chain as he thought this would be more appropriate for a track bike. Since the race chain cost over twice the amount of the VX-GB chain, I figured that I would just have to replace the chain a little more frequently if necessary. I’ve no doubts about the DID VX-GB being plenty tough enough for the Daytona 675 – in fact I read that the 520 chain has a higher tensile strength than the 525 chain!

The standard 525 chain length is 116 links. Because the new rear sprocket is larger then the original one I knew I would need a longer chain in order to be able to keep the rear wheel spindle in the same place as before – you want to do this to avoid changing the bike geometry. I wasn’t sure how long a chain to buy and ended up settling on a 120 link chain. This was slightly too long and I ended having to remove at least one link (and possibly two, I can’t remember now) using an angle grinder.

chain-linkOne of the annoying things about the 520 DID VX-GB chain is that a split link is provided to join the chain instead of a rivet link (like the one shown here). I only found this out after I went to join the new chain which resulted in a trip down to the nearest dealer to buy the rivet link. I don’t think using a split link on a high performance road or track bike is a particularly good idea.

Here are the parts for the whole conversion:

Part Description Cost
385U-520-15 Renthal 520 15T lightweight front sprocket £14 (US$22)
456U-520-49HA Renthal 520 49T alloy rear sprocket £30 (US$48)
520VXGB-120 DID 120 link Gold/Black chain £92 (US$147)
? DID 520 rivet link £10 (US$16)

After fitting the new chain and sprockets I test rode the bike on the street and to be honest I couldn’t really notice a massive difference between the old and new gearing. However, the first time I tried the new gearing on track I immediately noticed two things. Firstly the bike’s acceleration out of corners was much (10%) better than before. In fact a couple of riders at a Cartagena (short and twisty) track day remarked that they struggled to keep up with my Daytona as it out accelerated them from the same starting speed on corner exits. The second significant difference was that in (hairpin) corners where I would normally have to use second gear, I could now get away with third. In fact in four days at Cartagena this year, I only used second gear once on track and that was by mistake!

On short and twisty tracks, the -1/+2 gearing change is well worth doing. For faster circuits, it may be worth trying a lesser change in order not to compromise your top speed on the straights so much. In fact I might consider buying another 16T front sprocket to use on track days at faster circuits. Why a front? Because changing the front sprocket is generally quicker than changing the rear one.

One by-product of the gearing change is that my speedo now over-reads by 10%. Since this is going to cause the bike’s odometer to overestimate the bike’s mileage, I’m going to fix this by changing the gearing parameter in the bike’s ECU. I’ve documented this in my post on using TuneECU to recalibrate the speedo.